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number 19 december 1993
EDITORIAL STAFF
Richard A. Lancia, Editor
Suzanne A. Fischer, Assistant Editor Eloise F. Potter, Production Manager
EDITORIAL BOARD
James W. Hardin
Professor of Botany
North Carolina State University
Rowland M. Shelley Curator of Invertebrates North Carolina State Museum of Natural Sciences
William M. Palmer
Director of Research and Collections
North Carolina State Museum
of Natural Sciences
Robert G. Wolk Director of Programs North Carolina State Museum of Natural Sciences
Brimleyana, the Zoological Journal of the North Carolina State Museum of Natural Sciences, appears twice yearly in consecutively numbered issues. Subject matter focuses on systematics, evolution, zoogeography, ecology, behavior, and paleozoology in the southeastern United States. Papers stress the results of original empirical field studies, but synthesizing reviews and papers of significant historical interest to southeastern zoology are also included. Brief communications are accepted.
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James B. Hunt Jr., Governor Jonathan B. Howes, Secretary
CODN BRIMD 7 ISSN 0193-4406
Revision of the Milliped Genus Scytonotus Koch (Polydesmida: Polydesmidae)
Rowland M. Shelley
North Carolina State Museum of Natural Sciences P.O. Box 29555, Raleigh North Carolina 27626-0555
ABSTRACT — The milliped genus Scytonotus occurs in four regions of North America, one east of the Central Plains, and three west of the Continental Divide: from northern Utah to northeastern Idaho and northwestern Wyoming; from southeastern Washington and western Montana to southeastern British Columbia; and along the Pacific Coast from San Francisco Bay and the northern San Joaquin Valley to the northern extremity of the Alaskan panhandle, including all offshore islands except the Queen Charlotte Islands. Three of the nine component species occur in the East — S. granulatus (Say), broadly distributed across most of the area, and S. virginicus (Loomis) and S. australis Hoffman, both endemic to the Blue Ridge province. Six occur in the West — S. insulanus Attems and S. bergrothi and simplex, both by Chamberlin, inhabiting the Pacific Coastal region; S. inornatus new species, in the eastern Cascade foothills of southern Oregon; S. columbianus Chamberlin, in the interior of British Columbia and northeastern Washington; and S. piger Chamberlin, south of the International Border from Idaho to Utah. Polydesmus amandus Chamberlin and S. orthodox Chamberlin are placed in synonymy under S. piger, and S. michauxi Hoffman is reduced to a subspecies of S. virginicus. Taxonomic characters primarily involve the configurations of the medial, distal, and lateral laminae of the gonopodal endomerite and its length relative to the tibiotarsus. Except for S. columbianus, virginicus, and australis, the paranota of segments 5-9 of adult females are vestigial or absent, and the tibiae of legs 13-20/22 in males possess distal lobes on the anterior and/or caudal margins; the arrangements and sizes of the latter vary among the species and may hold taxonomic utility. Three lineages or species groups are recognized: the granulatus group, comprised of five species with teeth on the inner margin of the distal lamina; the bergrothi group, composed of three species in which the distal lamina is prolonged; and the monobasic inornatus group, in which the structure is unmodified. Relationships among the lineages are hypothesized as inornatus + ( bergrothi + granulatus ). Anatomical and distributional evidence point to the Cascade Mountains of southern Oregon as the primary source area, and a secondary center of evolution exists in the Blue Ridge Mountains of North Carolina and Virginia. Pertinent anatomical illustrations and dis- tribution maps are presented along with complete synonymies, diagnoses, and a key to species.
Brimleyana 19:1-60, December 1993
1
2
Rowland M. Shelley
Millipeds of the genus Scytonotus are common inhabitants of forests in eastern and western North America. The small, pink, tu- berculate polydesmids are often encountered on the undersurfaces of wet bark, twigs, and pieces of wood, sometimes in or very close to standing water, and are more prevalent in cooler seasons of the year. Scytonotus is one of four disjunct diplopod genera with representatives on both sides of the continent, the other being Ergodesmus (Polydesmida: Nearctodesmidae), Orinisobates (Julida: Nemasomatidae), and Brachycybe (Platydesmida: Andrognathidae) (Hoffman 1962a, 1975; Gardner 1975; Enghoff 1985). Scytonotus occurs in four separate areas (Fig. 1): 1) the eastern United States and southern Ontario and Quebec, Canada, east of the Central Plains; 2) the Wasatch and Teton mountains, and associated ranges, of northern Utah, eastern Idaho, and western Wyoming; 3) the Rocky and Selkirk mountains, and associated ranges, of northern Idaho, western Montana, eastern Washington, and southeastern British
Fig. 1. Distribution of Scytonotus. A smooth line has been drawn around range extremes in all directions in each of the four areas.
Genus Scytonotus
3
Columbia; and 4) along the Pacific Coast extending inland to the eastern slope of the Cascade Mountains from San Francisco Bay and the northern San Joaquin Valley, California, to Yakutat Bay, Alaska, including all major offshore islands in British Colum- bia and Alaska except the Queen Charlotte Archipelago. The eastern fauna was reviewed by Hoffman (1962 b), who recognized four spe- cies. One species was widespread throughout the region, S. granulatus (Say), and three were localized endemics in the southern Blue Ridge Province: S. australis and michauxi, both authored by Hoffman, and S. virginicus (Loomis). Material secured since that study shows that S. virginicus and michauxi are geographic races of a single species. As the former is the older name, michauxi is reduced to subspe- cific status. Consequently, there are only two endemic species in the Blue Ridge, S. virginicus and australis. Hoffman (19626, 1979) indicated that about seven poorly known species occur in the Rocky Mountains and the Pacific Northwest of the United States and Canada, as listed by Chamberlin and Hoffman (1958), but that in- adequate material precluded revision of the western fauna. With the collection of numerous samples of Scytonotus from the western United States and Canada in the past 30 years, a clarification of this fauna is now possible, and important new records are also available for the eastern congeners. This contribution therefore completes the study of Scytonotus and recognizes nine species, three in the east and six in the west. Acronyms of sources of preserved study mate- rial are as follows:
AMNH — American Museum of Natural History, New York, New York ANSP — Academy of Natural Sciences, Philadelphia, Pennsylvania BMNH — British Museum (Natural History), London, England BYU — Monte L. Bean Life Science Museum, Brigham Young University, Provo, Utah
CADFA — California Department of Food and Agriculture, Sacramento CAS — California Academy of Sciences, San Francisco CIS — California Insect Survey, University of California at Berkeley CMN — Canadian Museum of Nature, Ottawa, Ontario CNC — Centre for Land and Biological Resources Research, Agriculture Canada, Ottawa, Ontario DC — Natural Science Division, Dixie College, St. George, Utah EIL — Zoology Department, Eastern Illinois University, Charleston FMNH — Field Museum of Natural History, Chicago, Illinois FSCA — Florida State Collection of Arthropods, Gainesville GLFRS — Great Lakes Forestry Research Station, Sault Ste. Marie, Ontario, Canada
4
Rowland M. Shelley
ILNHS — Illinois Natural History Survey, Champaign ILSU — Department of Biological Sciences, Illinois State University, Normal
MCZ — Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts
MNHP — Museum National d’Histoire Naturelle, Paris, France NCSM — North Carolina State Museum of Natural Sciences,
Raleigh
NMNH — National Museum of Natural History, Smithsonian Institution, Washington, DC NMV — Naturhistorisches Museum, Vienna, Austria OHS — Ohio Historical Society, Columbus
PSU — Frost Entomological Museum, Pennsylvania State University, University Park
RBCM — Royal British Columbia Museum, Victoria RNP — Redwood National Park, Orick, California ROM — Royal Ontario Museum, Toronto
SDMNH — San Diego Museum of Natural History, San Diego, California
TMM — Texas Memorial Museum, University of Texas, Austin UA — Entomology Department University of Alberta, Edmonton UBC — Zoology Department, University of British Columbia, Vancouver
UCD — Bohart Entomological Museum, University of California at Davis UID — Department of Plant, Soil, and Entomological Sciences, University of Idaho, Moscow
UMMZ — University of Michigan Museum of Zoology, Ann Arbor UMN — Entomology Department, University of Minnesota, St. Paul USU — Biology Department, Utah State University, Logan UVT — Zoology Department, University of Vermont, Burlington UWBM — Thomas Burke Memorial Washington State Museum, University of Washington, Seattle VMNH — Virginia Museum of Natural History, Martinsville WAS — Private Collection of William A. Shear, Hampden- Sydney, Virginia
WSU — James Entomological Museum, Washington State University, Pullman
ZMH — Zoologishes Museum, Hamburg, Germany
LITERATURE REVIEW
The history of Scytonotus begins with the description of Polydesmus granulatus by Say (1821) for a form from Pennsylva- nia, one of the first dozen millipeds named from the North Ameri-
Genus Scytonotus
5
can continent. Gervais (1847) recognized the original combination a,s did Wood (1865), Bollman (1893), and Kenyon (1893a). Koch (1847) erected Scytonotus for three new species, all now synonyms of S. granulatus : S. scabricollis, from an unspecified locality in North America, and S. laevicollis and nodulosus, both from Penn- sylvania; Koch (1863) repeated these accounts. Sager (1856) pro- posed Stenonia hispida for an individual from Ann Arbor, Michigan, and Wood (1865) erected Polydesmus setiger for another specimen from Pennsylvania. Both names are additional synonyms of S. granulatus as is S. cavernarum , proposed by Bollman (1887) for a form from Indiana. Cook and Cook (1894) synthesized the earlier efforts and excluded five species that had been assigned to Scytonotus from Venezuela, New Zealand, Mexico, and the tropics. Under S. granulatus or a synonym, this common, eastern milliped has been recorded numerous times, and I have endeavored to list all refer- ences beside the appropriate names in the synonymy.
The second eastern species, S. virginicus (Loomis), type spe- cies of the genus Lasiolathus (Loomis 1943), was proposed for an immature specimen from Thornton Gap, Page/Rappahannock coun- ties, Virginia. Hoffman (1947) synonymized the name with S. granulatus before collecting an adult male topotype and realizing (Hoffman 1950a) that S. virginicus is a distinct species. In his latter work, he gave the range as being the Blue Ridge Province south to Linville Falls, North Carolina. Chamberlin and Hoffman (1958) included S. virginicus in their checklist. Hoffman (19626) altered the range by stating that it was unknown south of the Roanoke River and proposed the final two eastern species, S. australis and michauxi, from north Georgia and western North Carolina/eastern Tennessee, respectively.
Scytonotus was first recorded from western North America by Cook (1904), 83 years after Say (1821) described P. granulatus from the east. He reported juveniles and females of an unidentified species from Yakutat Bay, Sitka, and Juneau, Alaska, and illustrated a male from an unknown locality that he recognized as a new species. Unfortunately, Cook misplaced the specimen, so Chamberlin (1911) is credited with the authorship of S. bergrothi based on specimens from Bremerton, Kitsap County, Washington. Chamberlin (1910) described S. piger and the synonym, Polydesmus amandus , from Mill Creek Canyon, Salt Lake County, Utah, and 10 years later (Chamberlin 1920) added S. columbianus from the “Columbia Valley,” British Columbia, Canada. The precise locality is unknown, but he was probably referring to the valley of the Columbia River, which arises in this Canadian province. Chamberlin (1925) proposed
6
Rowland M. Shelley
S. orthodox , another synonym of S. piger, for specimens from Logan Canyon, Cache County, Utah. Attems (1931) described S. pallidus, a synonym of S. bergrothi, from Mukilteo, Snohomish County, Wash- ington, and S. insulanus from Nanaimo, Vancouver Island, British Columbia. Chamberlin (1941) described S. simplex from Days Creek, Douglas County, Oregon.
The remaining papers covering western forms of Scytonotus either provided new records or summarized existing ones. Attems (1940) reviewed all the congeners, from both the east and west, transferring amandus into Archipolydesmus . Chamberlin (1943) trans- ferred amandus into Scytonotus and recorded it from Georgetown, Bear Lake County, Idaho, the first record of the genus from this state. Causey (1954a, b) recorded S. amandus from Teton County, Wyoming; S. pallidus from Seattle, Washington; and female and immature specimens, identified only as Scytonotus sp., from five additional counties, one in eastern Washington. Chamberlin and Hoff- man (1958) summarized all the species in their Nearctic checklist, placing S. palidus in synonymy under S. bergrothi. Hoffman (1962b) estimated that about seven species occurred from northern California and Utah to British Columbia and Alaska; he (Hoffman 1979) re- peated this estimate and characterized the western range as the Rocky Mountains and west coast states. Loomis and Schmitt (1971) re- corded Scytonotus from Montana, citing S. amandus from Lincoln and Mineral counties. Kevan (1983) listed all the species that were known from, or probable for, Canada, both in the east and west, and Shelley (1990) summarized the generic range in British Colum- bia and Alaska, giving the type localities of species in the former and misspelling insulanus and insulans.
Thus at this writing, Scytonotus consists of the following spe- cies, listed chronologically below with their type localities and other reported occurrences:
S. granulatus (Say 1821). Vicinity of Philadelphia, Pennsylvania. Also recorded from Canada in general (Wood (1865), Ontario (Causey 1952, Hoffman 1962b, Judd 1967, Kevan 1983, Shelley 1988), and the following states: New York (Cook and Cook 1894, Bailey 1928, Chamberlin and Hoffman 1958, Hoffman 1962b, Kevan 1983), Penn- sylvania (Gervais 1847; Koch 1847, 1863; Wood 1865; Cook and Cook 1894; Dearolf 1938; Loomis 1939; Attems 1940; Chamberlin 1947, Chamberlin and Hoffman 1958; Hoffman 1962b; Kevan 1983), Maryland (Hoffman 1962b), District of Columbia (Cook and Cook 1894), West Virginia (Hoffman 1962b), Virginia (Cook and Cook 1894; Hoffman 1947, 1950a, 1962b), North Carolina (Brimley 1938; Chamberlin 1940; Hoffman 1950b, 1962b; Chamberlin and Hoffman
Genus Scytonotus
7
1958; Wray 1967; Shelley 1978; Filka and Shelley 1980), Michigan (Sager 1856, Wood 1865, Bollman 18886, Cook and Cook 1894, Johnson 1954, Hoffman 19626, Kevan 1983), Ohio (Morse 1902, Williams and Hefner 1928, Kevan 1983), Indiana (Bollman 1887, 1888a, 1893; McNeill 1888; Cook and Cook 1894; Attems 1940; Chamberlin 1952; Chamberlin and Hoffman 1958; Hoffman 19626), Kentucky (Causey 1955, Loomis 1944, Hoffman 19626), Tennessee (Bollman 18886, Hoffman 19626), Illinois (Rapp 1946, Chamberlin 1952, Hoffman 19626), Minnesota (Bollman 1893, Hoffman 19626, Kevan 1983), Iowa (Chamberlin 1942, Chamberlin and Hoffman 1958, Hoffman 19626), Missouri (Chamberlin 1928, Chamberlin and Hoff- man 1958, Hoffman 19626), Nebraska (Kenyon 1893a, 6), and Kansas (Gunthrop 1913).
S. piger Chamberlin 1910. Mill Creek Canyon, Salt Lake County, Utah. Also recorded from the Wasatch Mountains, Utah (Chamberlin and Hoffman 1958).
S. amandus (Chamberlin 1910). Mill Creek Canyon, Salt Lake County, Utah. Also recorded from Georgetown, Bear Lake County, Idaho (Chamberlin 1943), Teton County, Wyoming (Causey 1954a), the Wasatch Mountains of Utah (Chamberlin and Hoffman 1958), and Lincoln and Mineral counties, Montana (Loomis and Schmitt 1971).
S. bergrothi Chamberlin 1911. Bremerton, Kitsap County Washington. Also recorded from Port Ludlow, Jefferson County; Ta- coma, Pierce County; Mukilteo, Snohomish County; and Port Blakeley, Kitsap County, Washington (Attems 1931, Chamberlin and Hoffman 1958), and Seattle, King County, Washington (Causey 19546).
S. columbianus Chamberlin 1920. “Columbia Valley,” British Columbia, Canada, probably the valley formed by the Columbia River; also recorded from this site by Chamberlin and Hoffman (1958) and Shelley (1990).
S. orthodox Chamberlin 1925. Logan Canyon, Cache County, Utah. Also recorded from Coeur d’Alene, Kootenai County, Idaho, and the Bear Lake region of Idaho and Utah (Chamberlin and Hoff- man 1958).
S. insulanus Attems 1931. Nanaimo, Vancouver Island, British Columbia, Canada. Also recorded from Juneau, Alaska (Chamberlin and Hoffman 1958).
S. simplex Chamberlin 1941. Day’s Creek, Douglas County, Oregon.
S. virginicus (Loomis 1943). Thornton Gap, Page/Rappahannock counties, Virginia. Also reported from Sugar Hollow, Albemarle County, and Humpback Mountain, Nelson County, Virginia (Hoff-
8
Rowland M. Shelley
man 1950 a, 1962 6), and Peaks of Otter, Bedford County, Virginia (Hoffman 19626).
S. australis Hoffman 19626; 6 mi (9.6 km) W Amicalola Falls, Dawson County, Georgia. Also known from White County, Georgia (Hoffman 19626).
S. michauxi Hoffman 19626. Roan Mountain, Carver County, Tennessee. Also known from two other sites in Carter County and sites in Ashe, Avery, Buncombe-Transylvania, Macon, Mitchell, and Yancey counties, North Carolina (Hoffman 19626).
TAXONOMIC CHARACTERS
The taxonomically important features of Scytonotus chiefly involve aspects of the male gonopods, but as noted by Cook and Cook (1894), certain nonsexual features provide clues to a form’s identity and, in a few cases when combined with geography, a reliable determination. The genus is distinguished by two branches to the gonopod telopodite, the dentate paranota, and the flattened to lowly rounded, setiferous, dorsal tubercles that occur in relatively linear transverse rows. Species of Scytonotus are pink in color as is Bidentogon, a sympatric polydesmid genus occurring around San Francisco Bay (Shear 1972); it and trichopolydesmids also exhibit setose, tuberculate dorsums and can thus be confused with Scytonotus. However, their setae are stiffer and more noticeably clavate, and their tubercles are higher, more subconical, and more strongly el- evated above the dorsum and delineated from each other. Conse- quently, they differ from Scytonotus , which has a softer, “fuzzier” appearance, and adult trichopolydesmids, pallid in color, are also much smaller and narrower in proportion to their lengths. Though not sympatric with Scytonotus, Harpagonopus , occurring along the Pacific Coast of southern California and northern Baja California Norte, is also pink and dorsally setose and tuberculate (Loomis 1960, Shelley 1993), and at first glance appears to be Scytonotus. How- ever, the setae of its sole species, H. confluentus Loomis, also are stronger, stouter, and more clavate than those of S. simplex, the most proximate species of Scytonotus. In addition, the dorsal tu- bercles are more strongly demarcated from each other, as opposed to the lower, less pronounced ones of S. simplex. These attributes impart an almost velveteen appearance to specimens of Scytonotus, particularly juveniles, and with practice one can learn to distinguish this genus from phenotypically similar forms from California and Oregon with which it is often mixed in the same sample.
Scytonotus can also be recognized by the tibial lobes on legs 13-20/22 of most adult males and the reduced paranota on seg-
Genus Scytonotus
9
ments 5-9 of most adult females. Hoffman (1962b) correctly ob- served that the species in the Blue Ridge Province have normal paranota in adult females and lack tibial lobes in males, which distinguish them from S. granulatus in areas where their ranges abut near the Blue Ridge Province. Likewise, S. columbianus lacks the lobes in males and has normal paranota in females, allowing it to be distinguished from S. piger in the interior of British Colum- bia and the adjacent part of the United States. Details of the tibial lobes, paranota, and taxonomically important aspects of the gonopods are provided in the ensuing paragraphs. The species diagnoses in the descriptive accounts cite, in sequence, the attributes of the male tibiae; the relative lengths of the gonopodal tibiotarsi and endomerites; the characteristics of the medial, distal, and lateral laminae of the gonopods; and the condition of the paranota on segments 5-9 in females.
Tibia of legs 13-20/22 in males — As noted by Cook and Cook (1894), several leg articles are enlarged and papillose to varying degrees, but these traits are difficult to see, do not appear to hold taxonomic utility, and are not treated here. However, the tibiae of legs 13-20/22 (the posterior legs of segment 9 through the poste- rior legs of segment 13/anterior legs of 14) are modified in all species except S. columbianus , virginicus, and australis. The tibiae on these legs are swollen ventrally and possess one or two distal lobes on the caudal, anterior, or both margins. The lobes arise sud- denly on the 13th tibiae as long, subterminal projections from the caudal margins (Fig 2). They are glabrous and laminate, curve slight- ly, extend beyond the distal extremities of the podomeres, and are broad apically. The pattern varies (Table 1), but in general this configuration persists through the 16th legs (anterior legs of seg- ment 11). On the 17th legs (caudal legs of the 11th segment) there is a smaller, moderate-size lobe in the same position. On the 18th legs of most species, the anterior legs of segment 12, there is a small lobe at this position and one directly opposite on the anterior margin (Fig. 3). Depending on the species, the anterior lobe per- sists through the 20th/22nd tibiae, while the caudal lobe disap- pears. The anterior lobe also disappears after legs 20/22, and the remaining legs are unmodified.
Cook and Cook (1894) stated that legs 13-20 in S. granulatus, the ones with tibial modifications, clasp the segments of females with reduced paranota during copulation. No evidence was provided, but five segments are involved in females, numbers 5-9, and the legs on five or six segments (segments 9-13/14) are modified in males, so the statement is plausible because the modifications corre-
10
Rowland M. Shelley
late. Segment 7 of the male, the copulatory segment, must align with segment 3, the reproductive segment of the female, which places the first modified segments, 9 of the male and 5 of the female, opposite each other. Because of this correlation, it is not surprising that the species that lack one modification also lack the other, as is the case with S. columbianus , virginicus, and australis. Conse- quently, the presence or absence of these modifications is taxo- nomically important in the northern Rocky Mountains and the Blue Ridge Province (Figs. 10, 30), as they enable accurate determina- tions of S. columbianus versus S. piger , and S. granulatus versus S. virginicus or australis.
In spot checking males of each species with lobes, I noted that the number of leg pairs, the sequence of large versus small lobes, and the occurrence of anterior lobes vary among species. Table 1 shows the legs that are modified in the species possessing lobes; they are absent from the anterior or caudal margins where no size is indicated. This variation may hold taxonomic utility, par- ticularly for determining males when the gonopods are lost.
Segments 5-9 in females — In all species except S. columbianus, virginicus, and australis, the paranota on segments 5-9 of adult females are reduced or absent, resulting in a distinctly narrower,
Table 1. Comparison of Tibial Lobes of Adult Males of Scytonotus spp.1
|
Segment Number Leg Number |
9 1 13 |
10 14 | 15 |
16 |
11 | 17 |
12 18 | 19 |
13 20 | 21 22 |
14 | 23 |
|
|
piger |
1 1 ^ " C " |
i a - | a - c - s c - s |
a - c - s |
1 1 a ‘ c - s |
i a - s | a - s c - s c - s |
i a - mi c - |
1 l |
|
|
insulanus |
la - |
a - |
1 a - |
a - |
1 a - |
a - s 1 a - s |
a-s 1 a-s a-s |
1 |
|
1 c - 1 |
c - 1 |
1 c - 1 |
c - ml c - m |
c - ml c - s |
c - s 1 c - s c - |
1 c - |
||
|
bergrothi |
|a - |
a - |
1 a ' |
a - |
1 a " |
a - s | a - m |
a - m| a - m |
l |
|
|c - 1 |
c - 1 |
I c - 1 |
c - 1 |
1 c - m |
c - ml c - m |
c - ml c - |
| |
|
|
simplex |
la " c-1 |
a - c - 1 |
1 a " ■ c - 1 |
a - c - 1 |
1 a " c-i |
a - s | a - s c - s c - s |
a - s | c - |
1 1 |
|
inornatus |
'a - ■ |
a - |
1 a - |
a - |
■ a - |
a - s ■ a - s |
a-s * |
1 |
|
I c - 1 |
c - 1 |
1 c - 1 |
c - 1 |
1 c - s |
c - s 1 c - s |
c - s 1 |
1 |
|
|
granulatus |
|a - |
a - |
1 a ' |
a - 1 |
1 a - s |
a - 1 | a - 1 |
1 |
l |
|
|c-l |
c - 1 |
| c - 1 |
c - 1 |
1 c - m |
c - s 1 c - s |
c - |
1 |
1 Symbols in the table are: a -condition of anterior tibial margin c -condition of caudal tibial margin 1 -large lobes (Fig. 2) s -small lobes (Fig. 3)
m- moderate lobes, an intermediate conditon or small version of the large configuration
Genus Scytonotus
11
cylindrical shape to this part of the body. The paranota are vesti- gial on segments 5 and 9 and are absent from segments 6-8. The distinction applies only to adults; I have examined innumerable ju- venile females of different sizes, and presumably different instars, with well developed paranota on these segments. Loss of these structures thus appears to occur at the final molt and to coincide with the attainment of sexual maturity.
Male gonopods — As in all polydesmids, the most important taxonomic features in Scytonotus are located on the gonopodal telopo- dite, which consists of two branches that join basally. I adopt the system of Attems (1940) and Golovatch (1991) and label the blade- like, anterior projection as the “tibiotarsus” and the variable caudal structure with a pulvillus on the inner margin as the “endomerite.” Three laminae arise from the endomerite stem, one each on the medial and lateral sides and one distad. The principal taxonomic characters involve the relative lengths of the tibiotarsi and the endo- merites as well as the sizes and configurations of the three lamelae.
Medial lamina — The medial lamina arrises proximally on the endomerite, often proximal to the pulvillus, extends for varying lengths along the stem, and usually terminates before the modifications of the distal lamina. In most species the medial lamina expands ba- sally into a variable lobe or flange that may overhang and partly obscure the inner margin of the endomerite. Distally it varies greatly, tapering smoothly onto the endomerite in S. piger, columbianus, inornatus, and granulatus (Figs. 5, 7, 17, 21), and terminating in one or more variable teeth or spurs in S. insulanus, bergrothi, sim- plex, virginicus, and australis (Figs. 11, 13, 15, 23, 25, 27).
Distal lamina — The distalmost part of the endomerite, the dis- tal lamina arises at varying points along the stem beginning near midlength. There are three basic configurations: with two or three teeth on the inner margin, as in S. piger , columbianus, granulatus, virginicus, and australis (Figs. 5-8, 21-28); expanded basally into a small lobe or spur and prolonged distad to varying degrees, thus extending beyond the distal extremity of the tibiotarsus, as in S. insulanus, bergrothi, and simplex (Figs. 11-16); and unmodified, as in S. inornatus (Figs. 17-18).
Lateral lamina — Like its medial counterpart, the lateral lamina arises at various points along the endomerite stem, in some species proximal to the pulvillus, and usually terminates proximal to the modifications of the distal lamella. The structure is long, slender, and unmodified in S. piger, columbianus, inornatus, and australis (Figs. 6, 8, 18, 28); expands into rounded lobes in S. insulanus and bergrothi (Figs. 12, 14); possesses a subspiniform projection in
12
Rowland M. Shelley
S. virginicus (Figs. 24, 26); and is expanded with one or two mar- ginal teeth in S. granulatus (Fig. 22). The most intricate structure occurs in S. simplex , where the lamina expands basally into a lightly serrate lobe, narrows at midlength, and possesses a short spur around 2/3 length (Fig. 16).
Genus Scytonotus Koch
Scytonotus Koch, 1847:57. Bollman 1893:122,141-142. Cook and Cook, 1894:233-235. Cook, 1904:61. Williams and Hefner, 1928:111. Attems, 1898:255-256; 1931:144-145; 1940:155. Hoffman, 1950^:219- 250; 19626:242; 1979:173. Causey, 1955:22. Chamberlin and Hoffman, 1958:72. Jeekel: 1971:351. Kevan, 1983:2969. Lasiolathus Loomis, 1943:318-319. Jeekel, 1971:334.
Type species — Of Scytonotus , S. scabricollis Koch, by subse- quent designation of Bollman (1893). Hoffman (19626) states that designation was by Chamberlin and Hoffman (1958), but as noted by Jeekel (1971), it actually dates to Bollman (1893:151). Of Lasiolathus , L. virginicus Loomis, by original designation.
Diagnosis — Small polydesmids with four to five rows of rounded, setose tubercles dorsally on metatergites; adults with 19 segments; dorsum moderately convex; paranotal margins shallowly notched or deeply dentate, those of segments 5-9 of females of most species vestigial or absent; tibiae of legs 13-20/22 of males of most spe- cies swollen ventrad and with variable, elongate, subterminal lobes on anterior and/or caudal margins; telopodite of male gonopod with or without one or two barbed, aciculate projections proximally on medial surface, with elongate tibiotarsus arising basally anterior to endomerite, latter with basal pulvillus on caudal surface and vari- ably dentate medial, distal, and lateral laminas; prostatic groove in- ternal, with distal loop, opening at pulvillus.
Distribution — Occurring in four separate faunal regions, one east and three west of the Continental Divide (Fig. 1). In the East, Scytonotus covers a large, continuous area east of the Central Plains extending from near Sault Ste. Marie, Ontario, and Trois Rivieres, Quebec, to southcentral South Carolina, north Georgia, and north- eastern Arkansas; east-west, this area spreads from eastern Vermont, coastal Virginia, and the Outer Banks of North Carolina to eastern Kansas and Nebraska. In the West, Scytonotus occurs along the Pacific Coast and in two areas in the interior. The coastal area extends from Yakutat Bay, Alaska, to Marin and San Joaquin coun- ties, California, extending inland to the eastern slope of the Cas- cade Mountains in Oregon and Washington, and includes all interven- ing offshore islands in British Columbia and Alaska except the Queen
Genus Scytonotus
13
Charlotte Islands, where it never has been encountered. In the inte- rior, Scytonotus occurs in the Columbia River Valley and the Rocky and Selkirk mountains, and associated ranges, from Revelstoke and Yoho National Parks, British Columbia, to southeastern Washington, western Montana, and the southern extremity of the Idaho Pan- handle near the Salmon River. It is also known in the Wasatch and Teton mountains, and associated ranges, in western Wyoming, east- ern Idaho, and northern Utah south to Salt Lake County.
Species — Nine, three in eastern North America, one divided into two geographic races, and six in the west. The species are arranged into three lineages or species groups, which are named for the oldest component.
Key to Species of Scytonotus , based on adult males
1. Distal lamina of gonopodal endomerite with 2 or 3 distal
teeth (Figs. 5-8, 21-28) 2
Distal lamina otherwise 6
2. Medial lamina with 2 distinct teeth (Figs. 23, 25);
Warren County, Virginia, to Sevier County, Tennessee,
and Swain County, North Carolina
virginicus (Loomis)
Medial lamina with 1 or no teeth, with or without a rounded, basal lobe or flange 3
3. Distal lamina with 3 teeth, the apical one much smaller
and preceded by 2 larger, subequal teeth (Fig. 21); Ontario and Quebec to South Carolina, Tennessee, Arkansas,
and Kansas granulatus (Say)
Distal lamina with 2 subequal teeth 4
4. Medial lamina with distinct distal tooth (Fig. 27); Bun-
combe County, North Carolina, and Sevier County, Tennessee, to Oconee County, South Carolina, and Daw- son County, Georgia australis Hoffman
Medial lamina with variable basal lobe but without distal tooth 5
5. Endomerite much shorter than tibiotarsus; medial lamina
a short, narrow flange, not overhanging inner margin of endomerite (Fig. 7); interior of British Columbia and northeastern Washington columbianus Chamberlin
14
Rowland M. Shelley
Endomerite subequal in length to tibiotarsus; medial lamina longer, with rounded basal lobe overhanging and partly obscuring inner margin of endomerite (Fig. 5); north- eastern Washington, northern Idaho, and western Mon- tana to Salt Lake County, Utah
piger Chamberlin
6. Endomerite subequal in length to tibiotarsus, distal lamina
without modifications, not prolonged, inner margin
smooth, entire (Fig. 17); Klamath County, Oregon
inornatus , new species
Endomerite longer than tibiotarsus, inner margin of distal lamina variously modified and prolonged, with or with- out teeth 7
7. Distal lamina apically divided, medial part thin and nar-
row, greatly prolonged and strongly decurved, without teeth (Fig. 11); Yakutat Bay, Alaska, to Douglas County,
Oregon, and Whitman County, Washington
insulanus Attems
Distal lamina not divided, slightly to moderately prolonged, only slightly decurved 8
8. Distal lamina directed at about a right angle from endo-
merite stem, slightly prolonged and expanded basally into narrow lobe, without teeth; medial lamina narrow- ing greatly distad, with short apical tooth, not over- hanging endomerite stem (Fig. 15); Lincoln County, Oregon,
to Marin and San Joaquin counties, California
simplex Chamberlin
Distal lamina curving gently away from tibiotarsus, mod- erately prolonged, with sharply acute basal tooth, with- out lobes, medial lamina greatly expanded distad, with apical tooth, overhanging and obscuring inner margin of endomerite (Fig. 13); southern British Columbia to Douglas County, Oregon bergrothi Chamberlin
THE WESTERN SPECIES The Granulatus Group
The most speciose lineage in Scytonotus, the granulatus group occurs in the eastern region and both areas in the western interior and is absent from the Pacific Coast. It is characterized primarily by the presence of two or three teeth, usually subequal in size, on
Genus Scytonotas
15
the inner margin of the distal lamina. The medial lamina varies in length and is typically expanded into a basal lobe or flange, except on the Blue Ridge endemics, which have one or two distinct teeth. The lateral lamina is long, slender, and generally unmodified, ex- cept for S. granulatus and virginicus, in which the structure also has one or two teeth. Finally, the endomerite is shorter than or subequal in length to the tibiotarsus. The Blue Ridge species and S. columbianus have normal paranota on all segments in females, and males lack the tibial lobes. However, because all other conge- ners possess reduced paranota in females and lobes in males (Table 1), I regard the conditions in these three species as apomorphies representing secondary simplification rather than plesiomorphies, and the similarity between S. columbianus and S. virginicus/ australis represents convergence. Spatial distributions tend to be allopatric and parapatric, with only minimal sympatry between S. virginicus michauxi and australis, in the Great Smoky Mountains, and be- tween S. piger and columbianus, in northwestern Washington. Rela- tionships among the components are hypothesized as columbianus + ( piger + (granulatus + (virginicus + australis ))) (Fig. 34). The Blue Ridge Province seems to be a secondary center of evolution after the presumptive primary source area in the Cascade Mountains. The western representatives of the granulatus lineage are detailed below; the eastern species are characterized at the conclusion of the de- scriptive section.
Components — granulatus (Say), piger Chamberlin, columbianus Chamberlin, virginicus (Loomis) (v. virginicus, v. michauxi Hoff- man), australis Hoffman.
Scytonotus piger Chamberlin Figs. 2-6
Scytonotus piger Chamberlin, 1910:244-245, pi. 36, figs. 1-5. Attems,
1940:159. Chamberlin and Hoffman, 1958:73.
Polydesmus amandus Chamberlin, 1910:249-250, pi. 38, fig. 6, pi.
39, fig. 1. NEW SYNONYMY.
Scytonotus orthodox Chamberlin, 1925:61. Attems, 1940:159.
Chamberlin and Hoffman, 1958:73. Kevan, 1983:2969. NEW
SYNONYMY.
Archipolydesmus amandus: Attems, 1940:154-155. fig. 226. Scytonotus amandus: Chamberlin, 1943:143. Causey, 1954:223.
Chamberlin and Hoffman, 1958:72. Loomis and Schmitt, 1971:117.
Kevan, 1983:2969.
Type specimens — One male and one female syntype (NMNH) taken by an unknown collector on an unknown date in the upper reaches of Mill Creek Canyon, Salt Lake County, Utah.
16
Rowland M. Shelley
Figs. 2-8. 2-6, S. piger. 2, tibia of leg 13 of male from Teton County, Wyoming. 3, tibia of leg 17 of male from Mineral County, Montana, 4, distal extremity of telopodite of male from Mineral County, Montana, dor- sal view. 5, left gonopod of male from Teton County, Wyoming, medial view. 6, the same, lateral view. 7-8, S. columbianus. 7, left gonopod of paratype, medial view. 8, the same, lateral view. dl. distal lamina; e, endomerite; 11, lateral lamina; ml, medial lamina; tt, tibiotarsus. Scale line = 0.5 mm for all figures.
Diagnosis — Tibiae of legs 13-20 in males with distal lobes on anterior and/or caudal margins (Figs. 2-3); endomerite subequal in length and closely appressed to tibiotarsus; medial lamina extend- ing for about half the length of endomerite, with short but broad basal lobe, overhanging and obscuring inner margin of endomerite; distal lamina with two blunt teeth; lateral lamina extending for about 2/3 of length of endomerite, expanding slightly distad, with or without small marginal spurs, not overhanging margin of stem (Figs. 4-6); paranota of segments 5-9 reduced in females.
Variation — There are slight differences among the male gonopods that do not conform to a geographic pattern. The lobe on the me- dial lamina is located slightly distal to the pulvillus on a few males, and the spur proximal to the latter is absent from other. The teeth on the distal lamina are greatly reduced in individuals from Box Elder County, Utah, where they are more like small, rounded lobes, and the lateral lamina is expanded with slight marginal spurs in a few males from northern Idaho and western Montana (Fig. 4).
Genus Scytonotus
17
Ecology — According to labels with preserved samples, S. piger has been taken from the following microhabitats: aspen logs and litter, mixed lodgepole pine and fir litter, mixed aspen and fir lit- ter, moss on logs and stumps, big-toothed maple detritus, choke- berry duff, juniper litter, mixed yellow pine and fir litter, birch duff, and fern duff. In Montana, Loomis and Schmitt (1971) col- lected it from moist moss by a stream; red cedar, larch, white pine, and spruce litter; and under rocks by a creek in a lodgepole pine forest.
Distribution — Occurring in two allopatric populations separated by approximately 274 mi (438 km), one in the Rocky Mountains of northeastern Washington, northern Idaho, and western Montana, and the other in the Wasatch and Teton mountains, and associated ranges, of eastern Idaho, western Wyoming, and northern Utah as far south as Salt Lake County (Figs. 9-10). Specimens were examined as follows:
MONTANA: Flathead Co ., Columbia Falls, 16 juvs., 20 Au- gust 1966, D. R. Miller (UCD). Lincoln Co., 8.5 mi (13.6 km) E Libby, 3 juvs., 29 July 1958, C. C. Hoff (AMNH); and Bull L. Cpgd., M. 5F, 2 May 1965, R. Schmitt (FSCA). Mineral Co., 10 mi (16 km) S, 3 mi (4.8 km) W Superior, 4 juvs., 13 September 1978, A. K. Johnson (NCSM); and 10.5 mi (16.8 km) S, 3.5 mi (5.6 km) W Superior, along Trout Cr., 2M, 3 September 1978, A. K. Johnson (NCSM).
WASHINGTON: Stevens Co., Abercrombie Mtn., ca. 14 mi (22.4 km) E Northport, 48.927°N, 117.458°W, M, 3 September 1980, R. Crawford (UWBM).
IDAHO: Bonner Co., E of Kootenai, entrance U. ID. field sta., 2F, 11 August 1991, R. M. Shelley (NCSM). Kootenai Co., Coeur d’Alene, 6M, 4F, 3 juvs., 4 September 1949, S. Mulaik (NMNH). Latah Co., 4 mi (6.4 km) N, 8 mi (12.8 km) E Harvard, Banks Gulch, M, 2 juvs., 16 September 1977, and 7 juvs., 15 September 1978, A. K. Johnson (NCSM); 8 mi (12.8 km) NE Harvard, 2M, 11F, 9 June 1982, R. S. Zack (WSU); and S. slope Moscow Mtn., M, 3F, 3 October 1964, R. L. Westcott (UCD). Clearwater Co., 9.7 mi (15.5 km) W, 6 mi (9.6 km) S Pierce, M, F, 15 August 1978, A. K. Johnson (NCSM). Fremont Co., 2 mi (3.2 km) N Warm River, 4 juvs., 12 August 1959, C. C. Hoff (AMNH). Bear Lake Co., Georgetown, MM, FF, 17 August 1931, W. J. Gertsch (NMNH); Pineview, 6M, 14 August 1940, W. Ivie, (NMNH); Montpelier, Emigration Cyn., MM, FF, juvs., 17 August 1931, W. J. Gertsch (NMNH); 9 mi (14.4 km) NW Ovid, 5 juvs., 4 August 1959, C. C. Hoff (AMNH); and 13 mi (20.8 km) SW Ovid, F, 6
18
Rowland M. Shelley
June 1984, J. B. Johnson, F. W. Merickel (UID). Franklin Co., Cub R. Cyn., Wasatch Mts., M, 2F, 7 juvs., 4 July 1952, 12 Octo- ber 1963, and 8-18 May 1969, G. F. Knowlton (ILNHS, NMNH). Oneida Co., 11.6 mi (18.6 km) SW Downey, Summit Forest Camp, 2M, 4 September 1966, G. E. Ball, D. R. Whitehead (VMNH).
WYOMING: Teton Co., Grand Teton Natl. Pk., Sunset L., Alaska Basin, juv., 29 July 1961, J. G. Edwards (FSCA); Wilson, 2M, 4 juvs., 20 August 1979, A. G. Grubbs (TMM); 12 mi (19.2 km) W Jackson, 3 juvs., 7 August 1959, C. C. Hoff (AMNH); 9 mi (14.4 km) W Jackson, 5 juvs., 5 August 1959, C. C. Hoff (AMNH); 21 mi (33.6 km) SE Jackson, along hwys. 187/189, juv. 6 August 1949, C. C. Hoff (AMNH). Sublette Co., 28 mi (44.8 km) SE Jackson, along US hwys. 187/189, 8 juvs., 6 August 1959, C. C. Hoff (AMNH). Lincoln Co., Cyn. E. Bedford, F, 2 juvs., 27 June 1962, W. Ivie (AMNH); nr. Afton, M, F, 19 August 1931, W. J. Gertsch (NMNH); and 4 mi (6.4 km) S Alpine Jet., juv., 27 August 1991, R. M. Shelley (NCSM).
UTAH: Rich Co., Bear Lake, 2M, 2F, 2 juvs., 9 September 1919, R. V. Chamberlin (NMNH); and West Hodges Cyn., MM, FF, juvs., 7 June 1975-29 October 1976, G. F. Knowlton (MCZ). Cache Co., Tony Grove Cyn., M, 2 September 1977, G. F. Knowlton
(MCZ); Blacksmith Fork Cyn., M, 5 November 1966, G. F. Knowlton
(NMNH); Logan Cyn., 15 juvs., 2 July 1927, R. V. Chamberlin
(NMNH), 2F, 29 October 1952, G. F. Knowlton (NMNH), 3F, 11 April 1959, G. F. Knowlton (AMNH), 2F, juv., 14 May 1959, G.
F. Knowlton (USU), M, 10 juvs., 17-29 November 1966, G. F.
Knowlton (NMNH), M, F, 27 May 1970 (WAS), 14 juvs., 7 July
1970, G. F. Knowlton (UCD), 4M, 2F, 26 October 1977, G. F.
Knowlton (MCZ), 4M, F, juv., date unknown, R. V. Chamberlin
(NMNH), and MM, FF, 1 November 1976-20 May 1978, G. F.
Knowlton (MCZ); Green Cyn., M, 22 May 1968, G. F. Knowlton (NMNH), 2F, 27 April 1974, G. F. Knowlton (USU), and MM, FF, 29 October 1977, G. F. Knowlton (MCZ); Smithfield Cyn., M, juv., 27 April 1968, G. F. Knowlton (NMNH); Wellsville Cyn., M, 6F, 2 juvs., 25 May 1970, G. F. Knowlton (WAS); and Logan, Spring Hollow, F, 6 April 1959, R. Amoreaux (USU). Box Elder Co., Wellsville Mts., site not specified, 7 juvs., 22 June 1956, G. F.
Knowlton (CIS) and Cold Spring, 2 juvs., 19 June 1968, G. F.
Knowlton (NMNH); and Box Elder Cyn., M, 12 November 1968,
G. F. Knowlton (NMNH). Weber Co., Ogden Cyn., 12M, 10F, 7 May 1927, R. V. Chamberlin (NMNH). Salt Lake Co., Salt Lake City, City Cr. Cyn., 10M, 2F, 3 juvs., 11 September 1931, W. J. Gertsch (MNMH), Rotary Pk., M, 4F, 11 and 16 September 1942,
Genus Scytonotus
19
Fig. 9. Distribution of S. piger in eastern Idaho, western Wyoming, and northern Utah.
20
Rowland M. Shelley
Fig. 10. Distributions of S. piger (dots), columbianus (squares), and insulanus (stars) in eastern Washington, northern Idaho, western Montana, and south- eastern British Columbia. Circles denote literature records of S. piger deemed reliable; the question mark denotes a literature record of Scytonotus sp. (Causey 1954b) that could be either S. piger or columbianus.
Genus Scytonotus
21
W. Ivie (NMNH), Ft. Douglas, F, 17 July 1951, Y. M. Wang (NMNH), and Mill Cr. Cyn., M, F, date and collector unknown (NMNH), and F, date unknown, R. V. Chamberlin (NMNH) TYPE LOCALITY; and Lamb Cyn., F, 20 September 1930, collector un- known (NMNH) and juvs., 21 July 1942, S. and D. Mulaik (NMNH).
The following literature records are also deemed reliable and are designated by open symbols in figs. 9-10.
MONTANA: Lincoln Co ., 8.5 mi (13.6 km) W Libby, and along Zulu Cr., S Fork Yaak R. (Loomis and Schmitt 1971). Min- eral Co ., Saltese (Loomis and Schmitt 1971).
IDAHO: Bear Lake Co ., 7 mi (11.2 km) NW Georgetown (Chamberlin 1943).
WYOMING: Teton Co., Moose (Causey 1954a).
Remarks — With two teeth each on the distal laminas, S. piger and columbianus are very similar. I have seen only three males of the latter, so my concepts may need to be modified when more specimens are available. From this material, the endomerite and tibiotarsus are consistently subequal in length, closely appressed to- gether, and overlap basally in S. piger, whereas in S. columbianus, the endomerite is much shorter and widely separated from the tibio- tarsus (Figs. 5-8). Additionally, the medial lamina is just a short flange that does not overhang the inner margin of the endomerite in S. columbianus, whereas it is much longer and extends into a basal lobe that does overhang this margin in S. piger. In nonsexual features, the tubercles are much stronger and more clearly demar- cated from each other in S. columbianus; they are smaller, more lowly rounded, and tend to merge with one another in S. piger. Similarly, the paranotal margins are much more deeply indented and emarginate in S. columbianus, in contrast to the nearly smooth con- dition in S. piger.
Scytonotus columbianus Chamberlin Figs. 7-8
Scytonotus columbianus Chamberlin, 1920:166-167, fig. 16. Attems, 1940:158. Chamberlin and Hoffman, 1958:72. Kevan, 1983:2969. Shelley, 1990:20.
Type specimens — Male holotype (MCZ) taken by J. B. Tyrrell, 26 September 1883, in the Columbia Valley (probably the valley of the Columbia River), British Columbia, Canada. One male and one female paratypes (MCZ) taken by same collector, 1 September 1883, from a “swamp, tobacco plain” in the same locality.
Diagnosis — Tibiae of legs 13-20/22 in males without distal lobes; endomerite much shorter than tibiotarsus, segregated from the
22
Rowland M. Shelley
latter for most of length; medial lamina a short, inconspicuous, broadly rounded flange at level of pulvillus, not overhanging inner margin of endomerite; distal lamina with widely separated, poorly demarcated, subacuminate teeth, proximal one larger; lateral lamina moderately broad, overhanging inner margin of endomerite (Figs. 7-8); females with paranota of segments 5-9 not reduced.
Variation — The flange-like medial lamina is narrower and barely detectable on the male from Yoho National Park, and the proximal tooth on the distal lamina is much larger than the apical tooth in this individual.
Ecology — The specimens that I collected in Mt. Revelstoke and Kootenay National Parks, British Columbia, were encountered under wet deciduous litter near streams. The male from Washington was recovered from a pitfall trap in an old field.
Distribution — Extending from the Selkirk and Rocky Mountains at Revelstoke and Yoho National Parks, British Columbia, to the northeastern corner of Washington, ranging westward into the Co- lumbia River Valley (Fig. 10). Specimens were examined as fol- lows:
CANADA: BRITISH COLUMBIA: Mt. Revelstoke Nat. Pk., Skunk Cabbage area, 2 juvs., 9 August 1989, R. M. Shelley (NCSM). Yoho Nat. Pk., 2 mi (3.2 km) S Takkakaw Falls, M, 5 October 1963, A. Nimmo (VMNH) and Kicking Horse Camp, F, 5 October 1963, D. R. Whitehead (VMNH). 10 mi (16 km) E Golden, F, 2 juvs., 28 June 1988, S. & J. Peck (NCSM). Kootenay Nat. Pk., trail to Cobb Cpgd., juv., 7 August 1989, R. M. Shelley (NCSM). Columbia Valley, site not specified, 2M, F, 1 and 26 September 1883, J. B. Tyrrell (MCZ) TYPE LOCALITY. Kaslo, F. 18 juvs., 30 June-4 July 1903, A. M. Caudell (NMNH). 16 km E. Salmo, along Hwy. 3, ca. 1 mi (1.6 km) E jet. Hwy. 6, 2 juvs., 6 August 1989, R. M. Shelley (NCSM).
USA: WASHINGTON: Pend Oreille Co., ca. 7 mi (11.2 km) S Usk, Deer Cr., along WA hwy. 211 just S Davis L., 48.210°N, 117.289°W, 6M, F, 29 August-9 September 1980, R. Crawford (UWBM).
The Bergrothi Group
Aside from the allopatric population of S. insulanus in eastern Washington, the bergrothi group is found exclusively along the Pa- cific Ocean. It is the only lineage occurring west of the Cascades, and S. bergrothi extends across the crest and onto the eastern slope of these mountains in Yakima and Kittitas counties, Washing- ton. Anatomically, the endomerites are longer than the tibiotarsi be- cause the distal lamina is prolonged to varying degrees. The latter
Genus Scytonotus
23
also bends sharply or curves so that it is angular with respect to the endomerite stem, and it is divided in S. insulanus. The medial laminas exhibit a distal tooth in S. bergrothi and simplex, and the lateral laminas are short with rounded lobes except on S. simplex, which possesses a lightly serrate basal lobe and a distal tooth. Scytonotus bergrothi and insulanus are broadly sympatric in coast- al Washington, northwestern Oregon, and southwestern British Columbia, whereas S. simplex is parapatric to the south, with only minimal overlap of S. bergrothi (Figs. 20, 32). I am unable to resolve the relationships among the components and show them in Figure 34 as an unresolved trichotomy.
Components — bergrothi Chamberlin, insulanus Attems, simplex Chamberlin.
Scytonotus insulanus Attems Figs. 11-12
Scytonotus insulanus Attems, 1931:147-149, figs. 240-245; 1940:157- 158, figs. 229-231. Chamberlin and Hoffman, 1958:73. Kevan, 1983:2969.
Scytonotus insulans : Shelley, 1990:20.
Type specimens — One male and one female syntypes (NMV) taken by an unknown collector on an unspecified date in 1934 at Nanaimo, Vancouver Island, British Columbia, Canada.
Diagnosis — Tibiae of legs 13-22 in males with distal lobes; endomerite much longer than tibiotarsus; medial lamina relatively short, with moderately acuminate flange overhanging inner margin of endomerite; distal lamina apically divided, medial branch slightly expanded and broadly rounded basally, tapering into greatly pro- longed, strongly decurved projection, tip narrowly rounded, lateral branch about 1/3 as long as latter, expanding distad and tapering slightly to subacuminate tip; lateral lamina expanding into moderate- size, narrowly rounded lobe, overhanging inner margin of endomerite (Figs. 11-12); paranota of segments 5-9 reduced in females.
Variation — There is very little variation among the gonopods of S. insulanus. In the male from 12 mi (19.2 km) east of Salem, Marion County, Oregon, the flange on the medial lamina is nar- rower and more rounded than that of the type, and the lobe on the lateral lamina is smaller, more pointed, and located more proximad. A few other individuals exhibit similar, minor variation in the size of these structures, but most gonopods agree closely with the type.
Ecology — Labels with preserved samples give the following microhabitat information for S. insulanus : alder and birch litter,
24
Rowland M. Shelley
moss, maple and dogwood duff, hemlock duff, beach grass debris, and dried seaweed.
Distribution — Along the Pacific Coast from Yakutat Bay, Alaska, to eastern Douglas County, Oregon, with an allopatric population in southeastern Washington, around 308 mi (493 km) from the closest locality (Figs. 10, 19-20). Because S. insulanus is the only species represented by males in Alaska and Canada north of Vancouver Island, it is assigned to juvenile and female only samples from this area. Specimens were examined as follows:
CANADA: BRITISH COLUMBIA: VANCOUVER ISLAND: Nanaimo , M, F, 1934, collector unknown (NMV) and 4M, 2F, 17 October 1907, R. Paessler (ZMH) TYPE LOCALITY.
MAINLAND SITES: Stewart, 5 juvs., 7 August 1988, S. & J. Peck (NCSM). Terrace, 4 juvs., 10 August 1988, S. & J. Peck (NCSM). Vancouver, 2M, 2F, 22 February and 4 April 1933, H. B. Leach (NMNH).
USA: ALASKA: Juneau, M, 3F, 28 April 1945, J. C. Chamberlin (NMNH). Baranof /., Sitka, juv., June 1899, Harriman Exp. (NMNH). Kupreanof /., Lindenberg Penin., Ohmers Slough, M, 29 August 1951 (NMNH). Mitkof /., 8 mi (12.8 km) N Ideal Cove, M, 3 September 1951, B. Malkin (NMNH). Wrangell /., Wrangell, 2M, 1951, B. Malkin (NMNH). Etolin /., Menefee Inlet, M, 21 Septem- ber 1951, B. Malkin (NMNH).
WASHINGTON: Whatcom Co., Custer, 2M, 3 April 1951, J. T. Davis (UWBM). Skagit Co., Chuckanut Dr., S of Bow, 48.5 13°N 122.374°W, 12M 5F, 30 March 1982, R. Crawford (UWBM); and Pipeline Rd. at WA hwy 20 nr. Lyman, 48.527°N, 122.056°W, 2M, 28 September 1975, R. Crawford (UWBM). Snohomish Co., Mukilteo, 2M, 12 February 1905, R. Paessler (ZMH). Clallam Co., Olympic Nat. Pk., Waterhole Camp, 47.94°N, 123.42°W, 2M, 30 August 1966, R. Crawford (UWBM). Grays Harbor Co., Westport, 3M, 8F, date unknown, J. Wilcox (NMNH); and Pacific Beach, 2 juvs., 14 May 1933, R. V. Chamberlin (FSCA). Thurston Co., Nisqually R. Delta, 47.075°N, 122.707°W, M, 23 October 1984, R. Crawford (UWBM). Pacific Co., Cape Shoalwater, 5M, 10F, 18 February 1987, R. Craw- ford (UWBM). Wahkiakum Co., Grays River, Swede Park, 46.356°N, 123.58°N, M, F, 24 October 1984, R. Crawford (UWBM). Whitman Co., 4 mi (6.4 km) N Colfax, juv., 30 May 1941, J. C. Chamberlin (NMNH); and 8 mi (12.8 km) SW Pullman, Lyle Grove, M, F, 3 March 1973, W. J. Turner (WSU).
Genus Scytonotus
25
OREGON: Clatsop Co., Fort Stevens St. Pk., M, 27 No- vember 1971, E. M. Benedict (WAS). Columbia Co., 3 mi (4.8 km) SW Clatskanie, 2M, F, 8 January 1972, E. M. Benedict (WAS). Multnomah Co., Portland, 250 NE 114 Ave., M, FF, juvs., 9 April 1957, D. B. Monroe (FSCA), and Macleay Park, 3F, 2 January 1970, J. S. Buckett (UCD). Washington Co., 1.1 mi (1.8 km) N Gaston, along OR hwy 47, M, 2 October 1971, E. M. Benedict (WAS). Yamhill Co., 5 mi (8 km) NE Newberg, M, 26 October 1968, K. Goeden (UCD); and 0.2 mi (0.3 km) S Wapata, 4M, 2 October 1971, E. M. Benedict (WAS). Clackamas Co., 1.9 mi (3.0 km) W Carver, MM, FF, 9 October 1971, E. M. Benedict (WAS); and 2 mi (3.2 km) E. Rhododendron, 2 juvs., 18 November 1969, K. Goeden (UCD). Marion Co., 18 mi (28.8 km) N Salem, juvs., date and collector unknown (NMNH); 12 mi (19.2 km) NE Salem, M, 15 October 1968, B. Brown (UCD); Salem, F, 29 January 1921,
C. D. Duncan (NMNH); 2.5 mi (4.0 km) NW Mehama, 3M, 2F, 1
March 1969, E. M. Fisher (UCD) and MM, FF, 24 February 1970, J. S. Buckett, M. R. Gardner (UCD); 1.5 mi (2.4 km) S Mill City, F, 9 March 1969, E. M. Fisher (UCD); and 1 mi (1.6 km) E Gates, 2F, 9 March 1969, E. M. Fisher (UCD). Jefferson Co., Spring Creek, exact location unknown, M, 19 April 1952, V. Roth (FSCA). Benton Co., 6 mi (9.6 km) N Corvallis, Peavy Arboretum, F, 17 January 1973, L. Russell (VMNH); 5 mi (8 km) N Corvallis, Sul- phur Spgs., 3 juvs., 26 March 1969, E. M. Fisher (UCD); Oak Cr., M, F, 18 February 1972, L. Russell (VNMH); and McDonald For.,
ca. 5 mi (8 km) NNW Corvallis, M, F, 20 September 1959, V.
Roth (AMNH), 3M, F, 31 October 1968, 2F, 18 December 1968, and MM, FF, 26 February 1969, R. L. Westcott (UCD), and 3F, 4 March 1969, E. M. Fisher (UCD); and Corvallis, juvs., 1896, A. B. Cordley (NMNH), F, 27 January 1936, G. Ferguson (NMNH), and juv., 13 June 1949, R. D. Walters (NMNH). Lane Co. McCredie Spgs., 3M, 6F, 7 October 1947, B. Malkin (NMNH); 6 mi (9.6 km) S Oakridge, M, 4F, 4 March 1972, E. M. Benedict (WAS); and Dolly Varden Cpgd., along OR hwy 58 E of Oakridge, 7M, 4F, 4 March 1972, E. M. Benedict (WAS). Douglas Co., 3 mi (4.8 km) S, 9 mi (14.4 km) E Steamboat, Eagle Rock Cpgd. along OR hwy 138, 2M, 4F, 30 October 1971, E. M. Benedict (WAS); 3 mi (4.8 km) S, 10 mi (16 km) E Steamboat, Boulder Flat Cpgd. along OR hwy. 138, M, 30 October 1971, E. M. Benedict (WAS); and 5 mi (8 km) S, 1 mi (1.6 km) E Steamboat, Island Cpgd. along OR hwy. 138, 4M, 3F, 30 October 1971, E. M. Benedict (WAS).
The following literature records of Scytonotus sp. are consid- ered referrable to S. insulanus.
26
Rowland M. Shelley
USA: ALASKA: Yakutat Bay (Cook 1904).
WASHINGTON: Clallam Co., Elwha (Causey 19546).
Remarks — The records from the Columbia Plateau Physiographic Province in Whitman County, Washington, are quite surprising, but the data appear accurate, and the adults conform to all the diagnos- tic traits of S. insulanus. This is the only record of the genus from southeastern Washington, and it suggests occurrence of S. insulanus in the Hell’s Canyon area of northeastern Oregon. The Lane and Douglas county Oregon sites, about 90 mi (144 km), from the clos- est locality, in Benton County, also may represent an allopatric population.
Scytonotus bergrothi Chamberlin Figs. 13-14
Scytonotus sp. Cook, 1904:pl. 4, figs. 2a-d.
Scytonotus bergrothi Chamberlin, 1911:262-264, fig. 16. Attems, 1940:158. Chamberlin and Hoffman, 1958:72. Kevan, 1983:2969. Scytonotus pallidus Attems, 1931:145-147, figs. 234-239; 1940:156- 157, figs. 227-228. Causey, 1954:82. Shelley, 1990:20.
Type specimens — One male and 3 female syntypes (NMNH) collected by D. E. Bergroth on an unknown date at Bremerton, Kitsap County, Washington.
Diagnosis — Tibiae of legs 13-21 in males with distal lobes; endomerite slightly longer than tibiotarsus; medial lamina expand- ing into broad flange for most of length, terminating in sharply acute distal tooth; distal lamina with smaller, sharply acute tooth proximad, narrowing, curving gently, and slightly prolonged thereaf- ter, apically acuminate, with or without variable undulations, short teeth, or spurs on outer margin; lateral lamina relatively short, ex- panding into moderately large, broadly rounded lobe, overhanging inner margin of endomerite (Figs. 13-14); paranota of segments 5-9 reduced in females.
Variation — The most notable gonopodal variation are the en- largements of the undulations on the outer margin of the distal lamina in males from British Columbia. Barely noticeable in south- ern specimens, the undulations become larger and more distinct around Vancouver and on Vancouver Island, and even are denticulate on a few males. Other gonopodal variation involves minor differences in the length and position of the spur on the inner margin of the endomerite near the hairpad. It projects well beyond the hairpad and is visible in lateral view in some males but is shorter in oth- ers; it can also be distal or proximal to the pulvillus. The relative sizes of the distal tooth on the medial lamina and the basal tooth
Genus Scytonotus
27
gonopod of male from Jefferson County, Washington, medial view. 14, the same, lateral view. 15-16, S. simplex. 15, left gonopod of male from Lincoln County, Oregon, medial view. 16, the same, lateral view. 17-18, S. inornatus. 17, left gonopod of holotype, medial view. 18, the same, lateral view. Scale line = 0.5 mm for all figures.
28
Rowland M. Shelley
on the distal lamina also vary, and the flange below the former and the lobe on the lateral lamina are narrower on some males.
Ecology — Labels with preserved samples indicate that S. bergrothi was taken from the following microhabitats: alder litter, under wet bark of decaying logs by ponds, under bark of Douglas-firs, and moss on tree trunks.
Distribution — Known definitely from southern Vancouver Island and the mainland of southwestern British Columbia to the north- western corner of Oregon, with an allopatric population some 151 mi (251 km) to the south in the northeastern corner of Lane County. The range also extends across the crest of the Cascades onto the eastern foothills in Kittitas and Yakima counties, Washington (Figs. 19-20). Specimens were examined as follows:
CANADA: BRITISH COLUMBIA: VANCOUVER ISLAND: Parksville, 10 juvs., 17 September 1935, R. V. Chamberlin, W. Ivie (NMNH). Cameron L., 2M, 15 September 1935, R. V. Chamberlin, W. Ivie (NMNH). Errington, 2M, 1 October 1951, collector un- known (NMNH). Sooke, Sooke Harbor, M, 9 February 1969, E. Thorn (RBCM). Victoria, 2M, 1949, collector unknown (RBCM).
OTHER ISLANDS: S. Pender /., M, 2 juvs., 1 September 1955, G. C. Carl (NMNH).
MAINLAND SITES: Powell L., M, 20 September 1938, R. H. Boyd (NMNH). Vancouver, MM, FF, 20 August 1932, 22 and 26 March 1933, and 3 April 1937, H. B. Leach (NMNH); 4M, 14 September 1935, R. V. Chamberlin, W. Ivie (NMNH); 5M, 3F, 2 juvs., 1938, G. J. Spencer (NMNH); and Univ. of BC, M, F, 3 November 1960, D. G. Bandoni (UBC). Mt. Seymour, F, 31 May 1931, H. B. Leach (NMNH). North Surrey, 11M, 20 juvs., 6 Sep- tember 1965, J. & W. Ivie (AMNH).
USA: WASHINGTON: San Juan Co., San Juan Islands, 4 juvs., 1938, collector unknown (NMNH). Whatcom Co., Bellingham, Yew St., M, 4 October 1988, R. Crawford (UWBM); and Chuckanut Mt., 48.671°N, 122.471°W, 2M, 1 September 1975, R. Crawford (UWBM). Skagit Co., Samish R., NW Sedro Woolley, 48.552°N, 122.295°W, M, 8 September 1977, R. Crawford (UWBM); Island Co., Deception Pass St. Pk., 5 juvs., 21 August 1990, R. M. Shelley (NCSM); 7.5 mi (12.0 km) NNE Oak Harbor, 3 March 1988, Wright, Nelty (NCSM); 2 mi (3.2 km) E Ebey’s Landing, Whidbey, 48.188°N, 122.70°W, M, F, 4 December 1988, R. Crawford (UWBM); and S. Whidby St. Pk., 5 juvs., 21 August 1990, R. M. Shelley (NCSM). Mason Co., 11 mi (17.6 km) S Goose Prairie, 3M, 10 February 1991, K. Dorweiler (UWBM); and S of Hamma Hamma R., along US hwy 101, NW Eldon, 47.56°N, 123.072°W,
Genus Scytonotus
29
M, 2F, 15 October 1977, R. Crawford (UWBM). Jefferson Co., 5.5 mi (8.8 km) S Brinnon, along US Hwy. 101, 2M, 23 September 1978, A. K. Johnson (NCSM); and Ft. Flagler St. Pk., M, 19 Au- gust 1975, S. Lefler (UWBM). Grays Harbor Co., Canyon R., ca. 7 mi (11.2 km) WNW Matlock, 47.262°N, 123.526°W, 8M, F, 29 August-18 October 1976, R. Crawford (UWBM); and Chehalis R. nr. Porter, 46.93°N, 123.31°W, M, 24 December 1920, R. H. Palmer (UWBM). Kitsap Co., Bremerton, M, 3F, date unknown, D. E. Bergroth (NMNH) TYPE LOCALITY. Snohomish Co., Marysville, juv., 10 August 1929, R. V. Chamberlin (NMNH); Mukilteo, M, F, 1934, collector unknown (NMV, ZMH); L. Ballinger, nr. King Co. line, 47.77°N, 122.32°W, 2M, F, 10 November 1939, E. F. Daily (UWBM);
L. Stevens, 47.99°N, 122.07°W, M, F, 16 November 1921, V. G. Wood (UWBM); and Skykomish R., nr. Gold Bar on US hwy. 2, 47.837°N, 121.657°W, M, 25 October 1980, R. E. Nelson (UWBM). King Co., Seattle, U.WA campus, 2M, 7F, 8 January 1932 and 21 November 1940, E. F. Dailey (UWBM); Seattle, 2F, 9 April 1936,
M. H. Hatch (UWBM), 2M, 2F, 9 April 1936, collector unknown (FSCA), 3M, 4F, 22 October 1941, E. I. Smith (VMNH), M, 28 September 1944, H. S. Dybas (FMNH), and Discovery Park, 8M, 5F, 19 October 1980, R. Crawford (UWBM); Rutherford Slough nr. Fall City, 47.575°N, 121.888°W, 2M, 2F, 1 November 1980, R. E. Nelson (UWBM); 1 mi (1.6 km) E North Bend, M, 3 May 1983, W. F. Barr (NCSM); North Bend, M, F, 27 April 1939, E. F. Dailey (UWBM); Newcastle Hills, M, 6 April 1985, R. Crawford (UWBM); Snoqualmie Falls, 5 juvs., 16 September 1935, R. V. Chamberlin, W. Ivie (NMNH); Snoqualmie Pass, 2 juvs., 11 August 1929, R. V. Chamberlin (NMNH) and F, 16 September 1935, R. V. Chamberlin, W. Ivie (NMNH); and Bridle Trails St. Pk., M, 2F, 16 March 1985, R. Crawford (UWBM). Pierce Co., Mount Rainier Nat. Pk., locality not specified, 2M, F, 4 juvs., 12 September 1965, J. & W. Ivie (AMNH), Paradise Valley, F, juv., July 1922, Jones (NMNH), 2M, 2F, 28 August 1946 and 1 August 1948, E. F. Dailey (UWBM), nr. Paradise Lodge, 4 juvs., 30 June 1980, M. A. Brittain (NCSM), Tipsoo Lake, F, 5 July 1938, W. Ivie (NMNH), and Tahoma Cr., 5M, 7F, 13 juvs., 14 August 1947, E. F. Dailey (UWBM); Horseshoe L., nr. Eatonville, 46.915°N, 122.271°W, M, 9 juvs., 4 September 1977, A. Ruggles (UWBM); and Ft. Lewis, F, 5 January 1946, P. H. Arnaud (NMNH). Thurston Co., Olympia, M, F, 24 March 1932, T. Kincaid (UWBM) and 2M, 7 juvs., 28 August 1959, W. J. Gertsch (AMNH). Lewis Co., 2.5 mi (4.0 km) S Packwood, Johnson Cr. Rd., 2M, juvs., 22 September 1978, A. K. Johnson (NCSM); and Lewis and Clark St. Pk., M, 29 October 1988, R.
30
Rowland M. Shelley
Crawford (UWBM). Kittitas Co., Cle Elum, juv., 7 May 1933, W. W. Baker (NMNH). Yakima Co., White Swan, 6 juvs., 7 May 1933, W. W. Baker (NMNH).
OREGON: Clatsop Co., Youngs R. Falls Pk., nr. Olney, F, 4 June 1991, R. M. Shelley (NCSM); and 3 mi (4.8 km) SE Olney, M, 27 November 1971, E. M. Benedict (WAS). Lane Co., 22 mi (35.2 km) NE McKenzie Bridge, M, F, 16 October 1971, E. M. Benedict (WAS).
The following literature record to Scytonotus sp. is considered referrable to S. bergrothi :
USA: WASHINGTON: Island Co., Sunnyside (Causey 19546).
Remarks — The long, barbed, acicular projection on the medial face of the endomerite curves ventrad distally in all males that I examined. Its length and curvature seem to be unique to, and pos- sibly diagnostic of, S. bergrothi, as the structure is much shorter and at most only slightly curved in males of the other western species.
As stated on the vial label and reported by Attems (1931), the type locality of S. pallidus, a synonym of S. bergrothi, is Mukilteo, Snohomish County, Washington, and not Vancouver Is- land, British Columbia, as reported by Chamberlin and Hoffman (1958). Attems (1931, 1940) confusingly records Nanaimo, Vancouver Island, under S. pallidus but states in the prior work that this is the locality of S. insulanus. I have not seen any males of S. bergrothi from Nanaimo, but Parksville and Errington are very near, and S. bergrothi as well as S. insulanus should be expected at Nanaimo.
Scytonotus insulanus and S. bergrothi occur sympatrically from southwestern British Columbia to just south of the Columbia River in Clatsop County, Oregon, although the latter is much more abun- dant in Washington. South of the Columbia River, only S. insulanus has been taken in the Coast Range and Willamette Valley of Or- egon to about the level of Corvallis, where it overlaps slightly the northern periphery of S. simplex (Figs. 19-20, 31). The species, therefore, tend to replace each other in western Oregon and Wash- ington, and as stated previously only S. insulanus is known defi- nitely from northern British Columbia and Alaska. Neither species has been encountered on the Queen Charlotte Islands, nor have uni- dentifiable juveniles been taken there. As this archipelago has been intensively sampled by arthropod biologists for many years, it seems that Scytonotus does not occur there.
Genus Scytonotus
31
Scytonotus simplex Chamberlin Figs. 15-16
Scytonotus simplex Chamberlin, 1941:16, pi. 3, fig. 30. Chamberlin
and Hoffman, 1958:73. Kevan, 1983:2969.
Type specimens — Male holotype, female allotype, and one male and one female paratypes (NMNH) collected by J. C. Chamberlin, 18 November 1939, at Days Creek, Douglas County, Oregon.
Diagnosis — Tibiae of legs 13-20 in males with distal lobes; endomerite moderately longer than tibiotarsus; medial lamina expand- ing into moderate-size flange for proximal 2/3 of length, indenting broadly, then expanding into moderate-size, acuminate, distal tooth; distal lamina bent nearly perpendicular to tibiotarsus, narrowly ex- panded basally, inner margin curving slightly bisinuately into sub- acuminate tip; lateral lamina located well distal to pulvillus, expanding into moderate-size basal lobe with lightly irregular margin, narrow- ing slightly, then expanding into sharply acute tooth distal to mid- length (Figs. 15-16); paranota of segments 5-9 reduced in females.
Variation — The distal lamina and the distal parts of the medial and lateral laminas are closely similar on all specimens, but the
proximal parts of the last two lamellae vary considerably. The breadth of the basal flange on the medial lamina is often narrow- er than in the illustrated male, and an individual from Del Norte
County, California, has a sharply acute tooth at the corner of the flange. The distal tooth on the medial lamina is also much larger
in the male from San Joaquin County, California. On the lateral
lamina, the basal serrated lobe varies considerably. In a male from Coos County, Oregon, it is longer and located more proximad; it is also longer and narrower in individuals from Trinity County, Cali- fornia. Conversely, it is much shorter and narrower in the San Joaquin County male and is barely detectable in one from Del Norte County.
Ecology — Labels with preserved samples indicate the following microhabitats for S. simplex : pine tree trunks after rain, hemlock duff, birch litter, and under wet leaves.
Distribution — Along the Pacific Coast from northern Lincoln County, Oregon, to San Francisco Bay and the northern San Joaquin Valley, California (Fig. 20). The range extends eastward onto the western slope of the Cascades in Lane, Douglas, and Jackson coun- ties, Oregon, and overlaps slightly both the main area and the Lane County population of S. insulanus (Fig. 31). Specimens were exam- ined as follows:
OREGON: Lincoln Co., 0.6 mi (0.9 km) NW Elk City, along Yaquina R., M, F, 20 December 1971, E. M. Benedict (WAS). 5.5 mi (8.8 km) E, 2.5 mi (4.0 km) S, Tidewater, along Alsea R., 3M,
32
Rowland M. Shelley
Figs. 19-20. Distributions of Scytonotus spp. along the Pacific Coast of North America. 19, distributions in Alaska and British Columbia. 20, dis- tributions in western Washington, Oregon, and California. Solid stars, S. insulanus; dots, S. bergrothi ; squares, S simplex; star in dot, S. inornatus; open stars, literature records of S. insulanus considered reliable; question marks, female or juvenile samples and literature records that could be either S. insulanus or bergrothi.
Genus Scytonotus
33
3 juvs., 14 September 1977, A. K. Johnson (NCSM); and 10 mi (16 km) SE Kernville, M, 9F, 17 February 1969, R. L. Westcott, J. S. Buckett (UCD); Saddleback Mtn., 2 juvs., 12 August 1959, J. C. Dirks-Edmonds (NMNH); between Tidewater and Waldport, juvs., 25 April 1937, M, 2F, 19 September 1946, J. C. Chamberlin (FSCA, NMNH). Tillamook Co ., Boyer, juv., date and collector unknown (NMNH). Benton Co ., 2.3 mi (3.7 km) NW Glenbrook, S. Fk. Alsea
R. , 2M, 8F, 4 December 1971, E. M. Benedict (WAS); and 0.5 mi (0.8 km) NW Glenbrook, S. Fk. Alsea R., F, 4 December 1971, E. M. Benedict (WAS). Lane Co., October 1927, and M, 1 November 1927, D. T. Jones (NMNH); 11 mi (17.6 km) W Eugene, 5M, F, 4 December 1971, E. M. Benedict (WAS); and Dexter, M, January 1970, J. S. Buckett (UCD). Douglas Co., 20 mi (32 km) E Reedsport, along Vincent Cr., 4M, F, 4 October 1968, J. Schuh (FSCA); 11 mi (17.6 km) E, 4 mi (6.4 km) S Alleghany, Millicoma Tree Farm, M, F, 21 November 1971, E. M. Benedict (WAS); 8 mi (12.8 km) W Scottsburg, juvs., 6 September 1970, M. R. Gardner, T. L. Slay (UCD); 7 mi (11.2 km) W Scottsburg, along Umpqua R., M, 11 December 1971, E. M. Benedict (WAS); 3.2 mi (5.1 km) NE Scotts- burg, 6M, F, 11 December 1971, E. M. Benedict (WAS); 9 mi (14.4 km) SW Cottage Grove, juvs., 23 August 1959, W. J. Gertsch, V. Roth (NMNH); 6 mi (9.6 km) S Cottage Grove, Di- vide, F, 28 April 1937, J. C. Chamberlin (NMNH); 8 mi (12.8 km) and 20 mi (32 km) NE Sutherlin, 2F, 13 March 1968, J. S. Buckett, M. R. Gardner (UCD); Tree Horn Cpgd., along OR hwy. 138 E of Steamboat, F, 10 June 1991, R. M. Shelley (NCSM); 4.5 mi (7.2 km) E Wells Cr. Ranger Sta., M, 11 December 1971, E. M. Benedict (WAS); nr. Roseburg, M, F, 30 September 1931, col- lector unknown (NMNH); Days Creek, 2M, 2F, 18 November 1939, J. C. Chamberlin (NMNH) TYPE LOCALITY; and 1 mi (1.6 km)
S, 2 mi (3.2 km) W Ash, 6M, 9F, 11 December 1971, E. M. Benedict (WAS). Coos Co., 2.5 mi (4.0 km) E. Bandon, along OR hwy. 425, 2M, F, 24 September 1978, A. K. Johnson (NCSM); 0.25 mi (0.4 km) N Boundary, M, 19 February 1972, E. M. Benedict (WAS); Myrtle Grove Cpgd., MM, FF, 13 February 1972, E. M. Benedict (WAS); and Charleston, juvs., 15 August 1947, I. Newell (NMNH). Jackson Co., Applegate, juvs., 20 August 1977, R. O. Schuster (UCD); and Ashland, juvs., 9 July 1929 and 29 August 1931, R. V. Chamberlin, W. Ivie (NMNH). Josephine Co., Oregon Caves Nat. Mon., 2F, 11 June 1991, R. M. Shelley (NCSM); and 1 mi (1.6 km) S O’Brien, M, 18 December 1971, E. M. Benedict (WAS). Curry Co., Port Orford, M, 19 August 1961, W. Suter (FSCA); Humbug Mtn., ca. 5 mi (8 km) S Port Orford, 7 juvs., 19
34
Rowland M. Shelley
August 1961, W. Suter (FSCA); Pistol River, juvs., 7 July 1951, B. Malkin (NMNH); 4 mi (6.4 km) S Pistol R., along US hwy 101, MM, FF, 12 February 1972, E. M. Benedict (WAS); and 2 mi (3.2 km) N Brookings, M, 31 September 1959, V. Roth (AMNH).
CALIFORNIA: Del Norte Co., 7 mi (11.2 km) ENE Gasquet, Patrick Cr. Cpgd., M, F, 21-22 December 1979, A. K. Johnson (NCSM); 5 mi (8 km) S Cresent City, juv., 8 September 1958, L. M. Smith (VMNH); and 6 mi (9.6 km) N. Klamath, juvs., 13 Au- gust 1953, G. A. Marsh, R. O. Schuster (UCD). Humboldt Co., 1.5 mi (2.4 km) NE Orick, Redwood Nat. Pk., Redwood Cr., M, 2F, 26 March 1977, A. K. Johnson (NCSM) and 2F, 1 June 1991, R. W. Baumann, Stark (BYU), along Panther Cr., 2M, F, 29 August 1981, A. K. Johnson (NCSM) and MM, FF, 29-30 August 1981,
D. G. Anderson (RNP), along Wolfe Cr., MM, FF, 27-28 Septem-
ber 1981, D. G. Anderson (RNP), and along Tom McDonald Cr., MM, FF, 11-12 September 1981, D. G. Anderson (RNP); Fickel Hill Rd., 3M, 18 September 1976, A. K. Johnson (NCSM); Big Lagoon, 2M, 2F, 13 August 1953, G. A. Marsh, R. O Schuster (NMNH) and F, 12 November 1974, A. K. Johnson (NCSM); Patrick Pt. St. Pk., M, 21 September 1964, J. & W. Ivie (AMNH); Trinidad, M, 16 July 1968, W. Ivie (AMNH); 2 mi (3.2 km) E Trinidad, 20 January 1976, A. K. Johnson (NCSM); 2 mi (3.2 km) S Hoopa, F,
29 June 1991, R. M. Shelley (NCSM); 14 mi (22.4 km) W Willow
Cr., 4 juvs., 21 August 1959, W. J. Gertsch, V. Roth (NMNH); Jolly Giant Cyn. nr. Areata, 2M, 23 November 1974, A. K. John- son (NCSM); Areata, 12 juvs., 23 July 1969, C. Slobodchikoff (CIS); Eureka, juvs., date unknown, H. S. Barber (NMNH) and 3 juvs., 13 July 1937, R. V. Chamberlin (NMNH); and Dyersville, juvs., date unknown, G. A. Marsh, R. O. Schuster (NMNH). Trinity Co., 1.5 mi (2.4 km) E Hawkin’s Bar, along CA hwy 229, 11M, F, 9
October 1976, A. K. Johnson (NCSM). Mendocino Co., 2.5 mi (4.0
km) N Mendocino, juvs., 30 June 1964, J. S. Buckett, M. R. Gardner (UCD); and Mendocino, juvs., 6 March 1957, J. R. Heifer, R. O. Schuster (NMNH) and M, 11 December 1969, J. R. Heifer (UCD). Sonoma Co., 1 mi (1.6 km) SE Bodega Bay, 3M, 3F, 5 October 1963, P. Rubtzoff (FSCA); Sebastopol, 5 juvs., 25 August 1957, R.
E. Darby (NMNH) and 2F, date and collector unknown (BMNH); and ca. 6 mi (9.6 km) NE Santa Rosa, Petrified For., juvs., 26 August 1931, W. Ivie (NMNH). Marin Co., Lagunitas, 2M, 9 Janu- ary 1965, J. S. Buckett, M. R. Gardner (UCD); 2 mi (3.2 km) N Bolinas, 6M, F, 22 September 1963, J. and W. Ivie (AMNH); Bolinas Jet., 21M, 2 juvs., 21 September 1965, W. Ivie (AMNH); Mill Valley, F, date and collector unknown (BMNH); 2 mi (3.2
Genus Scytonotus
35
km) W Inverness, 2F, 1 May 1976, J. T. Doyen (CIS); and Inverness Ridge, M, 17 November 1962, N. B. Causey (FSCA) and MM, FF, 9 October 1963, J. S. Bucket (UCD, FSCA). San Joaquin Co., Stockton, M, 27 October 1973, L. S. Hawkins (NCSM).
Remarks — The name of this species is puzzling and clearly a misnomer; the gonopod of S. simplex is hardly “simple” either alone or in comparison with those of the other species that had been proposed by 1941. One wonders about Chamberlin’s reasoning, be- cause the only species with truly “simple” gonopods is S. inornatus.
The Inornatus Group
A monobasic lineage, this group is characterized by an ab- sence of modifications that is most noticeable on the distal lamina. The medial lamina expands into a broad flange; the lateral lamina is long and slender; and the endomerite and tibiotarsus are subequal in length. The lineage is thus the most plesiomorphic in Scytonotus, and from its apparently restricted distribution, the lone component species appears to be a relict and the sole surviving remnant of its line. Such a nondescript, unmodified ancestral form could have given rise to both other lineages, and its occurrence on the eastern slope of the Cascades points to this general region as the likely source for the other lines and the primary center of evolution within Scytonotus.
Component, inornatus, new species.
Scytonotus inornatus, new species Figs. 17-18
Type specimens — Male holotype and one female paratype (FSCA) collected by J. Schuh, 25 October 1972, along a canal at Geary Ranch (exact location unknown), Klamath County, Oregon; four fe- male paratypes (FSCA) taken by same collector at same locality on 28 October 1971.
Diagnosis — Tibiae of legs 13-20 in males with distal lobes; endomerite subequal in length to that of tibiotarsus; medial lamina expanding into large, broadly rounded flange for most of length, overhanging and extending well beyond inner margin of endomerite; distal lamina with inner margin smoothly linear, without denticula- tions or other modifications, outer margin narrowing abruptly to subacuminate termination with inner; lateral lamina long and nar- row, expanding slightly proximad and distad but not overhanging inner margin of endomerite; paranota of segments 5-9 of females reduced.
Description — Head normal for genus, densely covered with short, fine, parallel-sided setae; epicranial suture distinct; genae extending well beyond adjacent cranial margins.
36
Rowland M. Shelley
Collum much narrower than succeeding tergites, not covering epicranium, with about six transverse rows of setose tubercles, mar- gins smooth. Remaining tergites with around four rows of setose tubercles, latter low and flattened, only slightly elevated above metater- gal surface, poorly demarcated from each other; setae relatively long and slender, parallel-sided for most of length, tapering distad, many apically falcate, curving caudad. Paranota narrow but distinct, sub- parallel to substrate, margins lightly scalloped, notches sharpest on anteriormost tergites, vestigial on segments 5 and 9 and absent from segments 6-8 of females. Epiproct short, subtriangular, setae very long and conspicuous, tubercles barely detectable.
Sterna generally granular in appearance, without modifications, postgonopodal sterna with slight bicruciform impressions. Tibiae of 13th legs in males with short, glabrous spurs on outer margins; legs 12-15 with strong, rounded lobes in same locations; legs 16- 18 with lobes diminishing progressively, absent on caudal legs.
Gonopodal aperture broad, obcordate, sides strongly elevated above metazonal surface. Gonopods in situ with telopodites leaning anteriad over coxae then curving broadly ventrocaudad over caudal margin of aperture, subparallel to each other. Gonopod structure as follows (Figs. 17-18). Coxa relatively small and narrow, with large lobe arising from medial surface extending over base of telopodite. Latter relatively small. Tibiotarsus of normal shape and appear- ance, curving broadly caudad. Endomerite subequal in length to that of tibiotarsus, closely appressed to latter for about half of length, diverging distad, with short, barbed, acicular projection arising ba- sally on inner side of medial surface, terminating well short of outer margin of endomerite; inner surface with relatively long, sharply acuminate spur just distal to, and slightly shorter than, pulvillus, latter relatively long, narrowing slightly distad, apically blunt; me- dial lamina expanding rapidly into large, broadly rounded lobe, ex- tending for most of length of structure, overhanging and extending well beyond inner margin of endomerite; distal lamina without modi- fications, inner and outer margins smoothly sublinear, latter angling rapidly to subacuminate termination with inner margin; lateral lamina relatively long, arising basally and extending for most of length of endomerite, expanding slightly proximad and distad.
Ecology — The available samples were taken from “mixed broadleaf duff.”
Distribution — Known only from Klamath County, Oregon (Fig. 20). The following sample was examined in addition to the types: Klamath Falls vie., F., March 1972, J. Schuh (FSCA).
Remarks — With no modifications on the distal lamina, only a broad flange on the medial one, and only two narrow expansions
Genus Scytonotus
37
on the lateral lamella, S. inornatus is the most pleisiomorphic known species. A hypothetical ancestral Scytonotus would resemble S. inornatus with a reduced medial lamina, and all other species of Scytonotus could have arisen from such an ancestral form. The species occurs east of the crest of the Cascade Mountains in the foothills on the boundary with the arid Basin and Range Physiographic Province. This area is much drier than those west of the crest where S. simplex and bergrothi occur. Presumably, the Geary Ranch is near Klamath Falls and is therefore in the Klamath River drainage, which flows westward and empties into the Pacific Ocean in southern Del Norte County, California.
Scytonotus sp.
To completely detail the generic distribution in the West, I record here the samples of Scytonotus that lack adult males and cannot be assigned to a species on a geographic basis. In Canada, coastal Washington, and Oregon, the records could refer to either S. insulanus or bergrothi, and the Stevens County, Washington, literature record (Causey 1954b) could be either S. piger or S. columbianus. These records are indicated by question marks in Figures 10 and 19-20.
CANADA: BRITISH COLUMBIA: VANCOUVER ISLAND: Courtenay, F, juv., June 1965, N. L. H. Kraus (NMNH). Robson Bight, Tsitika R., 2 juvs., 28 July 1986, D. H. & J. L. Kavanaugh (CAS). Little Qualicum Falls Prov. Pk., 2 juvs., 30 July 1989, R. M. Shelley (NCSM). 5 km NE Port Renfrew, 2F, 31 July 1989, R. M. Shelley (NCSM). Goldstream Prov. Pk., F, 2 August 1989, R. M. Shelley (NCSM).
MAINLAND SITES: Shannon Falls Prov. Pk., FF, juvs., 29 July 1989, R. M. Shelley, (NCSM). Along hwy. 99, 132 mi (21 km) N Squamish, FF, juvs., 29 July 1989, R. M. Shelley (NCSM). Capilano Cyn. Reg. Pk., 4F, 28 July 1989, R. M. Shelley (NCSM). 1.9 mi (3 km) SE Elope, along Silver Skagit Rd., F, 30 June 1988, S. & J. Peck (NCSM). Ten Mile, exact location unknown, juv., 20 June 1903, R. F. Currie (NMNH).
USA: WASHINGTON: Jefferson Co., Olympic Nat. Pk., Graves Cr. Cpgd., 2F, 25 August 1990, R. M. Shelley (NCSM). Grays Harbor Co., along Moclips R., 6.4 mi (10.2 km) W US hwy. 101, F, juv., 25 August 1990, R. M. Shelley (NCSM).
OREGON: Hood River Co., Perham Cr., 5F, 2 juvs., 4 Au- gust 1929, collector unknown (NMNH); and 4 mi (6.4 km) S Parkdale,
38
Rowland M. Shelley
Dog R. Tr. #35, juv., 3 June 1991, R. M. Shelley (NCSM). Dou- glas Co ., Comstock, 4 juvs., 10 September 1935, R. V. Chamberlin (NMNH). County Unknown, Three Rocks, 2F, 31 May 1942, J. C. Chamberlin (NMNH).
Literature records to Scytonotus sp. by Causey (1954b) that cannot be assigned on a geographic basis are as follows:
USA: WASHINGTON: San Juan Co., Doubleneck. Snohomish Co., Edmonds. Stevens Co., Evans.
THE EASTERN SPECIES The Granulatus Group Scytonotus granulatus (Say)
Figs. 21-22
Polydesmus granulatus Say, 1821:107. Gervais, 1847:104-105. Wood, 1865:214-215, fig. 41. Bollman, 1893:146. Kenyon, 1893a:161; 18936:15.
Scytonotus scabricollis Koch, 1847:130; 1863:41-42, fig. 164. Bollman 1893:150-151. Attems, 1898:257; 1940:159.
Scytonotus laevicollis Koch, 1847:131; 1863:41, fig. 163. Bollman 1893:151. Cook and Cook, 1894:235. Attems, 1898:257; 1940:159. Scytonotus nodulosus Koch, 1847:131; 1863:43, fig. 165. Bollman, 1893:122, 151. Cook and Cook, 1894:235-236. Attems, 1898:257; 1940:159. Bailey 1928:20. Chamberlin and Hoffman, 1958:76. Stenonia hispida Sager, 1856:109.
Polydesmus setiger Wood, 1865:213-214. McNeill, 1888:5.
Scytonotus cavernarum Bollman, 1887:45; 1888^:407; 1893:122. Attems, 1898:257. Chamberlin and Hoffman, 1958:76.
Scytonotus granulatus : Bollman, 1887:47; 1888a:407; 1893:108, 122, 182, 184. Cook and Cook, 1894:238-246, pis. 6-9, figs. 1-41, 46-62, 64-71. Attems, 1898:256-257; 1940:156. Morse, 1902:187. Gunthorp, 1913:163. Bailey, 1928:20. Williams and Hefner, 1928:111, fig. 12B. Brimley, 1938:499. Dearolf, 1938:66. Chamberlin, 1928:155; 1940:56, 1942:16; 1947:24; 1952:558. Loomis, 1939:192. Rapp, 1946:666. Hoffman, 1950a:fig. 1; 19506: 30-31; 19626:243-245, fig. 1. Causey, 1952:145; 1955:22. Johnson, 1954:248, figs. 23-24. Chamberlin and Hoffman, 1958:72-72. Wray, 1967:150. Shelley, 1978:61, figs. 48-49; 1988:1653, fig. 29. Filka and Shelley, 1980:25, fig. 41. Kevan, 1983:2969. Scytonotus setiger : Bollman, 18886:340. Cook and Cook, 1894:237. Scytonotus cavernarus: Cook and Cook, 1894:237.
Lasiolathus virginicus: Loomis, 1944:175.
Scytonotus sp. Judd, 1967:192.
Genus Scytonotus 39
S. v. virginicus. 23, left gonopod of male from Albemarle County, Vir- ginia, medial view. 24, the same, lateral view. 25-26, S. v. michauxi. 25, telopodite of left gonopod of male from Yancey County, North Carolina. 26, the same, lateral view. 27-28, S. austrialis. 27, telopodite of left gonopod of male from Macon County, North Carolina, medial view. 28, the same, lateral view. Scale line = 0.5 mm for all figures.
40
Rowland M. Shelley
Type specimens — Not known to exist, although part of the type series may be extant at the BMNH. The type locality is the vicin- ity of Philadelphia, Philadelphia County, Pennsylvania.
Diagnosis — Tibiae of legs 13-20 in males with distal lobes; tibiotarsus and endomerite essentially subequal in length, former slightly longer; medial lamina expanded into broadly rounded flange extend- ing most of length of lamina, overhanging inner margin of endomerite; distal lamina with minute apical tooth preceded by two narrowly segregated teeth; lateral lamina expanding into narrow, flange, mar- gin irregular, with one or two variable teeth (Figs. 21-22); females with paranota of segments 5-9 reduced.
Variation — Hoffman (1962b) noted that S. granulatus maintains its structural integrity over the entire range and that he could not discern geographically variable details. In spot-checking samples from across the range, I can corroborate Hoffman’s observation: I found only minor differences in the sizes of the flanges on the medial and lateral laminas as well as in the size and degree of separation of the teeth on the distal lamina.
Ecology — I have encountered S. granulatus in a variety of mi- crohabitats and believe it can be expected in most moist environ- ments within its range; those with a preponderance of deciduous litter are more probable than those with a higher proportion of pine litter. The milliped will likely be found well within the litter, on the undersides of leaves or pieces of wood and bark.
Distribution — Covering almost the entire generic distribution in eastern North America, ranging from the vicinities of Trois Rivieres, Quebec, and Sault St. Marie, Ontario, to central South Carolina, central Tennessee, and northeastern Arkansas, and east/west, from Vermont, coastal Virginia, and the Outer Banks of North Carolina to eastern Kansas and Nebraska (Fig. 29). The only part of the eastern generic range that is not inhabited by S. granulatus is the Blue Ridge Province from northern Virginia to north Georgia, where it is replaced by the endemic species, S. virginicus and australis. The distribution encompasses parts or all of a dozen physiographic provinces and 16 states, 6 of which — Pennsylvania, West Virginia, Kentucky, Ohio, Indiana, and Illinois — are wholly within its range. Specimens were examined as summarized below. Complete locality data are provided for states and Canadian provinces where S. granulatus is known from five or fewer counties; the latter are listed in alphabetical order when the milliped has been collected in more than five counties.
CANADA: QUEBEC: Drummond Co., Drummondville, MM, FF,
Genus Scytonotus
41
4 April 1977, L. LeSage (NCSM). Nicolet Co., Becancour, Bois de Fevillus, Erublet Tremble, MM, FF, 16 June 1979, L. LeSage (NCSM).
ONTARIO: Algoma, Durham, Lanarck, Peterborough, Prescott and Russell, and York cos. (CNC, GLFRS, NCSM, ROM).
USA: VERMONT: Chittenden Co., Milton, M, 6 September 1975, J. Kantor (UVT). Windsor Co., Hartland, M, 4 November 1961, D. P. Moorman (UVT).
NEW YORK: Monroe Co., Ellison Park, M, F, 31 March 1963, collector unknown (NMNH). Onandaga Co., Syracuse, M, F, 8 August 1960. L. C. Stegman (FSCA); and E. Onadaga, F, 15 September 1904, R. V. Chamberlin (MCZ). Tompkins Co., Ithaca, along 6 Mile Cr., M, 8 May 1951, R. E. Crabill (VMNH). Chemung Co., Elmira, M, 29 March 1948, R. E. Crabill (VMNH).
NEW JERSEY: Essex Co., Caldwell, juvs., 12 April 1887, collector unknown (NMNH).
PENNSYLVANIA: Armstrong, Berks, Bucks, Centre, Mont- gomery, and Washington cos. (AMNH, ILNHS, MCZ, PSU).
MARYLAND: Alleghany, Anne Arundel, Frederick, Garrett, Prince Georges, and Queen Annes cos. (ILNHS, NCSM, NMNH, VMNH).
DISTRICT OF COLUMBIA: Catholic Univ., 3M, 2F, April and October 1893, collector unknown (NMNH). Glen Sligo, F, April 1898, collector unknown (NMNH). Rock Creek Park, F, 8 Novem- ber 1928, O. F. Cook (NMNH).
WEST VIRGINIA: Gilmer Co., Cedar Creek St. Pk., M, 22 October 1969, collector unknown (NCSM). Greenbrier Co., Green- brier St. For., 2M, F, 28 April 1973, W. A. Shear (WAS). Raleigh Co., Horse Cr., exact location unknown, juvs., 21 March 1966, J. Miller (WAS). Monroe Co., nr. Greenville, along Laurel Cr., M, 16 April 1972, W. A. Shear (WAS). Mercer Co., Speedway, along WV hwy. 20, M, F, 16 April 1966, J. Miller (WAS); and Athens, juvs., 16 May 1966, B. Carter (WAS), and M, 12 March 1967, W. A. Shear (WAS).
VIRGINIA: Albemarle, Alleghany, Appomattox, Arlington, Augusta, Bath, Bland, Botetourt, Dickenson, Fairfax, Giles, Halifax, Mecklenburg, Prince Edward, Princess Anne, Pulaski, and York cos. (AMNH, NCSM, NMNH, VMNH, WAS).
NORTH CAROLINA: Beaufort, Cabarrus, Carteret, Chatham, Cumberland, Dare, Durham, Gaston, Guilford, Halifax, Harnett, Lincoln, Montgomery, Onslow, Orange, Person, Richmond, Rockingham, Stanly, Surry, Vance, and Wake cos. (FSCA, NCSM, NMNH).
SOUTH CAROLINA: Orangeburg Co., Orangeburg, F, 28
42
Rowland M. Shelley
October 1929, O. F. Cook (NMNH).
MICHIGAN: Presque Isle Co., Ocquecoc Falls, F, 11 July 1949, Etges (FSCA). Livingston Co., E side George Res., M, 2F, 14 October 1949, K. Bohnsack (UMMZ) and 5 juvs., date unknown, E. Pruitt (MCZ). Berrien Co., Stevensville Swamp, M, 4 May 1962,
L. Lowry, H. Kamizge, W. Suter (FSCA); and Lakeside, Warren Woods, M, 3 October 1959, W. Suter (FSCA).
OHIO: Wayne Co., Wooster and vie., MM, FF, juvs., 1959- 1982, A. A. Weaver (NCSM). Champaign Co., Pat Frances St. Mem.,
M, 1973, K. Menders (OHS). Franklin Co., Snow Cave, M, 20 October 1979, M. Flynn (OHS). Hocking Co., Cantwell Cliffs, M, 29 September 1963, F. A. Coyle (NCSM); and Rock House St. Pk., M, 21 April 1962, W. A. Shear (WAS). Fairfield Co., Barnabey Ctr., 2M, 12 May 1984, collector unknown (SDMNH).
INDIANA: Grant, Greene, Howard, Lawrence, Marion, Monroe, Newton, Porter, Putnam, Tippecanoe, and Wells cos. (FSCA, ILNHS, MNHP, NMNH, UCD, UMMZ).
KENTUCKY: Bell, Boyd, Carter, Edmonson, Estill, Fayette, Hart, Metcalf, and Wolfe cos. (FSCA, ILNHS, NCSM, VMNH, WAS).
TENNESSEE: Anderson, Bledsoe, Blount, Cumberland, Frank- lin, Knox, Roane, Sevier, and Washington cos. (FSCA, MCZ, NMNH, VMNH).
WISCONSIN: Adams, Crawford, Dane, Fon du Lac, Grant, Ozaukee, Rock, Richland, Sauk, Sheboygan, Trempealeau, Vernon, Walworth, and Washington cos. (FSCA, ILNHS, MCZ, TMM, WAS).
ILLINOIS: Alexander, Carroll, Champaign, Clark, Coles, Cook, Crawford, Jackson, Kendall, Lake, LaSalle, Logan, Madison, Mason, McLean, Peoria, Piatt, Pope, Putnam, Randolph, Richland, Union, Vermillion, and Winnebago cos. (AMNH, EIL, ILNHS, ILSU, MCZ, NMNH, UCD, VMNH).
MINNESOTA: Washington Co., along St. Croix R., 2M, 2F, 10 May 1941, M. Wing (UMN). Hennepin Co., Minneapolis, FF, 1932, W. J. Gertsch (NMNH); and Ft. Snelling, M, F, date un- known, C. H. Bollman (NMNH) and M, 22 October 1931, A. C. Hodson (UMN). Rice Co., Northfield, Carleton Arboretum, M, 11 October 1953, A. R. Brummett (FSCA). County Unknown. Tama- rack Bog, M, F, 31 May 1931, A. C. Hodson (UMN).
IOWA: Delaware Co., Backbone St. Pk., F, 28 August 1954, L. Hubricht (VMNH); and Colesburg, Ellis Park, F, 10 April 1983, collector unknown (MCZ). Boone Co., Ledges St. Pk., M, 2 May 1961, D. P. Hansen (VMNH) and 2M, 3F, 10 April 1984, R. M. Shelley, R. L. Lewis (NCSM). Storey Co., Ames, F, 27 April 1957, A. H. Barnum (DC).
Genus Scytonotus
43
MISSOURI: Boone, Callaway, Chariton, Cole, Dent , and Phelps cos. (AMNH, ANSP, FSCA, PSU).
ARKANSAS: Craighead Co., Jonesboro, M, 26 November 1966, M. Hite (FSCA).
KANSAS: Douglas Co., Lawrence, M, 18 December 1947, M. W. Sanderson (ILNHS).
The following additional literature records are deemed valid and are denoted by open symbols in Figure 29.
CANADA: ONTARIO: Middlesex Co., London and vie. (Judd 1967).
USA: VIRGINIA: Montgomery Co., Elliston (Hoffman 1947).
Fig. 29. Distribution of S. granulatus.
44
Rowland M. Shelley
INDIANA: Clark Co., New Providence (Bollman 1888a). Hamilton Co., Westfield (Bollman 1888a). Washington Co., Salem (Bollman 1888a).
OHIO: Gallia Co., Vinton (Morse 1902).
KENTUCKY: Grant Co., Crittenden (Loomis 1944, Hoffman 1947). Hopkins Co., Nortonville (Causey 1955). County unknown, Indian Cave (Dearolf 1938).
TENNESSEE: Jefferson Co., Mossy Cr. (Bollman 1888 b).
ILLINOIS: Will Co., Monee (Chamberlin 1952).
MINNESOTA: Winona Co., Winona (Bollman 1893).
IOWA: Warren Co., Indianola (Chamberlin 1942).
MISSOURI: St. Charles Co., St. Charles (Chamberlin 1928).
NEBRASKA: Cass Co., Weeping Water (Kenyon 1893b). Richardson Co., Rulo (Kenyon 1893b).
KANSAS: Shawnee Co., locality not specified (Gunthorp 1913).
Scytonotus virginicus (Loomis)
Diagnosis — Tibiae of legs 13-20/22 of males without distal lobes; tibiotarsus and endomerite subequal in length; medial lamina with two distinct teeth, segregated to varying distances; distal lamina with two or three teeth, an apical tooth followed by one or two moder- ately segregated teeth; lateral lamina varying in length but with a strong proximal spine; females with paranota of segments 5-9 not reduced.
Remarks — Hoffman (1962b) distinguished S. virginicus and michauxi by the degree of segregation of the teeth on the medial lamina (narrow in the former, wide in the latter) and by the pres- ence of two ( virginicus ) or three ( michauxi ) teeth on the distal lamina. Although Chamberlin and Hoffman (1958) reported that S. virginicus ranged southward through the Blue Ridge Province to Linville Falls, Burke County, North Carolina, Hoffman (1962b) stated that the species was unknown on the Blue Ridge south of the Roanoke River and assigned the name michauxi to forms in North Carolina. Material secured in the past 30 years shows that these two forms intergrade in southwestern Virginia from Mt. Rogers, Gray- son County, to Pinnacles of Dan, Patrick County, and hence that they are only subspecifically related. As S. virginicus is the older name, michauxi is reduced to subspecific status.
Scytonotus virginicus virginicus (Loomis), new status
Figs. 23-24
Lasiolathus virginicus Loomis, 1943:319-320, fig. 1.
Scytonotus granulatus (nec Say): Hoffman, 1947:140.
Genus Scytonotus
45
Scytonotus virginicus : Hoffman, 1950a:220; 19626:247, fig. 5. West, 1953:123-176, figs. 1-41. Chamberlin and Hoffman, 1958:73. Type specimens — Juvenile male holotype (MCZ) and one juve- nile male paratype (NMNH) collected by H. F. and E. M. Loomis, 13 July 1937, at Thornton Gap, Page/Rapahannock counties, Vir- ginia.
Diagnosis — Teeth on medial lamina narrowly segregated; distal lamina with two teeth; lateral lamina relatively short, terminating well short of midlength of endomerite (Figs. 23-24.).
Ecology — Expected in moist litter anywhere within the known range, hardwood detritus being more likely than pine.
Distribution — The Blue Ridge Province of Virginia from War- ren to Bedford counties including Shenandoah National Park (Fig. 30). Specimens were examined as follows:
VIRGINIA: Warren Co., Shenandoah Natl. Pk., N end of Sky- line Dr., MM, FF, 24 September 1945, collector unknown (NMNH). Page/Rapahannock cos., Thornton Gap, off US hwy. 211, Shenandoah Nat. Pk., M, 29 March 1949, R. L. Hoffman (VNMH) TYPE LO- CALITY. Albemarle Co., Sugar Hollow, 6 mi. (9.6 km) W Whitehall, 6M, 10F, juv., 21 March and 9 April 1949, R. L. Hoffman (VMNH). Nelson Co., 4 mi (6.4 km) S Afton, Humpback Mtn. M, F, 14 October 1948, R. L. Hoffman (VMNH). Botetourt Co., 2 mi (3.2 km) E Arcadia, jet. VA hwys. 59 and 782, F, 6 March 1976, R. L. Hoffman (VMNH); and 1.3 mi (2.1 km) E Arcadia, along North Cr., 2M, 2F, 13 October 1973, R. L. Hoffman (VMNH). Bedford Co., Flat Top Mtn., 4M, 5F, 15 April 1951, L. Hubricht (VMNH); and Peaks of Otter, M, 15 October 1955, R. L. Hoffman (NMNH).
Scytonotus virginicus michauxi Hoffman, new status
Figs. 25-26
Scytonotus granulatus (nec Say): Chamberlin, 1940:56. Wray, 1950:150; 1967:150.
Scytonotus virginicus (nec Loomis): Wray, 1950:150; 1967:150. Scytonotus michauxi Hoffman, 19626:247-249, fig. 6.
Type specimens — Male holotype and one male paratype (NMNH) collected by L. Hubricht, 26 June 1950, on Roan Mountain, Carter County, Tennessee.
Diagnosis — Teeth on medial lamina widely separated; distal lamina with three teeth; lateral lamina relatively long, extending well be- yond midlength of endomerite (Figs. 25-26).
Ecology — Same as for the nominate subspecies.
Distribution — The Blue Ridge Province of North Carolina and Tennessee from the Virginia state line to the Great Smoky Moun- tains (Fig. 30). Specimens were examined as follows:
46
Rowland M. Shelley
NORTH CAROLINA: Ashe Co., 2.8 mi (4.5 km) W Warrensville, M, 5F, 18 October 1953, L. Hubricht (VMNH). Watauga Co., Blowing Rock, Residence on Goforth Rd., 0.5 mi (0.8 km) N US hwy. 321, juvs., 16 October 1971, R. M. Shelley (NCSM). Avery Co., Linville, Grandfather Mtn., M, 2F, 1939, collector unknown (NMNH). Burke Co., Linville Falls, M, 7 April 1949, D. L. Wray (VMNH). Mitchell Co., Summit of Roan Mtn., M, 11 October 1975, J. C. Clamp (NCSM); and Roan Mtn., below Carver’s Gap, along NC hwy. 261, M, F, juvs., 23 September 1950, L. Hubricht (VMNH). McDowell Co., nr. entrance to Black Mtn. cpgd. off NC hwy. 80, M, F, 11 October 1975, J. C. Clamp (NCSM). Yancey Co., Stepps Gap, Black Mtns. 2M, F, 26 May 1962, L. Hubricht (VMNH); Crabtree Mead- ows Rec. Area along Blue Ridge Pkwy., 4M, 6F, 30 October 1971, R. L. Hoffman, L. S. Knight (VMNH); and Mt. Mitchell, M, F, 17 August 1955, A. Van Pelt (VMNH), MM, F, 16 October 1965, J. & W. Ivie (AMNH), MM, FF, 1 November 1969, W. A. Shear (WAS), and 3M, 13 May 1970, F. A. Coyle (NCSM). Madison Co., 0.5 mi (0.8 km) W Windy Gap, E of Faust, F, 13 September 1952, L. Hubricht (VMNH). Swain Co., Great Smoky Mtns. Nat. Pk. precise locality unknown, M, 20 May 1961, R. E. Woodriff (FSCA).
TENNESSEE: Carter Co., Roan Mtn., 8M, 5F, 26 June 1950,
L. Hubricht (NMNH, VMNH) TYPE LOCALITY; and 1 mi N. Hampton, Doe R. Bluffs, M, 3 May 1951, L. Hubricht (VMNH). Sevier Co., Great Smoky Mtns. Nat. Pk., Rainbow Falls Tr., 27 September 1978, G. Summer (NCSM); and 2 mi (3.2 km) NNW Newfound Gap, 6M, F, 13 October 1970, W. A. Shear (WAS).
Scytonotus virginicus intergrades
The intergrade specimens are quite variable. Some have only an intermediate degree of segregation of the teeth on the medial lamina, whereas others have the characters of one race on the me- dial lamina and those of the other on the distal lamina.
Distribution — The southern extremity of the Blue Ridge Prov- ince in Virginia (Fig. 30). Specimens were examined as follows:
VIRGINIA: Smythe Co., north side of Whitetop Mtn., along VA hwy. 600, 2M, 2F, 4 May 1964, R. L. Hoffman (VMNH). Grayson Co., S slope of Mt. Rogers, 3M, 2F, juv., 20 October 1963, R. L. Hoffman (VMNH). Wythe/Grayson cos., vie. of Comer’s Rock, Iron Mtn. M, 12 December 1965, R. L. and L. Hoffman (VMNH). Patrick Co., 4 mi (6.4 km) SW Vesta, Pinnacles of Dan,
M, 9 April 1978, R. L. Hoffman (VMNH).
Genus Scytonotus
47
Fig. 30. Distributions of Scytonotus spp. in and near the Blue Ridge Physiographic Province; some symbols denote more than one locality. Squares, S. granulatus; upright triangles, S. v. virginicus; inverted triangles, 5. v. michauxi; X’s, S. virginicus intergrades; dots, S. australis; question mark, S. australis x v. michauxi hybrid.
Scytonotus australis Hoffman Figs. 27-28
Scytonotus granulatus (nec Say): Hoffman, 19506:30-31.
Scytonotus australis Hoffman, 19626:245-247, fig. 4.
Type specimens — Male holotype and one female paratype (NMNH) collected by L. Hubricht, 6 November 1960, from a ra- vine 6 mi (9.6 km) W Amicalola Falls, Dawson County, Georgia.
Diagnosis — Tibiae of legs 13-20/22 of males without distal lobes; tibiotarsus slightly longer than endomerite; medial lamina moder- ately expanded basally, with or without strong indentation at midlength,
48
Rowland M. Shelley
with strong apical tooth; distal lamina with two broad, subequal teeth; lateral lamina narrowly expanded basally, without modifica- tions (Figs. 27-28); females with paranota of segments 5-9 not reduced.
Ecology — As with the other eastern species, S. australis may be anticipated in moist habitats throughout its range, those with higher proportions of deciduous trees being more likely than those that are predominantly pine.
Distribution — The southern Blue Ridge Province from Buncombe County, North Carolina, to White and Dawson counties, Georgia, extending westward to the western periphery of the Great Smoky Mountains in Sevier County, Tennessee, and eastward onto the western periphery of the Piedmont Plateau in Oconee County, South Caro- lina, and Rutherford County, North Carolina (Fig. 30). The range very slightly overlaps the southern extremity of that of S. v. michauxi (Figs. 30, 32). Specimens were examined as follows:
NORTH CAROLINA: Buncombe Co ., Asheville, F, 5 Septem- ber 1961, R. L. Hoffman (VMNH); 4 mi (6.4 km) N Oteen, M, 16 October 1975, J. & W. Ivie (AMNH); and 20 mi (32 km) SW Asheville, foothills nr. Mt. Pisgah, M, 15 October 1965, J. & W. Ivie (AMNH). Buncombe/Haywood cos., Mt. Pisgah, M, 4F, 7 April 1949, D. L. Wray (VMNH). Henderson Co., Tuxedo, along co. rd. 1852, 6 mi (9.6 km) N jet. co. rd. 1850, M, 30 October 1975, R. M. Shelley (NCSM). Polk Co., 2 mi (3.2 km) NW Columbus, along co. rd. 1136, M, 15 October 1973, R. M. Shelley (NCSM). Ruther- ford Co., Rutherfordton, F, 15 October 1973, R. M. Shelley (NCSM). Transylvania Co., 4.9 and 5.7 mi (7.8 and 9.1 km) NW Brevard, 2M, 2F, 29 August 1973, R. M. Shelley (NCSM); nr. L. Toxaway, head of Thompson R. Gorge, 30 juvs., 5 September 1961, R. L. Hoffman (VMNH); and 12 mi (19.2 km) SW Rosman, along co. rd. 1152, 0.8 mi (1.3 km) N jet. co. rd. 1151, F, 28 August 1973, R. M. Shelley (NCSM). Jackson Co., Wolf Cr. Biol. Pres., Cullowhee Mtn. Rd., M, 10 June 1970, F. A. Coyle (NCSM). Ma- con Co., Highlands, 6M, 10F, 19 October and 16 November 1961, R. L. Hoffman (VMNH); and Coweeta Hydrologic Sta., 4M, 3F, 27 September 1964, H. R. Steeves (FSCA) and M, F, 31 March-28 April 1978, L. Reynolds (NCSM). Swain Co., 0.5 mi (0.8 km) N Oconoluftee Ranger Sta., Mingus Mill Cr., Great Smoky Mtns. Nat. Pk., 2M, 3F, 23 November 1973. F. A. Coyle (NCSM). Cherokee Co., 7.2 mi (11.5 km) NW Murphy, along co. rd. 1326, 0.3 mi. W jet. co. rd. 1406, juv., 27 July 1974, R. M. Shelley (NCSM); and 7.7 mi (12.3 km) WNW Culberson, along co. rd. 1137, 0.6 mi W jet. US hwy. 64, F, 27 July 1974, R. M. Shelley (NCSM).
Genus Scytonotus
49
Fig. 31. Comparative distributions of species of Scytonotus in western North America. 1, insulanus ; 2, bergrothi; 3, simplex ; 4, inornatus; 5, columbianus; 6, piger. The boundary line of 5. insulanus is continued through the ocean off British Columbia and Alaska to show that the dis- tribution excludes the Queen Charlotte Islands.
50
Rowland M. Shelley
TENNESSEE: Sevier Co., Gatlinburg, M, F, date and collector unknown (NMNH).
SOUTH CAROLINA: Oconee Co., Clemson, F, 22 December 1966, J. A. Payne (VMNH). Pickens Co., Burnt Mtn., F, 6 Novem- ber 1960, L. Hubricht (VMNH).
GEORGIA: White Co., 2.7 mi (4.3 km) N Robertsville, F, 12 March 1961, L. Hubricht (VMNH). Dawson Co., 6 mi (9.6 km) W Amicalola Falls, 3M, 8F, 6 November 1960, L. Hubricht (NMNH, VMNH) TYPE LOCALITY; and 6 mi (9.6 km) SW ' Dawsonville, F, 8 April 1961, L. Hubricht (VMNH).
Remarks — The record of juveniles from Highlands, Macon County, North Carolina, that Hoffman (1950a, 19626) assigned to S. granulatus and michauxi, respectively, is properly referrable to S. australis.
Scytonotus australis X S. virginicus michauxi hybrid
The gonopods of a male from the Great Smoky Mountains National Park, North Carolina/Tennessee, show features of both S. australis and v. michauxi. The distal lamina is clearly that of the former; the lateral lamina is clearly that of the latter; and the me- dial lamina combines aspects of both, with a distal tooth like that of the population of S. australis in the “Smokies,” and with a smaller, proximal tooth so that the lamella has two teeth as in S. v. michauxi. As all other samples from this area are clearly one species or the other, I do not think this one individual suffices to overturn my conclusion that these forms are specifically distinct; hence, I record it as a hybrid. The sample emphasizes the need for more material from the borderline counties in southwestern North Carolina and southeastern Tennessee. Data are as follows: the site is denoted by a question mark in Figure 30.
NORTH CAROLINA/TENNESSEE: Swain/ Sevier cos., Clingman’s Dome summit, M, F, 24 October 1969, W. A. Shear (WAS).
Distribution
The generic range is characterized earlier in this work and need not be repeated, but it is informative to examine the distribu- tions of the species and lineages (Figs. 31-33), and their spatial relationships. As shown in Figures 31-32, the species-group taxa demonstrate allopatric and parapatric spatial relationships with mini- mal range overlaps, except for the high level of sympatry between S. insulanus and bergrothi (Fig. 31, nos. 1 and 2, respectively) on Vancouver Island, the southwestern mainland of British Columbia, and western Washington. Large gaps exist between S. granulatus in the east and S. piger in the west (about 984 mi [1590 km]),
Genus Scytonotus
51
Fig. 32. Comparative distributions of species and subspecies of Scytonotus in eastern North America. 7, granulatus\ 8, australis ; 9, v. michauxi; 10, v. virginicus\ 11, virginicus intergrades.
between the two areas occupied by S. piger (approximately 274 mi [438 km]), and between the main range and the allopatric popula- tion of S. insulanus in southeastern Washington (around 208 mi [333 km]). Smaller distances separate apparently allopatric popula- tions of S. insulanus and bergrothi in Oregon’s Lane and Douglas counties, respectively, from the main areas of their ranges. Scytonotus is therefore cohesive along the Pacific Coast and demonstrates at- tributes of a small mosaic (see Shelley and Whitehead 1986, Shelley
52
Rowland M. Shelley
1989), although it is beginning to fragment as evidenced by the segregated populations of S. insulanus and bergrothi. Scytonotus is likewise cohesive in the east, particularly in the Blue Ridge Prov- ince, but the overall generic picture is so dominated by the three large lacunae and the three areas of the granulatus group (Fig. 33), as to create the impression of a highly dissected taxon. The bergrothi group, the only lineage west of the Cascades, is restricted to the Pacific Coastal region aside from the small area of S. insulanus in southeastern Washington; the inornatus group, essentially parapatric to the bergrothi group and S. simplex , and the allopatric granulatus group cover the other areas east of the Cascades. The absence of lacunae in the bergrothi group, in contrast to the granulatus group, suggests more recent evolution. The essentially parapatric occurrence of S. inornatus, the most plesiomorphic species, coupled with the nearly total dominance of the granulatus group to the east, point to the general area of the Cascades in southern Oregon as the primary source area or center of evolution. A secondary center exists in the Blue Ridge Province, and the distribution of S. granulatus appears to have been “unzipped” in a northeastwardly direction along the spine of the Blue Ridge beginning in north Georgia (Fig. 32). The greater distribution of S. australis and its spreading beyond the moun- tains onto the western periphery of the Piedmont Plateau suggest that it evolved first among the Blue Ridge endemics and has had time to expand and to attain reproductive isolation. In contrast, its younger counterparts to the north are still linked by intergrades and display progressively narrower ranges within the confines of this physiographic province.
Relationships
Generic — A cladistic analysis of genera in the Polydesmidae is beyond the scope of this work and is also impossible today, as many genus-group taxa are poorly known and consist of only one or two species. Many decades will doubtlessly pass before the al- pha taxonomy of the family is sufficiently stable to allow such an effort. Hoffman (1979) did not even attempt to divide the family into subfamilies, merely listing the component genera in alphabetical order and inadvertently omitting two monobasic ones: Mastodesmus Carl, 1911, from Java, as noted by Golovatch (1991), and Alpertia Loomis, 1972, from Washington state, United States. Consequently, only the most tenuous surmisals are possible about the affinities of Scytonotus. With two branches to the telopodite, it differs from the other native Nearactic polydesmid genera, so its relationships must lie with taxa on other continents, and Cook (1911) suggested, but
Genus Scytonotus
53
Fig. 33. Comparative distributions of species groups of Scytonotus. 1, the inornatus group; 2, the bergrothi group; 3, the granulatus group. The boundary line of the bergrothi group is continued through the ocean off British Columbia and Alaska to show that the range excludes the Queen Charlotte Islands.
did not formally propose, separate family status. Hoffman (19626) mentioned that this two-branched development might be homologous to that in some European species of Polydesmus, for example P. inconstans Latzel, which has been introduced into North America and occurs in many American and Canadian cities. Golovatch (1991) suggested that the Asian genera Schizoturanius Verhoeff and Turanodesmus Lohmander, from Kirgizstan and Turkestan, respec- tively, might be allied to Scytonotus because they also possess the two-branched structure. As illustrated by Attems (1940), the gonopods of T. stummeri (Attems) and T. inermis Lohmander resemble the basic structure of Scytonotus , so Golovatch’s idea seems plausible
54
Rowland M. Shelley
and should be evaluated when an analysis of the Polydesmidae becomes possible.
Specific — The species groups, or major components, are natural entities that could be regarded as subgenera, and all three could conceivably have arisen from an ancestral form similar to S. inornatus, considered the most plesiomorphic species because of the unmodified distal and lateral laminae. Evolution of the toothed and prolonged conditions of the distal lamella from such a nondescript structure is easily envisioned, whereas it is difficult to imagine the reverse, with either of the former configurations giving rise to the other. I therefore consider the inornatus group as sister to the bergrothi + granulatus lineage. Within the bergrothi group, I am unable to re- solve relationships between S. insulanus, bergrothi , and simplex , which are shown as a trichotomy in Figure 34. Within the granulatus group, I consider the “normal” male tibiae and female paranota, and the toothed medial laminae to be synapomorphies uniting S. australis + virginicus as a sister clade to S. granulatus. The “nor- mal” male tibiae and female paranota of S. columbianus, convergent with these features in the Blue Ridge endemics, are also apomorphic for this species. No apomorphies are know for S. piger and granulatus, but they are supported by geographic cohesiveness as discussed by Shelley and Whitehead (1986) for the xystodesmid genus Sigmoria. I therefore believe that relationships within this line are columbianus + ( piger + ( granulatus + {virginicus + australis ))) (Fig. 34).
CONCLUSION
As stated previously, the geographical locations of the lineages coupled with the ancestral phylogenetic position of S. inornatus point to the general area of the Cascade Mountain Range in southern Oregon as the primary center of evolution within the genus. A secondary center exists in the Blue Ridge Province, as the younger and possibly more successful endemic species appear to have dis- placed S. granulatus from these mountains and to be expanding into adjacent physiographic provinces. Thus, although the evidence in Scytonotus supports Hoffman’s contention (1969) that Appalachia, or in this case the Blue Ridge Province specifically, is an impor- tant evolutionary and dispersal center, analysis of the entire genus leads to the opposite conclusion regarding the relative ages of the eastern species. The broad occurrence of S. granulatus east of the Plains, including areas west of the Mississippi River, represents frag- mentation of an ancient range that extended west of the Continental Divide, and S. granulatus and piger were doubtlessly connected in the past. Scytonotus granulatus is thus much older than the Blue
55
Genus Scytonotus
inornatus insulanus bergrothi simplex columbianus piger granulatus virginicus australis
Fig. 34. Hypothesized relationships in Scytonotus.
Ridge endemics, which rather than being old forms relegated to relict statuses and restricted distributions in the Appalachians as sug- gested by Hoffman (1969), are really young, derivative entities. The absence of S. granulatus from the Blue Ridge suggests displace- ment by the endemics, and future displacement could occur in sur- rounding areas, as they expand their ranges. This process has already begun in the south, as S. australis , probably the oldest endemic, has spread beyond the Blue Ridge escarpment and apparently eradi- cated S. granulatus from the western periphery of the Piedmont Plateau in the Carolinas and north Georgia.
ACKNOWLEDGMENTS — I am indebted to the National Science Foundation (NSF) and the National Geographic Society (NGS) for supporting my field expeditions across North America for the past 15 years, which have produced numerous samples of Scytonotus. Pertinent grant numbers are DEB 7702596 and 8200556 for NSF, and 3871-88 and 4495-91 for NGS. Laboratory studies of the col- lections took place in January 1992, when I was working at the NMNH on an NSF Mid-Career Fellowship. Access to the types of P. amandus and 5. piger, bergrothi, orthodox, and simplex, and to nontypical material at the NMNH was courtesy of J. A. Coddington; the type of S. columbianus and other specimens at the MCZ were loaned by H. W. Levi; and the types of S. insulanus and pallidus (NMV) were provided by J. Gruber. Material in the following repositories was loaned by the indicated curator or collection man- ager: AMNH, N. I. Platnick; ANSP, D. Azuma; BMNH, P. Hillyard; BYU, R. W. Baumann; CADFA, A. R. Hardy; CAS, W. J. Pulawski;
56
Rowland M. Shelley
CIS, J. A. Chemsak; CMN, P. F. Frank; CNC, R. Footit; DC, A. H. Barnum; EIL, R. C. Funk; FMNH, D. A. Summers; FSCA, G. B. Edwards; GLFRS, K. Barber; ILNHS, K. C. McGiffen; ILSU, E. L. Mockford; MNHP, J. P. Mauries; OHS, D. L. Dyer; PSU, K. C. Kim; RBCM, R. A. Cannings; RNP, D. A. Anderson; ROM, D. C. Darling; SDMNH, D. K. Faulkner; TMM, J. R. Reddel; UA, G. E. Ball; UBC, S. G. Cannings; UCD, the late R. O. Schuster; UID, F. Merickel; UMMZ, M. F. O’Brien; UMN, R. Hozenthal; USU, W. Hanson; UVT, R. T. Bell; UWBM, R. Crawford; VMNH, R. L. Hoffman, WSU, R. S. Zack; and ZMH, H. Dastych. My colleague, W. A. Shear, provided his personal collection, and A. A. Weaver, Wooster, Ohio, generously donated his samples to the NCSM. Sampling in Kootenay and Mt. Revelstoke National Parks, British Columbia, was courtesy of a permit from Parks Canada. Figures 2- 8, 13-18, and 21-28 were prepared by R. G. Kuhler, NCSM scien- tific illustrator; Cathy Wood typed and retyped the manuscript.
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Hoffman, R. L. 1947. The status of the milliped Lasiolathus virginicus, with notes on Scytonotus granulatus. Proceedings of the Biological Society of Washington 60:139-140.
Hoffman, R. L. 1950a. Notes on some Virginia millipeds of the family Polydesmidae. Virginia Journal of Science 1:219-225.
Hoffman, R. L. 19506. Records and descriptions of diplopods from the southern Appalachians. Journal of the Elisha Mitchell Scientific Soci- ety 66:11-33.
Hoffman, R. L. 1962a. A new genus and species in the diplopod family Nearctodesmidae from Illinois (Polydesmida). American Midland Naturalist 68:192-198.
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Shelley, R. M. 1990. A new milliped of the genus Metaxycheir from the Pacific Coast of Canada (Polydesmida: Xystodesmidae), with re- marks on the tribe Chonaphina and the western Canadian and Alas- kan diplopod fauna. Canadian Journal of Zoology 68:2310-2322.
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Accepted 8 April 1993
New Molluscan ( Gastropoda and Bivalvia) Records for the Neuse River Basin, North Carolina
James R. Flowers and Grover C. Miller Department of Zoology North Carolina State University Raleigh, North Carolina 27695-7617
ABSTRACT — Twenty-three species of molluscs were collected from the Piedmont area of the Neuse River basin in North Carolina. Thirteen species of gastropods and ten bivalves (six sphaeriids and four unionids) were collected. New distribution records for six species are reported: Ferrissia fragilis, Laevapex fnscus, Gyraalus deflectus , Planorbella trivolvis, Musculium securis, and Pisidium variable.
Walter (1956) conducted the first intensive molluscan survey in North Carolina. This was the only survey conducted in the Neuse River basin. In the past 37 years only incidental sampling has taken place while the Neuse area has undergone rapid urbanization and industrialization which have affected aquatic habitats and have un- doubtedly altered molluscan communities. Mounting concern among malacologists about the impact of anthropogenic changes on mollus- can populations led the Scientific Council of Freshwater and Terres- trial Mollusks to recommend that surveys be performed to determine species distributions (Adams et al. 1990). From October 1989 to October 1990, we resurveyed some of the upper or Piedmont por- tion of the Neuse drainage.
METHODS
Molluscs were collected from 50 stations in the Piedmont area of the Neuse River basin of North Carolina. North Carolina Depart- ment of Transportation County Road Maps (revised 1988) were used to select 10 stations from each of five counties (Durham, Franklin, Johnston, Wake, and Wilson). Stations were explored from October 1989 to October 1990. Most collections occurred during summer and early fall 1990 when molluscs were most abundant.
Molluscs were collected by hand from the littoral zones of streams and ponds, from rocks in erosional zones of steams, and from the banks and bottoms of shallow streams. A dip net was used to sift the bottom substrate of deeper waters.
Snails and mussels were initially identified with the use of Environmental Protection Agency keys to “Freshwater Unionacean Clams (Mollusca: Pelacypoda) of North America” and “Freshwater
Brimleyana 19:61-64, December 1993
61
62
James R. Flowers and Grover C. Miller
Snails (Mollusca: Gastropoda) of North America” (Burch 1973, 1982), respectively. William F. Adams (Army Corps of Engineers, Wilmington, North Carolina) verified these identifications. The sphaeriacean clams were identified by Gerald L. Mackie (University of Guelph, Ontario, Canada).
Specimens were retained in the author’s collection for further study.
RESULTS AND DISCUSSION
Twenty-three species of molluscs (13 gastropods and 10 bivales) were collected from the upper Neuse River and its tributaries. This note reports only the six species that have not been previously recorded form the Neuse River system.
Ferrissia fragilis (Tryon, 1863) (Gastropoda: Pulmonata: Ancylidae) was encountered at 12 stations in five counties — Wilson, Franklin, Johnston, Wake, and Durham — primarily on debris (wood and leaves) and macrophytes of the littoral zone in lentic and lotic habitats. Ferrissia hendersoni (Walker, 1908), previously reported from the Neuse basin by Walter (1956) and Dawley (1965) and listed as a species of special concern (Adams et al. 1990), was not found. Basch (1963) considered F. hendersoni to be a variant of the “super species” F. fragilis; thus, further research and taxonomic clarifications are needed to determine the actual status of these two limpet snails.
Another limpet, Laevapex fuscus (Adams, 1841) (Gastropoda: Pulmonata: Ancylidae), was taken from rocks and debris in Wilson, Franklin, and Durham counties. Previously, Laevapex diaphanus (Haldeman, 1841) (Gastropoda: Pulmonata: Ancylidae) was reported from 22 stations in the Neuse River basin (Walter 1956); we did not find it during our survey. Although Basch (1963) reported the distribution of F. fragilis to be widespread throughout North America and L. fuscus to occur within the southeastern states, this is the first report of these two limpet snails from the Neuse drainage, specifically.
We collected the large planorbid, Planorbella trivolvis (Say, 1817) (Gastropoda: Pulmonata: Planorbidae), from wood and leaf substrates at two lotic stations in Franklin and Johnston counties, located on the Little River at US 401 and Cattail Creek at SR 1738, respectively. Other published reports of P. trivolvis from North Carolina include Lake Waccamaw (Pilsbry 1934) and Greenfiled Lake (Adams 1990).
Powell’s Pond at SR 2227 in eastern Wake County was the only station from which Gyraulus deflectus (Say, 1824) (Gastropoda:
Neuse River Molluscs
63
Pulmonata: Planorbidae) was collected. We found this small planorbid on wood and macrophyte substrates in the littoral zone. Prior to our collection, G. deflectus had been reported from North Carolina only from Greenfield Lake, New Hanover County (Adams 1990), although Lenat (1983) reported an unidentified Gyraulus sp. from Cane Creek, Orange County, that could be this species.
We encountered Musculium securis (Prime, 1852) (Bivalvia: Veneroida: Sphaeriidae) only in a narrow drainage ditch of a small pond in Wilson County, where it occurred in loose sediment among macrophytes. Adams et al. (1990) list M. securis as Undetermined status. Previously, Herrington (1962) reported this clam’s geographic distribution to include North Carolina, and Dawley (1965) examined specimens from Guilford County, North Carolina.
Pisidium variable (Prime, 1851) was collected from Cattail Creek at SR 1738 in Johnston County, the first report of this peaclam in North Carolina. Previously, this species was considered to have a northern distribution, with Virginia and Tennessee being its most southern limit (Herrington 1962, Heard 1963).
ACKNOWLEDGMENTS — We wish to acknowledge the follow- ing people for their assistance: William Adams for verification of snails and unionids, as well as for his professional advice, Gerald Mackie for identification of the sphaeriid clams, and Rowland Shelley for his assistance with the manuscript and his professional advice. Financial assistance has been received from the North Carolina Wildlife Resources Commission, Contract Number 92 SG 06.
LITERATURE CITED
Adams, W. F. 1990. Recent changes in the freshwater molluscan fauna of the Greenfield Lake basin, North Carolina. Brimleyana 16:103- 117.
Adams, W. F., J. M. Alderman, R. G. Biggins, A. G. Gerberich, E. P. Keferl, H. J. Porter, and A. S. Van Devender. 1990. A report on the conservation status of North Carolina’s freshwater and terrestrial molluscan fauna. The Scientific Council on Freshwater and Terres- trial Mollusks.
Basch, P. F. 1963. A review of the recent freshwater limpet snails of North America (Mollusca: Pulmonata). Bulletin of the Museum of Comparative Zoology, Harvard University 129:399-461.
Burch. J. B. 1973. Biota of freshwater ecosystems, identification manual no. 11, freshwater Unionacean clams (Mollusca: Pelecypoda) of North America. Environmental Protection Agency. W74-00564. PB 224 831.
Burch, J. B. 1982. Freshwater snails (Mollusca: Gastropoda) of North America. Environmental Protection Agency. EPA- 23: 600/3-82-026.
64
James R. Flowers and Grover C. Miller
Dawley, C. 1965. Checklist of freshwater mollusks of North Carolina. Sterkiana 19:35-39.
Heard, W. H. 1963. Survey of the Sphaeriidae (Mollusca: Pelecypoda)
of the southern United States. Proceedings of the Louisiana Academy of Science 26:102-120.
Herrington, H. B. 1962. A revision of the Sphaeriidae of North America (Mollusca: Pelecypoda). Miscellaneous Publications of the Museum of Zoology, University of Michigan 118:1-74.
Lenat, D. R. 1983. Benthic macroinvertibrates of Cane Creek, North
Carolina, and comparisons with other southeastern streams. Brimley- ana 9:53-68.
Pilsbry, H. A. 1934. Review of the Planorbidae of Florida, with notes on other members of the family. Proceedings of the Academy of Natural Sciences of Philadelphia 86:29-66.
Walter, W. M. 1956. Mollusks of the upper Neuse River, North Caro- lina. Journal of the Elisha Mitchell Scientific Society 72:262-274.
Accepted 28 January 1993
Morphometric Variation Between Bufo woodhousii fowler i Hinckley (Anura: Bufonidae) on Assateague Island, Virginia and the Adjacent Mainland
John M. Hranitz1, Thomas S. Klinger, Frederick C. Hill,
Robert G. Sagar, Thomas Mencken, and John Carr Department of Biological and Allied Health Sciences, Bloomsburg University of Pennsylvania, Bloomsburg, Pennsylvania 17815
ABSTRACT — Mark and recapture studies of Bufo woodhousii fowled in 1988 and 1989 on Assateague Island, Virginia, and the adjacent mainland showed that adult toads were significantly (P 0.05) more abundant on the island than the mainland in both years. The masses and snout-vent lengths (SVL) of toads were sig- nificantly greater on the mainland than on the island in both years, and adults were significantly larger at each location in 1989 than in 1988. Sex ratios were close to 1:1 or 1:2 on the island and the mainland in both years. Male and female toads were not sexually dimorphic in size at either location in 1988 or 1989. The smaller of two adult size classes on the island in 1988 was not present on the island in 1989; there were three size classes on the mainland in both years. Electrophoretic analysis revealed the low genetic diversity of the two populations. There were no noteworthy differ- ences in allele frequencies or polymorphism (P = 0.142) and mean
A A
heterozygosity (H = 0.01 island; H = 0.03 mainland) between the two populations.
This study documents morphometric differences that often exist between island and mainland populations. Factors that could affect the inverse relationship between toad abundance and size include low genetic diversity at loci controlling body size, the age structure of each deme, and instraspecific competition or physiological stress on the island. These explanations for small body size of island toads are consistent with the existing hypotheses of small immigrant size, small food particle or food supply, and age struc- ture of populations that are presented to account for the smaller size of island versus mainland conspecifics.
Differences in size between island and mainland conspecifics include gigantism and dwarfism, but explanations and correlations for differences in size structure of such populations are difficult to determine (Carlquist 1974). On Atlantic coast barrier islands, slider turtles ( Chrysemys scripta) are larger on Kiawah and Caper’s is-
1 Present address: Department of Biological Sciences, Drawer GY, Mississippi State University, Mississippi State, MS 39762.
Brimleyana 19:65-75, December 1993
65
66
John M. Hranitz et al.
lands than natural populations on the adjacent mainland, and Gib- bons et al. (1979) attributed this disparity in size to higher quality diets and warmer temperatures on the islands. The eastern hognose snake ( Heterodon platyrhinos) is smaller on Assateague Island, Vir- ginia, than on the adjacent mainland (Edgren 1961, Scott 1986). The basis for the smaller H. platyrhinos size on Assateague Island compared to the size of animals on the mainland is not known.
In typical amphibians, the effects of mainland versus island ecology on amphibian biology are more difficult to predict because environmental factors might differentially affect the aquatic and ter- restrial phases of the life cycle. We studied the size and abundance of Bufo woodhousii fowleri in three different habitats on Assateague Island compared with a population in three different habitats on the adjacent Delmarva peninsula.
MATERIALS AND METHODS
We captured Bufo woodhousii fowleri in drift fences and pit- fall traps (Gibbons and Semiitch 1981) randomly placed in three habitats on the island (146.78 ha) and mainland (30.45 ha) study areas. There was one replicate for drift fences and pitfall traps in each habitat at each location in 1988 and one replicate for each location in 1989. Upon capture, toads were measured (SVL, mm), weighed (g), sexed, toe clipped (Clarke 1972) and released. Recap- tured toads were measured and weighed before release, but the sizes of recaptured toads are not presented because periods between re- capture events were too brief to accurately assess growth in either toad population.
In 1988, toads were trapped in coniferous forests, meadows, and primary dunes on Assateague Island (37°56'N; 75°2CTW) from 2 to 29 June and in deciduous forests, coniferous forests, and meadows on the adjacent mainland (37°56"N; 75°29'W) from 2 to 16 July. We stopped trapping on the mainland when it was appar- ent that about 50% of the population in the area was marked (Davis 1982). In 1989, toads were trapped concurrently from 10 June to 10 July in coniferous forests and meadows on the island, and in deciduous and coniferous forests on the mainland. The Schnabel method (Schnabel 1938, Smith 1980) was used to estimate the mean abundance of toads in habitats at each location. The assumptions inherent in mark-release-recapture studies, constant population size and random samples (Schnabel 1938), were met because we could detect recruitment, represented by juveniles, and because the place- ment of drift fences and pitfall traps at each location was random.
Abundance and sex ratios were analyzed with the Systat™ ANOVA procedure. Adult SVL and mass were analyzed with a
Bufo woodhousii fowleri
67
2X3 nested ANOVA. Juvenile SVL was analyzed with a one-way ANOVA. We used Tukey’s w-test (Steel and Torrie 1980) to com- pare mean toad SVL and mass for each year and location. Size frequency distributions were tested with probit analysis (Harding 1949). The level of accepted significance was 95% (P < 0.05).
Horizontal starch (12%) gel electrophoresis was performed on muscle in toe clips taken from 25 toads at each location (N = 50) on 30 April and 23 May 1989. Muscle from toe clips was homog- enized in 200 pL of ice cold buffer and centrifuged at 10,000 g for 10 minutes. Proteins were originally separated using four buff- ers of different pH and composition (0.1445 M tris, 0.0471 M cit- rate, TC, pH 7.0; 0.0100 M tris, 0.0100 M maleate, 0.0013 M EDTA, 0.0010 MgCl2, TM, pH 7.4; 0.0884 M N-3-aminopropylmor- pholine, 0.0399 M citrate, AC, pH, 7.0; 0.0300 M lithium hydrox- ide, 0.1126 M boric oxide, LiOH A, pH 8.2; 0.0503 M tris, 0.0080 M citrate, LiOH B, pH 8.7) to determine the system best suited to identify enzyme polymorphisms. Buffers were those described by Selander and Yang (1969) and Clayton and Tretiak (1972). The following enzymes (EC number, locus abbreviation, buffer) were re- solved from prepared homogenates: lactate dehydrogenase (1.1.1.27, Ldh, TC), malate dehydrogenase (1.1.1.37, Mdh, TC), phosphoglu- comutase (5. 4. 2. 2, Pgm TC), peptidase 3.4.-.-, Ap, LiOH). Proteins were separated over 14 hours at 165 V for TC gels and 180 V for LiOH gels. Protein assays were modified from methods described by Shaw and Prasad (1970) and Harris and Hopkinson (1976). Al- lele frequency, deviation from Hardy-Weinberg equilibrium, poly-
/V
morphism, single locus heterozygosity (H), and mean heterozygosity (H) were calculated from the seven loci resolved (Hartl 1988, Smith 1989). A locus was considered to be polymorphic if the frequency of the most common allele was less than 0.99.
RESULTS
Two hundred forty-one adult toads were captured in 1988, and 139 adult toads were captured in 1989. The high percentage of recaptures (60.0%) for mainland toads in 1988 (Table 1) precipi- tated the termination of the study on the mainland because indi- viduals were consistently recaptured after only 9 days of mark and release. This suggested that the mainland population was adequately sampled to describe the status of the toads in the study area even though less time was allocated for trapping toads on the mainland. Trapping rates in 1988 support this assumption. Trapping rates (number of individuals per day ± 1 SE) were significantly greater for the island (11.9 ± 2.5) than the mainland (1.4 ± 0.5).
68
John M. Hranitz et al.
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Bufo woodhousii fowleri
69
Toads were significantly more abundant on the island than on the mainland in both years. We captured Bufo woodhousii fowleri in all habitats at each location except primary dunes on the island and meadows on the mainland. Although habitat had no significant effect on toad abundance in areas where toads were captured, toads in deciduous and coniferous forests made up a large portion of the mainland sample in 1988 (82.2%, 17.8%) and in 1989 (75.7%, 24.3%). Toads in coniferous forests and meadows made up a large portion of the island sample in 1988 (67.4%, 32.6%) and in 1989 (81.5%, 18.5%). Sex ratios close to 1:2 in 1988 (x2 = 1.049, P > 0.25) and 1:1 in 1989 (x2 = 0.26, P > 0.50) on the island (Table 1) and close to 1:1 in 1988 (x2 = 0.600, P > 0.25) and 1:2 in 1989 (x2 = 0.318, P > 0.50) on the mainland were observed.
The mean snout-vent lengths (SVL) and masses of B. w. fowleri were significantly larger in 1989 than 1988 at both locations (is- land-15.1%, 53.0% and the mainland-18. 1%, 66.8%). However, mainland toads were significantly larger than island toads in both years (Table 1). Male and female toads were not sexually dimorphic in size at either location (Table 1).
We observed size classes, detected by probit analysis, of 25- 45 and 46-57 mm SVL on the island in 1988 (Fig. 1); whereas two juvenile size classes (18-20 and 21-35 mm), which represent recruitment from the previous year in forest and meadow habitats, and one adult size class (36-57 mm) were observed in 1989. The
Fig. 1. Size frequency distributions of Bufo woodhousii fowleri collected in pitfall traps in 1988 and 1989 on Assateague Island (above the x-axis) and the adjacent mainland (below the x-axis).
70
John M. Hranitz et al.
mean size of the largest size class on the island decreased from 1988 to 1989, and the smaller of the two size classes observed in
1988 was not observed in 1989. Three size classes were observed on the mainland in 1988 (38-42, 45-48, and 52-57 mm) and in
1989 (39-50, 54-62, and 66-76 mm) (Fig. 1).
There were no juveniles on the island in 1988 or on the mainland in either year. Of the 111 juveniles captured on Assateague Island in 1989, 40 were from coniferous forests, and 71 were from meadows. Forest juveniles (25 8 ± 0.5 mm SVL) were significantly (P <> 0.05) larger than meadow juveniles (23.5 ± 0.4 mm SVL).
Genetic diversity was low at each location, and there were no noteworthy differences in allele frequencies between the island and mainland toad populations at the seven loci studied. Six of seven enzyme loci ( Ap , Ldh- 4, Ldh- 5, Mdh- 2, Pgm- 1, and Pgm-2) were monomorphic in both populations. Mdh-1 had two alleles, MDH-1100 and MDH-1105, in each population. The frequency of MDH-1100 was 0.96 on the island and 0.12 on the mainland, and the frequency of MDH-1105 was 0.04 on the island and 0.88 on the mainland. Poly- morphism (P) for toads' at both locations was 0.142. Heterozygosity (H) for MDH-1 was 0.08 on the island and 0.12 on the mainland. Mean heterozygosity (H) was 0.01 for island toads and 0.03 for mainland toads. Deviations from Hardy-Weinberg expectations at the Mdh-1 locus were not significant in the island (x2 = 0.0434, P < 0.01, 1 df) or mainland (x2 = 1.469, P < 0.01, 1 df) samples.
DISCUSSION
Differences between the size structure of island and mainland populations of animals (Edgren 1961, Carlquist 1974, Gibbons et al. 1979, Scott 1986) and between adjacent mainland toad populations (Oldham 1985) are not unusual. Our results show differences in body size between toads of Assateague Island and the adjacent main- land, providing an example of an insular population of amphibians with smaller body sizes than mainland conspecifics. However, the differences between the island and mainland populations of toads occurred within a narrow window of time in which mainland samples of toads were small; thus, further comparative study is required.
Reasons for smaller body sizes of island animals are reviewed by Carlquist (1974). Small immigrants might be more successful at colonizing an island, smaller body size might be in response to selective predator pressures, or small body size might be an adapta- tion to smaller food objects or food supplies. Although the eastern
Bufo woodhousii fowleri
71
hognose snake ( Heterondon platyrhinos Latreille) is a major preda- tor of toads and is abundant on the island (Scott 1986), we found only one hognose snake while trapping on the island. In the ab- sence of any predator-prey data, it is not possible to assess whether predator pressures on toad body size exist. We suggest other expla- nations for the smaller body size and greater abundance of island than mainland toads. Two of these are consistent with the hypoth- eses of Carlquist (1974), whereas a third hypothesis is consistent with the discussion of age structure of King (1989).
The island and mainland toad populations have very similar genetic composition with respect to each other and low genetic di- versity compared to other populations of this species (Green 1984, Breden 1988). The considerable genetic similarity of the two popu- lations is not entirely surprising. First, Assateague Island likely was colonized from the north as sand from currents was deposited on remnants of Pleistocene barriers (Leatherman 1979). Second, gene flow likely occurred between the two populations for the 200 or more years that existed between the time that Assateague Island assumed its current formation during colonial times and 1933, when a hurricane produced the inlet that exists today between Assateague Island and the part of the peninsula known as Fenwick Island (Leatherman 1979, Amos 1980). The low genetic variation exhibited in these two populations of toads could be attributed to a combina- tion of biological (e.g., inbreeding, fidelity to breeding sites) and historical factors (e.g., founder’s effects, post-Pleistocene changes in sea level which restricted gene flow to the narrow window of land at the northern end of the peninsula). Although no genetic variation was detected at each of seven loci studied in the island and main- land populations of Virginia, except Mdh- 1, considerable genetic variation is present at five of these seven loci in toads from east-central Mississippi (J. M. Hranitz and W. J. Diehl, Mississippi State Uni- versity, personal observation). Therefore, from the preliminary ge- netic analysis we present, further study of the genetic composition of the island and Delmarva toad populations and toad populations on the mainland proper, using a larger sample of individuals as well as enzyme loci, is warranted.
If body size is a quantitative genetic character, then the low genetic diversity of a population restricts the body size of in- dividuals in the deme to only a small proportion of the total distribution of body size in the species. If the seven loci studied serve as genetic markers for the loci controlling body size, then the small body size of toads on Assateague Island might result from low genetic diversity at loci controlling body size. Low genetic
72
John M. Hranitz et al.
diversity could be caused by genetic bottlenecks, most likely due to founder’s effects, such as only small immigrants colonizing the is- land (Carlquist 1974) as might occur simply by chance or because smaller body size confers an energetic or cryptic advantage during dispersal. This hypothesis can also explain why larger island than mainland conspecifics are observed in other instances.
An inverse relationship between size and abundance of toads on the mainland and the island could occur if the growth of toads on the island was stunted while “ecological release” (Soule 1966) permitted the species to be abundant in response to the depauperate herpetofauna of Assateague Island (Lee 1972). Size frequency distri- butions of toads at each location in both years suggest that this is true. Factors that can cause stunting on the island include intraspe- cific competition, which may be the predominant biotic factor con- trolling population size considering the depauperate herpetofauna of the island, and physiological stress caused by fluctuating environ- mental factors (Parsons 1990). The more important factors likely include salinity of impoundments, availability of water on the is- land, and quality of habitats at each location. Instraspecific compe- tition and physiological stress are consistent with the food supply hypothesis (Carlquist 1974) because each involves a limiting envi- ronmental factor that either favors or produces individuals with small body size.
The island and mainland demes could have different age struc- tures, with mainland toads being older and larger, and island toads being younger and smaller. The lack of sexual dimorphism and the overall increase in mean body size in each deme from 1988 to 1989 is similar to growth of young cohorts of B. calamita (Boomsma and Arntzen 1985). These results suggest that both demes are com- posed of young toads, although the demes might not be the same age or have the same proportion of toads from different cohorts. This concept is not consistent with any of the ideas of Carlquist (1974) but is consistent with an explanation for body size variation in Thamnophis sirtalis and Nerodia sipedon in the Lake Erie area (King 1989).
Studies reporting differences between island and mainland con- specifics often attribute differences between populations to unique features of islands (Carlquist 1974, Gibbons et al. 1979). In some cases, differences between island and mainland populations could, in fact, be artifacts of sampling two distinct populations, an opportu- nity that does not always present itself in continuous or adjacent mainland populations. Studies by Oldham (1985) and King (1989)
Bufo woodhousii fowleri
73
suggest this is true. Body sizes of mainland T. sirtalis and N. sipedon varied as much as, and in some cases more than, island versus mainland conspecifics. Variation in abundance and size be- tween mainland toads in adjacent agricultural habitats (Oldham 1985) was similar to our results for island versus mainland B. w. fowleri.
Assuming that similar-aged juveniles are involved, the differ- ences in SVL between juveniles from coniferous versus meadow habitats probably reflect an expression of the modifying factors early in ontogeny: faster growth rates for tadpoles in impoundments sur- rounded by forest habitat, faster growth rates for juveniles in forest habitats, or migration of juveniles from meadow habitats to conifer- ous forest habitats. An indication of greater abundance of toads in wooded versus meadow habitats on Assateague Island and the cap- ture of toads only in wooded habitat on the mainland indicate that adult B. w. fowleri prefer woodland habitat (see Lee 1972). Wood- land habitat likely plays an important role in the life history of B. w. fowleri on Assategue Island. Other investigations of herpetofaunal colonization patterns of Atlantic Coast barrier islands indicate that it is not island size but the amount of woodland habitat that is most highly correlated with numbers of reptile and amphibian spe- cies present (Gibbons and Coker 1978).
ACKNOWLEDGMENTS— We thank the Chincoteague National Wildlife Refuge an the Wallops Island Marine Science Consortium for providing areas for study. We also thank M. Melnychuk for his helpful suggestions, S. Klinger for her assistance in preparing the grant proposal, and W. Diehl and R. Altig for their assistance in preparing the manuscript. This research was supported, in part, by a Professional Development Grant from the Pennsylvania State Sys- tem of Higher Education.
LITERATURE CITED
Amos, W. H. 1980. Assateague Island National Seashore Maryland and Virginia. U.S. Department of the Interior, Washington D.C.
Boomsma, J. J., and J. W. Arntzen. 1985. Abundance, growth and feeding of natterjack toads {Bufo calamita ) in a 4-year-old artificial habitat. Journal of Applied Ecology 22:395-405.
Breden, F. 1988. Natural history and ecology of Fowler’s toad Bufo woodhousei fowleri (Amphibia:Bufonidae), in the Indiana Dunes Na- tional Lakeshore. Fieldianna Zoology 1393:1-16.
74
John M. Hranitz et al.
Carlquist, S. 1974. Island biology. Columbia University Press, New York, New York.
Clarke, R. D. 1972. The effect of toe clipping on survival in Fowler’s toad ( Bufo woodhousii fowleri). Copeia 1972:182-185.
Clayton, J. W., and D. N. Tretiak. 1972. Amine-citrate buffers for pH control in starch gel electrophoresis. Journal of Fisheries Research Board of Canada 29:1169-1172.
Davis, D. E. 1982. CRC Handbook of census methods for terrestrial vertebrates. CRC Press Incorporated, Boca Raton, Florida.
Edgren, R. A. 1961. A simplified method for the analysis of dines: geographic variation in the hognose snake ( Heterodon platyrhinos Latreille). Copeia 1961:125-132.
Gibbons, J. W., and J. W. Coker. 1978. Herpetofaunal colonization patterns of Atlantic Coast barrier islands. American Midland Natu- ralist 99:219-233.
Gibbons, J. W., G. H. Keaton, J. P. Schubauer, J. L. Green, D. H. Bennett, J. R. McAuliffe, and R. R. Sharitz. 1979. Unusual population size structure in freshwater turtles on barrier islands. Georgia Journal of Science 37:155-159.
Gibbons, J. W., and R. D. Semiitch. 1981. Terrestrial drift fences with pitfall traps: an effective technique for quantitative sampling of animal populations. Brimleyana 7:1-16.
Green, D. M. 1984. Sympatric hybridization and allozyme variation
in toads Bufo americanus and Bufo fowleri in southern Ontario. Copeia 1984:18-26.
Harding, J. P. 1949. The use of probability paper for the graphical
analysis of polymodal frequency distributions. Journal of the Ma- rine Biology Association of the United Kingdom. 28:141-153.
Harris, H., and D. A. Hopkinson. 1976. Handbook of electrophoresis in human genetics. American Elsevier, New York, New York.
Hartl, D. L. 1988. A primer of population genetics. Second Edition.
Sinauer Associates Incorporated, Sunderland, Massachussetts.
King, R. B. 1989. Body size variation among island and mainland
snake populations. Herpetologica 45:84-88.
Leatherman, S. P. 1979. Barrier Islands from the Gulf of St. Lawrence to the Gulf of Mexico. Academic Press, New York, New York.
Lee, D. S. 1972. List of the amphibians and reptiles of Assateague Island. Bulletin of the Maryland Herpetological Society 80:90-95.
Oldham, R. S. 1985. Toad dispersal in agricultural habitats. Bulletin
of the British Ecology Society 16:211-214.
Parsons, P. A. 1990. The metabolic cost of multiple environmental
stresses: implications for climatic change and conservation. Trends in Ecology and Evolution 5:315-317.
Schnabel, Z. E. 1938. The estimation of the total fish population of a lake. American Mathematics Monthly 45:348-352.
Scott, D. 1986. Notes on the eastern hognose snake Heterodon platyrhinos Latreille (Squamata: Coloubridae). Brimleyana 12:51-55.
Bufo woodhousii fowleri
75
Selander, R. K., and S. Y. Yang. 1969. Protein polymorphisms and genic heterozygosity in a wild population of the house mouse {Mus musculus ). Genetics 63:646-649.
Shaw, C. R., and R. Prasad. 1970. Starch gel electrophoresis of en- zymes: a compilation of recipes. Biochemical Genetics 4:297-320.
Smith, J. M. 1989. Evolutionary genetics. Oxford University Press, New York, New York.
Smith, R. L. 1980. Ecology and field biology. Third Edition. Harper and Row, New York, New York.
Soule, M. 1966. Trends in the insular radiation of a lizard. American Naturalist 100:47-64.
Steel, R. G. D., and J. H. Torrie. 1980. Principles and procedures of statistics: a biometrical approach. Second Edition. McGraw-Hill Com- pany, New York, New York.
Accepted 29 October 1992
Leatherback Turtle, Dermochelys coriacea (Reptilia: Dermochelidae): Notes on Near-shore Feeding Behavior and Association with Cobia
Gilbert S. Grant1 Department of Math and Science Coastal Carolina Community College Jacksonville, North Carolina 28540
AND
Danny Ferrell P.O. Box 751
Sneads Ferry, North Carolina 28460
ABSTRACT — Leatherback turtles ( Dermochelys coriacea ) were regularly seen 250 m off North Topsail Beach, North Carolina, during May and early June 1990 and 1991, in close associa- tion with and feeding on Stomolophus meleagris jellyfish. Cobia (Rachycentron canadum ) occurred in close proximity to the turtles.
Lee and Palmer (1981) summarized the near-shore occurrence of leatherback turtles in the waters of North Carolina. Even though leatherbacks are perhaps the most pelagic of all sea turtles (Ernst and Barbour 1972, Bustard 1973), Lee and Palmer (1981) encoun- tered most turtles in the shallow waters over the continental shelf, well away from the beach. Ernst and Gilroy (1979) reported that this turtle remains close to shore during migrations and is season- ally common along the coast from Virginia to New Jersey.
Because little is known about leatherback behavior and distri- bution, we report observations on feeding behavior, fish associa- tions, and two strandings at North Topsail Beach, Onslow County, North Carolina.
METHODS
Observations were made nearly daily from Salty’s Pier at North Topsail Beach, North Carolina, during May and June 1990 and 1991. D.F. was employed by the pier and fished near the distal end of the pier during his off-time. G.S.G. searched for turtles from the pier on 12-15 occasions during this time interval. Informal
1 Present address: Department of Marine and Wildlife Resources, P. O. Box 3730, Pago Pago, American Samoa 96799.
Brimleyana 19:77-81, December 1993
77
78
Gilbert S. Grant and Danny Ferrell
discussions with fishermen on the pier helped document the tempo- ral pattern of leatherbacks in the area. Salty’s Pier extends 250 m from the beach.
RESULTS
G.S.G. saw leatherbacks from Salty’s Pier on 19 May 1990 (0740 hours), 13 May 1991 (1600 hours), and another larger indi- vidual on 13 May 1991 (1638-1640 hours). D.F. witnessed leather- backs nearly daily while he was employed at the pier from May to mid-June 1991. The largest leatherback was estimated to be about 2-m long. Pier fishermen reported seeing these turtles several times a day on some occasions; the turtles passed within 10 m of the end of the pier. Water depth where most sightings occurred was about 4 m, and ocean surface temperatures recorded daily at North Topsail Beach during May and early June 1990 ranged from 16 to 24C.
Sightings of leatherback turtles seemed to correspond with cabbagehead or cannonball jellyfish ( Stomolophus meleagris). These jellyfish were so abundant at Salty’s Pier during May and early June 1990 and 1991 that 50-200 could be seen daily. These jelly- fish were about 20 cm in diameter, moved vertically in the water column, and most remained in close proximity to the pier. D.F. observed leatherbacks eating several cabbagehead jellyfish in May and June 1991 off Salty’s Pier.
C. Rader (pier employee, personal communication) reported watching a leatherback about 1.7-m long ingest 50-80 cabbageheads in spring 1991 at Myrtle Beach, South Carolina. From his fishing pier vantage point, Rader was able to observe feeding behavior at close range. He reported that just before ingesting a jellyfish, the turtle appeared to blow out air and water through its nose and mouth before consuming the entire jellyfish. No jellyfish or leather- backs were seen or reported by fishermen after mid-June 1991.
D. F. and other fishermen saw three to four cobia close to leatherbacks each time a turtle swam by the pier. The cobia ranged in size from 0.6 to 1.3 m and typically maintained positions either slightly above or below the swimming turtle.
Two stranded leatherback turtles on North Topsail Beach were examined and measured during the May to mid-June 1990 and 1991 observation period. One decomposing turtle without obvious external injuries washed up at Salty’s Pier on 16 May 1990. It was about 150-cm long. The second decomposing turtle washed up 5 km south of Salty’s Pier on 24 May 1991. It measured 162 cm (curved cara- pace length) by 90 cm (curved carapace width). Both were docu-
Leatherback Turtle Feeding
79
mented with photographs deposited at the North Carolina State Mu- seum of Natural Sciences, Raleigh.
DISCUSSION
Perhaps in some years leatherback turtles congregate with Stomolophus jellyfish along the coastline of Topsail Island, North Carolina, during May and early June. The feeding observation at Myrtle Beach, South Carolina, further suggests that leatherbacks could appear whenever cabbagehead jellyfish appear in abundance along the Carolina coast.
Further searches for turtles from the ends of fishing piers should be conducted elsewhere along the Southeast coast to docu- ment peaks of occurrence. Stomolophus meleagris occurs from Cape Hatteras, North Carolina, to Brazil (Schwartz 1979) and is found in North Carolina from May to November. It enters sounds and waterways when salinities are similar to that of the ocean (Schwartz 1979). One large leatherback encountered in the Neuse River near New Bern, North Carolina, on 16 November 1975 (Schwartz 1977, Lee and Palmer 1981) might not be atypical if it was associated with its jellyfish prey. Leary (1957) reported numer- ous leatherbacks within a dense school of Stomolophus meleagris off the Texas coast on 17 December 1956.
Stomach analyses have shown that leatherback turtles feed pri- marily on medusae, siphonophores, and salpae (Bleakney 1965, Eckert et al. 1989). Direct feeding observations include accounts of adults feeding on Aurelia off the coast of Washington State (Eisenberg and Frazier 1983) and on Rhizostoma octopus off Great Britain (Penhallurick 1991). Morgan (1989) and Penhallurick (1991) reported leatherbacks associating with Rhizostoma pulmo, R. octopus , Cyanea sp., and Chrysaora isoceles jellyfish off Great Britain. Col- lard (1990) reported seven leatherbacks in areas of maximum abun- dance of jellyfish and other gelatinous forms in the eastern Gulf of Mexico, and Lazell (1980) linked leatherback movements with the abundance of Cyanea sp. jellyfish off New England.
Eckert et al. (1989) and Eckert (1992) hypothesized that the daily diving patterns of leatherbacks are closely related to the abundance of jellyfish and other zooplankton in the deep scattering layer. For example, shallow dives would be more likely during the night when the jellyfish were closer to the surface, and deeper dives would be more likely during daylight when the prey could be 300 m or more deep.
On several occasions the leatherbacks passed close to live bait fishing rigs (mackerel rigs) at Salty’s Pier and did not attempt to
80
Gilbert S. Grant and Danny Ferrell
eat the tethered bluefish ( Pomatomus saltatrix), spots ( Leiostomus canthurus ), or menhaden ( Brevoortia tyrannus).
Cobia are known to swim in proximity to sea turtles, sharks, and large rays (Manooch and Raver 1984). We do not know if the cobia benefit from this association by scavenging on food scraps or by gaining hydrodynamic advantages. Cobia tend to be found most commonly around sea buoys and other floating shelters (Robins et al. 1986). Perhaps the association of cobia with swimming leather- backs is simply the result of cobia seeking their preferred habitat. Penhallurick (1991) reported remoras ( Remora remora ) and pilot fish (Naucrates ductor ) swimming alongside leatherback turtles off Great Britain.
CONCLUSIONS
Leatherback turtles were observed feeding on cabbagehead jel- lyfish at North Topsail Beach, North Carolina during May and early June 1990 and 1991. Jellyfish populations were high, and the turtles might be following the jellyfish bloom northward during this pe- riod. Leatherback turtles should be looked for whenever jellyfish populations are high. The association of cobia with the swimming leatherbacks also warrants further study.
ACKNOWLEDGMENTS— Viz thank Anna L. Bass, Alvin L. Braswell, and David S. Lee for reviewing this manuscript. This paper is dedicated to the memory of Karen Beasley whose concern for and interest in sea turtles was contagious.
LITERATURE CITED
Bleakney, J. S. 1965. Reports of marine turtles from New England and eastern Canada. Canadian Field Naturalist 79:120-128.
Bustard, R. 1973. Sea turtles: their natural history and conservation.
Taplinger Publishing Company, New York, New York.
Collard, S. B. 1990. Leatherback turtles feeding near a water mass boundary in the eastern Gulf of Mexico. Marine Turtle Newsletter 50:12-14.
Eckert, S. A. 1992. Bound for deep water. Natural History 1992:29-35. Eckert, S. A., K. L. Eckert, P. Ponganis, and G. L. Kooyman. 1989. Diving and foraging behavior of leatherback sea turtles (. Dermochelys coriacea ). Canadian Journal Zoology 67:2834-2840.
Eisenberg, J. F., and J. Frazier. 1983. A leatherback turtle (Dermochelys coriacea ) feeding in the wild. Journal of Herpetology 17:81-82.
Ernst, C. H., and R. W. Barbour. 1972. Turtles of the United States. University Press of Kentucky, Lexington.
Leatherback Turtle Feeding
81
Ernst, C. H., and M. J. Gilroy. 1979. Are leatherback turtles, Dermochelys coriacea , common along the middle Atlantic coast? Bulletin of the Maryland Herpetological Society 15:16-19.
Lazell, J. D., Jr. 1980. New England waters: critical habitat for marine turtles. Copeia 1980:290-295.
Leary, T. R. 1957. A schooling of leatherback turtles, Dermochelys coriacea coriacea, on the Texas coast. Copeia 1957:232.
Lee, D. S., and W. M. Palmer. 1981. Records of leatherback turtles, Dermochelys coriacea (Linnaeus), and other marine turtles in North Carolina waters. Brimleyana 5:95-106.
Manooch, C. S., Ill, and D. Raver, Jr. 1984. Fisherman’s guide: fishes of the southeastern United States. North Carolina State Museum of Natural Sciences, Raleigh.
Morgan, P. J. 1989. Occurrence of leatherback turtles ( Dermochelys
coriacea ) in the British Isles in 1988 with reference to a record specimen. Pages 119-120 in Proceedings of the ninth annual work- shop on sea turtle conservation and biology (S. A. Eckert, K. L. Eckert, and T. H. Richardson, editors). NOAA Technical Memoran- dum NMFS-SEFC-232.
Penhallurick, R. D. 1991. Observations of leatherback turtles off the Cornish coast. Marine Turtle Newsletter 52:12-14.
Robins, C. R., G. C. Ray, and J. Douglas. 1986. A field guide to Atlantic Coast fishes of North America. Houghton Mifflin Company, Boston, Massachusetts.
Schwartz, F. J. 1977. Cheloniidae. Pages 303-308 in Endangered and
threatened plants and animals of North Carolina (J. E. Cooper, S. S. Robinson, and J. B. Funderburg, editors). North Carolina State Mu- seum of Natural Sciences, Raleigh.
Schwartz, F. J. 1979. Common jellyfish and comb jellies of North
Carolina. Institute of Marine Sciences, University of North Carolina, Morehead City, North Carolina.
Accepted 31 July 1992
Additional Evidence for the Specific Status of Nerodia cyclopion and Nerodia floridana (Reptilia: Colubridae)
William E. Sanderson1 Museum of Natural Science Louisiana State University Baton Rouge, Louisiana 70893
ABSTRACT — Preserved specimens were used in a morphological comparison of Nerodia cyclopion and N. floridana. Data included counts of head and body scales and body scutes as well as mea- surements of head scale dimensions. Comparisons of these data re- vealed significant differences in the numbers of ventral scutes, subcaudal scutes, and dorsal scale rows. Discriminant analysis of head scale measurements proved to be a reliable tool separating these taxa and revealed no evidence of gene exchange. I concur with the recent elevation of the two taxa to full species; the two species are at least parapatric in the western Florida Panhandle.
Two subspecies of the green water snake, Nerodia cyclopion (Dumeril, Bibron, and Dumeril, 1854) have been recognized since the description of N. c. floridana by Goff (1936). Goff (1936) documented that, on the basis of ventral coloration, numbers of ventral and subcaudal scutes, numbers of infralabial scales, and relative tail lengths, the eastern form (N. c. floridana ) could clearly be separated from the western form (N. c. cyclopion). Goff (1936) speculated that intergrades between Nerodia c. cyclopion and N. c floridana would be found somewhere between Mobile, Alabama, and Leon County, in the Forida Panhandle. He had no specimens from this area, how- ever, and so had no direct evidence for distributional contact or intergradation.
Serological and immunoelectrophorectic comparisons within the genus Nerodia led Pearson (1966:8) to comment that “a low rela- tionship between N. c. cyclopion and N. c. floridana indicates that a re-evaluation of their status as subspecies should be considered; elevation to full species is suggested.” Mount (1975:208) cited lo- calities for both cyclopion and floridana from Baldwin County, Ala- bama, and stated that “clear evidence of intergradation ... is lacking,” although he noted that specimens from extreme southeast- ern Baldwin County appeared to be intermediate on the basis of ventral coloration. Lawson (1987) reported the results of molecular studies of the New World natricines, in which he proposed specific
1 Present address: Asheville High School, 419 McDowell Street, Asheville, North Carolina 28803.
Brimleyana 19:83-94, December 1993
83
84
William E. Sanderson
status for the two forms. Conant and Collins (1991) followed this suggestion and treated the two taxa as separate species.
In this article I present the results of a morphological com- parison of Nerodia cyclopion and N. floridana and report previously unpublished collection localities for green water snakes in western Florida.
MATERIAL AND METHODS
I examined 381 preserved specimens of green water snakes. Complete data (head, body, and tail length; scale counts; and head scale measurements) were obtained from 217 specimens. Fewer data (usually head, body, and tail lengths, and scale counts) were re- corded for the remaining ones.
Snout-vent length and tail length (for specimens with complete tails) were measured to the nearest millimeter with a 1-m rule. Head length was measured with dividers and a 10-cm rule to the nearest millimeter from the tip of the rostral scale to the posteriormost point of the mandible.
Ventral scutes were counted by the method of Dowling (1951). Subcaudal counts did not include the terminal scale. Dorsal row counts were made one head length posterior to the head, at midbody, and one head length anterior to the vent. Meristic data on head sealation included the number of suboculars, preoculars, postoculars, temporals, supralabials, and infralabials. Student’s Mest of equiva- lency of sample means was used to determine if any of these char- acters were useful in separating the two taxa. Relative tail length was found to decrease ontogenetically, and thus was treated by re- gression analysis.
Certain head scales were measured to quantify head shape (Fig. 1). These dimensions were determined to the nearest 0.01 mm with a dissecting microscope fitted with an ocular micrometer. For dis- criminant analysis of this mensural data, I used release 2.1 of the Statistical Package for the Social Sciences (SPSS), available through the Louisiana State University Systems Computing Center. For the discriminant analysis of head scale data, the raw measurements were separated into two groups. One group, termed the holdout group, contained data derived from 49 specimens of both taxa (46 cyclopion, 3 floridana ) from Alabama and the Florida pan- handle. This group, then contained those specimens most likely to possess intermediate character states if gene flow is occurring be- tween the two taxa. The second group, termed the calibration group, contained data from all remaining specimens: 90 cyclopion and 78 floridana.
Nerodia cyclopion and N. floridana
85
The first phase of the analysis tested the calibration group with stepwise discriminant analysis. The best discriminating vari- ables varied by sex, so in all analyses the sexes were treated sepa- rately. All head scale measurements were entered into the analysis program; those characters which did not contribute significantly to the discrimination of the two taxa were discarded. The program, using these data, then assigned each specimen to a species group {cyclopion or floridana) and calculated the probability of error in this assignment. The second phase then tested the specimens in the holdout group using the parameters established with the calibration group data.
Fig. 1. Views of the head of Nerodia cyclopion illustrating the method of measurement of head scales. The characters are (1) loreal dorsal length (LD), (2) loreal ventral length (LV), (3) muzzle width (MW), (4) internasal length (IL), (5) prefrontal length (PF), (6) muzzle length (ML), (7) frontal length (FL), (8) frontal extension length (EL), (9) parietal length (PL), (10) anterior genial length (AG), and (11) posterior genial length (PG).
86
William E. Sanderson
RESULTS
SCALATION
Mean numbers of preocular, postocular, subocular, supralabial, infralabial, and temporal scales do not distinguish N. cyclopion from N. floridana. Regression analysis revealed no significant difference between the two taxa in relative tail length.
Ventral scute counts do not appear to be related to a signifi- cant degree to either sexual dimorphism or geographic variation. However, the mean number of ventrals for cyclopion (x = 141.6, range = 133-145, n = 249) is significantly higher than that of floridana (x = 136, range = 129-141, n = 130, P < 0.01). As in most species of snakes, there is sexual dimorphism in the number of subcaudal scales. This difference is significant in both cyclopion and floridana ( P < 0.01); males of both taxa have 5-11 more subcaudals than females from the same localities. In both sexes cyclopion has fewer subcaudals than floridana. In cyclopion , north- ern populations have fewer subcaudals than southern populations, whereas there is no discernible geographic variation in floridana. Subcaudal counts in floridana show no significant geographic varia- tion. Samples from the vicinity of the presumed zone of parapatry are significantly different ( P < 0.01). The mean subcaudal number for male cyclopion from southern Alabama and Escambia County, Florida, is 73.9 (range = 70-76, n = 8), whereas that of male floridana from the western panhandle is 77.5 (range = 77-78, n = 2). Mean values for female cyclopion and floridana from the same areas are 66.7 (range = 61-69, n = 15) and 70 ( n = 1), respec- tively. The ranges of these values for the two taxa do not overlap, and the differences are significant even with the small sample sizes for floridana.
Table 1. Most frequent dorsal scale row formulae for Nerodia cyclopion and N. floridana. See Sanderson (1983) for complete scale row data.
|
Dorsal scale rows (anterior-midbody- posterior) |
Males |
Females |
||||||
|
cyclopion |
floridana |
cyclopion |
floridana |
|||||
|
%of Number sample |
% of Number sample |
% of Number sample |
% of Number sample |
|||||
|
25-23-19 |
15 |
31.3 |
0 |
0 |
0 |
0 |
0 |
0 |
|
27-25-21 |
33 |
68.8 |
15 |
34.1 |
57 |
70.4 |
0 |
0 |
|
29-25-21 |
0 |
0 |
15 |
34.1 |
10 |
12.3 |
11 |
22.9 |
|
29-27-21 |
0 |
0 |
11 |
25.0 |
12 |
14.8 |
15 |
31.3 |
|
29-27-23 |
0 |
0 |
3 |
6.8 |
2 |
2.5 |
22 |
45.8 |
Nerodia cyclopion and N. floridana
87
Fig. 2. Typical head profiles of large adult Nerodia cyclopion (A) and N. floridana (B). Bar = 20 mm.
There are no discernible patterns of geographic variation in the number of dorsal scale rows in either taxa. Significant sexual dimorphism occurs, with females typically having two rows more than conspecific males. The two taxa are separable on the basis of sample means (P < 0.01). Abbreviated dorsal scale row data are summarized in Table 1, and complete scale row data are in Sanderson (1983).
Head Scale Measurements
The head shape of cyclopion is distinctly different from that of floridana , particularly in the region of the snout. This difference is not pronounced in juveniles and small adults, but is conspicuous in larger individuals (Fig. 2). Particularly noteworthy is the abruptly sloped snout of floridana. Also, the head of floridana is narrower in dorsal view, being more laterally compressed than that of cyclopion.
Discriminant analysis of the head scale data from the calibra- tion group indicated that the two taxa are distinct groups, with an
88
William E. Sanderson
F
R
E
Q
U
E
N
C
Y
10
8
6
4
2
p = 0.18
rn r
±1
-1 -2
-3 -4 -5
DISCRIMINANT SCORE
Fig. 3. Histograms of discriminant scores for male (A) and female (B) Nerodia cyclopion calibration sample (open bars), N. cyclopion holdout sample (shaded bars), N. floridana calibration sample (stippled bars), and N. floridana holdout sample (crosshatched bars).
extremely high level of confidence (P < 0.0001) (Fig. 3). Internasal length, prefrontal length, muzzle length, and frontal extension length did not contribute significantly to the discrimination in either sex and were dropped from the analysis. The remaining variables (loreal dorsal length, frontal length, muzzle width, posterior genial length, loreal ventral length, anterior genial length, and parietal length) and their standardized discriminant function coefficients are given in Table 2. For both taxa, 100% of the specimens were classified correctly by the discriminant analysis, meaning that all specimens, which had been previously categorized as either cyclopion or floridana based
Table 2. Variables incorporated by the stepwise discriminant analysis, listed in order of entrance, with standardized discriminant function coefficients. See Figure 1 for description of variables.
Males Females
|
Variable |
Function |
Variable |
Function |
|
LD |
0.581 |
FL |
2.335 |
|
FL |
-1.561 |
MW |
-2.736 |
|
MW |
2.666 |
PG |
1.150 |
|
PG |
-0.922 |
LD |
-0.587 |
|
LV |
-0.797 |
LV |
0.916 |
|
AG |
0.972 |
AG |
-0.985 |
|
PL |
-0.843 |
Nerodia cyclopion and N. floridana
89
on ventral coloration and scale counts, fell within the predicted group based on head scale data alone.
I tested the holdout group against the classification criteria established in the calibration group analysis. Again, 100% of the males of both taxa were classified correctly. All female floridana were also correctly classified, but two female cyclopion were misclassified as floridanda. The first, (Auburn University Museum 22559, Ala- bama: Baldwin County, 6 miles NNW town of Stockton, Douglas Lake) has a typical cyclopion ventral color pattern. Its dorsal scale row formula (27-25-21) resembles that found in 70.4% of the fe- male cyclopion I examined. This dorsal scale formula was found in none of the female floridana. The snout of this individual is some- what shorter and narrower than is typical for cyclopion , and this feature caused the discriminant analysis to classify it as floridana. However, variation from the normal cyclopion pattern is slight; this individual was identified as floridana with an estimated 50.2% probability of being correct. Considering all the data available, as well as its geographic location, I conclude that this individual is a cyclopion.
The second misclassification (University of South Alabama 1930, Alabama: Baldwin County, Negro Lake) also has typical cyclopion ventral coloration and dorsal scale row counts (27-25-21). It is the longest specimen of cyclopion I examined (1,035-mm snout-vent length, 1,322-mm total length), which exceeds by 52 mm the record for cyclopion as listed by Conant and Collins (1991). The muzzle width is less than that of other cyclopion of similar length, which may be an allometric consequence of its large size. This variation probably exceeded the bounds of the classification criteria, which were estab- lished with data from smaller specimens. Again, the data suggest that this animal is also a cyclopion.
If gene flow has occurred between the two taxa in the zone of contact, the distributions of the discriminant functions of the holdout groups would be skewed away from those of the calibra- tion groups. This was tested (for cyclopion only due to the small sample sizes in floridana) by comparing sample means of the dis- criminant functions of the groups with /-tests. No significant differ- ence in sample means was found in female cyclopion (P = 0.183, t = 1.34, df = 76), but in the male population the scores of the holdout group did appear skewed away from the distribution of the calibration group scores. In addition, the /-test indicated a signifi- cant difference between the two groups (P = 0.012, t = 2.61, df = 56). An obvious explanation for these contradictory data is not ap- parent. Since gene exchange, if present, must affect both sexes, . I suggest that the relatively small sample size for male cyclopion
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William E. Sanderson
could have resulted in artificially dissimilar values. The distributions of the female cyclopion groups, with somewhat larger samples sizes, were not significantly different. Further, the distributions of the dis- criminant scores of the two taxa do not overlap (Fig. 3). I con- clude there is a lack of gene flow between parapatric populations of cyclopion and floridana. Continued investigation, ideally with ad- ditional specimens of floridana from this critical area, is definitely warranted.
Distribution
Fieldwork undertaken to clarify the distribution of green water snakes in western Florida was largely unsuccessful. Collecting trips to this area produced no specimens of N. floridana and only one N. cyclopion (Louisiana State University Museum of Zoology 40401, Florida: Escambia County, Perdido Bay Golf Club). Another cyclopion from the same locality (LSUMZ 40402) was procured for me by a local collector. The presence of this population in Escambia County indicates that N. cyclopion should be considered a resident of the state of Florida, although Ashton and Ashton (1981) did not in- clude cyclopion in their work on the snakes of Flordia.
Carr (1940) reported Nerodia cyclopion cyclopion from Leon County, Forida. These specimens could not be located and are pre- sumed lost, and Carr was not certain that they were cyclopion (P. Meylan, University of Florida, personal communication). The westernmost specimen of floridana (AUM 6087, Florida: Escambia County, Perdido River at Seminole) has an atypically dark venter when compared with specimens from the Florida peninsula. However, scale data identify it as floridana with a very high level of confidence ( P = 0.999). The green water snake remains unknown from Santa Rosa and Okaloosa counties, Florida, although a specimen clearly referable to floridana was taken in Walton County near the Okaloosa-Walton County boundary. Given the specimens presently available, it appears that the distribu- tions of cyclopion and floridana are adjacent or overlapping in Escambia County, Florida (Fig. 4).
DISCUSSION
Specimens intermediate between Nerodia cyclopion and N. floridana have been reported twice from southern Alabama. Mount (1975) reported a population of green water snakes in extreme southeastern Baldwin County that he considered to be intermediate on the basis of ventral coloration. Although some of these animals do have ven- ters that are somewhat lighter than cyclopion from more inland parts of Baldwin County, they are very similar to specimens from other Gulf coastal regions, especially those from coastal Mississippi and
Nerodia cyclopion and N. floridana
91
floridana (open circles) in southern Alabama and western Florida. The inset map shows localities of specimens examined in this study (most circles represent more than one specimen).
Dauphin Island, Alabama. This lightened coloration may be a result of selective pressures present in a coastal environment rather than an indication of gene exchange between cyclopion and floridana. On the basis of scale characters, these individuals are all clearly identifiable as cyclopion.
Mount (1975) also mentions specimens of floridana taken along the eastern shore of Mobile Bay. These specimens (LSUMZ 15780, Alabama: Baldwin County, Mobile Bay 3.95 miles west of Spanish Fort; Auburn University Museum 3030, Alabama: Baldwin County, west of Fairhope) are classified as cyclopion by body and head scale analysis, but both are nearly amelanistic, with extremely light ventral and dorsal color patterns. One of these (AUM 3030) has
92
William E. Sanderson
also suffered from extreme fading after preservation. Scalation clearly identifies both animals as cyclopion. Another specimen (LSUMZ 15779) collected at the same time as LSUMZ 15780 has typical cyclopion ventral coloration.
Cooper (1977) reported collecting an intergrade specimen in extreme southern Baldwin County, Alabama. This specimen was lost (W. E. Cooper, Auburn University, personal communication), but Cooper provided a second snake from this locality (LSUMZ 40089, Alabama: Baldwin County, Gulf Shores State Park, Lake Shelby) which he said has a ventral color pattern similar to that of the first specimen. In scalation, it is referable to cyclopion , but the ventral color is atypical in that the crescentic areas, which normally are cream to white in color, are nearly obliterated by blotches of dark pigment. I have seen two other specimens with similar atypi- cal patterns, both from Louisiana, and thus do not believe this col- oration to be indicative of intergradation.
Although cyclopion and floridana have not been collected to- gether, the two forms do appear to be at least parapatric in the area along the Perdido River, the Alabama-Florida state boundary. My analysis reveals no clear evidence of gene exchange between the two taxa. Additionally, the work of other researchers has re- vealed significant biochemical differences between the two taxa. Pearson (1966) reported a “low relationship” between the taxa and suggested elevation to full species. More recently, Lawson (1987) employed starch-gel electrophoresis to assay 35 gene loci of Thamnophiine snakes and found fixed allelic differences between cyclopion and floridana at seven of these loci. He concluded that cyclopion and floridana are sister species, with the degree of separation being somewhat greater than that which separates Nerodia rhombifera and N. taxispilota. In light of this body of evidence, I concur with Lawson and support his proposal that Nerodia c. cyclopion and N. c. floridana be elevated to monotypic species, Nerodia cyclopion and Nerodia floridana , respectively.
SPECIMENS EXAMINED
Nerodia cyclopion — Alabama: AUM 3030, 19345—46, 22105, 22290, 22448-52, 22455-59, 25970, 26618, 29371. CMNH 67353-55, 67385- 86. LSUMZ 15779-80, 40089. MCZ 318. MMNS (AR)2424(A-C). NMNH 56259. UAHC 51-546, 53-14. UF 50399. USA 757, 1801, 1929-32, 2074-76, 2127, 2194, 2227. Arkansas: UF 48036. NMNH 56258. Florida: LSUMZ 40401-2. Illinois: INHS 8749, 10002. LSUMZ 7543. NMNH 1639. Louisiana: LSUMZ 1566, 2839-43, 2846-47, 2937, 4785, 8205-06, 10466, 12071, 12933, 12985, 13135-36, 13556,
Nerodia cyclopion and N. floridana
93
13701-02, 13767-68, 13780-81, 13795, 14394, 16933, 17320, 17669, 18286, 18669, 18761-62, 20180, 20276, 20282-83, 20314, 20338- 39, 20340-41, 20703, 20722, 20729, 20734, 21059, 22557, 22953, 23179-80, 23305, 23531, 24081-84, 24086, 24093, 24521, 24669, 34308, 40285, 40296, 40329. MMNS AR-2427. TU 12830-31, 12836, 12860-61, 12863-66, 12872, 12914, 12965, 12995-96, 12998-99, 13000, 13040. UAHC 53-14, 53-42. Mississippi: AMNH 46751. CMNH 5248-49. MCZ 149576. MMNS (AR)2423, 2425, 2426(A-C), 2431 (A-B), 2433-37. NMNH 103179. UAHC 65-3517, 65-3518. Mis- souri: CMNH 7165. NMNH 24466, 35654, 56256-57. Tennessee: NMNH 10397-98. UIMNH 2159-60. Texas: AMNH 67626-27, 67891- 92. CMNH 827, 829, 1216, 1221, 1238, 1240, 1242, 1244, 1246- 50, 1254, 1258, 1260-63, 60261. INHS 3135. TCWC 3250, 14755, 18213, 27425-28, 27432-34, 33806-08, 33811, 46555-56. UF 4386- 87. UIMNH 1137-42, 1362-63.
Nerodia floridana — Alabama: AUM 6087. Florida: ChM CR2285. LSUMZ 40399, 40400. UAHC 53-36. UF 2127, 2286, 2370-72, 2491, 2809, 2858, 3913, 4712, 4758-59, 4762, 4766, 4779, 4850, 4883, 7125, 7217, 7286, 7511, 7869(1-2), 8800, 14211, 14498, 16126- 27, 17386, 18136, 18348, 21367, 21467, 45766-71, 45778-79, 45781- 83, 45789, 45790-92, 45804, 45806, 45808, 45858, 45860, 47859, 50366-67, 50369, 50372, 50374, 50377-78, 50388-89. Georgia: CMNH 33497. NMNH 130115-16. South Carolina: ChM (CR)2270, 2272, 2281-82, 2284. SREL 91, 739, 2223.
ACKNOWLEDGMENTS — I am very grateful to the personnel of the 17 museums and universities who allowed me to examine specimens in their care. I am especially indebted to Peter Meylan for personally packing and shipping over 100 specimens. Paul Moler and Kelly Thomas provided information on Nerodia in western Florida. Robin Lawson, Anthony Picheo, and William Cooper provided specimens from critical localities. Special thanks are extended to the personnel of Gulf Shores State Park, Gulf Shores, Alabama, for their excep- tional hospitality during a portion of the fieldwork. Louisana State University provided funds for computer analysis and a portion of my travel expenses, and Steven Buco of the Louisiana State Uni- versity Department of Experimental Statistics assisted with the dis- criminant analysis. Special thanks to Samuel Sweet, James Petranka, and two anonymous reviewers for their excellent statistical and edi- torial advice. Finally, thanks to my mentor and friend, Douglas Rossman, to whom this paper is dedicated, for expert guidance, boundless enthusiasm, and exceptional patience.
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William E. Sanderson
LITERATURE CITED
Ashton, R. E., Jr., and P. S. Ashton. 1981. Handbook of the reptiles and amphibians of Florida. Part one: The snakes. Windward Publica- tions, Miami, Florida.
Carr, A. F., Jr. 1940. A contribution to the herpetology of Florida. University of Florida Publications in Biological Sciences 3:1-118.
Conant, R., and J. T. Collins. 1991. A field guide to the reptiles and amphibians of eastern and central North America. Third edition. Houghton Mifflin, Boston, Massachusetts.
Cooper, W. E., Jr. 1977. Geographic distribution: Natrix cyclopion cyclopion x floridana. Herpetological Review 8:13.
Dowling, H. G. 1951. A proposed standard system of counting ventrals in snakes. British Journal of Herpetology 1:97-99.
Dumeril, A. M. C., G. Bibron, and A. H. A. Dumeril. 1854. Erpetologie generate ou histoire naturelle complete des reptiles. Paris: Librairie Encyclopedique de Roret, Volume 7, Part 2:781-1536.
Goff, C. C. 1936. Distribution and variation of a new subspecies of
water snake, Natrix cyclopion floridana, with a discussion of its re- lationships. Occasional Papers of the Museum of Zoology of the University of Michigan 327:1-11.
Lawson, R. 1987. Molecular studies of thamnophiine snakes: 1. The
phylogeny of the genus Nerodia. Journal of Herpetology 21:140-157.
Mount, R. H. 1975. The reptiles and amphibians of Alabama. Agricul- tural Experiment Station, Auburn, Alabama.
Pearson, D. D. 1966. Serological and immunoelectrophoretic comparisons among species of snakes. Bulletin of the Serological Museum 36:8.
Sanderson, W. E. 1983. Systematics of the water snakes of the Nerodia cyclopion complex. M.S. Thesis, Louisiana State University, Baton Rouge.
Accepted 15 April 1993
Observations on Crayfish Predation by Water Snakes, Nerodia (Reptilia: Colubridae)
Lance W. Fontenot and Steven G. Platt Department of Biological Sciences, Clemson University , Clemson, South Carolina 29634-1903
AND
Christine M. Dwyer
Museum of Natural History and Department of Systematics and Ecology, The University of Kansas, Lawrence, Kansas 66044-2454
ABSTRACT — Field observations of ingestion of crayfish are reported for the colubrid snake Nerodia cyclopion. We surmise that the presence of crayfish in the gut contents of water snakes might not be attributable solely to secondary ingestion of other food items. Crayfish seem to be of minor importance in the diet of water snakes, but patterns of use of this food resource are still poorly understood. Future studies should indicate the size and de- gree of digestion of crayfish so that a determination of primary or secondary ingestion can be made.
Water snakes of the genus Nerodia generally prey on fish and frogs (Mushinsky 1987), unlike the closely related crayfish special- ists in the genus Regina. However, the importance of other prey items is unclear. The significance of crayfish in the diets of fishes, amphibians, and reptiles has been addressed by Penn (1950) and Neill (1951). Penn (1950) noted that crayfish were important in the diet of Nerodia erythrogaster, but this conclusion was based on examination of only one specimen. Based on observations of re- cently captured N. sipedon disgorging crayfishes, Neill (1951) re- ported that N. rhombifer and N. sipedon also included crayfish in their diets.
Most of the literature concerning the predation of crayfish by water snakes is based on examination of stomach contents and not on field observations of actual ingestion. Neill and Allen (1956) argued that care must be taken in analyzing feeding habits of snakes so as not to discount the possibility of secondary ingestion (obtain- ing prey items from the gut of the primary prey species) of food items. They suggested that crayfish fragments found in the stom- achs of N. erythrogaster and N. sipedon might represent the stom- ach contents of fishes ingested by snakes. The chitinous exoskeleton of crayfish might be more resistant to digestion than the tissues of primary vertebrate prey, and therefore, the exoskeleton will persist
Brimleyana 19:95-99, December 1993
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96 Lance W. Fontenot, Steven G. Platt, and Christine M. Dwyer
in the predator’s stomach. This has been documented in crocodil- ians (Jackson et al. 1974, Garnett 1985), but evidence in snakes is lacking. The objectives of our paper are to provide data concerning field observations on the ingestion of crayfish by the green water snake (N. cyclopion) and to discuss the importance of crayfish in the diet of water snakes.
STUDY AREA AND METHODS
Observations of foraging snakes were made along Alligator Bayou, Ascension Parish, Louisiana. Alligator Bayou is in a swamp for- merly subjected to backwater flooding from the Mississippi River. Elevated areas in the swamp are dominated by bottomland hard- woods ( Quercus spp., Ulmus spp., Celtis laevigata , and Liquidam- bar styraciflua). Lower areas are dominated by Taxodium distichum,
Nyssa sylvatica , N. aquatica, and Cephalanthus occidentalis.
A 14-foot boat equipped with an outboard motor was used to search for snakes along waterways and canals. At night, a Q-beamR spotlight (250,000 candle power) was used to observe snakes. The stomach contents of snakes collected for a parasitological study were examined, and prey items were identified to the lowest possible
taxon (Fontenot 1990).
Crayfish are abundant at this site and are harvested commer- cially for human consumption. According to Huner (1975), red swamp crayfish (. Procambarus clarki) are most abundant during elevated water levels in the spring, when they mate. As water levels decline in the summer, the crayfish burrow down to the water level and
remain below ground until water levels rise again in the late v/inter and early spring.
RESULTS
One male N. cyclopion (SVL = 50.1 cm, BM = 123.3 g) was observed foraging in relatively clear water at 2241 hours on 30 May 1989. This snake slowly moved its head from side to side, while holding its jaws slightly agape in the characteristic foraging posture described for water snakes by Mushinsky (1987). The snake made contact with and immediately seized a red swamp crayfish, Procambarus clarki , (carapace length = 25.0 mm, total length = 48.3 mm). The crayfish was molting; consequently, it did not pos- sess a hardened exoskeleton. The snake twisted its head and body during prey capture, positioned the crayfish in its mouth, and then ingested the prey tail-first within 30 seconds of capture. This posi- tion was later verified when the snake was dissected. Several uni- dentified small fish were also present in the gut contents. Both the
Crayfish Predation by Water Snakes
97
specimen of N. cyclopion and the crayfish have been deposited in the Clemson University Vertebrate Museum (CUSC#931).
Examination of 60 N. cyclopion from this locality revealed that one other snake contained crayfish in its gut. Additionally, 3 of 29 N. fasciata and 1 of 24 N. rhombifer examined from the same locality contained crayfish remains (Fontenot 1990).
DISCUSSION
Conant and Collins (1991) listed frogs, salamanders, fish, and crayfish as food items for members of the genus Nerodia. How- ever, chemical preference studies of newborn water snakes have shown that crayfish are not a preferred food item (Burghardt 1968, Mushinsky and Lotz 1980). Crayfish have been reported as prey items for adult N. cyclopion (Kofron 1978), N. erythrogaster (Clark 1949), N. fasciata (Mushinsky and Hebrard 1977), N. rhombifer (Minton 1944, Sisk and McCoy 1964, Bowers 1966, Kofron 1978), and N. sipedon (Zelnick 1966, Fraker 1970, Camp et al. 1980), which suggests crayfish consumption might be restricted to larger individuals. In all cases except for N. erythrogaster (Clark 1949), crayfish were infrequent prey items. Brown (1958) concluded that the importance of crayfish in the diet of water snakes has been unintentionally exaggerated. He found no crayfish in 207 stomachs of N. sipedon he examined even though crayfish were abundant at his study site. Crabs, another crustacean, have been reported to be ingested by N. clarki (Mount 1975).
Although some crayfish remains could be attributed to secondary ingestion, in many instances it is likely that crayfish are consumed as a primary prey item. Because molting crayfish lack a digestive-resistant chitinous exoskeleton, they are probably consumed more frequently than food habits studies indicate. We suggest that in future studies the size and degree of digestion (intact crayfish or fragments) be noted to help determine if crayfish are primarily or secondarily ingested.
Based on our limited observations and a review of the litera- ture, we believe that crayfish do not comprise a large portion of the diets of most species of water snakes; however, crayfish might be consumed directly by water snakes. Differential digestion rates of vertebrate and crayfish prey might introduce bias in analysis of reptile food habits (Jackson et al. 1974, Garnett 1985). Patterns of use of this food resource by water snakes may be subject to onto- genetic shifts and seasonal or regional differences in foraging ecology.
98 Lance W. Fontenot, Steven G. Platt, and Christine M. Dwyer
ACKNOWLEDGMENTS— We thank Richard R. Montanucci, William I. Lutterschmidt, and Richard S. Knaub for their comments on earlier versions of the manuscript.
LITERATURE CITED
Bowers, J. H. 1966. Food habits of the diamond-backed water snake, Natrix rhombifera rhombifera, in Bowie and Red River counties, Texas. Herpetologica 22:225-229.
Brown, E. E. 1958. Feeding habits of the northern water snake, Natrix sipedon sipedon Linnaeus. Zoologica 43:55-71.
Burghardt, G. M. 1968. Chemical preference studies on newborn snakes of three sympatric species of Natrix. Copeia 1968:732-737.
Camp, C. D., W. D. Sprewell, and V. N. Powders. 1980. Feeding
habits of Nerodia taxispilota with comparative notes on the foods of sympatric congeners in Georgia. Journal of Herpetology 14:301-304.
Clark, R. F. 1949. Snakes of the hill parishes of Louisiana. Journal of the Tennessee Academy of Science 24:244-261.
Conant, R., and J. T. Collins. 1991. A field guide to reptiles and
amphibians of eastern and central North America. Houghton Mifflin Company, Boston.
Fontenot, L. W. 1990. Helminth parasites of aquatic snakes from south- eastern Louisiana. Masters Thesis, Southeastern Louisiana University, Hammond.
Fraker, M. A. 1970. Home range and homing in the watersnake, Natrix sipedon sipedon. Copeia 1970:665-673.
Garnett, S. T. 1985. The consequences of slow chitin digestion on
crocodilian diet analyses. Journal of Herpetology 19:303-304.
Huner, J. V. 1975. Observations on the life histories of recreationally
important crawfishes in temporary habitats. Proceedings of the Loui- siana Academy of Sciences 38:20-24.
Jackson, J. F., H. W. Campbell, and K. E. Campbell, Jr. 1974. The
feeding habits of crocodilians: Validity of the evidence from stomach contents. Journal of Herpetology 8:378-381.
Kofron, C. P. 1978. Foods and habitats of aquatic snakes (Reptilia,
Serpentes) in a Louisiana swamp. Journal of Herpetology 12:543-554.
Minton, S., Jr. 1944. Introduction to the study of the reptiles of Indi- ana. American Midland Naturalist 32:438-477.
Mount, R. H. 1975. The reptiles and amphibians of Alabama. Agricul-
tural Experiment Station, Auburn University, Auburn, Alabama.
Mushinsky, H. R. 1987. Foraging ecology. Pages 302-334 in Snakes: Ecology and evolutionary biology (R. A. Seigel, J. T. Collins, and S. S. Novak, editors). Macmillan Publishing Company, New York,
New York.
Crayfish Predation by Water Snakes
99
Mushinsky, H. R., and J. J. Hebrard. 1977. Food partitioning by five species of water snakes in Louisiana. Herpetologica 33:162-166.
Mushinsky, H. R., and K. H. Lotz. 1980. Chemoreceptive responses of two sympatric water snakes to extracts of commonly ingested prey species: Ontogenetic and ecological considerations. Journal of Chemi- cal Ecology 6:523-535.
Neill, W. T. 1951. Notes on the role of crawfishes in the ecology of reptiles, amphibians and fishes. Ecology 32:764-766.
Neill, W. T., and E. R. Allen. 1956. Secondarily ingested food items in snakes. Herpetologica 12:172-174.
Penn, G. H. 1950. Utilization of crawfishes by cold-blooded vertebrates in the eastern United States. American Midland Naturalist 44:643- 658.
Sisk, M. E., and C. J. McCoy. 1964. Stomach contents of Natrix r. rhombifera (Reptilia: Serpentes) from an Oklahoma lake. Proceedings of the Oklahoma Academy of Science 44:68-71.
Zelnick, G. E. 1966. Midsummer feeding habits of the midland water snake. The Southwestern Naturalist 11:311-312.
Accepted 18 March 1993
Food and Feeding Behavior of Adult Snowy Grouper, Epinephelus niveatus (Valenciennes) (Pisces: Serranidae), Collected off the Central North Carolina Coast with Ecological Notes on Major Food Groups
Jon Dodrill
Florida Department of Natural Resources Division of Recreation and Parks District 2, Administration 3540-A Thomasville Road Tallahassee, Florida 32308
Charles S. Manooch III and Ann Bowman Manooch
National Marine Fisheries Service Southeast Fisheries Science Center Beaufort Laboratory 1 01 Fivers Island Road Beaufort, North Carolina 28516-9722
ABSTRACT — Food items from snowy grouper ( Epinephelus niveatus ) (Valenciennes) were collected on 30 commercial handline fishing trips off central North Carolina from March 1985 through April 1986 in waters 146-228-m deep. More than 5,000 snowy grouper stomachs were examined, but fewer than 5% contained food. Em- bolism prevented the frequent extraction of intact digestive tracts. Snowy grouper fed on crustaceans (72% by volume), fish (18%), and mollusks (10%). Crabs, primarily Portunus spinicarpus (Stimpson), accounted for approximately 90% of the food items and 72% of the volume. Most foods were inhabitants of bottom or near-bottom waters and were small enough to be swallowed whole. Ecological notes are included on major food groups. Competition for food between E. niveatus and other serranids is believed to be minimal because only a few other groupers were caught. Of the other groupers, the yellowedge grouper ( E . flavolimbatus Poey) contained foods most similar to those con- sumed by snowy grouper. Compared with other sympatric species, E. niveatus fed on foods most similar to red porgy ( Pagrus pagrus).
Reef fish and macroinvertebrate assemblages on the outer continental shelf edge and upper slope of central North Carolina at depths between 140 and 240 m have received little scientific atten- tion. This is in spite of steadily increasing commercial hook-and- line activity in that depth range throughout the Carolinas since 1979
Brimleyana 19:101-135, December 1993
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John Dodrill et al.
(Low and Ulrich 1983). At these depths energy flow, trophic struc- ture, species competition for space and food, and the extent of
substrate use by deep reef associated predators remain poorly known (Duke University Marine Laboratory 1982).
The snowy grouper, a tertiary predator, is the dominant
grouper at depths greater than 140 m off the Carolinas (Low and Ulrich 1983, Chester et al. 1984). In 1984 the snowy grouper was by mass the most important reef fish caught commercially along the central North Carolina coast (eastern Onslow and Raleigh bays) (Epperly and Rhode 1985). That year an estimated 34,771 E. niveatus totaling 162,112 kg were harvested statewide. The species repre-
sented 14.0% by mass of all reef species commercially caught by bottom longline, handline, and fish traps.
Adult snow grouper are consistently found in deeper water,
whereas juveniles dominate the shallow end of the depth range. In part this may reflect years of intensive fishing pressure in 40-120- m intermediate depths and only relatively recent pressure beyond 183 m off central North Carolina where the largest adults were encountered. The shift toward larger grouper with increasing depth, which has been noted by Low and Ulrich (1983) in South Carolina and by Moore and Labisky (1984) in the lower Florida Keys, might also indicate movement of grouper into deeper water with the onset of maturity.
Inaccessibility of adult snowy grouper at depths beyond 140 m has restricted life history data collection in the South Atlantic Bight to limited exploratory cruise data or materials available from dock-side sampling (Low and Ulrich 1983, Matheson and Huntsman 1984, Epperly and Rhode 1985). Typical of other biological aspects of E. niveatus, little is known of its feeding habits. From 1972 to 1981 the National Marine Fisheries Service (NMFS) Beaufort, North Carolina, attempted to collect snowy grouper stomach samples from recreational headboats operating between Cape Hatteras and Cape Romain and from research vessels (Matheson 1981; G. Hunts- man, National Marine Fisheries Service, Beaufort, personal com- munication). In a live bottom study conducted on the outer conti- nental shelf off North Carolina for the Minerals Management Ser- vice, Bureau of Land Management (BLM), Duke University Marine Laboratory (1982) also collected snowy grouper food items, as did the South Carolina Wildlife and Marine Resources Department (1982) in a similar BLM study off South Carolina and Georgia.
Results of all three efforts were discouraging. Of hundreds of grouper stomach examined by NMFS (R. Matheson III, Apex High School, Apex, North Carolina, personal communication) only 131
Snowy Grouper Feeding
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were recovered intact. Eighteen contained food, represented by de- capod crustaceans (78% of number; 72% of volume) and unidenti- fied fish (20% of total prey number; 28% of volume). Identifiable food items included one Spanish lobster ( Scyllarus depressus) (Smith) and brachyuran crabs: Acanthocarpus alexandri Stimpson, Calappa angusta Milne Edwards, Calappa flammea (Herbst), Iliacantha subglobosa Stimpson, Ovalipes stephensoni Williams, and Portunus spinicarpus (Stimpson) (Duke University Marine Laboratory 1982, South Carolina Wildlife Marine Resources Department and Duke Uni- versity Marine Laboratory 1982, Parrish 1987). Food items were collected primarily from the outer shelf in summer from headboats operating in 37-110 m (R. Matheson III, personal communication). The North Carolina BLM effort produced only 14 intact stomachs, two of which contained food (Duke University Marine Laboratory 1982). The South Carolina and Georgia BLM outer shelf project obtained no snowy grouper stomachs with food (South Carolina Wild- life Marine Resources Department 1982).
The only other E. niveatus feeding study conducted in the southeastern United States was an analysis of intestinal tracts of 26 snowy grouper from the lower Florida Keys (Bielsa 1982). Speci- mens were collected from May through October at 123-256 m. Fish, primarily pelagic species, dominated (43% of prey number; 47% of total volume). Cephalopods ranked second in numerical importance (21%), although brachyuran crabs were second in volumetric impor- tance (32%).
Problems associated with sampling snowy grouper for food items include fish availability, condition of the fish at dockside, and stomach eversion resulting from embolism. Adult snowy grouper are uncom- mon in trawl catches (Bullis and Thompson 1965, Barans and Bur- rell 1976, Keiser 1976, Cupka et al. 1977), and hook-and-line sampling on small, patch reefs from large research vessels has proven expen- sive, labor intensive, and ineffective in providing sufficient samples for food analysis (R. Matheson III, personal communication; C. Manooch III, personal observation). Snowy grouper with intact stomachs are rarely brought to commercial docks because groupers normally are gutted and iced at sea. Ungutted snowy grouper caught by headboat anglers do reach the dock. However, they are not abundant and are now caught almost exclusively in waters less than 100 m where few large fish are found. Visual observations of snowy grou- per feeding behavior have been limited to a single submersible observation of individuals near a reef in 125-137 m off North Carolina (Parker and Ross 1986).
104
John Dodrill et al.
Epibenthic predators, particularly those associated with deep water reefs, often feed on small cryptic fish and macroinvertebrates. These prey are ineffectively sampled by trawls, dredges, grabs, and remote cameras. Thus, analysis of snowy grouper stomachs provides additional life history and distribution data on prey items that might otherwise have gone unsampled by conventional sampling methods.
The objective of our study was to define the role of adult snowy grouper as an epibenthic predator in the trophic structure of the shelf-edge and upper-slope communities off the central coast of North Carolina. By sampling abroad a commercial fishing vessel, we were able to (1) identify foods of snow grouper, (2) evaluate their contribution to the diet numerically and volumetrically, and (3) compare the diet of snowy grouper with those of other ser- ranids and with three important sympatric species.
METHODS
Thirty, 1-4-day commercial handline fishing trips targeting snowy grouper stocks in deep water were made off North Carolina (Table 1). Stomachs were examined and prey items were collected during fishing operations aboard a 12.5-m vessel, and occasionally aboard a 9.4-m sister vessel, based in Beaufort, North Carolina (Table 1). The primary study area was a narrow zone which began ap- proximately 83 km SSE of Cape Lookout and extended about 44 km to the northeast along the outer continental shelf edge and up- per-slope crown at depths of 137-194 m. Fishing was conducted from spring through fall. Several spring trips were made to a sec- ondary study area about 57 km south of Cape Hatteras in 168-238 m along the upper slope crown in a 10-km2 area. In both areas numerous stations, including at least two wrecks, were drift fished with weighted multiple hook rally rigs baited with squid on wire handlines operated from hydraulic reels. A single exploratory longline set in 108 m and a single handline station at 112 m were the shallowest depths fished and contributed fewer than 40 fish to the study.
Bottom topography at 137-194 m typically consisted of scat- tered rock outcroppings or ledge formations of variable relief and shape which protruded through terrigeneous sand substrate of vary- ing coarseness and a variable carbonate shell component. Deeper, particularly in the secondary study area beyond 219 m, a clay-mud substrate was sometimes encountered.
The senior author served full time as a commercial fisherman on the vessels. He cleaned large quantities of fish and recovered food items that would not have been available at dockside. This sampling was an unfunded, volunteer endeavor aboard a vessel whose
Snowy Grouper Feeding
105
primary objective was to catch, clean, and ice as many fish in as short a time as possible. Often only the senior author and the captain were aboard, and there was never more than a second crewman.
When grouper regurgitated food items on deck, it was usually not possible to assign specific items to a particular grouper or to
Table 1. Commercial fishing trips make off North Carolina where snowy grouper digestive tract contents were collected, 1985-86.
|
Date |
Depth (m) |
Number of Snowy Grouper |
Size (mm TL) |
Gutted Mass (kg) x Total |
|
|
2/22/85 |
194-205 |
28 |
14.7 |
411.6 |
|
|
4/13/85 |
205-236 |
44 |
455-1090 |
8.8 |
387.2 |
|
4/18-21/85 |
194 |
34 |
450-1070 |
6.8 |
231.2 |
|
4/26-29/85 |
111,194-208 |
157 |
510-1075 |
5.3 |
832.1 |
|
5/5/85 |
196,205 |
2 |
8.4 |
16.8 |
|
|
5/16-17/85 |
146-155 |
599 |
330- 990 |
2.7 |
1,617.3 |
|
5/21-23/85 |
146-192 |
290 |
330-1010 |
2.0 |
580.0 |
|
6/2-4/85 |
155,187-236 |
150 |
7-1100 |
8.1 |
1,215.0 |
|
6/9-11/85 |
236 |
58 |
(394.6)1 |
||
|
6/21-24/85 |
148-155 |
470 |
3.3 |
1,551.0 |
|
|
6/28-29/85 |
194 |
223 |
8.6 |
1,917.8 |
|
|
7/2-3/85 |
194 |
76 |
435-1030 |
6.5 |
494.0 |
|
7/9-10/85 |
146,194 |
124 |
410- 990 |
6.1 |
756.4 |
|
7/14-17/85 |
108-194 |
136 |
390- 990 |
5.6 |
761.6 |
|
7/20-21/85 |
194 |
277 |
380-1100 |
8.3 |
2,299.1 |
|
7/30-31/85 |
194 |
285 |
405-1020 |
4.7 |
1,339.5 |
|
8/5-7/85 |
143-146 |
252 |
404- 990 |
4.8 |
1,208.6 |
|
8/23/85 |
194 |
31 |
1.8 |
55.8 |
|
|
8/25-26/85 |
137-146 |
184 |
335- 770 |
2.9 |
533.6 |
|
8/29-30/85 |
201-238 |
85 |
5.0 |
425.0 |
|
|
9/3-6/85 |
141-192 |
453 |
?- 980 |
3.8 |
1,721.4 |
|
9/20-21/85 |
148 |
28 |
1.5 |
42.0 |
|
|
9/30-10/2/85 |
148-192 |
190 |
405- 860 |
2.7 |
513.0 |
|
10/19-20/85 |
159-194 |
54 |
515- 850 |
(158.8)1 |
|
|
11/7-8/85 |
159-194 |
49 |
2.2 |
107.8 |
|
|
11/9-11/85 |
146-159 |
178 |
2.5 |
445.0 |
|
|
11/19-20/85 |
146-155 |
157 |
335- 785 |
1.8 |
282.6 |
|
2/19/86 |
146 |
1 |
3.6 |
3.6 |
|
|
3/16-18/86 |
141-194 |
321 |
350- 876 |
2.4 |
770.4 |
|
3/25-27/86 |
146-163 |
152 |
365- 760 |
2.6 |
395.2 |
|
Combined |
5,088 |
4.2 |
21,370 |
1 Estimated gutted mass.
106
John Dodrill et al.
measure individual fish, because sometimes 12-15 grouper would be brought on deck at the same time. Grouper were secured in retain- ing boxes before gutting. As fish were cleaned, mouths and throats were examined, and boxes were checked for regurgitated prey. Be- tween drifts the deck was scanned for regurgitated foods before rinsing. The senior author examined most grouper caught but gutted only about half, relying on the other crew members to recover food from the remainder.
Catches were predominantly snowy grouper, but other species were occasionally caught (Table 2). If there was any question as to which species regurgitated given items, which was infrequent, the items were not recorded. Regurgitated items less than 15 mm were
Table 2. Additional fish species and numbers captured on hook and line in 141 — 236 m off central North Carolina during the time frame when snowy grouper were sampled, 1985-86.
Species Number Caught
Blueline tilefish ( Caulolatilus microps Goode and Bean) 358
Banded rudderfish ( Seriola zonata) (Mitchell) 90
Vermilion snapper ( Rhomboplites aurorubens ) (Cuvier) 57
Yellowedge grouper {Epinephelus flavolimbatus) (Poey) 52
Red porgy {Pagrus pagrus Linnaeus) 51
Almaco jack (, Seriola rivoliana Valenciennes) 45
Blackbelly rosefish ( Helicolenus dactylopterus ) (Delaroche) 16 1
Conger eel ( Conger oceanicus) (Mitchell) 12 2
Greater amberjack {Seriola dumerili ) (Risso) 6
Spinycheek scorpionfish (. Neomerinthe hemingwayi Fowler) 5 1
Reticulate moray {Muraena retifera Goode and Bean) 4
Scalloped hammerhead shark {Sphyrna lewini ) (Griffith and Smith) 4
Night shark {Carcharhinus signatus) (Poey) 3 2
Bignose shark {Carcharhinus altimus ) (Springer) 2
Tiger shark {Galeocerdo cuiveri ) (Person and Lesueur) 1
Tilefish {Lopholatilus chamaeleonticeps Goode and Bean) 1 1
Purplemouth moray {Gymnothorax vicinus ) (Castelnau) 1
Shark toothed moray {Gymnothorax madierensis) 1
Wreckfish {Polyprion americanus ) (Schneider) 1
Barrelfish {Hyperogloyphe periformis) (Mitchell) 1
Misty grouper {Epinephelus mystacinus ) (Poey) 1
Speckled hind {Epinephelus drummondhayi Goode and Bean) 1
Gymnothorax kolpos 1
Total 714
1 Between Cape Lookout and Hatteras beyond 219 m.
2 Captured only at dusk or night.
Snowy Grouper Feeding
107
not likely recovered with the same regularity as larger foods. Items positively identified as bait (squid or cut fish) were not saved. Intact stomachs and all loose items were placed in labeled bags on ice. At dockside the unusual food items were photographed, and then all items were preserved in 10% formalin.
In the laboratory prey items were rinsed in fresh water and were identified. Voucher specimens were transferred to 70% alco- hol. Decapods were identified from Williams (1984) and were vali- dated by comparison with the Duke University Marine Laboratory reference collection. Stomatopod and decapod voucher specimens were sent to the National Museum of Natural History for identification verification by A. B. Williams and R. B. Manning. Fish were iden- tified with the assistance of S. Ross, North Carolina State Univer- sity, and G. Burgess, Florida State Museum, Gainesville. Squid were identified from Roper et al. (1984). Food items were identified to the lowest taxon possible, counted, and measured volumetrically by water displacement. Contributions to the diet were calculated as percentage by number and as percentage of volume. Except for the few times when intact stomach samples were obtained, frequency of occur- rence could not be determined.
RESULTS AND DISCUSSION
A total of 5,088 snowy grouper was caught from February 1985 through March 1986. Specimens ranged from 335 to 1,100 mm in total length (TL). Based on the mass-length relationship W = 3.6 x 10'8 TL2 868 (where W = mass in kg and TL = total length in mm) (Matheson and Huntsman 1984), masses ranged from 0.6 kg to 19.0 kg (ungutted). We estimate that less than 5% of the snowy grouper boated contained food. Presumably most food items were regurgitated as the fish were brought to the surface. It is also possible that grouper feeding success or effort could have been re- duced at specific sites where there were seasonal aggregations of hundreds of grouper. Only 23 fish had contents in uneverted stom- achs; other items came from regurgitations on deck or were lodged in throats or gills.
All prey items (fish, squid, and crustaceans) had broad latitu- dinal distributions and represented a mix of tropical, temperate, and boreal affinities. The southerly flowing Virginian coastal current north of Cape Hatteras presents a cool-water barrier to established adult snowy grouper populations and limits the northerly range of the fish and their crustacean prey with tropical affinities (Cerame-Vivas and Gray 1966).
108
John Dodrill et al.
Synopsis of Foods
Crustacea
Snowy grouper fed most extensively on crustaceans. Approximately 91% of the items were crustaceans, representing 73% of the volume (Table 3). Brachyuran crabs dominated this group (90% by number; 72% of the volume) and were represented by 12 species. Other crustaceans were of relatively minor importance and included macruran shrimps, Solenocera sp. (probably S. atlantidis Burkenroad), and a stomatopod, Parasquilla coccinea. The volumet- ric percentage we recorded for decapods was almost identical to that reported from the earlier NMFS study of snowy grouper from the outer shelf of North Carolina and South Carolina (Duke Uni- versity Marine Laboratory 1982, Parrish 1987). However, our volu- metric percentage for brachyurans was more than twice that noted by Bielsa (1982) for snowy grouper from the lower Florida Keys.
All crustacean prey from snowy grouper have depth ranges extending seaward of 182 m (Williams 1984, Soto 1985). Adult crustaceans are mid-outer shelf or upper slope inhabitants whose bathymetric ranges seasonally overlap (Wenner and Read 1982). Only two crustacean prey, Ovalipes stephensoni and Calappa falmmea, extend into shallow waters (<10 m). There, seasonal temperature extremes, turbidity, freshwater runoff, light level, and substrate dif- ferences present major barriers to most outer-shelf-edge decapods (Cerame-Vivas and Gray 1966, Van Dover and Kirby-Smith 1979, Wenner and Read 1982, Williams 1984).
Although decapod distribution probably remains constant with latitude throughout the South Atlantic Bight (Wenner and Read 1982), bathymetric distribution patterns of prey probably result in major species differences in diet composition between snowy grouper ju- veniles on the mid shelf and adults on the upper slope. Predator and prey size variations with depth could also be a factor. Com- mercial hook-and-line captures of juvenile E. niveatus have occurred at depths as shallow as 23 m east of the Cape Lookout Shoals “Knuckle” buoy. Juvenile snowy grouper normally are not caught by hook and line until 42-64 m, and usually deeper. Adult snowy grouper have been caught on hook and line as deep as 293-394 m from January through March and as far north as 100 km northeast of Cape Hatteras. Both Cerame-Vivas and Gray (1966) and Wenner and Read (1982) reported only minor overlap of upper slope deca- pod fauna with inner-shelf species and considered the upper slope crest a major zoogeographical boundary.
Decapod prey of snowy grouper collected at 146-238 m be- came progressively less common the farther inshore dredging or
Snowy Grouper Feeding
109
Table 3. Items recovered from the digestive tracts of 5,088 snowy grouper caught off North Carolina (less than 5% of the fish were estimated to have contained food), 1985-86.
|
Item |
Number (673) |
Percent |
Volume (5,442.2mL) |
Percent |
|
Crustacea |
613 |
91.08 |
3,946.3 |
72.51 |
|
Crabs |
605 |
89.90 |
3,923.3 |
72.09 |
|
Portunus spinicarpus |
494 |
73.40 |
1,492.3 |
27.42 |
|
Ovalipes stephensoni |
19 |
2.82 |
584.0 |
10.73 |
|
Cancer irroratus |
8 |
1.19 |
779.0 |
14.31 |
|
Acanthocarpus alexandri |
13 |
1.93 |
206.5 |
3.79 |
|
Calappa angusta |
44 |
6.54 |
434.5 |
7.98 |
|
Cancer borealis |
2 |
0.30 |
130.0 |
2.39 |
|
Stenocionops spinimana |
9 |
1.34 |
154.0 |
2.83 |
|
Myropsis quinquespinosa |
10 |
1.49 |
99.5 |
1.83 |
|
Parthenope pourtelesii |
3 |
0.45 |
22.0 |
0.40 |
|
Nibilia antilocapra |
1 |
0.15 |
9.0 |
0.17 |
|
Portunus floridanus |
1 |
0.15 |
6.5 |
0.12 |
|
Stenorynchus seticornis |
1 |
0.15 |
6.0 |
0.11 |
|
Solenocera atlantidis |
7 |
1.04 |
12.0 |
0.22 |
|
Parasquilla coccinea |
1 |
0.15 |
11.0 |
0.20 |
|
Fish |
42 |
6.24 |
952.5 |
17.50 |
|
Unidentified remains |
22 |
3.27 |
341.5 |
6.27 |
|
Peprilus triancanthus |
7 |
1.04 |
69.0 |
1.27 |
|
Ophichthidae |
3 |
0.45 |
17.0 |
0.31 |
|
Myrophis punctatus |
2 |
0.30 |
13.0 |
0.24 |
|
Ophidiidae |
1 |
0.15 |
5.0 |
0.09 |
|
Macrorhamphosus scolopax |
1 |
0.15 |
20.0 |
0.37 |
|
Lepophidium jeannae |
1 |
0.15 |
39.0 |
0.72 |
|
Rhomboplites aurorubens |
1 |
0.15 |
325.0 |
5.97 |
|
Antigonia capros |
1 |
0.15 |
83.0 |
1.53 |
|
Hemanthias vivanus |
1 |
0.15 |
3.0 |
0.06 |
|
Synodus poeyi |
1 |
0.15 |
4.0 |
0.07 |
|
Congridae |
1 |
0.15 |
33.0 |
0.61 |
|
Mollosca |
16 |
2.38 |
536.0 |
9.85 |
|
Gastropoda |
1 |
0.15 |
4.0 |
0.07 |
|
Conus delessertii |
1 |
0.15 |
4.0 |
0.07 |
|
Cephalopoda |
15 |
2.23 |
532.0 |
9.78 |
|
Unidentified squids |
10 |
1.49 |
37.0 |
0.68 |
|
Loligo pealei |
3 |
0.45 |
275.0 |
5.05 |
|
Illex illecebrosus |
2 |
0.30 |
220.0 |
4.04 |
|
Miscellaneous contents |
2 |
0.30 |
7.5 |
0.14 |
|
Rock fragment |
1 |
0.15 |
4.0 |
0.07 |
|
Fishing lure skirt |
1 |
0.15 |
3.5 |
0.07 |
110
John Dodrill et al.
trawling was conducted. Of brachyurans recorded in the diet, Cancer borealis Stimpson and C. irroratus Say rarely leave the upper slope, whereas the following crab species have centers of adult distribution concentrated on the outer shelf or slope crown: Acanthocarpus alexandri, Calappa angusta, Iliacantha sub- globosa, Myropsis quinquespinosa Stimpson, Nibilia antilocapra (Stimpson), and Stenocionops spinimana (Rathbun) (Pequegnat 1970, Williams 1984).
Portunidae — Portunus spinicarpus was the most frequently en- countered prey ( n = 494). We found up to 23 whole P. spinicarpus in a single grouper stomach. Also, based on similar states of prey freshness, several grouper had eaten multiple P. spincarpus from the same sites at about the same time. Additionally, snowy grouper fed on both adult and juvenile P. spinicarpus of mixed sexes (286 males, 143 females, 65 juvenile or sex undetermined). These had a carapace width (CW) of 21-58 mm. Two gravid females (37 and 42 mm CW, orange and brown eggs, respectively) were recovered from grouper in May 1985, in depths of 146-155 m in the primary study area.
This crab occurred most frequently in gut contents from mid-May through August, declining in importance in fall. We re- corded none as prey past mid-October, although winter trawl records were noted from an outer Onslow Bay station (50-100 m) (South Carolina Wildlife Marine Resources Department and Duke Uni- versity Marine Laboratory 1982) and off Oregon Inlet north of our study area (Musick and McEachran 1972).
The abundance of this crab in the South Atlantic Bight based on trawl efforts parallels this dietary occurrence (Wenner and Read 1982). P. spinicarpus was the most common crab and fifth most common decapod collected between 38 and 188 m. Between 111 and 183 m, P. spinicarpus represented 16% of the decapod catch.
Ross (1982) reported it to be one of the most important crabs in the diet of the blueline tilefish ( Caulolatilus microps Goode and Bean), which co-occurs with snowy grouper. We also observed that P. spinicarpus was consumed by yellowedge grouper ( E . flavolimbatus Poey) (present study) and red porgy (Manooch 1977). Two other reef fishes, whitebone porgy ( Calamus leucosteus Jordan and Gil- bert) and vermilion snapper, ( Rhomboplites aurorubens) (Cuvier) also fed on P. spinicarpus in the Carolinas (South Carolina Wildlife Marine Resources Department and Duke University Marine Labora- tory 1982).
Rathbun (1930:93), however, made this statement regarding P.
Snowy Grouper Feeding
111
spinicarpus : “It is worthy to note thaf whereas this species is abun- dant in the Florida Keys, no remains were found among the hun- dreds of fish examined in recent years. This is attributable to the formidable armature of the chelipeds which is sufficient to ward off the enemy.” Our observations were that spines on this species and other crustaceans partially penetrated the inner stomach wall.
Ovalipes stephensoni was numerically the third most common prey item and was represented by seven males (37-65 mm CW), six females (54-78 m CW), and six specimens of undetermined sex. O. stephensoni occurred as prey at both study areas in 146- 236 m on nine cruises during March, May, June, July, September, and October.
Wenner and Read (1982) reported O. stephensoni to be the second most common portunid collected in the South Atlantic Bight (10-227 m). It comprised 2% of all depapods caught between 111 and 183 m. Cain (1974) reported that O. stephensoni burrows by day and forages at night.
Other reef fish preying on O. stephensoni off North and South Carolina include Warsaw grouper ( Epinephelus nigritus) (Holbrook) (J. Dodrill, personal observation), red porgy ( Pagrus pagrus), black sea bass ( Centropristis striata ) (Linnaeus), and vermilion snapper (juvenile crabs only) (South Carolina Wildlife Marine Resource Department and Duke University Marine Laboratory 1982).
Portunus floridanus was represented by a single female (30.5 mm CW) swallowed intact by a grouper caught at 143-152 m dur- ing August 1985. Off North Carolina the species occurs from spring through fall on the outer shelf (50-100 m) but is not overabundant. Wenner and Read (1982) caught three specimens while trawling at 81 m at one of 496 stations between Cape Fear and Cape Canaveral. This species is associated with hard bottom and does not range north of our primary study area (Cain 1972, South Carolina Wild- life Marine Resource Department and Duke University Marine Laboratory 1982).
Calappidae — Calappa angusta was the second most common decapod taken from snowy grouper caught in 108-201 m during 17 trips, all SSE of Cape Lookout. This crab occurred in every sam- pling month but May. C. angusta was represented by 34 males (21-40 mm CW), 5 females (22-34 mm CW), and 5 damaged speci- mens of undetermined sex. The predominance of male crabs and the presence of three of five recorded females in a single grouper stomach might indicate a spatial or temporal segregation by sex in depths of 146-155 m in the primary study area. Four C. angusta (30-34 mm CW) and nothing else in the intact stomach of a snowy
112
John Dodrill et al.
grouper caught 31 July 1985 in 146-155 m might also suggest a patchy distribution for this crab, or prey preference by the grouper.
The level of abundance indicated by occurrence in stomachs was not found by Wenner and Read (1982) from trawl sampling. They reported collecting only 45 specimens in 496 trawl tows in the South Atlantic Bight.
The presence of C. angusta in the stomachs of black sea bass and red porgy indicates some proximity to hard bottom areas (Manooch 1977, South Carolina Wildlife Marine Resource Department and Duke University Marine Laboratory 1982).
Acanthocarpus alexandri ( n = 13) was the fourth most abundant decapod collected from snowy grouper stomachs. Speci- mens were adults or subadults represented by nine males (29-37 mm CW), three females (25-32 mm CW), and one damaged speci- men, sex unknown. A. alexandri was found in stomachs in five trips in May, June, and August. Three specimens were taken from the same grouper caught in the primary study area at 146 m; all others were collected from grouper taken south of Cape Hatteras in 168-205 m. On a 5 May 1985 trip, two snowy grouper were caught in 196-205 m south of Cape Hatteras and both contained one A. alexandri. One grouper (925 mm TL) had four fresh, intact crabs in its stomach.
Wenner and Read (1982) collected only four A. alexandri at 496 trawling stations between 9 and 366 m in the South Atlantic Bight. A. alexandri was not collected by extensive dredging on the continental shelf off North Carolina (Cerame-Vivas and Gray 1966), although Pequegnat (1970) reported that this species was by far the most abundant deep water crab collected in the Gulf of Mexico.
Leucosiidae — Myropsis quinquespinosa ranked fifth in numerical prey abundance, with 10 individuals recovered. This de- capod was found in snowy grouper caught in 146-159 m SSE of Cape Lookout on five trips during June, July, October, and Novem- ber 1985. Three of these crabs were males (30, 33, 35 mm CW) and seven were females (24-41 mm CW). One 31-mm-CW female collected 15 July 1985 from a grouper caught in 155 m was ovigerous.
Wenner and Read (1982) collected this species in a narrow outer shelf depth range (102-155 m) with only 10 specimens trawled from 9 of 496 stations. Williams et al. (1968) reported 10 males and 1 ovigerous female (July) taken during four Duke University R/V Eastward cruises at eight stations in May, July, and October 1965 and in January 1966. Specimens were collected from the gen- eral vicinity of our fishing grounds on the shelf edge and upper slope between 100 and 210 m. Other central North Carolina outer
Snowy Grouper Feeding
113
shelf collections of M. quinquespinosa in 120-160 m were reported by Cerame-Vivas and Gray (1966).
Majidae — Stenocionops spinimana was the sixth most abundant decapod prey, with nine specimens collected. Two male (34 and 36.5 mm CW) and seven female (34-56 mm CW) Stenocionops spinimana were taken from grouper caught south of Cape Lookout in 155-194 m. Collections were made on four trips in June, July, and September.
Wenner and Read (1982) reported only 18 isolated specimens from 496 trawl tows in the South Atlantic Bight in 60-170 m. Rathbun (1925) reported the species as deep as 227 m in the vi- cinity of our fishing area.
Stenorynchus seticornis was represented by one specimen obtained from a snowy grouper taken at 154 m in the primary study area in May 1985. The adult female (20 cm CW) had been swallowed intact and was still fresh when collected.
In contrast, this species was the second most abundant crab collected by Wenner and Read (1982) across a wide depth range (17-188 m) in the South Atlantic Bight. Off North Carolina the species has been collected at a variety of hard bottom and reef sites at inner-, mid-, and outer-shelf stations (to 100 m) (McCloskey 1968, Vernberg and Vernberg 1970, South Carolina Wildlife Marine Resource Department and Duke University Marine Laboratory 1982).
In addition to being one of only two crab species reported from snowy grouper in the North Carolina BLM study (Duke Uni- versity Marine Laboratory 1982), S. seticornis has been reported off North Carolina in the stomachs of at least two other reef fishes: white grunt ( Haemulon plumieri) (Lacepede and black sea bass (South Carolina Wildlife Marine Resource Department and Duke University Marine Laboratory 1982). Randall (1967) also reported S. seticornis from three other epinpheline groupers: rock hind ( E . adscensionis) (Osbeck), red hind ( E . guttatus) (Linnaeus), and Nassau grouper ( E . striatus) (Bloch). Visual studies of S. seticornis by Barr (1975) in the Virgin Islands indicated that the species is an opportunistic detritivore. It is most abundant on reef edges and is normally seen in greatest numbers at dusk and at night, when it moves to upper reef areas to feed.
Nibilia antilocapra was found once in a snowy grouper stom- ach taken in the primary study area from 137 to 146 m in August 1985. The individual (25 mm CW) was swallowed whole.
Cancridae — Cancer irroratus and C. borealis were the largest crustacean prey. C. irroratus was more prevalent in samples (n = 8) than C. borealis (n = 2). Both prey were taken only from large
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John Dodrill et al.
(6.8-13.6 kg) grouper caught at depths of 194-236 m in June and July. They were represented by nongravid adults and were concur- rent to the extent that one 900-mm grouper (TL) had eaten two C. irroratus (89 and 90 mm CW) and one C. borealis (83 mm CW) (total volume 197 mL).
Both species are common year-round in the decapod assemblage of the upper continental slope from the Chesapeake Bight south. C. irroratus and C. borealis ranked first and second among crabs trawled during fall and winter between Cape Hatteras and Cape Henlopen, Delaware (Musick and McEachraji 1972). Wen- ner and Read (1982) ranked C. irroratus 15th, and C. borealis 18th numerically in 496 trawl stations in the South Atlantic Bight. At seven trawl stations between Charleston and Cape Lookout in 203- 293 m, either C. irroratus, C. borealis, or both, were taken in six of seven tows (North Carolina Division of Marine fisheries, Cruise Reports, R/V Dan Moore cruise number 36, 26-28 September 1979). Cerame-Vivas and Gray (1966) reported rock crabs commonly oc- curring on the upper slope off North Carolina.
Cancer irroratus and C. borealis are found on several substrates. Jeffries (1966) reported separation by substrate in shal- low waters off New England where C. borealis tended to associate with rocky habitat and C. irroratus with sand. Soto (1985) reported both species from mud bottom in the Florida Straits. Musick and McEachran (1972) noted both species trawled over sand, silt, clay, and coarse canyon sediments, though C. borealis seemed to be more stenothermal with a preference for rougher bottom.
Parthenopidae — Parthenope pourtelesii was represented by two intact females (22 and 36 mm CW) and one specimen of undeter- mined sex. They were taken from grouper caught on two trips (June, September) at 146 mm in the primary study area. This crab has been recorded over sand and sandy-mud bottoms (Powers 1977, Williams 1984).
Solenoceridae — Solenocera atlantidis (tentative identification) occurred in snowy grouper caught from May to September in the primary study area in 145-163 m. Seven of these shrimp were col- lected. Two species, Solenocera atlantidis and Mesopenaeus tropicalis Perez Farfante, numerically were among the top three decapod spe- cies trawled at depths of 56-183 m in the South Atlantic Bight (Wenner and Read 1982).
Squillidae — Parasquilla coccea was represented by a single individual taken from a grouper caught 6 August 1985 south of Beaufort Inlet, North Carolina in 148 m. It is a tropical stomato- pod of the shelf edge and upper slope (82-382 m) and has not
Snowy Grouper Feeding
115
been reported previously from North Carolina (R. Manning, Crusta- cean Section, National Museum of Natural History, Washington, D.C., personal communication).
Pisces
Fishes were the second most important major taxon in the diet, representing 6% of the food items and approximately 17% of the volume (Table 3). This is in contrast to Bielsa’s (1982) analy- sis of 26 snowy grouper from the lower Florida Keys where fish comprised 43% of the prey items, 47% of the prey volume, and occurred in 69% of the intestines. The paucity of fish remains com- pared to crustacean remains was probably not a sampling artifact in our study, because selective regurgitation of fish, versus retention of hard-bodied crustaceans, was not evident from an examination of 23 intact stomachs (Table 4) nor from the NMFS and BLM data.
Fish in the snowy grouper diet were small (39-320 mm TL) and were swallowed whole. Thirty-three of 42 ingested fish were less than 200 mm TL. Small fish can be digested at a more rapid rate than adult brachyurans or large squid; thus, small fishes could be more important in the diet than our results show. In small fish, musculature rapidly separates, increasing the digestive surface area. Fish we recovered were either fairly fresh or in such an advanced state of digestion that they were unidentifiable. Only 15 of 42 fish could be identified to species, and of the 27 unidentifiable fish, most were under 200 mm TL.
Fish prey represent three general categories: small midwater schooling fishes often found near the bottom or in close association with rock relief, non-schooling reef fishes associated with irregular or hard bottom, and benthic fishes that burrow or remain concealed.
Small, Schooling Fishes — Seven butterfish ( Peprilus triacanthus) (Peck) occurred as food during March and April in 146-225 m. A whole P. triancanthus (approximately 130 mm TL) was found in a snowy grouper on 20 April 1985 at a station south of Cape Hatteras in 194-225 m. A butterfish was also observed in a snowy grouper stomach from this area in late winter before our study (J. Dodrill, personal communication).
Butterfish can increase in abundance seasonally on the outer shelf and upper slope during cooler months off central North Caro- lina. This migratory trend is well documented from Cape Hatteras to southern New England, but is less apparent in more southern waters where the existence of a second, inshore population is hy- pothesized (S. Ross, North Carolina State University, personal com- munication; Murawski et al. 1977; Manooch 1984). The species tends
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John Dodrill et al.
Table 4. Comparison of major food groups from snowy grouper overlapping with those of three other sympatric species of bottom fishes studied off North Carolina and South Carolina.
|
Prey Group |
Predator |
|||
|
Snowy1 Grouper |
Vermilion3 Red2’4’5’6 Snapper Porgy |
Blueline7 Tilefish |
||
|
INVERTEBRATES |
||||
|
Cephalopods |
||||
|
(squid) |
X |
X |
X |
X |
|
Stomatopoda |
X |
X |
X |
X |
|
Calappidae |
X |
X (megalops |
X |
X |
|
only) |
||||
|
Cancridae |
X |
|||
|
Leucosiidae |
X |
|||
|
Majidae |
X |
X (zoea, |
X |
X |
|
megalops) |
||||
|
Parthenopidae |
X |
X |
X |
X |
|
Portunidae |
X |
X |
X |
X |
|
Scyllaridae |
X |
X |
X |
|
|
Solenoceridae |
X |
X |
X |
X |
|
FISH |
||||
|
Caproidae |
X |
|||
|
Centriscidae |
X |
|||
|
Congridae |
X |
X |
||
|
Ophichthidae |
X |
X |
X |
|
|
Serranidae |
X |
X |
X |
X |
|
Stromateidae |
X |
X |
X8 |
|
|
Synodontidae |
X |
X |
X |
1 Present study central North Carolina specimens.
2 Duke University Marine Laboratory (1982), North Carolina and South Carolina specimens.
3 Grimes (1979), North Carolina and South Carolina specimens.
4 South Carolina Wildlife Marine Resource Department (1982), South Carolina and Georgia specimens.
5 South Carolina Wildlife Marine Resources Department and Duke University Marine Laboratory (1982), North Carolina specimens.
6 Manooch (1977), North Carolina and South Carolina specimens.
7 Ross (1982), North Carolina and South Carolina specimens.
8 Personal Observation.
Snowy Grouper Feeding
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to remain close to the bottom by day, feeds on organisms on the bottom and in the water column, forms loose schools, and prefers sand instead of rock or mud bottom (Murawski et al. 1977).
We collected one juvenile red barbier ( Hemanthias vivanus Jordan and Swain) (78 mm TL) from a snowy grouper caught 22 May 1985 in 146-155 m south of Cape Lookout. Parker and Ross (1986) reported large, fast-moving schools of juvenile H. vivanus (<150 mm TL) at 9 of 10 reef stations viewed from a submersible in 51-152 m off the central North Carolina coast.
Miller and Richards (1980) considered the red barbier an important reef indicator species in the South Atlantic Bight at depths greater than 55 m. The species has been observed hiding in reef crevices (R. S. Jones, Harbor Branch Foundation, Fort Pierce, Florida, personal communication). Therefore, schools periodically must be close enough to the bottom to be accessible to snowy grouper. The sister vessel fishing adjacent to the senior author’s boat recovered several small (50-100 mm), reddish-orange serranids believed to be this species. At some deep reef areas (>180 m) such as the “Charles- ton Bump,” 80 km east of Charleston, South Carolina, the yellow- fin bass ( Anthias nicholsi Firth) displaces the red barbier as the most abundant small schooling serranid. Based on submersible ob- servations during the summers of 1982 - 1983, R. S. Jones noted A. nicholsi was the most abundant reef fish. He hypothesized that anthiids could be an important grouper prey item, though stomachs yielded no food because of eversion (R. S. Jones, Cruise Reports, R/V Johnson, Cruise Number J-143 (III), 31 July-10 August 1982; Cruise Number J- 158 (VI), 3-19 September 1983).
A vermilion snapper (305 mm TL) was found in the stomach of a snowy grouper (6.8 kg) taken in mid-November 1985 at 146 m, south of Cape Lookout. The vermilion snapper is one of the most common, commercially important schooling fish occurring over hard bottom on the mid and outer shelf off North Carolina. It is not surprising that small vermilion snapper in deeper water might fall prey to snowy grouper as they do in shallow water to speckled hind ( E . drummondhayi Goode and Bean), gag (Mycteroperca microlepis Goode and Bean), and scamp ( M . phenax Jordan and Swain) (South Carolina Wildlife Marine Resource Department 1982 South Carolina Wildlife Marine Resource Department and Duke University Marine Laboratory 1982). Vermilion snapper were noted by the senior au- thor as a snowy grouper prey item on at least one other trip made before our study.
Nonschooling Reef Fishes — A deepbody boarfish ( Antigonia capros Lowe) (129 mm TL, intact) was taken from a snowy grouper caught
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John Dodrill et al.
in May 1985 at 146 m. The boarfish is an outer shelf-upper slope species found over hard bottom with a tropical-subtropical distri- bution (Robins et al. 1986). A. capros is a common component of the ichthhyofauna found in depths of 100-200 m from Cape Look- out southward (Wenner et al. 1979; North Carolina Division of Ma- rine Fisheries, Cruise Reports, R/V Dan Moore , Cruise Number 19, Station Number 3332, 1-18 November 1977). Although trawl results and FAO species description profiles (Fischer 1978) suggest the species might be available to snowy grouper in small aggregations, deep reef submersible transects off Fort Pierce, Florida, and Charleston, South Carolina, reported this species either in pairs or singly, closely associated with rocky substrate (R. G. Gilmore, Harbor Branch Founda- tion, Fort Pierce, Florida, personal communication; R. S. Jones, Cruise Reports, R/V Johnson, Cruise Number J-43 (III) 31 July-10 August, Cruise Number J- 158 (VI) 3-19 September 1983).
One longspine snipefish ( Macrorhamphosus scolopax) (Linnaeus) (137 mm TL, intact), was collected on 29 April 1985 south of Cape Hatteras in the secondary study area in 201-238 m. Longspine snipefish are demersal inhabitants of the outer shelf-upper continen- tal slope associated primarily with rocky substrate. They also reside over sand, where they have been taken in trawls (Fischer 1978). They are a temperate species with a probable worldwide distribution (Bigelow and Schroeder 1953, Hoese and Moore 1977, Fischer 1978, Robins et al. 1986). Submersible transects off Charleston, South Carolina on deep reefs in 180-220 m suggest that snipefish are available to grouper as scattered, non-schooling individuals that seek shelter in the reef or among attached hydroids (R. S. Jones, Cruise Reports, R/V Johnson. Cruise Number J-143 (III) 31 July-10 Au- gust 1982).
Benthic Fishes — Five ophichthis eels (165-272 mm TL) were recovered from snowy grouper stomachs; two were tentatively iden- tified as Myrophis punctatus Liitken. Ophichthid eels are common prey of groupers and snappers (Robins et al. 1986). One ophichthid eel (252 mm TL), swallowed whole, was taken from a snowy grou- per caught 29 June 1985 in 194 m SSE of Cape Lookout. The snake eel had penetrated tail first through the grouper’s stomach, suggesting an augering motion during its death throes. The posterior half of the eel was encysted in the grouper’s body cavity whereas the anterior portion in the stomach was being digested. Penetration by an ophichthid eel through a grouper’s stomach has been re- ported by Breder and Nigrelli (1934), mentioned by Robins et al. (1986), and noted in sea bass ( Centropristis sp.) by Link (1980) and Breder (1953).
Snowy Grouper Feeding
119
Two cusk eels (Ophidiidae) occurred as prey in the primary study area. One specimen (110 mm TL) was from a 4.5-kg snowy grouper caught 17 May 1985 at 153 m, and a second (254 mm TL), tentatively identified as Lepophidium jeannae Fowler, was col- lected from a grouper caught 6 August 1985 in 192 m south of Cape Lookout. Typical of most snowy grouper fish prey, cusk eels are usually small (<;30 mm TL) (Robins et al. 1986), benthic spe- cies which bury tail first into the sand (Bohlke and Chaplin 1968).
Two other benthic fishes, a congrid eel and an offshore lizardfish (i Synodus poeyi Jordan) were removed from grouper stomachs. The former was a gravid female (320 mm TL) sampled 23 June 1985 from a grouper collected in 148 m south of Cape Lookout. The congrid ( Paraconger caudilimbatus) (Poey) was reported from snowy grouper in the North Carolina BLM study (Duke University Marine Laboratory 1982). Large conger eels ( Conger oceanicus) (Mitchell) (>1 m TL), concealed or inactive by day but feeding at night in proximity to large E. nivaetus, are probably immune to snowy grouper predation.
The offshore lizardfish was a juvenile (86 mm TL) recovered 1 October 1985 in 148 m south of Cape Lookout. Offshore lizardfish were the sixth most numerically abundant fish species taken in Marine Resources Monitoring, Assessment, and Prediction Program bottom trawls in the South Atlantic Bight in the 111-183 depth range, comprising 2.2% of the fish caught at that depth (Wenner et al. 1979).
Mollusca
Squid comprised almost 10% of the food volume (Table 3). Snowy grouper fed on at least two species, the long-finned squid {Loligo pealei) and the northern shortfin squid ( Illex illecebrosus) (LeSueur). Squid occurred in grouper in June, July, September, and November.
Loligo pealei is a neritic species occurring over the continental shelf and upper slope to 400 m. It ranges throughout the water column at night and is demersal by day (Roper et al. 1984). Thus, L. pealei is available as food on or near the bottom in the daytime when snowy grouper are active feeders.
Illex illecebrosus was the second most common squid trawled at depths greater than 128 m, with numbers increasing beyond 219 m (North Carolina Division of Marine Fisheries, Cruise Reports, R/ V Dan Moore , 1977-78). Wenner et al. (1979) reported that this species was more common on the upper slope (155-285 m). Shortfin squid might be a more important food for adult grouper toward the
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John Dodrill et al.
deeper end of the grouper’s bathymetric range. Two I. illecebrosus (130 and 175 mm mantle length) were swallowed intact by a 13.6- kg snowy grouper in 194 m in July 1985 south of Cape Lookout. Three L. pealei (142-, 130-, and 130-mm mantle length), two of which were taken from one 4.5-kg grouper, came from slightly shallow- er water, 146-155 m, in November. These specimens were swal- lowed whole. Although both species have been recorded from the same trawl tows, grouper appear to feed on unmixed groupings.
The few squid we found in stomachs might not indicate the value of this resource to snowy grouper. Probably only the gladius, eye lens, and beak are indigestible; digestion of other parts might proceed so rapidly that little remains. In winter, squid and fish might become more important in the diet. Seasonal abundance shifts might occur in some squids at that time, especially L. pealei , which is distributed over the shelf in spring and summer but concentrated on the outer shelf and upper slope in winter. Unfortunately, no extensive midwinter sampling was conducted to prove this; how- ever, before the start of our study in early March 1985, grouper containing squid were caught beyond 183 m. Whole, frozen squid about the size found in grouper guts was the most effective bait.
The only other mollusk identified was a cone shell ( Concus delessertii). The shell had a broken lip and worm tube inside, which suggests the grouper had picked up the shell empty.
Feeding Ecology
Foraging Away From The Home Reef — All snowy grouper aggregations we sampled were associated with hard bottom or wrecks. Sites were generally small, scattered, and surrounded by unproduc- tive sand bottom. Grouper aggregations were similarly scattered and highly localized. Adult snowy grouper seem to associate exclusively with rugged bottom. This has been recorded in other studies off the southeastern United States (Low and Ulrich 1983; Parker and Ross 1986; R. S. Jones and R. G. Gilmore, Harbor Branch Founda- tion, Ft. Pierce, Florida, personal communication).
Limited exploratory fishing was undertaken to determine (1) if snowy grouper could be located over open, smooth bottom and (2) if this species foraged over open bottom any significant distance away from reef areas. Because solitary, large (>9 kg) mutton snap- per (Lutjanus analis) (Cuvier) and red snapper (L. campechanus) (Poey), had been caught on experimental longlines set in less than 55 m over open bottom, we thought that snowy grouper might also be captured some distance from reefs. Twenty months of fathometer searching by two commercial vessels located no productive snowy grouper sites on open bottom between 128 and 247 m from south
Snowy Grouper Feeding
121
of Cape Lookout to south of Cape Hatteras. Exploratory fishing was occasionally conducted over smooth bottom (247-305 m) where bait fishes were detected by the fathometer. No snowy grouper and only a few scorpionfish were caught. In addition to exploratory handline effort, a longline set was made over sand bottom south of Cape Lookout on 23 June 1985. Between 1245 and 1410 hours 102 hooks were fished in 240 m. No fish were caught, and most of the bait was untouched. Open bottom sets were discontinued for eco- nomic reasons.
We suspect that adult snowy grouper are sedentary, remaining at a specific reef site at least seasonally. During daylight hours they forage in the open, often near the top of the reef. They feed on small, schooling fish and squid, ambush slower moving deca- pods and non-schooling fishes, and occasionally move short dis- tances onto sand or mud substrate adjacent to the reef to forage.
Direct observation to support territorial behavior of individual snowy grouper was impossible. Based on our experience with at- tempted release efforts of small (<335 mm) snowy grouper, an in- ternally injured fish could not survive a 155-m descent to the bottom. However, three different observations lead us to hypothesize that groupers associate with a home reef on a seasonal basis. First, specific locations produced grouper for several consecutive months and in some cases over a period of at least 5 years. Second, on at least two occasions snowy grouper were caught with rusting circle hooks in their mouths. These hooks were the same type and size used on our previous trips to the sites when several uncrimped hooks were pulled from leaders. These fishing sites were virgin or were infrequently fished commercially. Third, a specific plastic teaser skirt was torn from the terminal tackle during one trip and recov- ered 6 weeks later in a 1.4-kg snowy grouper at the same 146-m site.
Snowy grouper probably move short distances from hard bottom to feed over sand or mud substrate. Single shelf-edge or upper-slope wrecks and specific reefs in 146-219 m have provided harvests of 22,680 kg or greater in a period of less than 3 months (L. Davidson, commercial fisherman, personal communication). Small areas are not likely to support such biomass even seasonally if the fish were restricted to feeding on or above hard bottom, unless feeding was restricted because of spawning or other activity.
A submersible observation of a large snowy grouper aggregation was made in late August 1979 slightly inshore of our fishing area (Parker and Ross 1986). Observers estimated nearly 8,000 snowy grouper per ha, 238 blueline tilefish per ha, and 79
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John Dodrill et al.
speckled hind per ha in the vicinity of boulders at a depth of 125 to 137 m. Nearly all snowy grouper were over and immediately around the reef. However, some snowy grouper (24/ha), red porgy (660/ha), and silk snapper ( Lutjanus vivanus ) (Cuvier) (36/ha), were observed by day off to the side of the reef rooting in the sand, possibly for food (Parker and Ross 1986).
Longlines, which are not set directly on reefs, have been used extentively in the Carolinas, Georgia, Florida, and in the northern Gulf of Mexico since 1980. Snowy grouper represent part of the longline catch and thus might move short distances off the reef to take a bait. Also, an examination of decapod prey substrate prefer- ences, as discussed previously, suggests that grouper might wander a short distance from hard bottom areas in search of food.
Feeding ■ Association with the Bottom — Although our study indicates that snowy grouper feed both in the water column and on the bottom, grouper were always caught on or very near the sub- strate. Even in the cast of large aggregations of grouper, fish were hooked no more than 3-4 m above the bottom. When currents lifted baits higher than this, no fish were caught. Identifiable markings of snowy grouper on the depth recorded were very close to the bot- tom. Examination of data from a trawl tow off southern North Carolina where 544 kg of adult snowy grouper were collected (North Carolina Division of Marine Fisheries, Cruise Reports, R/V Dan Moore , Cruise Number 20, 1969) revealed fish to be so close to the bottom that depth recorder markings of the fish were barely discernible.
Most snowy grouper foods are closely associated with the bottom. Even schooling fishes such as butterfish and red barbier, which can move up into midwater, as well as squids and portunid crabs, are commonly captured by bottom trawling.
Feeding Mechanics — Virtually every prey item had been swal- lowed whole. Except when limb autotomy had taken place in the stomach or through subsequent handling on deck, most decapods were intact. On two occasions prey were found alive in grouper throats: a deepbody boarfish and a crab ( Myropsis guinguespinosa). Both were removed from grouper caught during daylight.
The intact condition of most prey in the stomachs supports the general feeding pattern of other grouper observed in the field (see Parrish 1987). The grouper either maneuvers close to the prey or waits in ambush, then opens its large mouth and expands its gill plates so abruptly that the prey is sucked whole into the mouth.
Prey size, Grouper Speed, and Sedentary Behavior — Prey size was surprisingly small for an adult fish as large as E. niveatus.
Snowy Grouper Feeding
123
This might indicate a limit to the size of prey that a snowy grou- per can chase down or consume whole. The largest crustacean prey, adult Cancer crabs, appeared to be restricted to large fish, those greater than 6.8 kg. However, this may be related to the tendency of larger grouper to inhabit the 146-228 m depths (Low and Ulrich 1983) where adult Cancer spp. are located.
Few fish more than 200 mm TL, and no fish more than 325 mm TL, were in the diet. This might result not only from an inability to swallow large prey whole, but also from an inability to pursue large fishes successfully. This stout-bodied, sedentary preda- tor might not be able to capture these faster and more maneuver- able species. Snowy grouper and tilefish both fed on blackbelly rosefish hooked on longlines off South Carolina, yet they were un- able to catch this species when observed pursuing it (R. S. Jones, Harbor Branch Foundation, Cruise Reports, R/V Johnson, Cruise Number J-143 (III) 31 July-10 August 1982). Almaco jack ( Seriola riviolana Valenciennes), banded rudderfish ( S . zonata) (Mitchell), and blueline tilefish were caught on handlines at the same time as snowy grou- per, yet none was observed in stomachs.
Snowy grouper apparently are not fast swimmers, so it is not surprising that demersal decapods dominate their diet. Fast-moving fishes tend to be the target of quick, slender-bodied serranids such as the Mycteroperca groupers (Table 4). Speed is not a requirement for snowy grouper survival. One robust, 2-kg specimen without a caudal fin was caught. The blunted caudal peduncle was completely healed, and the fish appeared to be in good condition, although incapable of rapid propulsion.
Drift fishing suggests that snowy grouper are so sedentary that they will not pursue prey or move more than a few meters to intercept moving prey. Grouper locations on the reef sites were discrete, and the fish so sedentary that none was caught if the vessel missed the fathometer mark by a few meters. Sometimes fishermen standing only 7-m apart and using the same bait, gear, and fishing technique had drastically different levels of success. If only a portion of the vessel was over the mark, the nearest fisher- man caught many fish, while others at end of the boat caught few. Grouper apparently would not pursue the bait once the lines had drifted off the reef.
Day Versus Night Feeding — More snowy grouper were caught in early morning or late afternoon than at midday or night. How- ever, night capture of large snowy grouper and the presence of nocturnally active prey in their diet suggest that in addition to day- light feeding, large E. niveatus feed at night under certain condi-
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John Dodrill et al.
tions. When large aggregations were present, fish were caught through- out the day. Only after fish were caught repeatedly during multiple drifts over a reef would catch rates decline, regardless of time of day.
Snowy grouper generally stopped taking baits at dusk. At depths beyond 183 m on calm, moonlit nights single large grouper (>9.1 kg) sometimes were caught. This contrasts with day catches when as many as eight small grouper (<4.5 kg) might take baits within a few seconds of each other.
The disparity in size of day versus night snowy grouper at the same station was noted in 194 m on 29 July 1985 SSE of Cape Lookout. A randomly measured sample ( n = 44) of specimens caught in daylight showed they were of mixed size (range = 465- 950 mm, mean = 691 mm TL). That night, 37 large snowy grou- per were caught at the same station between dark and 0400 hours. Fourteen representative specimens were measured revealing a nar- rower size range and larger average size (range = 890-990, mean = 921 mm TL) than those caught during the day.
Competition — Some other western Atlantic serranids, particularly members of the genera Epinephelus, Hypoplectrus , and Serranus have been found to prey heavily on crustaceans and less extensively on fishes (Parrish 1987). Conversely, Mycteroperca groupers feed al- most exclusively on fishes (Table 4).
At depths beyond 137 m, adult snowy grouper compete to a limited degree with other grouper species, which are either uncom- mon or absent at these depths. Beyond 137 m only three other grouper species were recorded, all epinephelines: E. mystacinus (Poey), (E. drummondhayi), and E. Flavolimbatus (Table 2).
Although the misty grouper ( E . mystacinus ) extends into our bathymetric fishing range and deeper in Bahamian, Caribbean, and Central American waters (Bohlke and Chaplin 1968; Robins et al. 1986; L. Davidson, personal communication), it is rare off North Carolina. Only two specimens (3-4 kg) were caught in 30 trips made in our study.
Speckled hind (E. drummondhayi) were as uncommon as misty grouper although they have been recorded at 130 m or less south of our fishing area, at times concurrently with small snowy grouper (Huntsman 1976, Manooch 1984). North Carolina and South Caro- lina headboats sampled by NMFS revealed only 18 speckled hind with food ( n = 168). Half contained fish (53% of all prey items; 65% of the volume). Decapods composed only 10% of all prey and 5% of the volume (Duke University Marine Laboratory 1982, Parrish 1987).
Snowy Grouper Feeding
125
Yellowedge grouper (E. flavolimbatus) were sometimes caught with adult E. niveatus in deep water, but they represented only 1.0% of our total grouper catch (52 of 5,142 grouper in 30 trips). The species is uncommon in South Carolina commercial landings (Low and Ulrich 1983) and in commercial landings off southeast Florida (B. Hardy, Jupiter, Florida, personal communication). Diets of yellowedge grouper and snowy grouper probably overlap to some extent. The senior author noted that one yellowedge grouper had eaten a squid (17 May 1985 in 152 m) and another had swallowed whole a 65-75-mm, bicolored reef fish, probably a serranid. A third grouper collected 24 June 1985 from 148 m contained 18 Portunus spinicarpus (20-50 mm CW; 62.5 mL total volume). Parrish (1987) reported a squid in the stomach of a yellowedge grouper from the Virgin Islands. In the Gulf of Mexico where the yellowedge grou- per is the dominant deep reef grouper, R. S. Jones (personal com- munication) saw them feeding on schooling anthiids and small reef fishes that were blinded by submersible lights.
Warsaw grouper ( E . nigritus) were extremely rare in our study. In 20 months of fishing, the only Warsaw grouper caught (755 mm TL, 8.4 kg) was captured at 77 m southeast of Cape Lookout on 17 July 1985 (much shallower than E. niveatus). This grouper had consumed two crabs whole: Calappa flammea (90 mm CW; 105 mL total volume) and Glyptoxanthus erosus (Stimpson) (66 mm CW; 100 mL volume). Both crabs have bathymetric ranges normally not extending beyond 70-90 m (Williams 1984). C. flammea has been reported as snowy grouper prey, but probably from a fish taken in waters shallower than covered in our study (South Carolina Wild- life Marine Resource Department and Duke University Marine Laboratory 1982). In addition, the stomach from a 226-cm (190 kg) state record Warsaw grouper was examined in September 1986. The stomach contained 13 Ovalipes stephensoni (70-80 mm CW). These crabs were swallowed whole and were in a similar state of digestion.
Food overlap of snowy grouper was compared with that of three other commercially important fishes that partially occupy the same bathymetric range as adult E. niveatus and for which food studies have been conducted (Table 5). Comparisons were based on 10 groups of invertebrates and 7 families of fishes. Red porgy contained 11 of the 17 categories, vermilion snapper contained 10 (excluding categories from which only zoea and megalopa were re- ported), and blueline tilefish contained 10 categories. Clearly, there is some dietary overlap, particularly with E. naveatus and P. pagrus, but competition on the upper slope is restricted by depth. Few red
126
John Dodrill et al.
Table 5. Percentage of contributions by volume of crustaceans and fishes to the diet of snowy grouper and other western Atlantic serranids.
|
Species |
Source |
Area All Crabs Crustaceans |
Fish |
||
|
Epinephelus afer |
Randall (1967) |
Caribbean |
90.5 |
77.0 |
7.0 |
|
Mutton hamlet |
|||||
|
E. fulvus |
Randall (1967) |
Caribbean |
54.0 |
17.2 |
46.0 |
|
Coney |
|||||
|
E. adscensionis |
Randall (1967) |
Caribbean |
75.1 |
66.7 |
20.1 |
|
Rock hind |
|||||
|
E. guttatus |
Randall (1967) |
Caribbean |
69.9 |
39.5 |
21.1 |
|
Red Hind |
|||||
|
E. morio |
Randall (1967) |
Caribbean |
81.1 |
12.2 |
13.3 |
|
Red grouper |
|||||
|
E niveatus Snowy grouper |
This study |
North Carolina |
72.8 |
72.4 |
17.1 |
|
See Parrish (1987) |
North Carolina and South Carolina |
72.0 |
72.0 |
28.0 |
|
|
E. striatus |
Randall (1967) |
Caribbean |
38.3 |
22.5 |
54.0 |
|
Nassau grouper |
|||||
|
E. cruentatus |
Randall (1967) |
Caribbean |
30.0 |
3.8 |
66.0 |
|
Graysby |
|||||
|
Hyopolectrus aberrans 1 |
Randall (1967) |
Caribbean |
88.1 |
18.7 |
11.9 |
|
Yellow-bellied hamlet |
|||||
|
H. chlorurus 1 |
Randall (1967) |
Caribbean |
75.0 |
17.1 |
25.0 |
|
Yellowtail hamlet |
|||||
|
H. nigricans |
Randall (1967) |
Caribbean |
55.8 |
17.6 |
44.2 |
|
H. puella 1 |
Randall (1967) |
Caribbean |
86.3 |
21.2 |
10.0 |
|
Barrel hamlet |
|||||
|
Mycteroperca bonaci |
Randall (1967) |
Caribbean |
0.0 |
0.0 |
100.0 |
|
Black grouper |
|||||
|
M. inter stitialis |
Randall (1967) |
Caribbean |
0.0 |
0.0 |
100.0 |
|
Yellowmouth grouper |
|||||
|
M. microlepis |
Naughton and Saloman (1985) |
North Carolina |
0.0 |
0.0 |
96.4 |
|
Naughton and Saloman (1985) |
South Florida |
0.2 |
0.0 |
99.8 |
|
|
Naughton and Saloman (1985) |
West Central Florida |
1.2 |
0.0 |
98.6 |
Snowy Grouper Feeding
127
Table 5. Continued
|
Species |
Source |
Area All Crabs Crustaceans |
Fish |
||
|
Naughton and Saloman (1985) |
Northwest Florida |
3.5 |
3.0 |
95.1 |
|
|
See Parrish (1987) |
South Carolina |
0.2 |
0.0 |
96.0 |
|
|
M. phenax Scamp |
Matheson et al. (1986) |
North Carolina and South Carolina |
1.0 |
0.5 |
90.0 |
|
See Parrish (1987) |
South Carolina |
0.0 |
0.0 |
90.0 |
|
|
M. spp Scamp/yellowmouth |
Nelson et al. (1986) |
Texas Flower Garden |
2.1 |
0.0 |
97.8 |
|
M. tigris Tiger grouper |
Randall (1967) |
Caribbean |
0.0 |
0.0 |
100.0 |
|
M. veneosa Yellowfin grouper |
Randall (1967) |
Caribbean |
0.8 |
0.0 |
95.3 |
|
Paranthias jurcifer Creole-fish |
Randall (1967) |
Caribbean |
79.2 |
0.0 |
0.0 |
|
Nelson et al. (1986) |
Texas Flower Garden |
36.7 |
0.0 |
5.8 |
|
|
Serranus tigrinus |
Randall (1967) |
Caribbean |
90.3 |
7.8 |
9.7 |
|
S. tortugarum Chalk bass |
Randall (1967) |
Caribbean |
92.0 |
0.0 |
0.0 |
1 All reported to be color phases of a single species, butter hamlet ( Hypoplectus unicolor ).
porgy and vermilion snapper were caught beyond 142 m; none were caught in waters deeper than 165 m.
Grouping major foods into crustacean, fish, and squid catego- ries revealed the following percentages of total food volume (mL): red porgy — 49, 15, and 1% (Manooch 1977); vermilion snapper — 38, 9, and 37% (Grimes 1979); blueline tilefish — 64, 32, and insig- nificant percent, respectively (Ross 1982). Snowy grouper had values of 73, 17, and 10% for crustaceans, fishes, and squids, respectively (Table 3).
Snowy grouper feeding mechanics differ from those of blueline tilefish, vermilion snapper, and red porgy. Snowy grouper engulf prey whole by suction into their mouths. Red porgy and blueline tilefish might also employ suction but then use their strong teeth to
128
John Dodrill et al.
crush large prey as well as armored sessile organisms. Vermilion snapper feed on the bottom and to at least 5 m off the bottom, based on our fishing experience in 64-82 m. Most food items were pelagic, planktonic, or epibenthic (Grimes 1979) and were juveniles or larvae of many species (Dixon 1975, Grimes 1979).
Prey Variability — Snappers and groupers rely on many different types of foods; however, the diets of snappers are more diverse (Parrish 1987). The diet of adult snowy grouper included few prey species compared with other reef fishes caught at depths of 100 m or less. Prey categories, reduced to lowest taxa from our study combined with NMFS and BLM data, were 29 for snowy grouper, compared to 199 for vermilion snapper and 121 for red porgy (South Carolina Wildlife Marine Resource Department 1982). At depths of 100 m or less, hard-bottom faunal diversity is greater than at 140 m or deeper. Parrish (1987) suggested that where many species occupy small, discrete, hard-bottom areas, greater diet range reduced competition among reef fishes. Below a depth of 140 m many reef fish species disappear, and the need for a diversified diet to reduce feeding competition might be lessened for adult snowy grouper.
Intact grouper stomachs showed low prey diversity per individual stomach (Table 6). In a representative sample of 23 in- tact stomachs where no regurgitation appeared to have occurred, 16 stomachs had 1 species, 21 had 1 or 2 species, and only 2 had 3 or 4 species. A similar pattern was seen with the few E. flavolimbatus and E. nigritus stomachs examined (see Competition section).
There are three possible explanations for low species variability in an individual stomach. First, a large number of deca- pod species is not available in the limited depth range and geo- graphic area sampled. Although Herbst et al. (1979) recorded 291 decapod species from Carolina shelf waters, Wenner and Read (1982) trawled only 54 species from the 111-183-m-depth range in the South Atlantic Bight, fewer than at inshore depth ranges of 28-55 m (87 species) or 56-110 m (84 species). Barans and Burrell (1976) reported 74 fish species trawled at 111-183 m in spring, declining to 43 species in summer. If we assume that snowy grouper are seasonally territorial and forage limited distances, prey possibilities for an individual fish during a specific feeding period are further reduced. Wenner and Read (1982), in 30-minute trawl tows at 111- 183 m, averaged 3 decapod species and 25 individuals per tow.
Second, grouper are opportunistic feeders, focusing on whatever species are readily available, and they do not seek prey that is less common or more difficult to catch. For example, eight
Snowy Grouper Feeding
129
Table 6. Summary of snowy grouper stomachs recovered intact with food captured off North Carolina, 1985.
|
Date |
Size |
Depth (m) |
Food Item |
Number |
Volume (mL) |
|
5/5/85 |
925 mm TL |
196 |
Acanthocarpus |
4 |
60 |
|
alexandri |
|||||
|
5/5/85 |
3.2 kg est. |
205 |
A. alexandri |
1 |
19 |
|
5/16/85 |
6.8 kg est. |
154 |
Portunus |
23 |
60 |
|
spinicarpus |
|||||
|
5/16/85 |
4.5 kg est. |
154 |
P. spinicarpus |
7 |
28 |
|
fish vertebral |
1 |
1 |
|||
|
column |
|||||
|
5/22/85 |
3. 2-4.5 kg |
146 |
P. spinicarpus |
15 |
30 |
|
5/22/85 |
3.6 kg est. |
146-154 |
P. spinicarpus |
7 |
22 |
|
6/2/85 |
A. alexandri |
3 |
32.5 |
||
|
squid frequent |
6 |
||||
|
6/10/85 |
13.6 kg est. |
236 |
Cancer irroratus |
1 |
150 |
|
6/21-24/85 |
148 |
P. spinicarpus |
11 |
47 |
|
|
small fish spines |
2 |
1 |
|||
|
6/21-24/85 |
148 |
P. spinicarpus |
2 |
6.5 |
|
|
Calappa angusta |
1 |
9 |
|||
|
probable Solenocera atlantidis |
1 |
5 |
|||
|
6/21-24/85 |
148 |
P. spinicarpus |
12 |
34.5 |
|
|
6/21-24/85 |
148 |
P. spinicarpus |
16 |
45 |
|
|
7/30/85 |
930 mm TL |
194 |
Ovalipes |
1 |
98 |
|
stephensoni Cancer irroratus |
1 |
150 |
|||
|
Ilex illecebrosus |
2 |
220 |
|||
|
squid beaks |
2 |
1 |
|||
|
7/14/85 |
900 mm TL |
194 |
C. irroratus |
1 |
125 |
|
7/20-21/85 |
900 mm TL |
194 |
C. irroratus |
2 |
112 |
|
C. borealis |
1 |
85 |
|||
|
7/31/85 |
2.3-3. 2 |
146-154 |
Calappa angusta |
4 |
31 |
|
kg est. |
|||||
|
7/31/85 |
13.6 kg est. |
194 |
O. stephensoni |
1 |
50 |
|
9/4/85 |
9.1 kg est. |
146-163 |
O. stephensoni |
3 |
110 |
|
9/4/85 |
9.1 kg est. |
146-163 |
O. stephensoni |
1 |
50 |
|
9/6/85 |
9.1 kg est. |
192 |
Stenocionops |
2 |
59 |
|
spinimana |
|||||
|
9/20/85 |
850 mm TL |
159 |
O. stephensoni |
2 |
92 |
|
Myropsis |
1 |
6 |
|||
|
quinquespinosa |
|||||
|
11/20/85 |
4.5 kg est. |
146 |
Rhomboplites |
1 |
325 |
|
aurorubens |
|||||
|
11/20/85 |
4.5 kg est. |
150 |
Loligo pealei |
2 |
175 |
130
John Dodrill et al.
intact stomachs contained 2-23 fresh Portunus spinicarpus, a total of 93 individuals. The only other remains found in these stomachs were two small, well-digested fish possible from previous feeding, one Solenocera atlantidis , and one bottom dwelling crab, Calappa angusta. Assuming that P. spinicarpus was locally abundant, snowy grouper apparently fed in the water column, ignored bottom organ- isms, and selected the most abundant prey at that site. At the same depth on the same day 2 km away, P. spinicarpus was not present in E. niveatus stomachs, nor were they on a later occasion at the original site. At other sites, feeding emphasis was on bottom-dwell- ing crabs, often adults of the same species and size or species with similar habits.
Third, low food variety within individuals might be volumetrically limited by the number of prey items that can be accommodated. Fewer large prey such as adult or subadult brachyurans will fit into the stomach of even a large snowy grouper. In one snowy grouper (930 mm TL), four food items, Ovalipes stephensoni. Cancer irroratus, and two Ilex illecebrosus totaled a volume of 486 mL, along with two additional squid beaks (1 mL). This was the greatest volume from any grouper stomach in our study (Table 5).
CONCLUSIONS
The snowy grouper is one of the most important large, deep-reef, tertiary predators found on the outer continental shelf edge and upper slope off central North Carolina. An analysis of 5,088 snowy grouper, 335-1,100 mm TL, collected during 30 com- mercial bottom fishing trips in waters 137-238-m deep, revealed a diet dominated by crustaceans, particularly adult and subadult brachyurans (89.9% by number; 71.1% by volume). Small, benthic, midwater, schooling and nonschooling, reef-associated fishes (6.2% by number; 17.5% by volume) were of secondary impor- tance, followed by squids (2.2% by number; 9.8% volume).
The abundance of decapods found in the diet might result from the reduced digestive rates for brachyurans compared to small (<200 mm TL) fish or squid. Crabs are also more accessible than fishes to slow-moving grouper, which probably feed by ambushing prey. In contrast to more slender, piscivorous Mycteroperca grouper species, snowy grouper probably are not capable of sustained or high-speed pursuit because of their stout bodies and sedentary na- ture. All prey were swallowed whole, and large brachuryans ( Can- cer sp., Ovalipes stephensoni) were found in larger grouper.
Slow speed, seasonal territoriality, apparent disuse of plank- tonic organisms or sessile invertebrates, absolute size of prey, and close association with the bottom probably limit variety of prey
Snowy Grouper Feeding
131
taxa consumed as well as prey diversity in any feeding episode. After accounting for embolism, a low percentage of stomachs with food suggests irregular feeding.
Although there appears to be major food overlap with such congeners as E. nigritus and E. flavolimbatus, these two species were uncommon in snowy grouper areas fished between 137 and 238 m. Prey item overlap was noted with three sympatric species, Pagrus pagrus, Rhomboplites aurorubens, and Caulolatilus microps, although competition for specific species was low (highest with P. pagrus). All three species seemed to have a more diverse diet than snowy grouper as well as different feeding strategies. P. pagrus and R. aurorubens were uncommon beyond 140 m and were absent beyond 165 m.
Snowy grouper are predominantly daylight feeders, and fishing success suggests greater feeding activity during morning or late af- ternoon. Small grouper generally feed only in daylight, whereas large individuals (>850 mm TL) at depths beyond 183 m, occasionally feed on calm, moonlit nights. Crepuscular or nocturnally active prey are sought at those times.
Snowy grouper are associated with the bottom and are con- fined almost exclusively to widely scattered, hard bottom, deep reef sites. Prey habits suggest grouper move short distances to feed. Extensive exploratory effort could not confirm the presence of grouper over open bottom areas away from hard bottom habitat of varying vertical relief.
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Snowy Grouper Feeding
135
Soto, L. A. 1985. Distributional patterns of deep-water trachyuran crabs in the Straits of Florida. Journal of Crustacean Biology 5:480-499.
South Carolina Wildlife and Marine Resources Department. 1982. Final report: South Atlantic OCS area living marine resources study, year II, volume I. An investigation of live-bottom habitats off South Carolina and Georgia. Minerals Management Service, Washington, D.C., Con- tract AA 551-CT1-18.
South Carolina Wildlife and Marine Resources Department and Duke University Marine Laboratory, Beaufort, North Carolina. 1982. Fi- nal report, South Atlantic OCS area living marine resources study, year II, volume III. Appendices. Minerals Management Service, Wash- ington, D.C., Contract AA551-CT1-18.
Struhsaker, P. 1969. Dermersal fish resources: composition, distribution, and commercial potential of the continental shelf stocks off south- eastern United States. Fishery Industrial Research 4:261-300.
Van Dover, C., and W. Kirby-Smith. 1979. Field guide to common
marine invertebrates of Beaufort, N.C. Part 1: Gastropoda, Bivalvia,
Amphipoda, Decapoda, and Echinodermata. Duke University Marine Laboratory, Beaufort, North Carolina.
Vernberg, F. J., and W. B. Vernberg. 1970. Lethal limits and the zoogeography of the faunal assemblages of coastal Carolina waters. Marine Biology (Berl.) 6:26-32.
Wenner, C. A., C. A. Barans, B. W. Stender, and F. H. Berry. 1979.
Results of MARMAP otter trawl investigations in the South Atlantic
Bight. I. Fall 1973. South Carolina Marine Resources Center Techni- cal Report 33.
Wenner, E. L., and T. H. Read. 1982. Seasonal composition and abun- dance of decapod crustacean assemblages from the South Atlantic Bight, USA. Bulletin of Marine Science 32:181-206.
Williams, A. B. 1965. Marine decapod crustaceans of the Carolinas.
United States Fish and Wildlife Service Fishery Bulletin 65:1-298.
Williams, A. B. 1984. Shrimps, lobsters, and crabs of the eastern United States, Maine to Florida. Smithsonian Institution Press, Washington, D. C.
Williams, A. B., L. R. McCloskey, and I. E. Gray. 1968. New records of brachyuran decapod crustaceans from the continental shelf off North Carolina, U.S.A. Crustaceana 15:41-66.
Williams, A. B., and R. L. Wigley. 1977. Distribution of decapod Crus- tacea off northeastern United States based on specimens at the Northeast Fisheries Center, Woods Hole, Massachusetts. NOAA (National Oce- anic and Atmospheric Administration) Technical Report NMFS (Na- tional Marine Fisheries Service) Circular 407.
Accepted 3 December 1992
v
A Communal Winter Roost of Silver-haired Bats,
Lasionycteris noctivagans (Chiroptera: Vespertilionidae)
Mary K. Clark
North Carolina State Museum of Natural Sciences
P.O. Box 29555,
Raleigh, North Carolina 27626-0555
ABSTRACT — A communal roost of the silver-haired bat, Lasionycteris noctivagans, was found in January 1993 in Granville County, North Carolina. This is the first confirmed report of com- munal winter roosting for this species.
The silver-haired bat (j Lasionycteris noctivagans ) occurs in for- ested areas throughout much of North America (Kunz 1982) and is a common migrant and winter resident across North Carolina (Lee et al. 1982). This bat has been found in tree cavities and behind loose bark and, especially while hibernating in winter, will use a variety of shelters including buildings, mines, and rock crevices (Kunz 1982). It sometimes migrates in small groups (Barbour and Davis 1969), but is generally regarded as a solitary bat.
Most reports of large winter or summer aggregations were not considered reliable (Barbour and Davis 1969, Kunz 1982). Barbour and Davis (1969) attributed to C. H. Merriam (1884a and 1884b) two reports that suggested L. noctivagans occasionally forms nurs- ery colonies; however, Merriam did not make either observation. One report of 13 young bats found in a crow’s nest near Lowville in Lewis County, New York, was told to Merriam by Frank Hough some years after the discovery. Merriam (1884b:92) included this report under the L. noctivagans account stating that they “presum- ably were of the species now under consideration, because it is by far the most common in the region.” Additionally, Merriam (1884b:93- 94) printed an anecdotal report of a summer aggregation described to him in a letter by William Brewster. While looking for wood- peckers on 18 June 1880 along the shores of Lake Umbagog, New York, Brewster found a colony of bats in a snag. He reported that there were “certainly hundreds and probably thousands” of bats, and he described them all as adults of the same “small dark-colored” species, “which as you [Merriam] suggest, was probably Vesperugo [Lasionycteris] noctivagans.” No specimens were saved, and Merriam ’s decision to include this report under the L. noctivagans account appears based on the vague physical description and Merriam’s as-
Brimleyana 19:137-139, December 1993
137
138
Mary K. Clark
sertion that this was the most common bat in the area. There is one summer record of a family of silver-haired bats found in an abandoned woodpecker hole (Novakowski 1956).
Several sightings of pairs of L. noctivagans roosting together in winter have been reported. Notes by N. B. McCulloch, in the files at the N.C. State Museum of Natural Sciences, describe a male and female L. noctivagans found together in a house in Ra- leigh, North Carolina (Wake County), on 11 December 1951. Brimley (1897) wrote that two were taken 26 December 1892 from a hol- low tree in Bertie County, North Carolina, but did not note the sex of either. Barbour and Davis (1969) also reported finding two L. noctivagans , hibernating about 3 feet from each other, in a mine in Illinois. No information was provided on the sex of these. While conducting- field investigations of rabies in wildlife, Pearson (1962) visitied silica mines to sample bats and recorded occasions when more than one L. noctivagans was found, but he did not describe the roost associations.
Several sources described multiple L. noctivagans found in a single locality, but it is unclear whether any of them were found roosting together. Frum (1953) took six L. noctivagans from the same sandstone ledge in West Virginia on two different dates in March, but no comments on roost associations were made. Brimley (1897) reported taking four on 9 July 1891 in Bertie County, North Carolina, but there were no comments on whether the bats were taken from a roost or whether they were shot while flying.
On 10 January 1993 I received two silver-haired bats that had been obtained by Matt Shimmel (Raleigh, North Carolina) while he was looking for old lumber for carpentry projects in Granville County, North Carolina. He found the bats behind cardboard that had been nailed as insulation to the inside of wooden walls of an abandoned house. The bats fell to the floor when the cardboard was lifted, and his efforts to get them to hang back on the wall failed. Fear- ing the bats would die if left there, Shimmel retrieved them and contacted me. He told me there had been several more bats behind the cardboard, perhaps as many as eight.
I kept the two bats in a refrigerator (at a temperature ranging from 4 to 5 C), until 25 January 1993, when I visited the house in Granville County (about 2.4 km northeast of Grissom) to return them to the capture site. At that time I found three other L. noctivagans behind the piece of cardboard where I was told the other two had been found. They were roosting 1.75-2.0 m above the floor of the
Lasionycteris noctivagans
139
house. Before they were exposed, the bats vocalized when the card- board was lifted, but otherwise they were lethargic and moved slowly. They roosted close to each other, but were not touching.
The temperature behind the cardboard where the bats were roosting was 6 C at 1615 EST. One of the three bats found on 25 January weighed 10.6 g (a female), the other two (one male and one female) each weighed 11.1 g. The two I received from Shimmel on 10 January were both females. Their masses on 26 January were 10.6 and 10.0 g. Nearby (approximately 0.75 km) another abandoned, dilapidated house also had cardboard nailed to the walls. I checked behind the cardboard and found a single male L. noctivagans, weighing 10.6 g. Both houses were open and offered little protec- tion from the elements. In fact, the room in the second site where I found the L. noctivagans had only two intact walls. Both houses were located at the edges of mature, second-growth oak forest. The communal winter roost that I observed appears to be the first con- firmed report of more than two L. noctivagans using the same roost.
LITERATURE CITED
Barbour, R. W., and W. H. Davis. 1969. Bats of America. The Univer- sity Press of Kentucky, Lexington.
Brimley, C. S. 1897. An incomplete list of the mammals of Bertie County, North Carolina. American Naturalist 31:237-239.
Frum, W. G. 1953. Silver-haired bat, Lasionycteris noctivagans, in West Virginia. Journal of Mammalogy 34:499-500.
Kunz, T. H. 1982. Lasionycteris noctivagans. Mammalian Species, 172:1-5.
Lee, D. S., J. B. Funderburg, Jr., and M. K. Clark. 1982. A distribu- tional survey of North Carolina mammals. Occasional Papers of the North Carolina Biological Survey.
Merriam, C. H. 1884a. The mammals of the Adirondack region, north- eastern New York. Privately published, New York.
Merriam, C. H. 18846. The vertebrates of the Adirondack region, north- eastern New York. (Mammalia, concluded.) Transactions of the Linnaen Society of New York. 2:90-96.
Novakowski, N. S. 1956. Additional records of bats in Saskatchewan. Canadian Field-Naturalist 70:142.
Pearson, E. W. 1962. Bats hibernating in silica mines in southern Illinois. Journal of Mammalogy 43:27-33.
Accepted 6 April 1993
A Preliminary Body Fat Index for Cottontails (Lagomorpha: Leporidae)
Edward M. Lunk
Department of Forestry, North Carolina State University, Raleigh, North Carolina 27695
ABSTRACT — Total body fat is frequently used as an indicator of an animal’s physical condition, but its determination requires post- mortem analysis. A field index of total body fat useful on live cottontails ( Sylvilagus floridanus ) was developed. I collected a small sample of cottontails in April 1984 to determine total body fat. Carcasses were homogenized and assayed for ether extraction of crude fat. A significant regression equation predicting the natural log of crude fat expressed as a percentage of dry mass from the natural log of the mass/head-length was developed.
An animal’s plane of physical condition is considered directly related to the abundance and quality of life’s necessities in the habitat, which ultimately affect population productivity (Martin 1977). Body fat reserves are commonly used to indicate an animal’s physi- cal condition, which in turn, can be used to infer habitat quality or rate of population increase (Caughley 1970, Martin 1977). I had particular interest in determining the feasibility of developing a quick field index of body condition for use in mark-recapture, radio te- lemetry, and other investigations of live eastern cottontails.
In previous studies, Havera (1977) found that total percentage of carcass fat was the best indicator of the condition of fox squir- rels ( Sciurus niger), and Robel et al. (1974) found that total car- cass fat was related to food quality in northern bobwhite ( Colinus virginianus).
Indices of fat content are often practical surrogates for the much more costly laboratory determinations of total body fat. Fin- ger et al. (1981) used a kidney fat index, which proved to be correlated with total body fat of white-tailed deer ( Odocoileus virginianus). Bamford (1970) found significant correlation between both abdominal and kidney fat indices and total body fat. Riney (1955) developed a kidney fat index, and combined fat measures have been used by Anderson et al. (1969, 1972). Martin (1977) used an abdominal fat index for indicating fat reserves in European wild rabbits ( Oryctolagus cuniculus). Bamford (1970) found a sig- nificant relationship between a length:standardized-mass ratio and to- tal body fat in the brush-tailed possum (Trichosurus vulpecula). Bailey (1968) reported on the use of mass/length (nose tip to tip of fur on fully extended hind feet) as an index of physical condition in
Brimleyana 19:141-145, December 1993 141
142
Edward M. Lunk
cottontails, but did not present substantiating data on total fat or other physical condition.
The objectives of my study were (1) to identify a postulated relationship between a morphometric measure of body size and total body fat in cottontails and (2) to develop a field index for body condition of live cottontails. I present preliminary evidence that a massdength ratio was significantly correlated with total body fat in a small sample of cottontails in North Carolina. I also discuss de- velopment of a field index using mass/head-length as a predictor of the percentage of total body fat, an indicator of body condition.
METHODS
During April 1984 12 cottontails were trapped or shot from three different study sites in the North Carolina Piedmont. Total length (nose tip to tail tip) was measured with a tape; head length (nose tip to back of skull at posterior edge of lambdoidal crest) was measured with calipers. Animals were weighed with a spring scale and were frozen within 4 hours for later laboratory analysis. When collected, two of the heaviest animals, collared as part of an earlier telemetry study, had skin lesions caused by the collars, and had dropped in rank to second and third lowest in terms of crude fat. These values were retained in the analysis.
Frozen cottontails were weighted with a Mettler digital bal- ance. I used frozen masses obtained on the digital balance in pref- erence to fresh masses obtained with a spring balance because of the greater precision of the former and later determination that the spring scale might have been unreliable. Specimens were homog- enized before assay of crude fat. In preparation for homogenizing, hair was shaved to avoid clogging the homogenizer, carcasses were sliced laterally, and digestive tracts were cleaned. Animals were au- toclaved for 30 minutes to soften tissues and masticated with a laboratory homogenizer (Janke & Kunkel IKA Werk Ultra-Turrax Type T45-S4). Homogenate from each animal (500-600 mL) was dried for 4 days in a ventilated oven and was stirred twice daily to break up crust and to promote drying. Triplicate 2-g samples were weighed and oven-dried for 5 hours for percentage of dry- mass determination. Triplicate 2-g samples were weighted into ex- traction crucibles for determination of ether extract (Pickel extraction of crude fat) expressed as a percentage of ovendried tissue mass.
Because of the small sample size I investigated relationships between body measurements and total fat with single dependent variable models for both sexes combined. A natural log transformation nor- malized the distribution of fat content as shown by normal prob- ability plots and the Shapiro-Wilk W-test (SAS Institute, Inc. 1990)
Index for Cottontails
143
(JP < 0.05). Examination of residuals revealed apparently randomly distributed error.
RESULTS
Total masses ranged from 1,022 to 1,364 g and averaged 1,176 g (SE = 33). Total lengths ranged from 29.2 to 45.7 cm and aver- aged 33.9 cm (SE = 1.7). Head length ranged from 7.20 to 9.70 cm and averaged 8.49 cm (SE = 0.20). Crude fat ranged from 3.7 to 12.6% and averaged 7.2% (SE = 0.8) of tissue dry mass. Coef- ficients of variation of fat content among triplicate samples from each animal were all less than 5%. Females generally had higher (but not significantly higher) fat content than did males.
Crude fat content was significantly correlated to total mass (P = 0.04) and to head length (P = 0.09), but not to total length measurements (P = 0.9). The best predictive equation (Fig. 1) was
log crude fat ) = 2.78957 x Ioge / (Mass(gm) \ - 11.85897
\ Head Length(cm) /
This equation was highly significant (P = 0.007) and had an r2 of 0.697.
3.0
| 2.5
c
o
o
0)
■o
2.0
<D
o 1'5
r2=0.697
A Male ■ Female
1.0
I i I l I | | 1 — I — 1 — I — I — I — I — I — I — I 1 — I — I — I — I — I — I — I — I — I — L.
4.7
4.8
4.9
5.0
5.1
5.2
Loge(mass/head length)
Fig. 1. Regression of crude fat content and mass/head-length of collected cottontails.
144
Edward M. Lunk
DISCUSSION
My sample, though admittedly small, nonetheless produced a strongly significant relationship between a massdength ratio (head length, in this case) and total body fat content in cottontails in the area studied. Total mass and head-length, in particular, are readily obtained from live cottontails handled by one person in the field. Because of the demonstrated relationship between the index and to- tal body fat content, the index could indicate habitat quality for cottontails, though the relationship between body fat and habitat could be complex.
Jacobson et al. (1978) postulated a positive correlation between adequacy of diet and fat stores. Chapman et al. (1977) observed a geographic gradient of increasing body fat in western Maryland co- inciding with increasing severity of winter weather. Thomas (1987) however, postulated that leporids could optimize fat storage with the likelihood of predation and starvation so that rabbits in low quality habitats would tend to begin winter with higher fat levels than those in better quality habitats. Jacobson et al. (1978) and Chapman et al. (1977) observed seasonal fluctuations in several con- dition and fat indexes as well as variations between sexes, though female cottontails tended to be in better condition in the spring than were males. Due to possible sex and season effects on body fat, sex ratios of samples and the season of application should be standardized. This preliminary model should be verified on an independent set of data before being used as a predictor of fat content.
Lack of significant relationship between fat and body length could have been partly due to inaccurate measurements caused by inconsistent body extension. Bailey (1968) described such error in measuring total body length (tip of nose to tip of fir at end of fully extended hind legs) of live cottontails. Use of calipered head- length avoids errors related to body extension. If sufficiently accu- rate measurements of total length could be obtained, total length might prove to be a better predictor. Usefulness of other body di- mensions should be investigated.
ACKNOWLEDGMENTS — I wish to thank Terry Coffey, Dennis Herman, the NCSU Department of Animal Science and Hershell Ball, the NCSU Department of Food Science, for use of equipment, mate- rials, and lab space and for advice on the chemical analyses. Carl Betsill, North Carolina Wildlife Resources Commission, made valu- able suggestions at the beginning of the study and provided support
Index for Cottontails
145
in the field. This research was funded by the Pittman-Robertson program administered by the North Carolina Wildlife Resources Commission.
LITERATURE CITED
Anderson, A. E., D. E. Medin, and D. C. Bowden. 1972. Indices of carcass fat in a Colorado mule deer population. The Journal of Wildlife Management 36:579-594.
Anderson, A. E., D. E. Medin, and D. P. Ochs. 1969. Relationships of carcass fat indices in 18 wintering mule deer. Proceedings of the Western Association of State Game and Fish Commissioners 49:329- 340.
Bailey, J. A. 1968. A weight-length relationship for evaluating physical condition of cottontails. The Journal of Wildlife Management 32:835- 841.
Bamford, J. 1970. Estimating fat reserves in the brush-tailed possum, Trichosurus vulpecula Kerr (Marsupialia:Phalangeridae). Australian Journal of Zoology 18:415-425.
Caughley, G. 1970. Fat reserves of Himalayan thar in New Zealand by season, sex, area and age. New Zealand Journal of Science 13:209- 219.
Chapman, J. A., A. L. Harman, and D. E. Samuel. 1977. Reproductive and physiological cycles in the cottontail complex in western Mary- land and nearby West Virginia. Wildlife Monograph 56:1-73.
Finger, S. E., I. L. Brisbin Jr., and M. H. Smith. 1981. Kidney fat as a predictor of body condition in white-tailed deer. The Journal of Wildlife Management 45:964-968.
Havera, S. P. 1977. Body composition and organ weights of fox squir- rels. Transactions of the Illinois State Academy of Science 70:286- 300.
Jacobson, H. A., R. L. Kirkpatrick, and B. S. McGinnes. 1978. Disease and physiologic characteristics of two cottontail populations in Vir- ginia. Wildlife Monograph 60:1-53.
Martin, J. T. 1977. Fat reserves of the wild rabbit, Oryctolagus cuniculus (L.). Australian Journal of Zoology 25:631-639.
Riney, T. 1955. Evaluating condition of free ranging red deer ( Cervus elaphus), with special reference to New Zealand. New Zealand Jour- nal of Science and Technology 36(Sect B):429-463.
Robel, R. J., R. M. Case, A. R. Bissett, and T. M. Clement. 1974. Energetics of food plots in bobwhite management. The Journal of Wildlife Management 38:653-664.
SAS Institute, Incorporated. 1990. SAS® Procedures Guide, Version 6 Third Edition. SAS Institute, Cary, North Carolina.
Thomas, V. G. 1987. Similar winter energy strategies of grouse, hares and rabbits in northern biomes. Oikos 50:206-212.
Accepted 1 November 1992
Diets of Marsh Rabbits,
Sylvilagus palustris (Lagomorpha: Leporidae), from Coastal Islands in Southeastern North Carolina
Kevin W. Markham and Wm. David Webster Department of Biological Sciences,
University of North Carolina at Wilmington,
Wilmington, North Carolina 28403
ABSTRACT — Dietary analyses were conducted for marsh rabbits from barrier and dredge-material islands near Wilmington, North Caro- lina. Marsh rabbits primarily consumed upland vegetation, espe- cially during the summer and winter, and they ate a wide variety of plant species available to them. Forbs and grasses comprised the bulk of the diet; shrub utilization was low, even in winter.
Diets of marsh rabbits, Sylvilagus palustris (Bachman), are poorly known despite the local abundance of these herbivores in wetland habitats in the southeastern United States. Blair (1936) conducted feeding trials in Florida using captive marsh rabbits to check for acceptance of particular wetland plants, and his results have been cited by others describing the diet of marsh rabbits (Chapman and Willner 1981, Chapman and Feldhamer 1982). Diets of free-ranging marsh rabbits, however, have not been described in any part of the range of the species. The purpose of this investigation, therefore, was to determine the diets of marsh rabbits inhabiting estuarine islands in southeastern North Carolina.
METHODS
Islands in southeastern North Carolina are of two types: low, narrow barrier islands separated from the mainland by marshes and the Atlantic Intracoastal Waterway, and small oval-shaped islands adjacent to the Waterway where the U.S. Army Corps of Engineers deposits dredged material. Because vegetative zonation and species composition on these islands are similar (Parnell and Soots 1979, Hosier and Eaton 1980) and marsh rabbits are common to abundant on both island types, we combined data from both island types to increase sample sizes.
Floristic diversity and abundance (from Braun-Blanquet approximations for 0.25-m2 plots at 3-m intervals along four to six transects across each island) were used to describe the plant com- munities from which rabbits were taken. Six communities were de- fined: low marsh, high marsh, grass flat, shrub thicket, dune, and berm. Reference slides for 78 species of plants taken along these transects were prepared for use in comparisons with plant fragments
Brimleyana 19:147-154, December 1993
147
148
Kevin W. Markham and Wm. David Webster
Table 1. Abundance (percentage of diet attributable to plant), followed by range (in parentheses), of flora consumed by marsh rabbits on estuarine islands in southeastern North Carolina. Asterisks indicate significant seasonal variation in consumption.
Abundance
|
Plant species |
Spring (n = 5) |
Summer (n = 9) |
Winter (n = 7) |
Total (n = 21) |
|
Low Marsh |
||||
|
Spike grass {Distichlis spicata )* |
9(19) |
3(19) |
||
|
Seablite ( Suaeda linearis ) |
1(7) |
5(42) |
2(42) |
|
|
Seabeach orach (Atriple x arenaria ) |
<1 (2) |
<1 (2) |
||
|
Sea lavender (Limonium carolinianum ) |
6(18) |
2(18) |
||
|
High Marsh |
||||
|
Reed ( Phragmites australis )*a |
12 (59) |
4(59) |
||
|
Marsh sedge ( Fimbristylis spadicea ) |
<1(1) |
<1(1) |
<1(1) |
|
|
Black needlerush {J uncus roemerianus ) |
1(13) |
<1 (13) |
||
|
Marsh pink ( Sabatia stellaris ) |
3(8) |
<1(1) |
1(8) |
|
|
Silverling {Baccharis halimifolia) |
<1 (1) |
<1 (1) |
||
|
Sea ox-eye (Borrichia frutescens ) |
1(6) |
<1 (6) |
||
|
Grass Flat |
||||
|
Wild rye grass ( Elymus virginicus) |
<1 (6) |
<1 (6) |
||
|
Muhly ( Muhlenbergia capillaris ) |
<1 (3) |
<1 (3) |
||
|
Finger grass ( Chloris petraea ) |
4(4) |
1(4) |
||
|
Saltmeadow cordgrass ( Spartina patens ) |
13 (44) |
4(15) |
17 (42) |
11(45) |
|
Foxtail grass ( Setaria geniculata ) |
4(19) |
7(52) |
4(52) |
|
|
Bunch grass ( Panicum virgatum ) |
3 (18) |
1(18) |
||
|
Sedges ( Cyperus spp.) |
2(7) |
2(12) |
<1 (3) |
1(12) |
|
Dayflower ( Commelina erecta) |
1(5) |
2(9) |
1(9) |
|
|
Cottonweed (Iresine rhizomatosa) |
2(5) |
11 (31) |
4(31) |
|
|
Marsh pennywort ( Hydrocotyle bonariensis ) 7 (36) |
2(15) |
11 (39) |
7(39) |
|
|
Morning glory ( Ipomoea sagittata ) |
4(16) |
3(18) |
2(18) |
|
|
Blue curl ( Trichostema sp.) |
<1(2) |
<1(2) |
||
|
Buttonweed ( Diodia teres ) |
5(24) |
2(24) |
||
|
Bedstraw {Galium spp.)b |
8(38) |
6(29) |
5 (38) |
|
|
Seaside goldenrod {Solidago sempervirens) |
9(14) |
12 (45) |
10 (20) |
10 (45) |
|
Camphorweed {Heterotheca subaxillaris)* |
8(49) |
35 (30) |
14(51) |
|
|
Firewheel {Gaillardia pulchella) |
6(28) |
<1 (2) |
2(28) |
|
|
Shrub Thicket |
||||
|
Greenbriar {Smilax spp.)c |
<1 (2) |
<1 (2) |
||
|
Beach pea {Strophostyles helvola )* |
<1(1) |
25 (64) |
8(64) |
|
|
Yaupon {Ilex vomitoria ) |
7(33) |
9(18) |
5 (33) |
|
|
Vir. creeper {Parthenocissus quinquefolia) |
1(11) |
<i(n) |
||
|
Creeping cucumber {Melothria pendula) |
1(8) |
<1 (8) |
Marsh Rabbit Diet
149
Table 1. Continued.
|
Abundance |
||||
|
Spring |
Summer |
Winter |
Total |
|
|
Plant species |
(n = 5) |
(n = 9) |
(n = 7) |
(n = 21) |
|
Dune |
||||
|
Purple sandgrass (Triplasis purpurea ) |
<1 (1) |
<1 (4) |
1(7) |
1(7) |
|
Sea oats ( Uniola paniculata) |
2(14) |
1(14) |
||
|
Lovegrass ( Eragrostis pilosa) |
2(13) |
1(13) |
||
|
Sandspur {Cenchrus tribuloides) |
5(15) |
<1(1) |
2(15) |
|
|
Panic grass ( Panicum amarum) |
Berm |
<1 (4) |
1(9) |
<1 (9) |
|
Dune elder ( Iva imbricata) |
<1(1) |
<1(1) |
||
|
Unidentified forbs |
3(10) |
<1 (1) |
4(7) |
2(10) |
|
Unidentified grasses |
<1(1) |
<1 (3) |
<1 (2) |
<1 (3) |
a Phragmites australis (= P. communis ) b includes Galium tinctorium and G. hispidulum c includes Smilax bona-nox and S. laurifolia
recovered from rabbit stomachs. The methods of fixing and staining plant epidermal tissues and microtechniques for diet analysis were modifications of those used by Dusi (1949).
Rabbit collections were made during three periods coinciding with new plant growth in the spring (March 1987), abundant green forage of late summer (August/September 1986), and sparse old growth in winter (December 1986). Relative ages of rabbits were deter- mined by the degree of fusion between the exoccipital-supraoccipital suture (Hoffmeister and Zimmerman 1967). Stomachs were fixed in 10% formalin and stored in 45% isopropanol.
Stomach contents were removed and gently agitated in 45% isopropanol to mix the fragments. A random sample was drawn from the slurry and was stained in a 10-mg/L Rhodamine B solu- tion for 48-72 hours. Twenty subsamples were drawn from each sample and were mounted on clean slides. Five fields of view were selected, using a chart of random coordinates, for each of the 20 slides. Fragments were identified by diagnostic epidermal character- istics and comparison with reference slides. Unidentifiable fragments were recorded as either unknown grass or forb. For each plant species, dietary data are expressed as abundance, or proportion of the diet attributable to that plant.
Principal component analysis indicated that the abundance of plants found in marsh rabbit stomachs varied seasonally but without regard to age and sex; therefore, rabbits of all ages and both sexes
150
Kevin W. Markham and Wm. David Webster
were combined for the analysis of seasonal variation. Chi-square was used to test the hypothesis that marsh rabbits display no sig- nificant (P < 0.05) seasonality in plant consumption using trans- formed (square root) abundance data.
RESULTS
Spring — The spring collection included five marsh rabbits. There were 25 species of plants identified from the stomachs of these rabbits, with each stomach averaging eight species (range = 6-10). Diets of individual rabbits were varied, and no plant appeared to be dominant during this period (Table 1). Grasses accounted for 41% of the spring diet, whereas forbs comprised 52% and shrubs 7%. Marsh vegetation comprised 32% of the diet, and together with plants typical of the adjacent low grasslands, accounted for 89% of the diet. Spike grass ( Distichlis spicata), sea lavender ( Limonium carolinianum), and reed (Phragmites australis) collectively comprised 27% of the spring diet; these marsh plants were not eaten in sum- mer and winter (Table 1).
Summer — Nine marsh rabbits were collected during August and September. Twenty-five plant species were found in their stomachs, although each stomach averaged eight species (range = 5-11). Beach pea ( Strophostyles helvola) was the dominant plant in the stomachs of most rabbits collected during summer and accounted for 25% of the total diet (Table 1). Beach pea, seaside goldenrod ( Solidago sempervirens), and cottonweed ( Iresine rhizomatosa) accounted for 48% of the cumulative diet of these rabbits. Forbs averaged 70% of the diet with grasses contributing 29% and shrubs 1%. Marsh vegetation comprised 6% of the diet for this season.
Winter — The winter diet was examined in seven marsh rabbits. Seventeen plant species were represented, with each stomach con- taining an average of seven species (range = 5-10). The abundance of camphorweed ( Heterotheca subaxillaris) was higher in winter than in other seasons, representing 35% of the diet (Table 1). Camphorweed and saltmeadow cordgrass ( Spartina patens) were consumed by all rabbits collected in winter and together averaged 52% of the diet. Forbs (including camphorweed) accounted for 70% of the diet, whereas grasses and shrubs comprised 22% and 8%, respectively. Marsh vegetation accounted for less than 1% of the diet.
Combined — We found 40 species of plants in the stomachs of 21 marsh rabbits collected in spring, summer, and winter (Table 1). Five species were eaten year-round, especially marsh pennywort ( Hydro - cotyle bonariensis), seaside goldenrod, and saltmeadow cordgrass, with seasonal shifts in the importance of each. Marsh vegetation was relatively more important in spring, with significant consumption of
Marsh Rabbit Diet
151
spike grass (x2 = 6.00, 2df, P < 0.05) and reed (x2 = 6.91, 2df, P < 0.05). Marsh rabbits primarily consumed upland vegetation during summer and winter, with significantly higher consumption of beach pea (x2 = 10.00, 2df, P < 0.01) in summer and camphorweed (x2 = 6.01, 2df, P < 0.05) in winter than in other seasons. Rabbits consumed nearly equal amounts of grasses and forbs in spring, but their dependence on forbs increased to more than double the con- sumption of grasses during summer and winter. Shrubs did not con- tribute a major portion of the diets, even in winter. Thirty-eight other species of plants were found along the transects but were not consumed by the marsh rabbits we collected (Appendix A).
DISCUSSION
Tomkins (1935) noted that marsh rabbits in coastal Georgia fed in dunes and upland areas adjacent to wet marshes on dredge- material islands, but he did not identify the plants upon which these rabbits were feeding. Our study, despite relatively small sample sizes, indicates that marsh rabbits forage extensively in upland com- munities on estuarine islands in southeastern North Carolina, and that they eat a wide variety of plant species available to them. Blair (1936) offered captive marsh rabbits plants common to Florida swamp habitats where he collected the rabbits. Some plant species (or related species) eaten by Blair’s rabbits were also found in the island communities of our study and were eaten in southeastern North Carolina as well. These plants included greenbriars (Smilax), pennyworts (. Hydrocotyle ), hollies {Ilex), silverling ( Baccharis ), and rushes ( Juncus ). Blair (1936) noted that marsh pennywort was rel- ished by captive rabbits. In our study, consumption of marsh pen- nywort averaged 7% in spring, 2% in summer, and 11% in winter.
In southeastern North Carolina marsh rabbits rely on saltmeadow cordgrass, pennywort, and seaside goldenrod throughout the year; other species of plants are consumed seasonally, especially beach pea in summer and camphorweed in winter. MacCracken and Hansen (1984) noted that Nuttall’s cottontails (5. nuttalli) also tended to utilize many of the same species year-round with seasonal shifts in the importance of species. Holloran et al. (1981) found that eastern cottontails ( S . floridanus) in Virginia consumed more forbs in sum- mer and fall than in winter and spring, with grasses forming the bulk of the diet in winter and spring. Other cottontail species have been shown to display seasonal shifts in reliance on forbs, grasses, and shrubs mostly in response to availability and environmental con- ditions (Dalke and Sime 1941, Turkowski 1975, Green and Flinders
152
Kevin W. Markham and Wm. David Webster
1980, MacCracken and Hansen 1984). The consumption of different species at different times of year may be related to the water con- tent (Getz 1966, Dunson and Lazell 1982), availability of nutrients and secondary compounds (de la Cruz and Poe 1975), or the amount of fiber in different stages of plant growth cycles.
ACKNOWLEDGMENTS — This research was supported in part by the North Carolina Wildlife Federation, North Carolina Conser- vation Educational Foundation, and the Department of Biological Sciences and Center for Marine Science Research (Contribution No. 34) of the University of North Carolina at Wilmington.
LITERATURE CITED
Blair, W. F. 1936. The Florida marsh rabbit. Journal of Mammalogy 17:197-207.
Chapman, J. A., and G. A. Feldhamer. 1982. Wild mammals of North America. John Hopkins University Press, Baltimore, Maryland.
Chapman, J. A., and G. R. Willner. 1981. Sylvilagus palustris. Mamma- lian Species 153:1-3.
Dalke, P. D., and P. R. Sime. 1941. Food habits of the eastern and New England cottontails. The Journal of Wildlife Management 5:216- 227.
de la Cruz, A. A., and W. E. Poe. 1975. Amino acid content of marsh plants. Estuarine and Coastal Marine Science 3:243-246.
Dunson, W. A., and J. D. Lazell. 1982. Urinary concentrating capa- city of Rattus rattus and other mammals from the lower Florida Keys. Comparative Biochemistry and Physiology 71:17-21.
Dusi, J. L. 1949. Methods for the determination of food habits by plant microtechniques and histology and their application to cottontail rab- bit food habits. The Journal of Wildlife Management 13:295-298.
Getz, L. L. 1966. Salt tolerances of salt marsh meadow voles. Journal of Mammalogy 47:201-207.
Green, J. G., and J. T. Flinders. 1980. Habitat and dietary relation- ships of the pygmy rabbit. Journal of Range Management 33:136- 142.
Hoffmeister, D. F., and E. G. Zimmerman. 1967. Growth of the skull in the cottontail (Sylvilagus floridanus) and its application to age- determination. American Midland Naturalist 78:198-206.
Holloran, D. J. S., R. L. Kirkpatrick, and B. S. McGinnis. 1981. Com- parative food habits of two cottontail rabbit populations in Virginia. Proceedings of the Annual Conference of the Southeastern Associa- tion of Fish and Wildlife Agencies 35:84-91.
Hosier, P. E., and T. E. Eaton. 1980. The impact of vehicles on dune and grassland vegetation on a south-eastern North Carolina barrier beach. Journal of Applied Ecology 17:173-182.
Marsh Rabbit Diet
153
MacCracken, J. G., and R. M. Hansen. 1984. Seasonal foods of black- tail jackrabbits and Nuttall cottontails in southeastern Idaho. Journal of Range Management 37:256-259.
Parnell, J. F., and R. F. Soots. 1979. Atlas of colonial waterbirds of North Carolina estuaries. North Carolina Sea Grant, UNC-SG-78-10, Raleigh.
Tomkins, I. R. 1935. The marsh rabbit: an incomplete life history. Journal of Mammalogy 16:201-205.
Turkowski, F. J. 1975. Dietary adaptability of the desert cottontail. The Journal of Wildlife Management 39:748-756.
Accepted 21 August 1992
Appendix A. Species of plants found on estuarine islands in southeastern North Carolina but not found in stomachs of marsh rabbits.
Low Marsh
Smooth cordgrass ( Spartina alterniflora )
Glasswort ( Salicornia virginica and S. europaea)
High Marsh
Cattail ( Typha sp.)
Wax myrtle ( Myrica cerifera )
Seashore mallow ( Kosteletskya virginica )
Marsh elder ( Iva fructescens )
Marsh aster ( Aster tenuifolius )
Grass Flat
Foxtail grass (Setaria magna )
Broomsedge ( Andropogon virginicus and A. scoparius )
Yucca ( Yucca aloifolia and Y. filamentosa )
Mexican tea ( Chenopodium ambrosioides)
Prickly-pear ( Opuntia drummondii and O. compressa)
Climbing milkweed ( Cynanchum palustre )
Ragweed ( Ambrosia artemisiifolia )
Dog-fennel ( Eupatorium capillifolium )
Climbing hempweed ( Mikania scandens)
Shrub Thicket
Red cedar (Juniper us virginiana)
Live oak ( Quercus virginiana )
Pokeweed (Phytolacca americana )
Red bay (Persea borbonia )
Blackberry (Rubus spp.)
Black cherry (Prunus serotina)
Hercules’-club (Zanthoxylum clava-herculis)
Muscadine grape (Vitis rotundifolia)
Wild lettuce (Lactuca canadensis )
154
Kevin W. Markham and Wm. David Webster
Appendix A. Continued.
Dune
American beach grass (Ammophila breviligulata) Croton ( Croton punctatus )
Seabeach evening-primrose ( Oenothera humifusa) Ground-cherry ( Physalis maritima )
Horseweed (Erigeron canadensis )
Berm
Russian thistle ( Salsola kali)
Seabeach amaranth (Amaranthus pumilus )
Sea rocket ( Cakile harperi)
Seaside spurge (. Euphorbia poly goni folia)
Notes on the Geographical and Ecological Distribution of Relict Populations of Synaptomys cooperi (Rodentia: Arvicolidae) from Eastern North Carolina
Mary K. Clark
North Carolina State Museum of Natural Sciences
P.O.Box 29555
Raleigh, North Carolina 27626-0555
AND
Michael S. Mitchell and Kent S. Karriker North Carolina State University, The Wildlife Program,
Department of Forestry Raleigh, North Carolina 27695-8002
ABSTRACT — As part of a study to evaluate the effects of forest management on North Carolina pocosin communities, small mammals were trapped between May 1991 and May 1992 in 15 stands in Carteret, Craven and Jones counties, North Carolina. Captures included three Synaptomys cooperi, extending the known range of the species in eastern North Carolina about 170 km south of Dismal Swamp localities. These specimens, and others collected since 1977, indicate that the paucity of records be- tween 1896 and the 1970s is the result of ineffective trap- ping methods and insufficient fieldwork in appropriate habitat. S. cooperi is more widely distributed in eastern North Carolina than previously reported. Populations are disjunct and appear to be Pleistocene relicts.
The southern bog lemming, Synaptomys cooperi , occurs in eastern North America (Fig. 1) from southeastern Canada west to western Minnesota, and south to southwestern Kansas, northeastern Arkansas, southeastern Tennessee, and western North Carolina (Linzey 1983.). A population in the Dismal Swamp in Virginia and North Carolina is disjunct and is recognized as a separate subspecies, S. c. helaletes (Wetzel 1955). For almost a century this subspecies was known only from 24 specimens collected between 1895 and 1898 (Handley 1979). Between 1977 and 1980, field work in the Dismal Swamp (Rose 1981) and in adjacent areas in northeastern North Carolina yielded additional specimens of S. c. helaletes , some from new localities, but all in close proximity to the Dismal Swamp (Rose 1981, Lee et al. 1982). This subspecies is now con-
Brimleyana 19:155-167, December 1993
155
156 Mary K. Clark, Michael S. Mitchell, and Kent S. Karriker
sidered to be common in many habitats in that area (Rose et al. 1990, Handley 1991).
Before 1989 S. cooperi had been reported in eastern North Carolina only from Gates, Pasquotank, and Perquimans counties (Brim- ley 1905, Rose 1981, Lee et al. 1982). After intensive trapping on the Dare Country mainland, often in what might be regarded as optimal habitat for the species, Clark et al. (1985) concluded that S. cooperi did not occur south of the Albemarle-Pamlico penin- sula. Four specimens collected between 1989 and 1992 proved that conclusion erroneous. An S. cooperi was captured in Beaufort County in 1989 (Webster et al. 1992), and in 1991 and 1992 M.S.M. and K.S.K. captured three S. cooperi in Jones and Craven counties in the Croatan National Forest. The National Forest captures were about 170 km south of the southernmost Dismal Swamp record and ap- proximately 57 km south of the Beaufort County record.
To better understand populations of S. cooperi in the Dismal Swamp and eastern North Carolina (Fig. 1), we describe the circumstances of the National Forest captures, review the ecology of these populations in southeastern Virginia and eastern North Caro- lina, and discuss the disjunct distribution of this species in the region.
METHODS
Study site description — Small mammals were trapped in and around the Croatan National Forest in parts of Carteret, Jones and Craven counties (Fig. 1). The 382,716-ha National Forest is gener- ally bounded by the Neuse River to the north, the Trent and White Oak rivers to the west, White Oak River and Bogue Sound to the south, and the Atlantic Ocean to the east. There are five spring-fed shallow lakes totaling 10,617 ha in the National Forest. The wide variety of habitat types there includes timberlands, sand ridges, long-leaf pine ( Pinus palustris) savannah, blackgum-cypress ( Nyssa sylvatica-Taxodium spp.) swamp, Carolina bays, and some of the largest pocosins in the state.
Pocosins are distinct freshwater wetlands formed on deep peat deposits. Dominant pocosin vegetation includes evergreen shrubs (■ Cyrilla racemiflora, Ilex coriacea, /. glabra , Lyonia lucida), dwarf pond pine ( Pinus serotina ), and bay trees ( Gordonia lasian- thus, Magnolia virginiana, Persea borbonia). Pocosins can vary con- siderably in species composition, tree density, and stature of the vegetation (Ash et al. 1983). Pocosins where all of the vegetation is stunted and the community is dominated by shrubs are called
Distribution of Synaptomys cooperi
157
Fig. 1. The locations of records of S. cooperi from eastern Virginia and North Carolina are indicated by dots. Dots in Virginia represent specimens from the Dismal Swamp. Counties in North Carolina discussed in the text are identified by numbers: 1. Beaufort, 2. Craven, 3. Dare, 4. Gates, 5. Jones, 6. Pasquotank, and 7. Perquimans. The blackened area on the map of North America shows the current range of Synaptomys cooperi.
158 Mary K. Clark, Michael S. Mitchell, and Kent S. Karriker
short pocosins. Tall pocosins are characterized by a taller under- story and are generally dominated by pond pines.
To establish baseline data on pocosin mammals and to describe the changes in these communities associated with intensive forest management, M.S.M. and K.S.K. selected 15 stands in natural and managed pocosin communities for small mammal sampling. Three stands each represented five treatments: three man- aged habitats — open canopy, closed canopy, and thinned — and two natural stands — short pocosin and tall pocosin. The nine managed stands were in pine plantations on the periphery of the Croatan National Forest (on Weyerhaeuser Company land), and the six natu- ral pocosin areas were within the Croatan National Forest.
One short pocosin stand was in the interior of the Great Lake Pocosin, and one tall pocosin stand was on its periphery. The high- est elevations in the National Forest are in the Great Lake Pocosin, which has no history of anthropogenic modification and is one of the largest contiguous expanses of short pocosin in the state.
Small mammal trapping — Trapping was conducted for three field seasons: summer 1991, winter 1992, and summer 1992. Snap traps and pitfall traps were used each field season. Snap traps were ac- tive for 5 consecutive nights; pitfall traps were active 7. One-hun- dred snap traps (Museum Specials and Victor rat traps), baited with a mixture of peanut butter, rolled oats, and raisins, were set in each stand. There were five trap-lines per stand. In the first two field seasons pitfall traps were located at the end of each trap-line. Pitfalls with drift fences were added in the interior of each stand in the last field season (see Mitchell 1992 for details).
Vegetation sampling — Vegetation data were collected to provide a context for interpreting faunal community structure. Parameters for overstory, shrub layer, herbaceous vegetation, and fallen dead material were evaluated for each stand (see Mitchell 1992 and Karriker 1993 for details).
Specimen identification — Specimens collected were deposited in the North Carolina State Museum of Natural Sciences (NCSM) where they were identified and were placed in the research collection as vouchers. Skull measurements used by Wetzel (1955) to separate subspecies of S. cooperi were compared to measurements taken from the skulls of two specimens (NCSM 6778 and NCSM 7190) col- lected in the National Forest. The skull of the other specimen (NCSM 7191) was that of a juvenile and was not compared because Wetzel analyzed only adults.
Distribution of Synaptomys cooperi
159
RESULTS
Small mammal trapping — We recorded 22,206 snaptrap-nights and 3,322 pitfall trap-nights. The projected trap quota was not achieved primarily due to a wildfire which burned one short pocosin stand while traps were in place. A total of 926 small mammals, repre- senting 15 species, were trapped, and at least ten other mammals or their sign were recorded from the study area (Table 1) (Mitchell 1992).
Table 1. Number of mammals collected or observed in the Croatan National Forest, 1991 and 1992.
|
Species |
Open canopy |
Closed canopy |
Thinned |
Pocosin Short Tall |
Total trapped |
|
|
Didelphis virginianus |
*i |
* |
2 |
0 |
0 |
2 |
|
Sorex longirostris |
8 |
19 |
16 |
46 |
19 |
108 |
|
Blarina brevicauda |
14 |
18 |
15 |
19 |
5 |
71 |
|
Cryptotis parva |
14 |
0 |
0 |
0 |
0 |
14 |
|
Scalopus aquaticus |
0 |
* |
0 |
0 |
0 |
0 |
|
Sylvilagus floridanus |
* |
* |
0 |
* |
0 |
0 |
|
Sylvilagus palustris |
* |
0 |
1 |
* |
* |
1 |
|
Sciurus carolinensis |
0 |
0 |
* |
0 |
0 |
0 |
|
Oryzomys palustris |
10 |
2 |
1 |
0 |
0 |
13 |
|
Reithrodontomys humulis |
69 |
2 |
29 |
21 |
0 |
121 |
|
Peromyscus leucopus |
4 |
0 |
12 |
20 |
1 |
37 |
|
Peromyscus gossypinus |
0 |
15 |
17 |
0 |
48 |
80 |
|
Ochrotomys nuttalli |
20 |
34 |
27 |
40 |
79 |
200 |
|
Sigmodon hispidus |
186 |
2 |
55 |
0 |
0 |
243 |
|
Microtus pinetorum |
0 |
0 |
0 |
12 |
0 |
12 |
|
Mus musculus |
20 |
0 |
0 |
0 |
0 |
20 |
|
Synaptomys cooperi |
0 |
0 |
0 |
2 |
1 |
3 |
|
Procyon lotor |
* |
* |
* |
* |
* |
0 |
|
Ursus americanus |
* |
* |
* |
* |
* |
0 |
|
Lynx rufus |
* |
* |
* |
0 |
* |
0 |
|
Canis spp. |
* |
0 |
* |
* |
* |
0 |
|
Urocyon cinereoargenteus |
0 |
0 |
0 |
0 |
* |
0 |
|
Lutra canadensis |
* |
* |
* |
0 |
0 |
0 |
|
Mustela frenata |
0 |
0 |
0 |
1 |
0 |
1 |
|
Odocoileus virginianus |
* |
* |
* |
* |
* |
0 |
|
Totals |
346 |
92 |
175 |
161 |
153 |
926 |
1 An asterisk (*) denotes a sighting or sign observed.
Table 2. Percent cover and dominant species in the canopy, midstory, and understory of sampled treatments, Croatan National Forest, 1991 and 1992.
160 Mary K. Clark, Michael S. Mitchell, and Kent S. Karriker
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3 |
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|
Cx |
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CJ |
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|
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|
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3 |
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X
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X
03
|
cx |
cx 0 |
_G S |
||
|
0 |
G |
O |
||
|
G |
G |
O |
||
|
G |
O |
■a |
O |
|
|
D |
~o |
D |
CX |
|
|
53 |
D |
c |
4_> |
|
|
D CX |
C/3 O |
G • X |
t-c O 42 |
|
|
0 |
u |
H |
cd Vh |
00 |
G
z
Tall pocosin 97 P. serotina 67 L. lucida 4 A. gigantea
P. taeda Cyrilla racemiflora Smilax spp.
Distribution of Synaptomys cooperi
161
Capture success varied considerably between field seasons with rates of 2.5, 2.1, and 6.5% recorded for each respective season.
Species composition within the treatments was relatively consistent among the field seasons.
Three S. cooperi were trapped in 2 of the 15 stands. Two were taken in snap traps, one in a pitfall trap. All captures of Synaptomys were from natural pocosin stands associated with the
Great Lake Pocosin. Two were taken in the short pocosin stand, and one was taken from the periphery at the tall pocosin stand.
Vegetation sampling — The percent cover and dominant species in the canopy, midstory, and understory of all sampled treatments is presented in Table 2. The short pocosin stand where two
S. cooperi were taken was dominated by shrubs that rarely ex-
ceeded 1 m in height. It had an open canopy primarily com- posed of pond pine ( Pinus serotina ) with a few loblolly bay trees (Gordonia lasianthus). Trees were sparsely distributed, stunted, and poorly developed. Dominant shrubs were fetterbush ( Lyonia lucida ), titi ( Cyrilla racemiflora), red bay ( Persea borbonia), loblolly bay, young pond pine, zenobia ( Zenobia pulverulenta ), and sweetbell ( Leucothoe spp.). Dominant herbaceous species included cinna- mon fern ( Osmunda cinnamonea), pitcher plant ( Sarracenia spp.), and sphagnum moss ( Sphagnum spp.)
The average height of the overstory in the tall pocosin stand where one S. cooperi was captured was 13 m. Dominant trees were pond pine and loblolly bay; the shrub layer height averaged 1.5-3 m. The most common shrubs were fetterbush, loblolly bay, small gallberry {Ilex glabra), titi, and huckleberry ( Gaylussacia sp.). There was little herbaceous vegetation, only sparsely distributed Smilax.
Specimen identification — Based on geographic proximity, the specimens are expected to represent S. c. helaletes, a race pre- viously regarded as endemic to the Dismal Swamp region. The sub- specific identity of the National Forest specimens is not clear from the skull measurements. We compared these measurements to those of the S. c. stonei and S. c. helaletes specimens that were mea- sured by Wetzel (1955) (Table 3). Wetzel’s conservative treatment of the adult category precludes subspecific determination by skull measurements because none of the National Forest specimens had all characteristics used by Wetzel to place them in the adult category.
DISCUSSION
The habits of the southern bog lemming certainly contribute to the low capture rates for this rodent. A. K. Fisher found Synaptomys
162 Mary K. Clark, Michael S. Mitchell, and Kent S. Karriker
Table 3. Summary of selected cranial measurements from 10 adult Synaptomys cooperi helaletes and 26 adult S. c. stonei from the Southern Appalachians (Wetzel 1955) compared to measurements of two specimens (NCSM 6778, NCSM 7190) taken in the Croatan National Forest, 1991 and 1992.
|
S. c. |
stonei |
S. c. helaletes |
||||
|
Measurements |
X |
SD |
X |
SD |
NCSM 6778 NCSM 7190 |
|
|
Width of upper incisors |
3.5 |
0.01 |
4.0 |
0.03 |
3.9 |
3.8 |
|
Condylobasilar length |
24.8 |
0.08 |
25.1 |
0.20 |
25.2 |
24.7 |
|
Nasal width |
3.4 |
0.04 |
3.5 |
0.07 |
3.2 |
3.6 |
|
Zygomatic width |
16.7 |
0.11 |
17.1 |
0.22 |
16.4 |
16.4 |
|
Height of skull |
10.1 |
0.08 |
10.5 |
0.17 |
9.3 |
9.2 |
|
“hard to catch, because |
it will |
not take |
any |
sort of bait; |
the only |
|
|
way to capture it is |
to |
set a trap in its |
runway” (cited in |
Handley |
||
|
1979:325). Rose et |
al. (1990) described |
S. c. |
helaletes as |
an enig- |
matic study subject, noting that sign was observed 10 months be- fore they caught 11 S. c. helaletes in only a few weeks. There is some evidence that pitfall traps and live traps might be more effec- tive than snap traps for capturing S. c. helaletes (Rose et al. 1981, Rose et al. 1990). We could not compare trapping methods for S. cooperi in the National Forest because only three individuals were caught.
Insufficient field effort in appropriate habitat might also account for low capture rates. Previous studies (Handley 1979, Breidling et al. 1983) in the Great Dismal Swamp only sampled forested sites. Rose (1981) trapped both forested and nonforested sites in the Dismal Swamp, and all of his S. c. helaletes captures were from nonforested areas. Rose’s study sites varied from purely herbaceous vegetation to natural or planted pine stands up to 15 years old. Some' were taken from a grassy remnant marsh, others were captured under an electrical powerline where the 40-m- wide right-of-way was dominated by giant cane ( Arundinaria gigantea ) and softstem rush (Juncus effusus ). Rose (1981) stated that as long as grasses remained in the understory, S. c. helaletes persisted.
A review of the habitat descriptions from other captures demonstrates that S. c. helaletes can be found in a variety of suc- cessional communities. The data tag for a specimen (AMNH 265071) captured in Gatesville, Gates County, reads “young-2-3’ pine planta- tion on cleared forest land.” The Pasquotank County specimen (NCSM 4019) obtained from a barn owl pellet certainly came from
Distribution of Synaptomys cooperi
163
open habitat. The Beaufort County specimen was captured in a pit- fall trap set in the ecotone between communities characterized as a xeric pine savannah and a lowland pocosin (Webster et al. 1992). There is no detailed habitat information available for the Perquimans County record (Brimley 1905) or for two other speci- mens (NCSM 2654 and NCSM 4019) taken in the Dismal Swamp area. Although trapping in the Croatan National Forest yielded specimens from only unmanaged stands, it is clear from other efforts that some human alterations create habitats suitable for this lemming.
There are few structural differences between the three short pocosin stands sampled in the National Forest that could account for the presence of Synaptomys in one and not in the other two. Drainage in the Great Lake Pocosin is limited to ditches associated with roads on the pocosin’s boundary, remote from its interior. By contrast, the other two stands of short pocosin where no Synaptomys were caught were considerably smaller and were bounded on at least two sides by ditches. The Great Lake Pocosin interior has a greater degree of surface saturation than the other areas, as evi- denced by the abundance of Sphagnum observed in the interior.
The lack of records of S. c. helaletes from 1897 to the 1980s was once believed to be the result of changes in habitats caused by human activities (Handley 1979), particularly those involving changes in the water table. Rose (1981) concluded that fire preven- tion probably had a greater negative effect on Synaptomys habitat than did draining and ditching because the exclusion of fire re- duced the number and size of natural openings. Succession in poco- sin communities is naturally suppressed; therefore, pocosins provide a diverse assemblage of early successional habitats. These habitats are one of the few natural, open canopy plant communities in the southeastern Coastal Plain. Lee (1986) considered that pocosins might have provided the only available local habitat for many early successional birds before colonial development. Pocosins ap- pear to play a similar role for S. cooperi in eastern North Carolina.
Because S. cooperi has now been captured both to the north and south of the Albemarle-Pamlico peninsula, one would assume that Synaptomys can be found in appropriate habitat on the penin- sula as well. Dare County has large expanses of pocosin and other wetlands, and it is separated from the Dismal Swamp area only by Albemarle Sound. No Synaptomys were taken in the 1980s on the Dare County mainland even though it was intensively trapped by both Clark et al. (1985) and by U.S. Fish and Wildlife Service personnel at the Alligator River National Wildlife Refuge (Mike
164 Mary K. Clark, Michael S. Mitchell, and Kent S. Karriker
Phillips, Refuge Manager, personal communication). Trapping fre- quency has been high and efforts have covered all wetland and upland habitats, so it is unlikely that S. cooperi occurs on the Albemarle-Pamlico peninsula.
Doutt et al. (1973) suggested that the major feature common to all Synaptomys habitats was that they were marginal for Microtus, and Linzey (1983) documented competitive exclusion of Synaptomys by Microtus in Virginia. Results from the National Forest investiga- tion and Clark et al. (1985) seem to lend further support to this relationship. No Microtus pinetorum were caught in the National Forest stands in which Synaptomys were captured, but 13 M. pinetorum were caught in one of the other short pocosin stands. Additionally, M. pennsylvanicus was abundant in wet, early succes- sional communities on the Dare County mainland (Clark et al. 1985).
The geographic distribution and genetic structure of modern populations are determined by historical patterns of dispersal as well as current ecological associations. The presence of S. cooperi south of the Dismal Swamp is not unexpected when one considers that the late Pleistocene range of S. cooperi extended much farther south- ward than the present range. Pleistocene fossil records are known from as far south as Citrus County, Florida (Linzey 1983). In Wetzel’s (1955) examination of the subspeciation and dispersal of the south- ern bog lemming, he determined that S. c. helaletes does not differ so greatly from the nearest form ( S . c. stonei) as did the other subspecies he studied. The close relationship was attributed to a relatively recent loss of interconnecting range.
Pocosin habitats might have provided refugia for species at the extreme limits of their distributions since the Pleistocene. Ther- mal properties of evergreen vegetation and saturated soils character- istic of pocosins likely provide a buffer from temperature extremes. Clark et al. (1985) reviewed the role of late Pleistocene climates as they relate to some small mammal distributions in the south- eastern United States and noted that in pocosin areas both northern and southern faunal elements co-exist in local refugia supported by subclimax communities.
Zoogeographically, a number of Atlantic Coastal Plain mammals presently reach either northern, southern, or eastern limits of distribution in pocosin-rich areas. Other taxa formerly believed to be confined largely to the Dismal Swamp, such as Blarina brevicauda telmalestes and Microtus pennslyvanicus nigrans , have been documented south of the Dismal Swamp area (Lee et al. 1982, Clark et al. 1985). The star-nosed mole ( Condylura cristata parva) also has a broader distribution on the southeastern Coastal Plain
Distribution of Synaptomys cooperi
165
than previously believed (Paradiso 1959, Lee 1987), and records reported here demonstrate a similar distributional pattern for Synaptomys cooperi.
Although we were unable to make a subspecific determination from the National Forest sample of S. cooperi , further taxonomic investigation is warranted. Eight of the 13 cranial measurements used by Wetzel to distinguish the S. cooperi subspecies did not show significant differences between stonei and helaletes. The un- clear subspecific identity of the specimens reported here could be a result of a wider and more southern distribution of S. c. stonei in the past. Individuals captured in southeastern North Carolina might be a relict population of that race, or represent an intergrade be- tween S. c. stonei and helaletes.
CONCLUSIONS
In general, the new records of S. cooperi, along with the recent captures of other small mammals in eastern North Carolina that were once thought to have narrower distributions, emphasize the need for more small mammal investigations in wetlands and associated habitats. Considering the wide variety of early succes- sional habitats that S. cooperi has been captured in, and the abun- dance of those habitats in eastern North Carolina, it seems reasonable to expect that S. cooperi is widespread there. Based on the Na- tional Forest trapping results and other studies, it appears that populations in this region are disjunct.
More specimens of S. cooperi are needed to better understand the taxonomy of these disjunct populations. Future surveys for S. cooperi should include trap methods other than snap-trapping and should encompass a variety of both natural and managed early suc- cessional communities.
ACKNOWLEDGMENTS — Field studies were conducted in part to fulfill the requirements for graduate degrees pursued by M. S. Mitchell and K. S. Karriker at North Carolina State University un- der the guidance of committee members R. A. Lancia, E. J. Jones, and K. H. Pollock. Funding, by Weyerhaeuser Company and the National Council of the Paper Industry for Air and Stream Im- provement (NCASI), was administered by M. A. Melchoirs and T. B. Wigley. Croatan National Forest employees, in particular Warren Starnes, helped with stand selection and provided numerous other services. We thank D. Drake, C. Jordan, M. Lusk, L. Sadler, and
R. Stanley for assistance with mammal trapping. We also thank D.
S. Lee, R. K. Rose, and an anonymous reviewer for their many helpful comments.
166 Mary K. Clark, Michael S. Mitchell, and Kent S. Karriker
LITERATURE CITED
Ash, A. N., C. B. McDonald, Emilie S. Kane, and C. A. Pories. 1983. Natural and modified pocosins: literature synthesis and management options. United States Fish and Wildlife Service, Division of Bio- logical Services, Washington, D.C. FWS/OBS-83/04.
Breidling, F. E., F. P. Day, Jr., and R. K. Rose. 1983. An evaluation of small rodents in four Dismal Swamp plant communities. Virginia Journal of Science. 34:14-28.
Brimley, C. S. 1905. A descriptive catalog of the mammals of North Carolina, exclusive of the Cetacea. Journal of the Elisha Mitchell Scientific Society 21:1-32.
Clark, M. K., D. S. Lee, and J. B. Funderburg, Jr. 1985. The mammal fauna of Carolina bays, pocosins, and associated communities in North Carolina: An overview. Brimleyana 11:1-38.
Doutt, J. K., C. A. Heppenstall, and J. E. Guilday. 1973. Mammals of Pennsylvania. Third Edition. Pennsylvania Game Commission, Harrisburg.
Handley, C. O., Jr. 1979. Mammals of the Dismal Swamp: An historical account. Pages 297-357 in The Great Dismal Swamp (P. W. Kirk, editor). University Press Virginia, Charlottesville.
Handley, C. O., Jr. 1991. Mammals. Pages 551-552 in Virginia’s en- dangered species: Proceedings of a symposium (K. Terwilliger, editor). McDonald and Woodward Publishing Company, Blacksburg,
Virginia.
Karriker, K. S. 1993. Effects of intensive silviculture on breeding and wintering birds in North Carolina pocosins. MS Thesis. North Caro- lina State University, Raleigh.
Lee, D. S. 1986. Pocosin breeding bird fauna. American Birds. 40:1263- 1273.
Lee, D. S. 1987. Star-nosed mole on the Delmarva Peninsula: Zoogeo- graphic and systematic problems of a boreal species in the South.
The Maryland Naturalist. 31:44-57.
Lee, D. S., J. B. Funderburg, Jr., and M. K. Clark. 1982. A distribu- tional survey of North Carolina mammals. Occasional Papers of
the North Carolina Biological Survey. North Carolina State Museum, Raleigh.
Linzey, A. V. 1983. Synaptomys cooperi. Mammalian species. Number 210. American Society of Mammalogists.
Mitchell, M. S. 1992. The effects of intensive forest management on
the mammal communities of selected stands of North Carolina poco- sin habitats. MS Thesis. North Carolina State University, Raleigh.
Paradiso, J. 1959. A new star-nosed mole ( Condylura ) from the south- eastern United States. Proceedings of the Biological Society of Washington 72:103-108.
Rose, R. K. 1981. Synaptomys not extinct in the Dismal Swamp. Jour- nal of Mammalogy 62:844-845.
Distribution of Synaptomys cooperi
167
Rose, R. K., R. K. Everton, J. F. Stankavich, and J. W. Walke. 1990. Small mammals in the Great Dismal Swamp of Virginia and North Carolina. Brimleyana. 16:87-101.
Webster, W. D., A. P. Smith, and K. W. Markham. 1992. A noteworthy distributional record for the Dismal Swamp bog lemming ( Synaptomys cooperi helaletes) in North Carolina. The Journal of the Elisha Mitchell Scientific Society 108:89-90.
Wetzel, R. M. 1955. Speciation and dispersal of the southern bog lem- ming, Synaptomys cooperi (Baird). Journal of Mammalogy 36:1-20.
Accepted 29 September 1992
,
Responses of Deer Mice, Peromyscus maniculatus (Mammalia: Rodentia), to Wild Hog Rooting in the Great Smoky Mountains National Park
Michael R. Lusk1 Department of Forestry North Carolina State University Raleigh, North Carolina 27695-8002
Michael J. Lacki Department of Forestry University of Kentucky 205 Thomas Poe Cooper Building Lexington, Kentucky 40546
AND
Richard A. Lancia Department of Forestry North Carolina State University Raleigh, North Carolina 27695-8002
ABSTRACT — A mark-recapture study was conducted to assess the impacts of wild hog ( Sus scrofa ) rooting on small mammal popula- tions in the upper elevation beech (Fagus grandifolia ) forests of the Great Smoky Mountains National Park. Small mammals were captured using live traps and pitfalls. Microhabitat variables were measured in the vicinity of each live trap site and analyzed using discriminant function analysis. Populations of cloudland deer mice {Peromyscus maniculatus nubiterrae) showed no significant differ- ences between rooted and unrooted sites and are apparently unaf- fected by rooting. Although the presence of other small mammals was noted on both rooted and unrooted sites, deer mice were the only mammals caught with sufficient frequency to allow statistical analysis. Discriminant analysis of microhabitat variables indicates that deer mice orient toward areas dominated by deciduous trees with heavy midstory cover and light ground cover. We hypothesize that habitat selection by deer mice in this ecosystem is dominated pri- marily by predator avoidance.
A population of exotic European wild hogs entered the bound- aries of Great Smoky Mountains National Park sometime during the
1 Present address: Commonwealth of the Northern Mariana Islands, Division of Natural Resources, Rota, MP 96951.
Brimleyana 19:169-184, December 1993
169
170 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
1940s or 1950s (National Park Service Uplands Field Research Laboratory, 1985, European wild hogs in Great Smoky Mountains National Park). Since that time their population has spread through- out the Park, damaging its rich flora and fauna (Bratton 1975, Singer 1981). The upper elevation beech forests have received especially heavy impact because of their small total acreage, rich herbaceous layer, and preferential rooting by hogs in summer (Bratton 1974, Singer et al. 1981). Research has been conducted on the effects of rooting on the flora of these areas, but very little work has ad- dressed the effects of rooting on the animal communities (Bratton 1974, Howe et al. 1981, Lacki and Lancia 1983, Singer et al. 1984).
The objective of our study was to evaluate the responses of deer mice and other small mammal populations to wild hog rooting in the beech forest in the following ways: (1) compare populations of deer mice and other small mammals on rooted and unrooted sites, (2) identify important microhabitat variables for trap success and failure, and (3) determine if the presence or absence of impor- tant microhabitat variables affects population levels at each site.
METHODS
Site Selection
Russell (1953) and Whittaker (1956) defined the Gray Beech Forest or “beech gaps” in the Great Smoky Mountains National Park. These gaps are beech ( Fagus grandifolia) forests that occur between 1,430 and 1,800 m in elevation (Bratton 1975) and are usually found on south-facing slopes on the ridge that bisects the Park in a northeast-southwest direction (Russell 1953). These gaps occur as small islands of deciduous trees in spruce-fir ( Picea rubens -Abies fraseri ) forests.
We grouped our beech gap study sites into rooted or unrooted categories based on history and intensity of hog rooting. Selection of unrooted (or control) sites and rooted sites was made difficult by the high variability of hog densities, the widespread and uni- form distribution of the hogs within the Park, and the ephemeral nature of some small mammal populations. Because it is impossible to say that any beech gaps exist that have never been rooted, we use the term “unrooted” to refer to sites that appeared undisturbed at the time of our study. We selected three rooted and three unrooted trap sites each year. Sites were comparable in elevation, slope, and aspect.
Mammals
Sampling — We livetrapped small mammals for five trap-nights on each site with Sherman live traps arranged in a 6 x 6 grid with
Wild Hog Rooting
171
10-m spacing. Trapping was conducted from 3 July through 11 Au- gust in 1989 and 28 June through 4 August in 1990. We baited traps with sunflower seeds packaged in a bag of cheesecloth and suspended in the back of the cage. Baiting traps with a mixture of rolled oats and peanut butter in the beginning of 1989 attracted foraging bears ( Ursus americanus ) to the trap sites. These bears destroyed a significant number of traps at each site, effectively shut- ting down the trap grid. Each captured small mammal was identi- fied to species, sexed, aged (juvenile or adult), weighed, toe clipped for future identification, and released.
In 1990, we added pit-fall traps because of the lack of shrew captures during the 1989 field season. Pits were constructed by burying a 1-gallon plastic planter along a fallen log, lining the planter with plastic, and filling it about one-third full with water. Ten pit-fall traps were interspersed among each live trap site, with one or two pit-fall traps per live trap line. All animals collected from pit-falls were identified according to species, weighed, and when possible, aged and sexed.
Data Analysis — We used Program CAPTURE (Otis et. al. 1978, White et. al. 1982) to analyze data from the Sherman live traps for the capture of deer mice. CAPTURE selected the appropriate popu- lation model for the data and calculated a population estimate and capture probabilities for each site. Because of insufficient capture rates, no data on small mammal species other than deer mice from the live traps and no data from the pit-fall traps were analyzed with CAPTURE. We combined the results of the 1989 and 1990 CAPTURE analyses and tested them with a two-way ANOVA (al- pha level = 0.05) to determine if (1) pooling the data would reveal significant differences between rooted and unrooted sites, (2) there were differences in overall populations between the two years, and (3) there were any signifiant interaction effects between year and rooting class.
Vegetation
Sampling — We selected 20 variable classes for measurement at each trap. Table 1 contains a list of the variable classes measured and the method by which measurements were taken. Several of the classes (e.g., percent species cover) involved measurements for each plant species represented. Therefore, the number of variables consid- ered is greater than the number of variable classes. The point-quar- ter method for sampling trees followed that suggested by Phillips (1959). We defined overstory as woody vegetation >7.5-cm dbh and
172 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
Table 1. Microhabitat variable classes selected for measurement.
|
Stratum |
Variable Class |
Method |
|
Overstory |
canopy closure |
densiometer |
|
nearest tree size |
point-quarter |
|
|
nearest tree distance |
point-quarter |
|
|
Understory |
nearest tree size |
point-quarter |
|
nearest tree distance |
point-quarter |
|
|
Over/understory |
richness |
species total |
|
% evergreenness |
point-quarter |
|
|
Shrub |
% total cover |
line intercept |
|
% species cover |
line intercept |
|
|
richness |
species total |
|
|
Herb |
% total cover |
line intercept |
|
% species cover |
line intercept |
|
|
richness |
species total |
|
|
Forest floor |
log diameter |
dbh tape |
|
log distance |
tape measure |
|
|
% bare soil |
line intercept |
|
|
% exposed rock |
line intercept |
|
|
% leaf litter |
line intercept |
|
|
depth leaf litter |
ruler |
|
|
Soil |
resistance |
penetrometer |
Wild Hog Rooting
173
the understory as woody vegetation >2 m in height and <7.5-cm dbh. Snags and odd limbs (living or dead) touching the ground were included in these measurements because deer mice are known to preferentially use snags for refuges (Wolff and Hurlbutt 1982), and only small woody trunks are required for escape routes. The shrub layer was defined as all vegetation between 0.4 and 2.0 m in height and the herb layer as all vascular vegetation in the 0.0-0. 4- m range. Our use of the line intercept method followed Hays et al. (1981) and consisted of laying out two 2.5-m transects in random directions from the center of each trap.
During the 1990 field season several variables were not measured: measurements involving the shrub layer, percentages of individual herb species cover (except for greater star chickweed, Stellaria pubera, and spring beauty, Claytonia virginica), herb richness, percent bare soil, percent leaf litter cover, and soil resis- tance were omitted because analysis of the 1989 data indicated these variables were not significant. We chose not to use the dbh of the closest overstory and understory tree in 1989, but included it in the 1990 analysis. Barry et al. (1984) found that deer mice oriented towards larger trees.
Data Analysis — We performed a series of discriminant function analyses on microhabitat data to determine the most important vari- ables. To “identify” truly important microhabitat variables, we be- lieved it was important to test the ability of variables to classify the success or failure of a trap to capture a small mammal and to produce a directional relationship consistent with known animal ecology (Tacha et al. 1982).
To begin the discriminant analysis, we pooled the data from the measured variables for all six sites each year. Variables were grouped as belonging to successful or unsuccessful live traps. We defined a successful trap as any live trap with one or more cap- tures and an unsuccessful trap as having no verified captures. All variables represented as percentages were arcsine transformed before analysis to approximate normal distributions. We performed a corre- lation matrix on all combined variables using PROC REG with the collinearity diagnostics option (SAS Institute 1985) to eliminate intercorrelated variables. Interrelatedness can lead to switching of variables in a stepwise discriminant function analysis and to diffi- culty in interpreting the importance of predictor variables (Green 1979). Multicollinearity among regressors also results in unstable estimates and high standard errors (SAS Institute 1985). All vari- ables with variance inflation factors (VIFs) of greater than 2.0 were removed from further analysis.
Table 2. CAPTURE data for 1989-90 livetrapping of P. maniculatus, Great Smoky Mountains National Park.
174 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
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Wild Hog Rooting
175
We used PROC STEPDISC (SAS Institute 1985) to select remaining variables for construction of a discrimination model. The stepwise selection process was used with a significance level of variable entry into the model set at 0.15. We selected a moder- ate significance level in order to “choose the model that provides the best discrimination using the sample estimates” (SAS Institute 1985:750). We then analyzed variables selected for inclusion in the discrimination model using PROC DISCRIM (SAS Institute 1985) to test the assumption of homogeneity of the within-group covari- ance matrices and to generate a classification outcome. Signifi- cance level for the test of homogeneity was set at 0.05. We set prior probabilities proportional to sample sizes.
We used the Kappa statistic to measure the improvement of the classification rates over chance assignments. This statistic ranges from zero, which indicates no improvement in assignments, to one, which indicates perfect assignment (Fleiss 1973, Rexstad et al. 1988) Alpha level for this test was set at 0.05.
We used PROC CANDISC (SAS Institute 1985) on the vari- ables selected by PROC STEPDISC to test separation of traps into successful and unsuccessful classifications and to obtain standard- ized canonical coefficients that suggest directional relationships be- tween the selected variables and the two classifications. In an attempt to identify important microhabitat variables properly, we validated models by analyzing data from both years individually, and then compared the results. For each year’s data, the discriminant func- tion analyses identified significant variables that were associated with successful and unsuccessful traps.
RESULTS
Mammals
Populations of deer mice were low during both 1989 and 1990 (Table 2). Because population sizes were so small during both years, the models selected by CAPTURE did not perform well (Otis et al. 1978), and the estimates are likely biased with low precision (White et al. 1982). The two-way ANOVA performed on deer mouse population means pooled from both years revealed no significant differenes: (1) between population sizes on rooted and unrooted sites (F = 0.18, P = 0.68), between the population sizes of 1989 and 1990 ( F = 2.99, P = 0.12), or due to interactions between site class and year ( F = 0.12, P = 0.74).
Table 3 summarizes all non -Peromyscus captures. Low capture frequencies prevented statistical analysis of any of these data.
176 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
|
Table 3. 1989-90 non -Peromyscus captures on rooted and unrooted sites, Great Smoky Mountains National Park. Totals listed by trap type. |
||
|
Site |
Species |
Number |
|
Rooted: |
||
|
Live trap |
Napaeozapus insignis |
5 |
|
Synaptomys cooperi |
1 |
|
|
Blarina brevicauda |
2 |
|
|
Mustela frenata |
1 |
|
|
Pitfall |
Sorex cinereus |
5 |
|
Unrooted: |
||
|
Live trap |
Napaeozapus insignis |
2 |
|
Blarina brevicauda |
1 |
|
|
Mustela frenata |
2 or 31 |
|
|
Clethrionomys gapperi |
1 |
|
|
Pitfall |
Napaeozapus insignis |
1 |
|
Sorex cinereus |
8 |
|
|
Sorex fumeus |
1 |
|
|
Synaptomys cooperi |
1 |
|
|
1 No attempt was made to mark live weasels; therefore, two captures at one site |
||
|
could represent one or |
two individuals. |
|
Table 4. Discriminant analysis between successful and unsuccessful traps in the capture of P. maniculatus, Great Smoky Mountains National Park, 1989-90. Variables are listed in order of entrance into the model. |
|||
|
Wilks’ |
Probability |
Standardized |
|
|
Variable |
lambda |
< lambda |
coefficient |
|
1989 |
|||
|
% herb cover |
0.93 |
0.0001 |
-0.57 |
|
% evergreenness |
0.87 |
0.0001 |
-0.48 |
|
% canopy cover |
0.83 |
0.0001 |
0.45 |
|
% star chickweed |
0.81 |
0.0001 |
0.34 |
|
% spring beauty |
0.79 |
0.0001 |
-0.34 |
|
% exposed rock |
0.78 |
0.0001 |
0.24 |
|
1990 |
|||
|
understory distance |
0.98 |
0.0276 |
-0.63 |
|
% canopy cover |
0.96 |
0.0090 |
-0.73 |
|
% herb cover |
0.94 |
0.0058 |
-0.50 |
|
% exposed rock |
0.91 |
0.0020 |
0.43 |
Wild Hog Rooting
177
Vegetation
Analyzing the 1989 data with PROC REG and then discarding all variables with VIFs above 2.0 eliminated all but 39 of the original 97 variables. PROC STEPDISC retained six variables for inclusion in the final model. These six variables, in order of entry into the model, included percent total herb cover, percent ever- greenness, percent canopy cover, percent greater star chickweek, percent spring beauty, and percent exposed rock (Table 4).
The combined 1989 data set failed to meet the assumption of homogeneity between within-group covariance matrices (P = 0.0001). PROC DISCRIM was programmed to use a pooled covariance ma- trix. The equality between within-group covariance matrices assump- tion is similar to the equal variance assumption of univariate analysis (Green 1979). For the 1989 data set, there was a significant differ- ence (P = 0.0001 for each) between the equality of within-group covariance matrices. Despite the failure of the data to meet the required assumption, we programmed PROC DISCRIM to use a pooled covariance matrix.
Our line of reasoning for this approach was the following. First, the test used by PROC DISCRIM is extremely sensitive to nonnormality and rejects too often (Dr. Thomas Gerig, Department of Statistics, North Carolina State University, personal communica- tion). Second, many investigators believe that discriminant function analysis is robust and that the assumptions need not be strictly met (Johnson 1981, Taylor 1990). Third, we used linear discriminant analysis primarily as an exploratory tool and not a confirmatory tool (Williams 1983, James and McCulloch 1990). Fourth, our study had a relatively large number of observations and a large observa- tion to variable ratio. Data from both years consisted of 216 obser- vations (one set of observations per trap). During 1989, the ratio of observations to variables entered into the stepwise discrimination analysis was 30:1. In 1990, the ratio was 15:1. Rexstad et al. (1988) found that the median sample size of 28 multivariate studies pub- lished between 1985 and 1987 in The Journal of Wildlife Manage- ment was 99 observations and 12 variables, or an 8:1 ratio. Taylor (1990:188) stated that “relaxation of assumption is most justified with large data sets.” However, some authors do caution that the assumption is important and should not be dismissed lightly (Wil- liams 1983, Rexstad et al. 1990).
Classification success using this method was fair. Of the 102 unsuccessful traps, 66.7% were correctly classified as being unsuc- cessful. Of the 114 successful traps, 79.0% were correctly classi- fied. The Kappa statistic indicated that these classification rates were
178 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
significantly different than zero (Kappa = 0.46, P <0.0001). Stan- dardized coefficients (Table 4) indicate trap success was directly related to percent canopy cover, percent greater star chickweed, and percent exposed rock, but inversely related to percent total herb cover, percent evergreenness, and percent spring beauty. The group centroid on the discriminant axis for successful traps (0.50) was significantly different (F = 9.74, P = 0.0001) from the group controid of unsuccessful traps (-0.56). This suggests that the discriminant function could separate successful and unsuccessful traps based on the habitat variables under consideration.
We ran a series of one-way ANOVAs on the six variables that were included in the final model to determine if these vari- ables could separate rooted and unrooted sites (Table 5). None of the six variables was significantly different between rooted and un- rooted sites.
In 1990, the multicollinearity test revealed that no variables had to be removed from the analysis because of interrelatedness. PROC STEPDISC chose five variables for the model (in order of entrance): distance to closest understory tree, percent canopy cover, percent total herb cover, percent spring beauty, and percent exposed rock (Table 4). As compared to the 1989 model, one new variable (understory tree distance) was added and two variables (percent ever- greenness and percent greater star chickweed) were deleted. We re- moved percent spring beauty from further analysis because of a scarcity of observations that resulted in a covariance matrix that
Table 5. ANOVAs to separate rooted and unrooted sites, Great Smoky Mountains National Park, performed on variables chosen by discriminant analysis (Table 4).
|
Variable |
Rooted mean |
Unrooted mean |
F |
P |
|
1989 |
||||
|
% herb cover |
1.18 |
1.13 |
0.16 |
0.71 |
|
% evergreenness |
0.04 |
0.21 |
4.04 |
0.11 |
|
% canopy cover |
0.99 |
1.09 |
3.84 |
0.12 |
|
% star chickweed |
0.17 |
0.13 |
0.34 |
0.59 |
|
% spring beauty |
0.001 |
0.02 |
0.84 |
0.41 |
|
% exposed rock |
0.04 |
0.003 |
4.19 |
0.11 |
|
1990 |
||||
|
understory distance |
1.38 |
1.45 |
0.08 |
0.79 |
|
% canopy cover |
1.01 |
1.07 |
0.73 |
0.44 |
|
% herb cover |
0.88 |
0.94 |
0.32 |
0.60 |
|
% exposed rock |
0.01 |
0.008 |
0.12 |
0.74 |
Wild Hog Rooting
179
was not a full rank and therefore could not be properly analyzed by PROC DISCRIM.
PROC DISCRIM revealed that the 1990 data also failed to meet the assumption of equality between within-group covariance matrices (P = 0.0008). As was done for 1989 data, we ran PROC DISCRIM with a pooled covariance matrix. Results of this classifi- cation were almost as good as in 1989. Of the 139 unsuccessful traps, 61.0% were correctly classified. The Kappa statistic indicated that classifications were also significantly different from zero (Kappa = 0.26, P < 0.0001). Standardized coefficients (Table 4) indicated that trap success was directly related to percent exposed rock and inversely related to percent canopy cover, percent total herb cover, and distance to closest understory tree. These relationships are simi- lar to the previous year’s except that in 1989 percent canopy cover was directly related to trap success. The group centroid on the discriminant axis for successful traps (0.36) was significantly differ- ent (F = 3.93, P - 0.004) from the centroid for unsuccessful traps (-0.20).
None of the 1990 variables was significantly different between rooted and unrooted sites (one-way ANOVAs, Table 5).
DISCUSSION
Mammals: Population Trends
Our findings are in agreement with Singer et al. (1984) that there was no significant difference in populations of deer mice be- tween rooted and unrooted sites. We believe that the semi-arboreal habits (Wolff and Hurlbutt 1982, Singer et al. 1984), choice of food items (Howe et al. 1981, Linzey and Linzey 1973), and gen- eralist nature (Baker 1968) of deer mice allow them to quickly adapt to or not be affected by hog rooting disturbances. Although we did not capture enough shrews or voles to allow a quantitative comparison, their presence on rooted sites indicates that populations of these mammals are not permanently extirpated from rooted areas and that they may recolonize disturbed areas quickly.
Vegetation: Microhabitat Selection
One problem all habitat studies of this type face is the assumption that the reason a particular habitat is unused is that the habitat in that area is unsuitable for the animal (Johnson 1981, James and McCulloch 1990). However, habitat might not be used simply because of low population size. Our classification rates were probably lowered by this circumstance because mouse populations at some sites were extremely low.
180 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
Validation of the discriminant analysis models by replication of the study is highly recommended (Taylor 1990), but proper ap- proaches to validation are usually not performed in wildlife habitat studies (Rexstad et al. 1990). One advantage of our study is that we had two years of data, and thus we attempted to confirm the importance of variables selected by the discriminate function analy- sis. Of the three variables that appeared in both years and that produced standardized coefficients, percent herb cover was inversely related in both years, percent exposed rock was directly related in both years, and percent canopy cover was directly related in one year and inversely related the next.
The failure of the ANOVAs to detect any significant difference between microhabitat variables at rooted and unrooted sites confirms what is to be expected. Assuming deer mice are selecting certain microhabitat features as preferred habitat, and if there are no differences in mice populations between rooted and unrooted sites, then it seems reasonable that there would be no differences in the key microhabitats between rooted and unrooted sites.
It is difficult to compare our research with other discriminant analysis studies of small mammal habitat because the majority of other studies concentrated on separating the preferred habitat of two or more small mammal species within a homogeneous or heteroge- neous habitat (Dueser and Shugart 1978, Kitchings and Levy 1981, Vickery 1981, Buckner and Shure 1985). We feel that our study is unique in that it focuses on the use of discriminant analysis to predict trap success for one species within a generally homogeneous habitat type.
Two microhabitat variables appeared in both the 1989 and 1990 overall models and maintained the same directional relation- ship both years. Therefore, these variables seem to be particularly important to deer mice. Mice seem to be more likely to orient toward traps with greater exposed rock in the area and less herba- ceous cover. Open areas very close to the ground, as the result of exposed rock and thin ground cover, would provide deer mice with a wide view of the terrain. This open view might be advantageous to the mice for two reasons. First, perhaps foraging would be fa- cilitated in that seeds, fruits, and insects would be more visible. Second, the open ground could make it easier for mice to detect and avoid terrestrial predators such as the long-tailed weasel (Mustela frenata). Open ground cover would not necessarily expose foraging mice to avian predators if the midstory was thick enough to compensate.
Wild Hog Rooting
181
The understory distance variable is perhaps the easiest to confirm and interpret. Trap success decreased as distance to under- story trees increased, which might be a reflection of available refuges or a measure of midstory canopy. Vickery (1981) found that deer mice used areas with heavy midstory cover which may be related to predator avoidance. The heavy midstory would provide cover from aerial predators while at the same time providing close- ly accessible escape routes from terrestrial predators. Lockard and Owings (1974) hypothesized that bannertail kangaroo rats ( Dipodomys spectabilis) seasonally vary foraging patterns to avoid exposure on moonlit nights because of increased predation pressure. The prefer- ence of deer mice for a heavy midstory cover, coupled with the importance of a wide view at ground level, suggest a habitat pref- erence that allows protection from both terrestrial and aerial preda- tors while at the same time providing optimal foraging opportunities.
The inverse relation of trap success to percent evergreenness agrees with the findings of Kirkland and Griffin (1974) that deer mice avoid coniferous areas. Most of the individual trap sites with a high ratio of evergreenness were located near the edges of the trap grid where beech forest faded into spruce-fir forest. The ap- pearance of percent evergreenness as an important variable prob- ably represents marginal deer mouse habitat. Avoidance of these areas may be related to the preference of the more dominant Clethrionomys gapperi (Crowell and Pimm 1976) for coniferous areas in the Great Smoky Mountains National Park (Linzey and Linzey 1971). Competition may be a factor in microhabitat selec- tion only along the fringes of primary deer mouse habitat.
Other variables in the models are difficult to interpret. It is doubtful that the presence of spring beauty is of any biological importance. This vernal herb was very difficult to detect, and the few times it was detected it did not seem to be contributing any- thing to the habitat requirements of the mice. Greater star chickwood is a fairly ubiquitous herb in the beech forests, and there is no obvious explanation for its appearance as a variable. Perhaps, chick- weed had set seed by our trapping dates, thus mice were orienting toward this plant as a food source. We have no ready explanation as to why these variables appeared in the model.
Neither can we offer an explanation for canopy cover being directly correlated to trap success one year and inversely correlated the next. This might simply be a stochastic artifact, or it could be related to the nature of the statistics themselves. Dr. Gerig (per- sonal communication) stated that it was not surprising that a vari- able appearing in one year’s analysis might switch signs if it appeared
182 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
in another year’s analysis and if the suite of variables with which it was found had changed even slightly.
Future Research
Our data indicate that deer mice populations are not significantly affected by hog disturbance in the beech gaps. It is not clear, however, if this is because hog rooting does not disturb microhabitats important to the mice or because the mice are such generalists that they easily adapt to microhabitat changes. Future studies comparing food selection or home range use of mice in rooted and unrooted areas might help to clarify this question.
ACKNOWLEDGMENTS — Funding for this project and other support was provided by the Garden Club of North Carolina, the Great Smoky Mountains Conservation Association, the U.S. Fish and Wildlife Service Cooperative Fish and Wildlife Research Unit at North Carolina State University, and the Forestry Department, North Carolina State University. We especially want to thank Kim DeLozier of the Resource Management Section of the Great Smoky Moun- tains National Park for his technical and field support.
LITERATURE CITED
Baker, R. H. 1968. Habitats and distribution. Pages 98-126 in Biology of Peromyscus (Rodentia) (J. A. King, editor). American Society of Mammalogists. Stillwater, Oklahoma.
Barry, R. E., Jr., M. A. Botje, and L. B. Grantham. 1984. Vertical stratification of P. leucopus and P. maniculatus in southwestern Vir- ginia. Journal of Mammalogy 65:145-148.
Bratton, S. P. 1974. The effect of European wild boar ( Sus scrofa ) on the high elevation vernal flora in Great Smoky Mountains National Park. Bulletin of the Torry Botany Club 101:198-206.
Bratton, S. P. 1975. The effect of the European wild boar, Sus scrofa, on gray beech forest in the Great Smoky Mountains. Ecology 56:1356- 1366.
Buckner, C. A., and D. J. Shure. 1985. The response of Peromyscus to forest opening size in the southern Appalachian mountains. Journal of Mammalogy 66:299-307.
Crowell, K. L., and S. L. Pimm. 1976. Competition and niche shifts of mice introduced onto small islands. Oikos 27:251-258.
Dueser, R. D., and H. H. Shugart. 1978. Microhabitats in forest-floor small mammal fauna. Ecology 59:89-98.
Dueser, R. D., and H. H. Shugart. 1979. Niche pattern in a forest-floor small mammal fauna. Ecology 60:108-118.
Fleiss, J. L. 1973. Statistical methods for rates and proportions. John Wiley and Sons, New York, New York.
Green, R. H. 1979. Sampling design and statistical methods for environ- mental biologists. John Wiley and Sons, New York, New York.
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183
Hays, R. L., C. Summers, and W. Seitz. 1981. Estimating wildlife habitat variables. United States Department of Interior Fish and Wildlife Service. FWS/OBS-81/47.
Howe, T. D., F. J. Singer, and B. A. Ackerman. 1981. Forage relation- ships of European wild boar invading northern hardwood forest. The Journal of Wildlife Management 45:748-754.
James, F. C., and C. E. McCulloch. 1990. Multivariate analysis in ecology and systematics: panacea or Pandora box? Annual Review of Ecology and Systematics 21:129-166.
Johnson, D. H. 1981. The use and misuse of statistics in wildlife
habitat studies. Pages 11-19 in The use of multivariate statistics in studies of wildlife habitat (D. E. Capen, editor). United States De- partment of Agriculture Forest Service General Technical Report RM-87. Rocky Mountain Forest and Range Experiment Station,
Fort Collins, Colorado.
Kirkland, G. L., Jr., and R. J. Griffin. 1974. Microdistribution of small mammals at the coniferous-deciduous forest ecotone in northern New York. Journal of Mammalogy 55:417-427.
Kitchings, J. T., and D. J. Levy. 1981. Habitat patterns in a small
mammal community. Journal of Mammalogy 62:814-820.
Lacki, M. J., and R. A. Lancia. 1983. Changes in soil properties of
forests rooted by wild boar. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 37:228- 236.
Linzey, A. V., and D. W. Linzey. 1971. Animals of the Great Smoky Mountains National Park. The University of Tennessee Press, Knox- ville.
Linzey, D. W., and A. V. Linzey. 1973. Notes on food of small mam- mals from Great Smoky Mountains National Park, Tennessee-North Carolina. Journal of the Elisha Mitchell Scientific Society 89:6-14.
Lockard, R. B., and D. H. Owings. 1974. Seasonal variation in moon- light avoidance by bannertail kangaroo rats. Journal of Mammalogy 55:189-193.
National Park Service, Uplands Field Research Laboratory. 1985. Euro- pean wild hogs in Great Smoky Mountains National Park. Unpub- lished manuscript.
Otis, D. L., K. P. Burnham, C. G. White, and D. R. Anderson. 1978. Statistical inference from capture data on closed animal populations. Wildlife Monographs 62:1-135.
Phillips, E. A. 1959. Methods of vegetation study. Henry Holt and Company, Incorporated, New York, New York.
Rexstad, E. A., D. D. Miller, C. H. Flather, E. M. Anderson, J. W. Hupp, and D. R. Anderson. 1988. Questionable multivariate statis- tical inference in wildlife habitat and community studies. The Jour- nal of Wildlife Management 52:794-798.
184 Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia
Rexstad, E. A., D. D. Miller, C. H. Flather, E. M. Anderson, J. W. Hupp, and D. R. Anderson. 1990. Questionable multivariate statis- tical inference in wildlife habitat and community studies: A reply. The Journal of Wildlife Management 54:189-193.
Russell, N. H. 1953. The beech gaps of the Great Smoky Mountains. Ecology 34:366-374.
SAS Institute, Incorporated. 1985. SAS User’s Guide: Statistics, Version 5 Edition, Cary, North Carolina.
Singer, F. J. 1981. Wild pig populations in the National Parks. Environ- mental Management 5:263-270.
Singer, F. J., D. K. Otto, A. R. Tipton, and C. P. Hable. 1981. Home ranges, movements, and habitat use of European wild boar in Ten- nessee. The Journal of Wildlife Management 45:343-353.
Singer, F. J., W. T. Swank, and E. E. C. Clebsch. 1984. Effects of wild pig rooting in deciduous forest. The Journal of Wildlife Man- agement 48:464-473.
Tacha, T. C., W. D. Warde, and K. P. Burnham. 1982. Use and inter- pretation of statistics in wildlife journals. Wildlife Society Bulletin 10:355-362.
Taylor, J. 1990. Questionable multivariate statistical inference in wildlife habitat and community studies: A comment. The Journal of Wildlife Management 54:186-189.
Vickery, W. L. 1981. Habitat use by northeastern forest rodents. The American Midland Naturalist 106:111-118.
White, G. C., D. R. Anderson, K. P. Burnham, and D. L. Otis. 1982. Capture-recapture and removal methods for sampling closed popula- tions. Los Alamos National Laboratory, LA-8787-NERP.
Whittaker, R. H. 1956. Vegetation of the Great Smoky Mountains. Eco- logical Monographs 26:1-80.
Williams, B. K. 1983. Some observations on the use of discriminant analysis in ecology. Ecology 64:1283-1291.
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Accepted 15 December 1992
Notes on Post-breeding American Swallow-tailed Kites, Elanoides forficatus (Falconiformes: Accipitridae), in
North Central Florida
David S. Lee and Mary K. Clark North Carolina State Museum of Natural Sciences
P.O. Box 29555
Raleigh , North Carolina 27626-0555
ABSTRACT — In 1982 we made observations and collected a limited sample of American swallow-tailed kites (Elanoides forficatus ) summering in central Florida. Birds occurred in esti- mated densities of about three adult kites per kilometer of river. Post-breeding birds had heavy accumulations of subcutaneous fat. Adult males (n = 4, x = 550 g) weighed less than females (n =
5, x - 613 g), but more than immatures (n = 2, x = 481 g). Mean mercury loads were 0.09 ppm for muscle, 0.25 ppm for
liver, and 0.31 ppm for kidney tissues. All adults were actively
molting flight feathers, making it possible to visually census for adult/young-of-year ratios in mid-July. Most food items were small flightless insects (8-50 mm), apparently gleaned from
flower heads of cabbage palmettos. Major prey items consisted of various bugs: palmetto weevils (Rhynchophorus cruenlatus ), horntails (Eriotrenex formosanus ), queen fire ants ( Solenopsis invicta), and young flightless grasshoppers (Melanoplus sp.).
Several larger prey items — one green treefrog (Hyla cinerea ) four anoles (Anolis carolinensis ), and one bat (Pipistrellus subflavus ) — were also recovered.
Examination of recent records of birds north of their current breeding range indicates that the main period of northward dis- persal is mid-April through June, a period when nesting is in progress. Thus, these individuals probably represent young nonbreeding birds. After the mid-March to late June nesting sea- son, local birds gather in small flocks, complete their molt, and move to larger communal summer roosts. By mid-August to early September, the kites depart for their South American wintering grounds.
The reduced breeding range of the American swallow-tailed kite is difficult to explain in view of the information obtained in our study. Our work suggests that the species is a feeding gener- alist and that it does not feed high on the food chain.
While the breeding biology of American swallow-tailed kites ( Elanoides forficatus forficatus) has been examined in some detail (Synder 1974), other aspects of this bird’s life history are described, for the most part, as scattered notes. This information has been
Brimleyana 19:185-203, December 1993
185
186
David S. Lee and Mary K. Clark
summarized by Bent (1937) and Robertson (1988). Skutch (1965) reports on nesting activities and feeding habits of the South Ameri- can race E. f yetapa. Other than nest biology studies, little recent information on this kite has been published, and that which has is limited mostly to reported occurrences of individual birds at inter- esting sites (i.e., Gross 1958) or dates (Hicks 1955). Millsap (1987) provided important information on pre-migration staging in South Florida. In this article, we provide information on the post-breeding biology of this bird and comment on its relationship to the phenol- ogy and conservation status of the species.
STUDY AREA
Between 13 and 21 July 1982 we surveyed the St. Johns River by houseboat from the outlet of Lake Monroe near Sanford, Semi- nole County-, downstream (north) to Black Creek near Orange Park, Clay County, Florida. Side excursions into major tributaries were made into Lake Dexter, parts of Murphy Creek, Dunns Creek, Crescent Lake, and Black Creek. We surveyed 252 km of the St. Johns River, its tributaries, and connected lakes, with some areas being resurveyed on the return trip. Width of the river varied from 100 to 200 m upstream to 6.5 km near Orange Park. Some
of the lakes in the river were much wider (up to 10 km on Lake
George). This entire stretch of the river was largely undeveloped on one or both banks.
The St. Johns River is bordered largely by river swamp communities, particularly on the west bank, which is lower in el- evation than the east bank, and on most of the islands in the river.
Portions of the east bank that are higher and better drained have
more upland communities such as mesic hammocks. The swamp forests are frequently flooded by a combination of high water, wind, and tidal action. Trees dominating the river swamp communities are bald cypress ( Taxodium distichum), swamp tupelo (Nyssa sylvatica), water locust ( Gleditsia aquatica), water ash ( Fraxinus pauciflora), red maple (Acer rubrum), water hickory (Carya aquatica), and cab- bage palm (Sabal palmetto). A characteristic shrub layer of button- bush (Cephalanthus occidentalis), willow (Salix longipes), palmetto (Sabal minor), and wax myrtle (Myrica leriferus) densely lines the river, but is less conspicuous in the swamp interior.
Inland the swamp forests are typically bordered by a hydric hammock community — a transition between the swamp and upland communities. Where topographic change is gradual, transition zones between habitats are poorly defined. Trees common in this community include swampbay (Persta pubescens), water oak
Swallow-tailed Kites
187
( Quercus nigra), sweet gum ( Liquidambar styraciflua), loblolly-bay ( Gordonia lasianthus ), cabbage palm, Florida elm ( Ulmus floridana), and longleaf pine ( Pinus palustris). Shrubs and vines are prominent, and herbaceous vegetation is sparse. These two communities in many cases extend for several kilometers from the river’s edge.
METHODS
Individual kites and flocks of soaring kites were photographed. We studied these images for molt sequence. Small images were enlarged so that feather details of individual birds were obvious. Some individuals may have been photographed several times, but the photographs were taken at a number of locations over a 7-day period, so it is clear that most images represent different individu- als. The photographs are catalogued in the North Carolina State Museum of Natural Sciences’ collection of bird photographs.
We collected specimens with a 12-gauge shotgun while birds were in flight. Gizzards were preserved in 25% formaldehyde and were later examined for prey items. Three specimens were frozen and were later thawed for analysis of mercury loads in muscle, liver, and kidney tissues as per methods outlined by Stoneburner and Harrison (1981). The specimens are in the collection of the North Carolina State Museum of Natural Sciences (NCSM).
We examined 75 study skins in major North American collections for additional information on age and molt. Data from museum collections allowed us to illustrate the documented egg dates for the species in Florida. Information on vagrants found north of their current breeding area was compiled from various sources, but data are from dates after extirpation of the species from the northern portion of their range.
RESULTS AND DISCUSSION
Because swamp forests such as those bordering the St. Johns River appear to be the preferred habitats for these kites, and the habitat is duplicated throughout much of central Florida, it seems likely that we were observing local resident birds. Along the same lines, examination of stomach contents (see below) did not indicate that birds were converging from great distances to opportunis- tically feed on some locally abundant prey species.
Apparently this area has been used by nesting swallow-tailed kites for a long time; there are 12 egg collections from San Marito, Putnam County from between 1887 and 1895 in various North American museums.
Density and age ratios — On the 7 days of our field study, 200-250 swallow-tailed kites were seen along a 252-km stretch of
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the St. Johns River. Evening counts of flying, pre-roosting adult kites which could be distinguished from younger birds (see below) suggested an average of one adult per kilometer of river, but all sightings were in the upper reaches where the river channel was the narrowest and the swamp forest best developed. Density calcu- lations for just the upper reaches indicated there are about three adults per kilometer of river north of Lake George. This calculation does not account for secondary tributaries or additional kilometers of river frontage created by islands. There is a strong probability of additional flocks away from the main river or small flocks which were not detected.
Interestingly, very few young kites were observed. Only 2 of the 12 collected birds were immatures, and these were selectively collected because of plumage differences in our sampling bias that favored nonmolting birds. Of 142 individual bird images on photo- graphs (Fig. 1), 61 (43%) were too far away or angled in such a way that molt, if present, could not be seen. Of the remaining 81 images, 84% were adults in molt, and 16% were young-of-the-year.
Food and feeding habits — Although there is a considerable amount of literature on feeding of swallow-tailed kites, much re- peats Audubon’s (1840) observations or comments on large, spec- tacular prey items noted in field observations. Swallow-tailed kites did not come under the attention of the food habit studies of the early portion of this century (i.e., McAtee 1935). Skutch (1951, 1965) and other mention that swallow-tailed kites were seen pluck- ing young birds from nests, and Skutch (1965) and Haverschmidt (1962) provide firsthand accounts of the importance of insects in the diet of South American birds. Bent (1937:49-50) summarizes the observations of Audubon and others on food and feeding hab- its; he adds “its food includes small snakes, for which it is often called ‘snake hawk,’ lizards, frogs, and tree toads. It feeds very largely on grasshoppers, locusts, crickets cicadas, beetles of various kinds, bees, wasp grubs, dragonflies, cotton worms and various other insects.” Unfortunately, Bent did not indicate how this documenta- tion was obtained. Presumably it was from a combination of data compiled from specimen labels, correspondence, and literature; but the size of the series examined and the geographic area and season taken are unknown. In our examination of museum specimens we found only two references to prey items on specimen tags “ stomach contents - grasshoppers, crickets, etc.” (AMNH 352039, Georgia, Richmond Co., 21 July 1900, adult, female) and “stomach contents - grasshoppers and beetles” (AMNH 352038, Georgia, Richmond Co., 23 July 1890, adult, male). Robertson (1988:130) summarizes
Swallow-tailed Kites
189
Fig. 1. Photographs of American swallow-tailed kites (Elanoides forficatus ) taken July 1982 near Sanford, Seminole County, Florida. A. Enlarged por- tion of flock of kites; B. Enlargement showing no indication of molt of flight feathers (assumed first year bird); C. Enlargement showing gaps in flight feathers and asymmetrical tail feathers of adult.
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literature on the food habits of this species and notes that the bird was apparently “more insectivorous in its former central U.S. range taking more vertebrate prey in the south.” However, much of the information obtained in the Southeast, and all recent information, is from observations at nests where adults regularly bring vertebrate prey. If small insects are brought to nestlings as food items, they would be difficult to detect by observing the birds from blinds.
Only two of the birds that we collected were actively foraging. A single adult female, collected on 16 July, was seen in aerial pursuit of a small flying insect. This bird was one of a few seen over the river in the morning (1020 hours) and one of the few solitary birds we encountered. Its stomach contained only fragments of beetles (Coleoptera). The remaining birds were all col- lected late in the afternoon, before roosting, and had extremely full stomachs. Another foraging individual, an immature, was col-
Table 1. Food items recovered from gizzards of eight swallow-tailed kites, St. Johns River, Florida, 1982.
|
Number of Food Items Individuals |
% of Total |
Frequency of Occurrence |
Length of Food Items (mm) |
|
|
Cicada ( Tibiceu sp.) |
4 |
1 |
2 |
40-50 |
|
Cicada (Cicadidae) |
1 |
<1 |
1 |
20 |
|
Palmetto weevil |
||||
|
{Rhynchophorus cruenlatus ) |
44 |
13 |
8 |
20-31 |
|
Horntail (Eriotrenex formosanus) |
21 |
6 |
5 |
25-30 |
|
Wasp |
1 |
<1 |
1 |
30 |
|
Leaf-footed bug (Coreidae) |
66 |
19 |
6 |
25 + |
|
Grasshopper ( Melanoplus ) |
146 |
42 |
4 |
18-25 |
|
Wheelbug (. Arilus cristatus) |
5 |
1 |
3 |
25 + |
|
Assassian bug (Reduviidae) |
2 |
<1 |
1 |
25 |
|
Cot inis sp. |
5 |
1 |
4 |
25 |
|
Shield-backed bug (Scutellerinae) |
3 |
<1 |
1 |
20-25 |
|
Stink bug ( Podisus sp.) |
4 |
1 |
1 |
20 |
|
Pentatomidae |
11 |
3 |
1 |
20 |
|
Bee (Apoidae) |
1 |
<1 |
1 |
20 |
|
Cricket (tree or brush) (Gryllidae) |
1 |
<1 |
1 |
20 |
|
Imported fire ant ( Solenopsis invicta ) |
21 |
6 |
6 |
8-10 |
|
Cerambyeid beetle ( Clytus ruriocla ) |
4 |
1 |
3 |
|
|
Spider (Araneae) |
1 |
<1 |
1 |
20 |
|
Mite (Acarina) |
1 |
<1 |
1 |
0.1 |
|
Bat {Pipistrellus subflavus) |
1 |
<1 |
1 |
|
|
Anole (Anolus carolinsus ) |
1 |
<1 |
1 |
|
|
Tree frog (Hyla cineria ) |
1 |
<1 |
||
|
Total |
345 |
Swallow-tailed Kites
191
lected on 15 July. At about 1800 hours it descended from a flock of 15-20 birds soaring above the canopy of the swamp forest adja- cent to the river and made repeated passes at some tangled branches hanging over the river. The bird would glide into the area, reach out for prey items with its talons, miss, glide out over the river, circle up over the sites, and glide back to repeat the attempted catch. We did not see the prey item. This behavior was repeated at least four times before the bird was collected. The stomach con-
tained three adult Carolina anoles (Anolis carolinensis), various beetles, and true bugs.
We examined the stomachs (gizzards) of all 12 birds collected for food items. The two described above and one other individual were examined only superficially in the field. The stomachs of the remaining nine birds were preserved in formalin. Eight were exam- ined later (Table 1), and one was lost. Mass of individual stomach contents ranged from 11.7 to 47.8 g, and by volume each con-
tained 10-62 mL of food. Based on the degree of digestion, the bat was probably eaten the evening before the bird was collected. It would be interesting to know if the bat was captured while it was roosting or in flight because Pipistrells often emerge before dark.
Insects represented the bulk of the diet. Those consumed varied between 8 and 50 mm in length, whereas the majority were between 20 and 30 mm long (Fig. 2). Several of the prey organ- isms are flightless, many do not fly regularly, and some were in immature stages (grasshoppers [Acrididae], bugs) which were not yet capable of flight. We surmised that the majority of feeding
activity consists of capturing prey from the tree tops or shrubs, by
repeatedly swooping in vegetation until prey is flushed, or a com- bination of these two methods. The presence of palmetto weevils (. Rhynchophorus cruenlatus ) in all stomachs we examined in- dicates that a large percentage of feeding is done in the crowns of cabbage palms, a tree common in the higher portions of river swamp forest. The presence of wheel ( Arilus cristatus ) and assassin bugs (Reduviidae), a bee, and several other insects suggests that the kites may have been foraging around the flowering stalks of the palmettos. A local resident reported seeing on several occasions kites repeatedly flying around the tops of these palms. Percentages for major prey items we identified are shown in Figure 3.
Snyder (1974:91) reports two types of foraging behavior: talon- grabbing of resting prey from the outer leaves and branches of trees, and captures of flying prey “so effortless that it did not ever appear to disturb the soaring pattern of the bird.” Observations of
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David S. Lee and Mary K. Clark
PREY SIZE IN MM
Fig. 2. Prey size of food items recovered from the stomachs of eight American swallow-tailed kites ( Elanoides forficatus) based on 345 identi- fied items.
earlier workers and our observations suggest that all feeding is cer- tainly done on the wing.
Popular accounts of swallow-tailed kites feeding emphasize aquatic snakes and dragonflies as important food items. Synder’s (1974) observation of prey items brought to nests by parents is one of the few systematic treatments of feeding and food habits. He observed that very few insects were brought to the nest, and the most conspicuous food items were anoles, hylid frogs, and nestling birds. Nevertheless, Synder (1974:91) noted that he “often observed adults hawking insects and believed that such food may form a significant fraction of adult diet.” It is interesting that although we saw many genera of dragonflies in great abundance along the St. Johns River, none was recovered as prey items in the stomachs of birds we collected.
Most of the food items in Table 1 were certainly not captured when the prey items were flying. A possible exception is the im- ported fire ant ( Solenopsis invicta), as all individuals recovered were winged queen ants. Queen fire ants are capable of flight and could easily have been captured while flying, although exhausted ants
Swallow-tailed Kites
193
could have been gleaned while resting. Although these ants are only 8-mm long, they may represent a major food source. Morrill (1974) studied imported fire ants in several habitats in northern Florida and found that emergence of alates averaged 187,000/acre/year (75,700/ha/year). The heaviest flights occurred between April and August, indicating that they could be an important food source throughout most of the kites’ period of summer residence. Haver- schmidt (1962) noted that the gizzard of one kite ( E . /. yetapa ) collected in Surinam was full of flying ants.
The recovery of 21 individuals of Eriotremex formosanus, a horn tail, in five of the stomachs is of interest entomologically. This is an exotic species, and these individuals represented the first examples found east of Louisiana (J. Green, North Carolina Depart- ment of Agriculture, personal communication).
Mercury analysis of body tissues indicated that these birds are not receiving much mercury in their diets. This is probably indica- tive of the intermediate trophic level of this species. Mean mercury loads for three adults of the series collected were 0.09 ppm for muscle, 0.25 ppm for liver, and 0.31 ppm for kidney tissue. The higher concentrations for liver and kidney tissue in the kites sug- gest that the birds are successfully regulating (excreting) mercury. Comparisons of various seabird species we examined at the same time and with the same methods show high mercury loads (0.23-98 ppm for muscle, 0.61-60 ppm for liver, and 0.34-26 ppm for kid- ney) (P. Whaling and D. Lee, unpublished data).
OTHER
8.12
TRUE BUGS 5.2
HORNTAIL
6.1
FIRE ANT 6.1
GRASSHOPPER
42.4
PALMETTO WEEVIL 12.7
LEAF-FOOTED BUG 19.18
Fig. 3. Percentages of major prey types recovered from eight swallow- tailed kites, Elanoides forficatus collected in July 1982.
194
David S. Lee and Mary K. Clark
Body mass — Little information is available on masses of swallow-tailed kites, and examinations of museum labels indicates that few specimens in collections contain mass information. For example, Dunning (1984) found reference to only two unsexed swallow-tailed kites that weighed 445 and 504 g for his mono- graph on body masses of North American birds, and Robertson (1988) cited only five recorded masses for the North American race. Of the 75 birds we examined in museum collections, we found only two with information on mass (see below). Of the se- ries we collected, four adult males averaged 550.6 g (range = 520.0- 576.1), and five adult females averaged 613.0 g (range = 551.0-654.5).
The heavier masses of adult females compared to adult males corresponds with the sexual size dimorphism already documented for the Species (Friedmann 1950). Immature birds weighed less than adults (2 males x = 481 g, range = 459-503 g). John Cely (South Carolina Wildlife and Marine Resources Department, personal communication) provided information on masses of six birds he followed in telemetry studies in South Carolina. The one of known sex was a female that weighed 510 g. The other five adults (sex unknown) weighed 440-502 g (x = 471.4). Males from south Florida weighed 475 and 422.7 g (Robertson 1988).
Table 2. Molt of primary feathers on 11 swallow-tailed kites collected on the St. Johns River, Florida, July 1982. All from this study except the American Museum (AMNH) specimen, which is from the same general locality and was collected on 14 July 1877. Feather condition, O = old, S = in sheath, N = new.
|
Primary Numbers |
||||||||||
|
NCSM |
10 |
9 |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
|
male 8521 |
O |
O |
0 |
O |
o |
0 |
0 |
O |
S |
N |
|
male 8525 |
O |
O |
0 |
O |
o |
0 |
o |
O |
S |
S |
|
male 8527 |
O |
O |
0 |
0 |
0 |
0 |
s |
N |
N |
N |
|
male 8502 |
O |
O |
0 |
0 |
0 |
0 |
0 |
N |
N |
N |
|
female 8523 |
O |
O |
0 |
0 |
0 |
0 |
0 |
O |
O |
S |
|
female 8479 |
O |
O |
0 |
0 |
0 |
s |
N |
N |
N |
N |
|
female 8522 |
O |
0 |
0 |
0 |
0 |
0 |
0 |
O |
N |
N |
|
female 8504 |
O |
0 |
0 |
0 |
0 |
0 |
s |
N |
N |
N |
|
female 8503 |
O |
0 |
0 |
0 |
0 |
0 |
0 |
N |
N |
N |
|
female 8526 female (AMNH |
O |
0 |
0 |
0 |
0 |
0 |
0 |
N |
N |
N |
|
352031) |
O |
0 |
0 |
s |
s |
N |
N |
N |
N |
N |
Swallow-tailed Kites
195
Three specimens provide some insight into extreme and normal masses. One female found live with a broken wing on 14 May 1981 in Monroe County, Florida, died in captivity the same day and weighed only 331.5 g (MSB 9080). An adult female found dead in Bermuda on 17 March 1957 weighed 354 g (AMNH 788956). In our survey one adult female collected while it was feeding late in the afternoon weighed 485.5 g and had no accumulation of sub- cutaneous fat. With the exceptions of the one female mentioned above, all of the birds we collected in 1982 had heavy to very
heavy subcutaneous deposits of fat. The fat buildup is probably related to fall migration. Perhaps fall migratory fat reserves were
just starting to develop when we surveyed the population.
Molt — Based on his examination of five birds collected in August, Bent (1937) believed that swallow-tailed kites do not molt flight feathers until after the birds leave for their wintering areas. Robertson (1988) had no additional information but noted that individuals had been seen in south Florida and Costa Rica lack- ing remiges and rectrices as early as late May.
We found all adults along the St. Johns River to be in active flight feather molt in July. The birds all had new flight-feathers or feathers in sheath on the inner-most primaries, and the outer-most
six to ten were old. At the time we collected the birds, feathers
one to five were replaced or were being replaced (Table 2). Fe- males appear to be slightly more advanced than males in feather replacement. In addition to the series collected, flight feather re- placement is also apparent from photographs taken of birds in flight during the same period. Molt of tail feathers was also obvious on specimens obtained and from analysis of photographs. The new tail feathers were quite advanced in development, but replacement or feather growth was not symmetrical, and right and left forks of the tails were different lengths. Young-of-the-year birds exhibited no molt.
Only a few specimens of adult swallow-tailed kite skins that were examined from other places and dates showed any indi- cation of molt. Thus, the total replacement of flight feathers is likely completed very rapidly after the nesting and fledgling season. Probably the entire process is typically completed between late June and the end of July. However, some Florida birds might still be in wing molt in mid-August. One adult female specimen collected on 18 July 1899 (AMNH 352035, Marco Island, Florida) had com- pleted molt and had all new flight feathers. A 17 July 1988 adult female (AMNH 469954, Chatham Bend River, Florida) had com- pleted its primary molt and had replaced all but the outer two tail
196
David S. Lee and Mary K. Clark
Fig. 4. Plumage comparison of adult (NCSM 8479, female) and young- of-the-year (NCSM 9988, male) American swallow-tailed kites ( Elanoides forficatus ). Specimens from July 1982, St. Johns River, Florida; A. Top ventral aspect left adult, right young-of-year. Bottom dorsal aspect, adult on left. Streaking on head and neck of young-of-year is caused by tan feather shafts. The occasional dark feather shafts on adult are black. B. Dorsal feathers of adult (left) and young-of-year. Feathers of young are white edges, whereas new feathers of adult lack white edges.
Swallow-tailed Kites
197
^Kuhler,
198
David S. Lee and Mary K. Clark
feathers. An adult female from 21 July 1900 (AMNH 352039, Richmond County, Georgia) still had two old outermost tail feathers, and all others were new. The primaries were also new. An adult male col- lected on 23 July 1890 (AMNH 3520 38, Richmond County, Geor- gia) had primaries 1-4 new, the outer 7-10 were old, and 5 and 6 were in sheath. An adult male from 14 July 1877 (AMNH 352031, St. Johns River, Florida) still had its old tail feathers, but new ones were coming in, primaries 6 and 7 were growing, and 1-5 were new. Adult specimens from January ( n = 3), February ( n = 2), March (n = 8), April ( n = 9), May ( n = 9), and June (n = 3) showed no signs of molt. Those from August ( n - 6) and Novem- ber (n = 1, captive UF11256) had all new feathers (specimens from various museums and various localities, individuals from January and February were E. f forficatus from Central and South America). Based on the lack of molting birds (from specimens or photographs) from months other than July and August, we assumed that young- of-the-year molt their flight feathers the following year at the same time as adults. We found no other molt evidence except for the specimens and photographs reported here. Robertson’s (1988) com- ments on birds which were seen in late May with missing flight feathers would appear to be just that and probably do not represent a molt sequence.
Northward dispersal — Rapp (1944) examined 33 records of American swallow-tailed kites from the northeastern states (south through Pennsylvania) and concluded, based on four specimens, that (1) these birds did not represent the South American race, E. f. yetapa (this race is not an obligate long-range migrant), (2) there was no relationship between sun spots and northward movement of kites, and (3) there was no relationship between occurrence records and tropical storms.
After examining 143 records gleaned from the literature for states north of the species’ current breeding range, we found the main period of occurrence to be mid-April through June (78% of total records). The largest number of records is in May (42%), a time when nesting activity is in progress in all portions of the breeding range of the North American subspecies. Thus, the north- ern occurrence records are probably of young nonbreeding birds. Bent (1937) reports egg dates of March 10 to May 18 for 81 records from Texas to Florida. Examination of Florida egg set data from various museums shows eggs from 10 March to 19 May with a reproductive peak in mid-April ( n = 120 egg sets).
Robertson (1988) believes that this kite reproduces in its first year based on three “adult” spring birds which retained some juve-
Swallow-tailed Kites
199
nile plumage characters. Based on museum skins, we could not identify plumage differences between post-hatching year and older swallow-tailed kites in the spring after they return from wintering areas. Age of post-breeding-season birds and their distribution, how- ever, could be documented. Young-of-the-year individuals can be recognized by their generally duller plumage, by the finely streaked (tan colored feather shafts) neck and upper breast, and by the nar- row white edge on the wing, wing covert, and tail feathers (Fig. 4). This white edging likely wears away quickly. Young birds also lacked the bloom of the adults, but the bloom does not hold up well on museum specimens. Furthermore, because adults are in ac- tive molt in July, it is possible to distinguish young-of-the-year birds from older ones when the birds are in flight. Observers are encouraged to report plumage and molt (or lack of molt) for July- August sightings. This information would help considerably in as- sessing population size and age structure. Unfortunately, at this time, museum specimens and literature records offer no concrete informa- tion to clarify differential movements of various age classes.
Present and former distribution — In view of the generalized diet of swallow-tailed kites and the wide dispersal of non-nesting individuals, it is difficult to explain the marked contraction of the breeding range of the species. Formerly these kites nested through- out much of the Mississippi drainage north to Oklahoma, Kansas, Nebraska, northwestern Minnesota, and southern Wis- consin. Ridgway (1895) stated that swallow-tailed kites were once common in Illinois. Parmalle (1958) reported a complete femur of this species from a Middle Mississippian Midden (1200-1500 AD) in Madison County, Illinois, and Goslin (1955) had zooarchaelogical evidence for this species from rock shelters used by Indians in Ohio, suggesting that in recent times the interior breeding range may have been larger than what was documented by early natural- ists. Pearson et al. (1942) suggested that swallow-tailed kites nested on the Atlantic Coastal Plain north to North Carolina, and while North Carolina is generally regarded as the northernmost nesting area in the East (AOU 1982), there are no actual nesting records north of South Carolina. Presently the breeding range is restricted to the lower Gulf Coastal Plain and the Outer Atlantic Coastal Plain north to coastal South Carolina. While the decline and abun- dance of the snail kites ( Rostrhamus sociabilis) in North America is well documented and the reasons for its decline are understood (see Sykes 1984), the change in the breeding distribution of the swallow-tailed kite over the last century has never been adequately explained. This becomes even more perplexing when one considers
200
David S. Lee and Mary K. Clark
the currently expanding ranges of the two remaining North Ameri- can kites: black-shouldered kite ( Elanus leucurus) and Mississippi kite (Ictinia mississippinsii) (Palmer 1988). Futhermore, the latter species occupies habitats similar to those of the swallow-tailed kite in the Southeast.
Although general accounts cite habitat destruction, over- collecting of eggs, and shooting adult birds as primary reasons for the disappearance of the species from the northern portion of its range, this is not documented. The limited amount of existing mu- seum material does not support the contention that over-collecting occurred. Additionally, not only is the diet opportunistic, but also the nesting habitat discussed for former northern populations by various authors (see Bent 1937) does not seem restrictive. The general dis- appearance at the turn of the centry from northern nesting sites was well before the invention of persistent pesticides, and our pre- liminary evidence on natural mercury loads suggests that the spe- cies’ position in the food chain would not make it particularly vul- nerable to human-induced contaminants.
Historical records indicate that the upper Mississippi basin population was much larger, and probably more uniformly dis- tributed, than the scattered records indicate. For example, Simpson (1972) records that swallow-tailed kites were regular late summer visitors in the mountains of North Carolina during the 1800s and had almost disappeared by 1900. Simpson attributed this loss to the shrinkage in the breeding range and believed that the fall migratants were from the breeding population in the upper midwest that were moving east and south down through the Appalachians. Loomis (1890) noted a similar situation in the mountains of South Carolina. Nev- ertheless, this may not be the case, and in the north the species
may have been restricted to only a small number of relict breeding sites in the historical period.
Phenology — Millsap (1987) reported on massive pre-migration staging at a site near Lake Okeechobee, Florida, where he observed large numbers of kites in communal roosts from mid-July through
mid-August. Monitoring the following year provided additional data (Millsap and Runde 1988). The roost he described was used by at least 1,339 kites on 7 August 1987, and the kites used the roost
from 12 July to 1 September 1988. The numbers of kites in the
Okeechobee roost, those in other communal roosts reported on by Millsap and Rude (1988), and historical information on summer flocks (1924-82) of swallow-tailed kites in the same general area (Millsap 1987) suggest that the low population estimates of swallow-tailed kites from the late 1970s may have been underestimates. As of
Swallow-tailed Kites
201
1985, the species is a Category 2 candidate for federal listing as a threatened or endangered species (United States Fish and Wildlife Service 1985).
Whether our observations and collections represent another roosting area for pre-migration staging or simply a gathering of local post-nesting birds is unknown. No mention of molt is made in the summer roosting flocks reported to date (Millsap 1987, Millsap and Runde 1988). Because of this and the general lack of young birds in our study area in early July, we theorize that after the nesting season (mid-March through late June) local adult birds gather in small flocks, forage, build up pre-migratory subcutaneous fat re- serves, and complete their flight feather molt (July). They undergo short distance movements (late June and August with a peak in early July) to larger communal summer roosts that are adjacent to extensive foraging areas. The appearance of numbers of birds at communal roosts in early to late July may represent immature birds that do not undergo molt. The subsequent build up in early August would then result from adults coming to the roost after molt was completed. From mid-August to early September, the kites depart for wintering grounds in South America (Brown and Amadon 1968, Robertson 1988); the south Florida birds take a trans-Caribbean or trans-Gulf migration route (Millsap 1987).
CONCLUSION
The American swallow-tailed kite is currently regarded as a “Category 2” species under the Endangered Species Act, mean- ing that not enough is known about its status to list it as Threat- ened or Endangered. There is documentation showing an overall decline in the breeding range during the historical period, but in most regions this documentation is less than adequate. Further- more, the generalized diet and the fact that the kite feeds low on the food chain combined with the nonspecific habitat require- ments confound efforts to determine reasons for the decline. Its disappearance from northern nesting sites was long before per- sistent pesticides were introduced in the environment. Over-collect- ing of eggs and shooting of adult birds has often been cited as the primary reason for the disappearance of the species from portions of its breeding range, but there is no evidence that this is the case.
Our documentation of the molt period of adults will allow field workers who monitor summer populations to obtain much needed information on age ratios and post-breeding movements of different age classes. This information should prove useful in deter- mining the conservation status of this kite.
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David S. Lee and Mary K. Clark
ACKNOWLEDGMENTS— We thank James Green, North Carolina Department of Agriculture, for assistance with iden- tification of the entomological material recovered from the stom- achs. Lloyd Kiff, Western Foundation of Vertebrate Zoology, Will Post, Charleston Museum; Thomas Webber, Florida State Museum; J. V. Remson, Louisiana State University; George Barrowclough and Mary LeCroy, American Museum of Natural History; David Willard, Field Museum of Natural History; Timothy O. Matson, the Cleve- land Museum; Ned K. Johnson, Museum of Vertebrate Zoology, Berkeley; R. D. James, Royal Ontario Museum; Nathan Kraucunas, Milwaukee Public Museum; Scott Wood, Carnegie Museum of Natural History; and J. Philip Angle, United State National Museum provided access to material in their respective care. John Cely, South Carolina Wildlife and Marine Resources, provided masses of South Carolina birds, and Patrick Whaling conducted the mercury analysis laboratory work. Renaldo Kuhler, North Carolina Museum of Natu- ral Sciences, prepared Figure 4. Specimens were collected under permits provided by the U.S. Fish and Wildlife Service (PRT-2- 4007) and the Florida Game and Fresh Water Fish Commission. A grant from the Chapman Fund of the American Museum of Natural History allowed examination of the specimens there.
LITERATURE CITED
Audubon, J. J. 1840. The birds of America. Volume 1. New York and Philadelphia.
Bent, A. C. 1937. Life histories of North American birds of prey. Part 1, Bulletin Number 167, United States National Museum.
Brown, L., and D. Amadon. 1968. Eagles, hawks and falcons of the world. Volume 1. Country Life Books, London.
Dunning, J. B., Jr. 1984. Body weights of 686 species of North Ameri- can birds. Western Birds Banding association. Monograph 1:1-38.
Friedmann, J. 1950. The birds of North and Middle America, part XI. Bulletin Number 50. United States National Museum.
Goslin, R. M. 1955. Animal remains from Ohio rock shelters. Ohio Journal of Science 55:358-362.
Gross, A. O. 1958. Swallow-tailed kite in Bermuda. Auk 75:91.
Haverschmidt, F. 1962. Notes on the feeding habits and food of some hawks in Surinam. Condor 64:154-158.
Haverschmidt, F. 1977. Roosting habits of the swallow-tailed kite. Auk 94:392.
Hicks, T. W. 1955. An early seasonal record of the swallow-tailed kite in Florida. Wilson Bulletin 67:63.
Swallow-tailed Kites
203
Loomis, L. M. 1890. Summer birds of the mountain portions of Pickens County, South Carolina. Auk 7:30-39.
McAtee, W. L. 1935. Food habits of common hawks. United States Department of Agriculture. Circular 370:1-36.
Millsap, B. A. 1987. Summer concentration of American swallow-tailed kites at Lake Okeechokee, Florida, with comments on post-breeding movements. Florida Field Naturalist 15:85-112.
Millsap, B. A., and D. E. Runde. 1988. American swallow-tailed kite population monitoring. Annual Performance Report. Florida Game and Fresh Water Fish Commission, Tallahassee.
Morrill, W. L. 1974. Production and flight of alate red imported fire
ants. Environmental Entomology 3:265-271.
Palmer, R. S. (Editor) 1988. Handbook of North American birds. Vol- ume 4. Smithsonian Institute Press, Washington, D.C.
Parmallee, P. W. 1958. Remains of rare and extinct birds from Illinois Indian sites. Auk 75:169-176.
Pearson, T. G., C. S. Brimley, and H. H. Brimley. 1942. Birds of North Carolina. North Carolina Department of Agriculture, Raleigh.
Rapp, W. F. 1944. The swallow-tailed kite in the northeastern states.
Bird Banding 15:156-160.
Ridgway, R. 1895. The ornithology of Illinois State Lab. Natural His- tory Part 1, Volume 1:1-520.
Robertson, W. B., Jr. 1988. American swallow-tailed kite, Elanoides forficatus. Pages 109-131 in Handbook of North American birds, Volume 4 (R. S. Palmer, Editor). Smithsonian Institution Press, Wash- ington, D.C.
Simpson, M. 1972. The swallow-tailed kite: a review of its occurrence in the southern Appalachians. Chat 36:69-72.
Skutch, A. F. 1951. Life history of the boat-billed flycatcher. Auk 68:30-49.
Skutch, A. F. 1965. Life history notes on two tropical American kites. Condor 67:235-246.
Snyder, N. F. R. 1974. Breeding biology of swallow-tailed kites in Florida. The Living Bird 13:73-97.
Stoneburner, D. L., and C. S. Harrison. 1981. Heavy metal residues in sooty tern tissues from the Gulf of Mexico and North Central Pa- cific Ocean. The Science of the Total Environment 17:51-58.
Sykes, P. W. 1984. The range of the snail kite and its history in Florida. Bulletin Florida State Museum 29:211-264.
U. S. Fish and Wildlife Service. 1985. Endangered and threatened wild- life and plants; review of vertebrate wildlife; notice of review. Fed- eral register 50:37958-37967.
Received 11 September 1992 Accepted 2 July 1993
.
■
First Specimen of the Shiny Cowbird, Molothrus bonariensis (Aves: Emberizidae),
in North Carolina
William Post
Charleston Museum , 360 Meeting Street Charleston, South Carolina 29403
ABSTRACT — The first North Carolina specimen of the shiny cow- bird ( Molothrus bonariensis ), representing the fourth collected in North America, was obtained at New Bern, Craven County, in 1990.
Since about 1900, the shiny cowbird has been spreading northward through the West Indies at an accelerating pace (Post
and Wiley 1977, Post et al. 1992). This species was first sighted in North America, on the Florida Keys, in 1985 (Smith and Sprunt 1987). It was photographed on the Florida mainland in 1987 (Smith and Sprunt 1987). Since it was first noted on the mainland of North America, the shiny cowbird has spread throughout Florida, particularly south of Tampa (Post et al. 1992). Individual cow-
birds have begun to make long-range movements from the Florida population center, reaching as far northwest as Oklahoma (Grzy- bowski and Fazio 1991) and northeast to Maine (Surner 1992).
As yet, only a few shiny cowbirds have been collected in North America. The first North American specimen was obtained in 1989 in South Carolina (Hutcheson and Post 1990). The second and third were obtained in 1990, in Texas (G. D. Baumgardner, Texas A & M University, in litt.) and in Oklahoma (Grzybowski and Fazio 1991), respectively.
The fourth North American specimen, and the first for North Carolina, was obtained by Robert P. Holmes, III at New Bern,
Craven County, on 29 October 1990. The specimen is an adult
(after second-year) male (USNM No. 597,185). The skull was fully pneumetized. Testes measurements were left: 1.5 x 1.5 mm and right: 1.0 x 1.0 mm. The bird had no subcutaneous fat. Mass was not recorded. The flattened wing length (wrist to tip of longest primary) was 100.0 mm. The wing molt was completed. The bird was still undergoing a slight body molt in the region of the malars and upper breast. By comparison with specimens in the Charleston Museum, I determined that the individual belongs to the subspecies M. b. minimus.
Besides being the first specimen for North Carolina, this also appears to be the first verifiable record for the state. The species
Brimleyana 19:205-206, December 1993
205
206
William Post
was reported from North Carolina in 1989, and that report was accompanied by a photograph (Cooper 1990). Although the observer meticulously recorded the details of his observation, and the report is undoubtedly correct, the photograph itself is not clear enough to exclude the possibility that the individual is a brown-headed cow- bird ( Molothrus ater).
ACKNOWLEDGMENTS— I thank John O. Fussell, III for ar- ranging for the delivery of the specimen to the U. S. National Museum, and Roxie C. Laybourne and John Anderson for the speci- men’s preparation. Dave Lee called my attention to an important reference.
LITERATURE CITED
Cooper, S. 1990. North Carolina’s first shiny cowbird ( Molothrus bonarienses). Chat 54:28-84.
Grzybowski, J. A., and V. W. Fazio, III. 1991. Shiny cowbird reaches Oklahoma. American Birds 45:50-52.
Hutcheson, W. H., and W. Post. 1990. Shiny cowbird collected in South Carolina: first North American specimen. Wilson Bulletin 102:561.
Post, W., A. Cruz, and D. B. McNair. 1992. The North American
invasion pattern of the shiny cowbird. Journal of Field Orinthology 64:32-41.
Post, W., and J. W. Wiley. 1977. The shiny cowbird in the West Indies. Condor 79:119-121.
Smith, P. W., and A. Sprunt, IV. 1987. The shiny cowbird reaches the United States. American Birds 41:370-371.
Surner, S. 1992. First record of shiny cowbird ( Molothrus bonariensis ) in Maine. Maine Bird Notes 5:1-2.
Accepted 29 October 1992
207
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Brimleyana 18 was mailed on 9 July 1993.
ERRATA
Joshua Laerm has informed the editor of an error in Brimleyana 18. On page 23 of “A Late Pleistocene Vertebrate Assembly from the St. Marks River, Wakulla County, Florida,” the sentence beginning on line 7 should read: “Two species of rabbit occur in the St. Marks region today, the eastern cottontail, Sylvilagus floridanus, and the more common marsh rabbit, S. palustris.” The swamp rabbit, S. aquaticus , is not known to occur in Wakulla County, Florida.
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BRIMLEYANA NO. 19, DECEMBER 1993
CONTENTS
Revision of the Milliped Genus Scytonotus Koch (Polydesmida: Ploydesmidae).
Rowland M. Shelley \
New Molluscan ( Gastropoda and Bivalvia) Records for the Neuse River Basin,
North Carolina. James R. Flowers and Grover C. Miller 61
Morphometric Variation Between Bufo woodhousii fowleri Hinckley
(Anura: Bufonidae) on Assateague Island, Virginia, and the Adjacent Mainland.
John M. Hranitz, Thomas S. Klinger, Frederick C. Hill, Robert G. Sagar,
Thomas Mencken, and John Carr 65
Leatherback Turtle, Dermochelys coriacea (Reptilia: Dermochelidae):
Notes on Near-shore Feeding Behavior and Association with Cobia.
Gilbert S. Grant and Danny Ferrell 77
Additional Evidence for the Specific Status of Nerodia cyclopion and Nerodia floridana
(Reptilia: Colubridae). William E. Sanderson 83
Observations on Crayfish Predation by Water Snakes, Nerodia (Reptilia: Colubridae).
Lance W. Fontenot, Steven G. Platt, and Christine M. Dwyer 95
Food and Feeding Behavior of Adult Snowy Grouper, Epinephelus niveatus
(Valenciennes) (Pisces: Serranidae), Collected off the Central North Carolina Coast with Ecological Notes on the Major Food Groups.
Jon Dodrill, Charles S. Manooch III, and Ann Bowman Manooch 101
A Communal Winter Roost of Silver-haired Bats, Lasionycteris noctivagans
(Chiroptera: Vespertilionidae). Mary K. Clark 137
A Preliminary Body Fat Index for Cottontails (Lagomorpha: Leporidae).
Edward M. Lunk ^4^
Diets of Marsh Rabbits, Sylvilagus palustris (Lagomorpha: Leporidae), from Coastal Islands in Southeastern North Carolina.
Kevin W. Markham and Wm. David Webster 147
Notes on the Geographical and Ecological Distribution of Relict Populations
of Synaptomys cooperi (Rodentia: Arvicolidae) from Eastern North Carolina.
Mary K. Clark, Michael S. Mitchell, and Kent S. Karriker 155
Responses of Deer Mice, Peromyscus maniculatus (Mammalia: Rodentia), to Wild Hog Rooting in the Great Smoky Mountians National Park.
Michael R. Lusk, Michael J. Lacki, and Richard A. Lancia 169
Notes on Post-breeding American Swallow-tailed Kites,
Elanoides forficatus (Falconiformes: Accipitridae), in North Central Florida.
David S. Lee and Mary K. Clark joc
First Specimen of the Shiny Cowbird, Molothrus bonariensis (Aves: Emberizidae),
in North Carolina. William Post 205
Miscellany 207
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