| ISSN 0038-3872 ty ee | SOUTHERN CALIFORNIA ACADEMY OF SCIENCES BULLETIN Volume 93 Number 1 BCAS-A93(1) 1-44 (1994) RNS APRIL 1994 Founded 6 November 1891, lanes eal 17 May 1907 © Souther California Academy of Sciences, 1994 OFFICERS _ Hans M. Bozler, President David L. Soltz, Vice-President ead Kristine B. Hartney, Secretary . Margaret A. Neighbors, Treasurer Daniel A. Guthrie, Editor BOARD OF DIRECTORS 1992-1994 1993-1995 ee 1994-1996 © Kristine B. Hartney Jack W. Anderson Donald G. Buen a Lillian Y. Kawasaki. Hans M. Bozler Martin F. Golden Edward J. Kormondy Margaret A. Neighbors Daniel A. Guthrie — David L. Soltz Jane R. Peterson R. Nichols Hazelw« Susan E. Yoder Maria E. Zavala - Gloria J. Takaha Membership is open to scholars in the fields of natural and social sciences, and to any perso in the advancement of science. 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Date of this issue 4 May 1994 @) This paper meets the requirements of ANSI/NISO 239.48-1992 (Permanence of Pap SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 4 / NCORPORATED 1 1994 Annual Meeting May 6-7 University of California, Irvine Symposia being planned include: The Impact of Changes in Federal Science Policy on Southern California; Restoration of Wildlands After Fires; Wetlands Restoration; Earthquakes in Southern California; The Effects of Science Policy on Women. Southern California Academy of Sciences 900 Exposition Boulevard Los, Andeles, California 90007 Telephone: 213/744-3384 Abstract Instructions Abstracts will appear exactly as submitted. Consequently, they must be cleanly typed and correct in format. Abstracts which fail to conform to the guidelines or are mailed after the deadline will not appear in the symposium program. Abstracts must be typed and submitted on an 8'2” x 11” sheet. 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The subject field in which you wish to present. BRwWhNWe Abstract and card are due MARCH 1, 1994 to Program Chair Southern California Academy of Sciences 900 Exposition Boulevard Los Angeles, CA 90007 Sample Abstract vase 6” MICROBIAL ACTIVITY IN THE DIGESTIVE TRACT OF THE HALFMOON, Medi- aluna californiensis. J. S. Kandel', J. R. Paterek* and M. H. Horn!. 'California State Univ. Fullerton, CA 92634 and ?Agouron Institute, La Jolla, CA 92037. We report the presence of a diverse microbial flora and of microbial fermentation products in the hindgut region of the halfmoon, Medialuna californiensis, a seaweed-eating fish from southern California coastal waters. Viable aerobic and anaerobic bacteria were found in all sections of the gut, but were of highest concentration (10°—108/ml) in the hindgut. Microscopy revealed vibrios, spirilla, rod-shaped bacteria and flagellated protozoa in the midgut and hindgut, but primarily vibrios and rods in the stomach and foregut. Acetic, isobutyric and butyric acids, the volatile products of microbial breakdown of carbohydrates, were found only in the hindgut, as was ethanol, a nonvolatile product. These results provide the first evidence for microbial fermentation and its possible contribution to the energy supply in a north-temperate herbivorous fish. Bull. Southern California Acad. Sci. 93(1), 1994, pp. 1-12 © Southern California Academy of Sciences, 1994 The Biology and Current Status of the Long-eared Owl in Coastal Southern California Peter H. Bloom Western Foundation of Vertebrate Zoology, Calle San Pablo, Camarillo, California 93010 Abstract. —The Long-eared Owl (Asio otus) is poorly known in southern California. This paper reviews its historic nesting distribution in Orange and western San Diego counties as determined from 79 egg set records from 5 museum collections, and contrasts this with the distribution of 50 nesting attempts as recorded in Orange and northern San Diego counties between 1968-1992. Comparisons reveal a substantial area of extirpation in the coastal region with a small, remnant population in interior areas. The number of historic breeding territories has de- creased by at least 55%. Reproduction appears good with 85% of 40 nests fledging young. Diet was typical of other regions with small rodents (Microtus californicus, Reithrodontomys megalotis, and Thomomys bottae) comprising 90% of the prey by number. Except for anecdotal accounts from early in this century, little is known about the biology of the Long-eared Owl (Asio otus) in coastal southern California (Dawson 1923; Willett 1933; Bent 1938). In this paper I present information obtained over a 24-year period (1968-1992) on nesting Long-eared Owls in coastal Orange and San Diego counties, California (Fig. 1) and contrast this with the historic (1889-1961) nesting distribution (Table 1). Also included are data on the breeding biology, nesting habitat, predators, diet, and the results of 1991 and 1992 surveys of historic and recent nest territories. These data were collected largely on an opportunistic basis while monitoring the breeding biology of the more common raptor species. The impetus for this paper stems in part from reports of declines of Long-eared Owls in Pennsylvania, New Jersey, and California (Clark and Klem 1986; Bo- sakowski et al. 1989; Marti and Marks 1989), and recent distribution maps (Burton 1984; Johnsgard 1988; Marti and Marks 1989) which incorrectly indicate that the species does not breed in southwestern California. It also updates previous Long-eared Owl status reports provided in Garrett and Dunn (1981) and Unitt (1984). Study Area The historic breeding distribution of the Long-eared Owl included all of south- ern California (Grinnell and Miller 1944) with the likely exception of some interior eastern desert areas. For the purposes of this paper the historic study area included all of Orange County, the coastal slope of San Diego County west of Mount Palomar, and the Cuyamaca and Laguna mountains (Fig. 1). My study area in- cluded southern and western Orange County, and northern San Diego County, ] 2 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES ” Lt = 3 SEI os es 1 oof ME Chino: So Ee OS t = *: Pike = Mte=Palomar =Fallbrook = Green Oceanside Pacific Ocean SOUTHERN CALIFORNIA 0 5 10 15 20 25 30 35 rt — Kilometers @ Recent Nest © Historic Nest Fig. 1. Historic (1889-1961) and recent (1967-1992) locations of nesting Long-eared Owls in Orange and western San Diego counties. California. Within Orange County, specific study sites included Rancho Mission Viejo, Irvine Ranch, Starr Ranch Audubon Sanctuary, Casper’s Wilderness Park, Irvine Park, Wagon Wheel Park, Whiting Ranch Park, and Aliso-Wood Canyon Park. Within San Diego County, specific study sites were restricted to Camp Pendleton Marine Corps Base. Oak woodland, riparian woodland, coastal sage scrub, native grassland, and non-native grassland are the predominant habitats in this region and elevation varies from sea level to 460 m. Precipitation averages 36 cm/yr and is seasonal, peaking in February (Bloom 1989). Methods All Orange and San Diego county egg set records were examined at the Western Foundation of Vertebrate Zoology (WFVZ), Museum of Vertebrate Zoology (MVZ), BIOLOGY AND STATUS OF LONG-EARED OWLS 3 San Bernardino County Museum (SBCM), and the Santa Barbara Museum of Natural History (SBMNH) (Table 1). These collections contained the majority of Orange and San Diego county sets (L. Kiff pers. comm.). Owing to the vagueness of locality data on nesting records, no attempt was made to recheck exact nest locations. However, I examined street maps and conducted 15 aerial surveys, 1— 2 hr in duration, to determine the extent of urbanization and the likelihood of a former territory being occupied. I have never found an active Long-eared Owl nest within 1 km of a residential! area in California. Therefore, if a residential street now exists within | km of a historic Long-eared Owl nest site I considered it abandoned. Many Long-eared Owl nesting territories were encountered while searching for nests of other raptorial species. Specific surveys for nesting Long-eared Owls in 1991 and 1992 lasting 0.5—4 hr in duration, were conducted between 15 January and | June each year, and consisted of examining known and potential nest groves and listening for calling adults or begging young. Bal-chatri traps and mist nets were also used to ascertain the presence or absence of Long-eared Owls (Smith et al. 1983; Bloom 1987). Additional recent nest records were provided by other observers (Table 2). Calculations of habitat loss figures in Orange County between 1972 and 1990 were derived from reports detailing land use changes (County of Orange 1972, 1993). For the purposes of this paper I used only land-use classifications that might support breeding Long-eared Owls. These included only the designations ““open space”’ and “‘vacant,’” which (in the 1974 edition) were defined as parks, cemeteries, beaches, and unused urban land. Unused urban land contained large ranches and the Trabuco District of the Cleveland National Forest. From the 1993 edition I used the designations that most closely approximated the 1974 edition, including “‘open space/recreation,” ““vacant <31% slope,” and “‘vacant >30% slope.’ These include beaches, local and regional parks, national forests, golf courses, cemeteries, wildlife preserves, recreational marinas, and public and private campgrounds (County of Crange 1993). The latter 2 categories contain mostly ranchlands. While habitats such as cemeteries, beaches, golf courses, and marinas are not typically Long-eared Owl breeding habitat, excluding their acre- ages would make this part of my methodology difficult to repeat; therefore, my breeding habitat acreage estimates as they relate to changes between 1972-1990 for Orange County are undoubtably inflated and the actual acreage of suitable owl habitat is substantially less. Foods habits were ascertained from pellets found in and directly below all active nests. Skulls and mandibles were used in the identification of rodents. A nest was considered successful if it fledged at least one young. Results Historic record. —Seventy-nine egg sets collected between March 1889 and March 1961 from Orange (2) and coastal San Diego counties (77), respectively, were found in museum collections. Mean clutch size for these sets was 5.1 (S.D. = 1.0; range 2—7). Nests were located throughout the coastal region in 10 species of trees and shrubs. Of 69 nest substrates recorded, 21 were oak (Quercus sp.), 18 each in willow (Salix sp.) and cottonwood (Populus fremonti), 4 in Eucalyptus sp., 3 in sycamore (Platanus racemosa), and | each in orange, alder (A/nus rhombifolia), 4 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Historic nesting records of Long-eared Owls in Orange and San Diego counties from collections at the WFVZ, MVZ, SBCMNH, and SBMNH. Museum no. Date Locality San Diego County WFVZ 4,463 7 Feb. 1931 9 mi. W of Pala WFVZ 48,109 25 Feb. 1926 McCoy Grove WEVZ 73,766 17 Mar. 1898 Lakeside WFVZ 52,699 14 Mar. 1920 San Diego River WEFVZ 73,763 19 Mar. 1893 Lakeside WFVZ 46,973 11 Mar. 1923 Near San Marcos WFVZ 48,256 11 Mar. 1923 Near San Marcos WFVZ 73,759 14 Mar. 1925 Lakeside WFVZ 4,466 9 Mar. 1933 5 mi. E of Escondido WFVZ 96,063 10 Mar. 1901 Griejito WFVZ 73,784 10 Mar. 1907 Crescent Valley WFVZ 72,133 13 Mar. 1936 Sweetwater Lake WFVZ 4,468 14 Mar. 1936 Santa Margarita Ranch WFVZ 52,701 14 Mar. 1923 Lakeside WFVZ 73,782 11 Mar. 1923 San Marcos WFVZ 52,702 13 Mar. 1921 Sweetwater River WFVZ 73,772 10 Mar. 1921 Near Lakeside WEFVZ 52,698 14 Mar. 1920 San Diego River WFVZ 9,986 15 Mar. 1916 Jamacha WFVZ 72,021 15 Mar. 1916 Near Lakeside WFVZ 9,886 15 Mar. 1913 Near Lakeside WFVZ 73,768 22 Mar. 1897 Near Lakeside WFVZ 73,769 22 Mar. 1897 Lakeside WFVZ 73,764 18 Mar. 1894 Lakeside WFVZ 4,467 20 Mar. 1934 Ys mi. N of Bonsall WFVZ 73,792 16 Mar. 1933 Flinn Springs WFVZ 73,774 16 Mar. 1933 Dihissa WFVZ 4,470 26 Mar. 1940 10 mi. E of Encinitas WFVZ 4,469 26 Mar. 1940 10 mi. E of Encinitas WFVZ 32,412 28 Mar. 1949 Bonsall WFVZ 52,099 27 Mar. 1919 San Diego WFVZ 73,785 30 Mar. 1919 © Escondido WFVZ 73,700 27 Mar. 1920 Lakeside WFVZ 71,995 27 Mar. 1927 Dihissa WFVZ 73,783 30 Mar. 1913 Crescent Valley WFVZ 89,900 25 Mar. 1895 Lakeside WEVZ 73,765 25 Mar. 1895 San Diego River WFVZ 73,761 30 Mar. 1889 Lakeside WFVZ 83,462 18 Mar. 1961 San Luis Rey Mission WFVZ 4,471 22 Mar. 1942 Rancho Santa Fe WFVZ 75,642 20 Mar. 1949 San Luis Rey River WFVZ 73,762 21 Mar. 1892 Lakeside WFVZ139,573 17 Mar. 1923 Old Maids Canyon WFVZ 4,464 26 Feb. 1933 2 mi. E of Bonsall WFVZ 4,465 27 Feb. 1933 Y) mi. E of Bonsall WFVZ147,086 12 Mar. 1949 San Luis Rey River WFVZ161,078 5 Mar. 1919 Bandy Can., San Pasqual WFVZ 48,108 21 Feb. 1926 Bandy Canyon WFVZ127,962 6 Apr. 1917 Bonsall WFVZ 73,786 4 May 1919 Marikle Canyon RMMNDNDNDNDDHDNAMANHP DHAWAN NADAINANANAANADHDAI ANP AWAAAADAHNDAHAANANANAHN Hh HLH HW Collector Harrison Gallup Ingersoll Ingersoll Ingersoll Gallup Gallup Burnham Roberts Dixon Sharp Harvey Harrison Burnham Sharp Burnham Ingersoll Ingersoll Ingersoll Huey Huey Ingersoll Ingersoll Ingersoll Harrison Potter Ingersoll Harrison Harrison Dixon Piltifield Sharp Ingersoll Huey Sharp Ingersoll Ingersoll Ingersoll Quigley Harrison Hall Ingersoll Heaton Harrison Harrison Hall Carpenter Gallup Carpenter Sharp a... BIOLOGY AND STATUS OF LONG-EARED OWLS 5 Table 1. Continued. No. Museum no. Date Locality eggs Collector WEFVZ124,571 5 May 1903 San Pasqual 4 Wood WEFVZ 89,899 28 Mar. 1917 San Diego County 5 Potter WFVZ 72,134 6 Apr. 1934 Sweetwater Lake 5 Harvey WFVZ 73,781 13 Apr. 1902 San Pasqual 4 Sharp WFVZ126,245 13 Apr. 1902 San Pasqual 7 Carpenter WFVZ 55,120 7 Apr. 1901 San Pasqual 6 Carpenter WFVZ 89,898 30 Apr. 1917 Lakeside 3 DeGroot WFVZ 48,009 19 Apr. 1908 San Pasqual 5 Carpenter WEFVZ 73,760 8 Apr. 1923 Santa Isabel 5 Burnham WEFVZ 48,107 8 Apr. 1923 San Pasqual Valley 5 Gallup WFVZ 4,476 3 Mar. 1920 Near Lakeview 7 Ingersoll WFVZ 73,767 1 Mar. 1897 Lakeside 5 Ingersoll WEFVZ 52,700 6 Mar. 1920 San Diego River 4 Burnham WEVZ 4,477 4 Mar. 1921 Fanita Ranch, Santee 5 Meanley WEFVZ107,394 15 Mar. 1903 San Pasqual i] Dixon WFVZ 52,703 6 Mar. 1921 Mission Valley 6 Burnham WEFVZ128,897 16 Mar. 1904 San Pasqual 5 Sharp WFVZ 73,790 2 Mar. 1923 Fanita Ranch, Santee 5 Bancroft WEVZ 73,771 10 Mar. 1901 Lakeside 7 Ingersoll WEFVZ 73,773 12 Mar. 1893 Escondido 3 Ingersoll MVZ 13,305 29 Mar. 1925 Bonsall 30 Dixon MVZ 5,973 17 Mar. 1896 Lakeside 5 Ingersoll MVZ 5,974 25 Mar. 1900 Lakeside 5 Ingersoll MVZ 5,972 27 Mar. 1920 Lakeside 5 Brown SBCM — 8,788 12 Mar. 1932 Bonsall 5 Hanna SBCM_ 19,303 18 Feb. 1928 Lakeview 7 Sechrist SBMNH_ 368-3* 20 Mar. 1897 Lakeside 6 Arnold Orange County WFVZ115,182 12 Apr. 1891 Alamitos 6 Shields WEVZ147,087 12 Mar. 1939 Near La Habra 4 Hall * County location not given on original data slip; I presumed it was San Diego County. sumac (Rhus sp.), walnut (Juglans regia), and grape (Vitis girdiana). Of 47 nests for which the original nest builder was noted, 38.3% were American Crows (Corvus brachyrhynchos), 25.5% “‘rat’? (Neotoma sp.), 12.8% Cooper’s Hawks (Accipiter cooperil), 12.8% Red-shouldered Hawks (Buteo lineatus), 6.4% Swainson’s Hawks (B. swainsoni), and 4.3% Red-tailed Hawks (B. jamaicensis). Since egg collectors frequently returned to nesting territories each year, I de- termined that the minimum number of localities included in the 79 historic nest records represented at least 33 different localities. Eighteen (54.5%) of these 33 localities are now densely settled urban areas, or agricultural areas, and are no longer capable of supporting nesting Long-eared Owls. Nine localities given on data slips were too general to evaluate their current potential for nesting by Long- eared Owls or could not be found on maps. Only 6 (18%) (Jamacha, Sweetwater Lake, Bandy Canyon, San Pasqual Valley, Santa Ysabel, Santa Margarita Ranch) still showed any potential (> 1 km from residential area) of being used by Long- eared Owls for nesting. Recent studies. — Fifty observations of Long-eared Owl nesting attempts were Table 2. SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Recent Long-eared Owl nest records in Orange and San Diego counties. Date Location/observation April 1968 April 1973 1 April 1971 April 1973 8 April 1974 May 1982 22 May 1977 28 April 1984 24 April 1984 11 May 1986 22 May 1988 April 1988 11 May 1988 18 May 1989 19 April 1991 18 April 1991 29 March 1992 29 March 1992 12 April 1992 13 April 1992 15 April 1992 15 May 1992 19 May 1992 22 May 1992 25 May 1992 Orange County Weir Can., 3 km N of confluence with Santiago Can., Orange Co., CA. Five young, 2 fledged. Arroyo Trabuco, 0.5 km S of O’Neill Park, Orange Co., CA. Active nest (E. Lindquist pers. comm.). Weir Can., 4 km N of confluence with Santiago Can., Orange Co., CA. Five small young. 18 April 1971, 3 young. Fox Can., 0.5 km E of confluence with Bell Can., Starr Ranch Audubon Sanctuary, Orange Co., CA. Fledged young present. Weir Can., 4 km N of confluence with Santiago Can., Orange Co., CA. Five eggs. 10 May 1974, failed. 0.5 km N of Blind Can.,.Orange Co., CA. One recently predated fledged young (J. Bryan pers. comm.). Bell Can., 0.75 km N of confluence with Crow Can., Starr Ranch Audubon Sanctuary, Orange Co., CA. Fledged young present (D. Bontrager pers. comm.). Bell Can., 0.75 km N of confluence with Crow Can., Starr Ranch Audubon Sanctuary, Orange Co., CA. Six eggs, 2 young, 4 weeks old. Canada Gobernadora, Wagon Wheel Park, Orange Co., CA. One young (G. Chester pers. comm.). Gabino Can., 2.6 km N of confluence with La Paz Can., Orange Co., CA. Five young. 27 May 1986, | young predated. La Paz Can., 0.5 km N of confluence with Gabino Can., Orange Co., CA. Fledged young, 2 predated by Cooper’s Hawk. Bell Can., 1 km S of Starr Ranch Audubon Sanctuary, Casper’s Wilderness Park, Orange Co., CA. Fledged young present. Canada Gobernadora, Wagon Wheel Park, Orange Co., CA. Fledged young, | predated by Cooper’s Hawk. La Paz Can., 0.5 km N of confluence with Gabino Can., Orange Co., CA. Three fledged young, | predated by Cooper’s Hawk. Canada Gobernadora, Wagon Wheel Park, Orange Co., CA. Three young. Cristianitos Can., 0.1 km N of confluence with Talega Can., Orange Co., CA. Four young, one of which was predated by a Red-shouldered Hawk. Cristianitos Can., 0.1 km N of confluence with Talega Can., Orange Co., CA. Two young. Cristianitos Can., 0.1 km N of confluence with Talega Can., Orange Co., CA. Three young, one of which was predated by a Red-shouldered Hawk. Gabino Can., 2.3 km N of confluence with La Paz Can., Orange Co., CA. Five young. Canada Gobernadora, Wagon Wheel Park, Orange Co., CA. Four young. Cristianitos Can., Talega Reserve, Orange Co., CA. Fledged young. Gabino Can., 2.6 km N of confluence of La Paz Can., Orange Co., CA. Three fledged young. Santiago Can., 0.25 km S of Irvine Lake, Orange Co., CA. Fledged young present. Canada Gobernadora, 0.25 km S Wagon Wheel Park, Orange Co., CA. Fledged young present. Bell Can., 0.1 km N of Fox Can., Starr Ranch Audubon Sanctuary, Orange Co., CA. Two fledged young. BIOLOGY AND STATUS OF LONG-EARED OWLS Date 8 April 1992 15 April 1992 1 May 1992 21 April 1974 10 April 1983 6 May 1983 1 April 1983 Spring, 1988, 1989, 1990 Spring 1973, 1974, 1975, 1983, 1988 22 April 1983 4 March 1984 20 April 1984 18 May 1985 May 1989 May 1989 27 April 1991 16 May 1991 29 March 1992 29 March 1992 Table 2. Continued. Location/observation La Paz Can., 0.5 km N of confluence with Gabino Can., Orange Co., CA. Two young. La Paz Can., 0.6 km N of confluence with Gabino Can., Orange Co., CA. Three fledged young. La Paz Can., 1.2 km N of confluence with Gabino Can., Orange Co., CA. Fledged young. San Diego County Horno Can., Camp Pendleton, San Diego Co., CA. Three fledged young. Lower San Onofre Can., Camp Pendleton, San Diego Co., CA. Five young. 16 April, failed due to mammal predation. Santa Margarita River, 8 km upstream from ocean, Camp Pendleton, San Di- ego Co., CA. Fledged | young. Talega Can., at confluence with Cristianitos Can., Camp Pendleton, San Die- go Co., CA. One addled egg, failed. South of Fallbrook, Hwy 76 and Gird St., San Diego Co., CA. Active nest (J. Oakley pers. comm.). Near Vista at Calveva Lake. San Diego Co., CA. Active nest (J. Oakley pers. comm.). Talega Can., 4.5 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. Three fledged young. Talega Can., 4.5 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. One addled egg, 4 young. Talega Can., 4.6 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. Fledged young present. Talega Can., 4.5 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. Failed with small young and eggs. Talega Can., Camp Pendleton, San Diego Co., CA. Failed with 3 small young (J. R. Bryan pers. comm.) Three km NE of Poway, San Diego Co., CA. Two fledged young (J. R. Bryan pers. comm.). Talega Can., 4.5 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. Fledged young present. Talega Can., 2.6 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. Three fledged young. Talega Can., 4.5 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. Two Long-eared Owl eggs and 3 Cooper’s Hawk eggs in the same nest being incubated by a Cooper’s Hawk. Long-eared owl nesting attempt failed. Talega Can., 4.6 km N of confluence with Cristianitos Can., Camp Pendleton, San Diego Co., CA. Five young. 8 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES made in 30 different nesting territories in Orange and San Diego counties between 1968 and 1992 (Table 2). Specific surveys of known Long-eared Owl nest terri- tories were conducted in 1991-1992. Of 20 nest territories surveyed in 1991, 6 were active and 4 of these produced young. Fourteen territories were inactive. Of 18 nest territories surveyed in 1992, 12 were active and 11 produced young. Six territories were inactive. Of 29 nests where the identity of the original nest builders was known, 68.9, 17.2, and 13.7 percent, respectively, were in abandoned nests of Cooper’s Hawks, American Crows, and Common Ravens (Corvus corax). Thirty nest trees were coast live oaks (Q. agrifolia), and | was a willow. The most frequently used nesting habitat was closed canopy, young, coast live oak woodland where Cooper’s Hawks and American Crows nested simultaneously, or, in alternating years, with the owls. In 4 instances in 1992, 2 pairs of Long-eared Owls nested within 25-100 m of each other. Clutch sizes ranged from 2-8 eggs; mean clutch size was not determined. Thirty- four (85%) of 40 nests were successful. Nest failures from predation of individual Long-eared Owl chicks by Cooper’s Hawks and Red-shouldered Hawks was fre- quent, especially if they nested in the same grove (Table 2). Competition for nests was occasionally intense. On 29 March 1992, I observed an old Cooper’s Hawk nest with an adult Cooper’s Hawk incubating 2 Long-eared Owl eggs and 3 of its own. The presence of an agitated adult Long-eared Owl in adjacent trees suggested that the Cooper’s Hawk had recently usurped the Long-eared Owl nest and eggs. The nest fledged only Cooper’s Hawks. Predation by Cooper’s Hawks on Long- eared Ow! chicks occurred during 3 nesting attempts at 2 territories, and in at least one instance all young were taken. D. R. Bontrager (pers. comm.) also observed an instance of attempted predation by an adult Red-shouldered Hawk on a Long-eared Owl fledgling in Orange County (Table 2). Red-shouldered Hawks preyed on at least 1 young from each of four nesting attempts and on one adult. One dead young Long-eared Owl was also found in the nest of a Red-tailed Hawk (B. jamaicensis). Elsewhere the Red-tailed Hawk has been recorded as a predator of adult Long-eared Owls (Collins 1960). One hundred thirty-four pellets collected from 11 Long-eared Owl territories between 1985-1992 contained 102 vertebrates including California vole (Microtus californicus) (39), western harvest mouse (Reithrodontomys megalotis) (30), Botta pocket gopher (Thomomys bottae) (23), white-footed mouse (Peromyscus) sp. (4), pocket mouse (Perognathus) sp. (3), ornate shrew (Sorex ornatus) (1), and 2 unknown passerines. Discussion Long-eared Owls were formerly common in San Diego and Orange counties but are now becoming increasingly rare in southern California. New and early investigators (Cooper 1870; Sharp 1907; Dawson 1923; Willett 1933) all reported the species as common in oak woodland and willow thicket habitats of south- western California. Sharp (1907) regarded it as a ““common resident” and further stated that ‘‘Up to a few years ago almost every crow’s, hawk’s, or rat’s nest along the river in San Pasqual had its pair of owls.” Grinnell and Miller (1944) described the status of Long-eared Owls in California as “numbers are so large as to warrant term ““common,” even “abundant” locally. Reduction of late years BIOLOGY AND STATUS OF LONG-EARED OWLS 9 iS apparent, in the main probably mainly as result of clearing bottomlands for farming.”’ Marti and Marks (1989) noted that the species is declining in California, and Garrett and Dunn (1981) stated that the Long-eared Owl has “‘virtually been eliminated there [in southern California] as a breeder.” Unitt (1984) provided further documentation of the scarcity of recent San Diego County breeding records for this species and its substantial decline, stating that the species now nests only in the Anza Borrego Desert. He placed the last known coastal San Diego County breeding record at that time (1984) as 13 May 1973 near Oceanside. The known present breeding population and historic distribution as determined from recent surveys and egg collections from two southern California counties suggest the Long-eared Owl has declined by at least 55% and possibly as much as 82%. Based upon recent habitat use trends in Orange County, the species will probably continue to decline. Of 112,195 ha (277,234 ac) of potential Long-eared Owl breeding habitat available under the categories of ““open space” and “‘vacant”’ (County of Orange 1974) in 1972, only 94,982 ha (234,701 ac), representing a 15.3% decline, were still available in 1990 (County of Orange 1993). The reduction of active nesting territories is directly attributable to habitat change; however, a limited quantity of unsurveyed potential nesting habitat exists within the Cleve- land National Forest which, when coupled with county, state park, National Audubon Society, and private conservancy acreages, may afford some continuing protection for owls within Orange and San Diego Counties. Presently, no Long- eared Owl breeding activity is known in any Orange County ranch or parklands west of the I-5 freeway. However, potential habitat remains there, and much of it may be designated as wilderness park additions. If so, these areas may yet be able to support a few breeding pairs of Long-eared Owls. The species was extirpated in most of western San Diego County west of I-15 with the exception of Camp Pendleton, and possibly portions of the San Luis Rey River, Santa Margarita River, and Fallbrook vicinity (Fig. 1). Most notable is the lack of any recent nesting records from the San Diego vicinity that was referred to by Grinnell and Miller (1944) as one of three “‘centers of abundance” in California and an area from which a minimum of 36 historic nesting records are known within 25 km of San Diego (Table 1, Fig. 1). The only hints of continued nesting activity in this area is from Cedar Canyon, east of San Diego, where a recently killed Long-eared Owl was found in summer, and 4 roosting owls were found in winter in the Proctor Valley, Otay Ranch area (Preston et al. 1992). Unitt (1984) also referred to records of roosting Long-eared Owls on the coastal slope with a maximum of 12 at Rancho Otay in 1979. Based upon observations of 7 adults at different spring locations (1972-1992), I suspect that Camp Pendleton may still support several breeding pairs of Long- eared Owls along the Santa Margarita River between the coastal estuary and the confluence of De Luz Creek, and in the Santa Margarita Mountains near Case Springs. However, after 20 years of nesting raptor surveys which resulted in only 7 confirmed Long-eared Owl breeding territories I suspect the population is small (Table 2). One of the above territories has been inactive since 1974, and 2 have been inactive since 1983. Long-eared Owls use a variety of vacant raptor and corvid nests and do not build their own. Hence, as numbers of other raptors decline so do opportunities for surplus nest structures that the owls depend upon. For example, 3 historic 10 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES nest sites in San Diego County were built by Swainson’s Hawks, a species Sharp (1902) called formerly “‘abundant” near Escondido. Swainson’s Hawks are now completely extirpated from coastal southern California (Bloom 1980; Risebrough et al. 1990). As competition between raptors for increasingly smaller areas of nesting habitat and nest sites grows, so will the potential for predation on Long- eared Owls, as exemplified by the observed interactions with adjacent nesting Cooper’s Hawks and Red-shouldered Hawks. Crow and raven breeding populations are large and probably increasing on the study area (pers. observ.). Although nest site availability may be proportionately greater now than historically due to increased numbers of nesting ravens, the degree of predation exerted by ravens on breeding Long-eared Owls may be an additional important factor in the decline of the owl. It is interesting that none of 69 historic Long-eared Owl nests were built by ravens, yet 13.7% of 29 recent nests were built by this species. Compared with nest success studies in Idaho (34-51%) (Marks 1986) and Or- egon (70%) (Bull et al. 1989) the 85% nest success reported in this study is high and may in part be attributable to the inclusion of nests discovered late in the season which could have inflated nesting success. It may also be due to nesting habitat quality. As suggested by Bull et al. (1989) on their coniferous Oregon study area, dense canopy cover probably reduces predation. The majority of territories in my study were composed of dense, closed canopy oak woodland which probably afforded greater protection from predation than shrubsteppe hab- itats in Idaho (Marks 1986). Higher quality foraging habitat would also be expected to increase nesting success. The high proportion of small rodents found in Long-eared Owl diets in this study was similar to that found elsewhere in the United States, with voles and gophers predominating (Marti 1976; Craig and Trost 1979; Marks and Yensen 1980; Bull et al. 1989). However, as would be expected due to different habitats, they were distinct from Long-eared Owl diets in the Colorado Desert of California where pocket mice and kangaroo rats (Dipodomys sp.) were dominant (Barrows 1989). Although I did not perform a rigorous analysis of Long-eared Owl nesting and foraging habitat, all territories contained substantial quantities of grasslands within 1 km of oak woodland and riparian nesting habitat where voles and gophers could be caught, suggesting that adjacent grasslands were important in the selection by Long-eared Owls of nest sites. The destruction of grassland foraging habitat in spite of the preservation of small riparian and oak woodland nesting habitats has probably contributed to the Long-eared Owl’s decline in southern California. Preservation of substantial open space reserves that contain both nest groves and adequate foraging habitats may yet prevent the local extirpation of this wide ranging owl species. Acknowledgments Rancho Mission Viejo, Western Foundation of Vertebrate Zoology, and the National Audubon Society provided funding for this study and are gratefully acknowledged. D. L. O’Neill and R. J. O’Neill are thanked for the numerous ways they supported the research. The field assistance of R. Jackson, E. H. Henckel, J. L. Henckel, R. J. Morales, and D. L. O’Neill was very helpful. Special thanks go BIOLOGY AND STATUS OF LONG-EARED OWLS 11 to D. R. Bontrager, G. Chester, J. R. Bryan, J. A. Chubb, E. Lindquist, and J. Oakley for the use of unpublished observations. The assistance of L. Smith with records from Orange County is appreciated. Constructive comments were pro- vided by C. T. Collins, J. S. Marks, C. D. Marti, M. L. Morrison, and L. F. Kiff. T. Danufsky (SBMNH), L. F. Kiff(WFVZ), G. Cardiff (SBCM), and N. K. Johnson (MVZ) are thanked for making museum records available. Literature Cited Barrows, C. W. 1989. Diets of five species of desert owls. Western Birds, 20:1-10. Bent, A. C. 1938. Life histories of North American birds of prey. U.S. Nat. Mus. Bull., 170:1-482. Bloom, P. H. 1980. The status of Swainson’s Hawk in California, 1979. Final report IJ-8.0, Bureau of Land Management and Federal Aid in Wildlife Restoration, Project W-54-R-12, California Department of Fish and Game. The Resources Agency, California Department of Fish and Game, and Bureau of Land Management, Sacramento, California, 42 pp. 1987. Capturing and handling raptors. National Wildlife Federation. Raptor Management Techniques Manual. Pp. 99-123. 1989. Red-shouldered Hawk home range and habitat use in southern California. M.Sc. thesis. California State Univ., Long Beach. Bosakowski, T., R. Kane, and D. G. Smith. 1989. Decline of the Long-eared Owl in New Jersey. Wilson Bull., 101:481-485. Bull, E. L., M. G. Henjum, and A. L. Wright. 1989. Nesting and diet of Long-eared Owls in conifer forests, Oregon. Condor, 91:908-912. 3 Burton, J. A., ed. 1984. Owls of the world. Tanager Books, Dover, New Hampshire. 208 pp. Clark, R. J., and D. Klem, Jr. 1986. An overview of endangered declining birds of Pennsylvania and adjacent states. Pp. 211-233 in Endangered and threatened species programs in Pennsyl- vania and other states: causes issues, and management. (S. K. Majundar, F. J. Brenner, and A. F. Rhoades, eds.), Pa. Acad. Sci., Philadelphia. Collins, C. T. 1962. Red-tailed Hawk attacks Long-eared Owl. The Wilson Bull., 74:89. Cooper, J.G. 1870. Ornithology, vol. 1, Land birds. Pp. 426-427 in Geological survey of California. (S. F. Baird, ed.), Univ. Press, Cambridge, Massachusetts. County of Orange. 1974. Orange County progress report, October 1974. Vol. 11. 1993. Orange County progress report, January 1993. Vol. 27. Craig, T. H., and C. H. Trost: 1979. The biology and nesting density of breeding American Kestrels and Long-eared Owls on the Big Lost River, southeastern Idaho. Wilson Bull., 91:50-61. Dawson, W. L. 1923. The birds of California. 3:1080—1087. South Moulton Company, San Diego, California. Garrett, K., and J. Dunn. 1981. Birds of southern California: status and distribution. The Artisan Press, Los Angeles, California. 408 pp. Grinnell, J.,and A. H. Miller. 1944. The distribution of the birds of California. Pacific Coast Avifauna No. 27. Johnsgard, P. A. 1988. North American Owls Biology and Natural History. Smithsonian Institution Press. Washington D.C., 295 pp. ; Marks, J.S., and E. Yensen. 1980. Nesting sites and food habits of Long-eared Owls in southwestern Idaho. Murrelet, 61:86—-91. . 1986. Nest-site characteristics and reproductive success of Long-eared Owls in southwestern Idaho. Wilson Bull., 98:547-560. Marti, C.D. 1976. A review of prey selection by the Long-eared Owl. Condor, 78:331-336. , and J. S. Marks. 1989. Raptor status reports: medium-sized owls. Pp. 123-134 in Proc. western raptor management symposium and workshop. (B. G. Pendleton, ed.), Natl. Wildl. Fed., Washington, D.C. Preston, K. L., J. C. Lovio, and P. J. Mock. 1992. Otay Ranch Management Study. Ogden Envi- ronmental and Energy Services Co., 37 pp. Risebrough, R. W., R. Schlorff, P. H. Bloom, and E. Litrell. 1990. Investigations of the decline of Swainson’s Hawk populations in California. J. of Raptor Res., 23:63-71. Sharp, C. S. 1902. Nesting of Swainson’s Hawk. The Condor, 4:116-118. 12 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 1907. The breeding birds of Escondido. The Condor, 9:84-88. Smith, J. C., M. J. Smith, B. L. Hilliard, and L. R. Powers. 1983. Trapping techniques, handling methods, and equipment use in biotelemetry study of Long-eared Owls. N. Amer. Bird Band., 8:46-47. Unitt, P. 1984. The birds of San Diego County. Memoir 13. San Diego Society of Natural History, 276 pp. Willett, G. 1933. A revised list of the birds of southern California. Pacific Coast Avifauna Number 21, 204 pp. Accepted for publication 23 April 1993. Bull. Southern California Acad. Sci. 93(1), 1994, pp. 13-29 © Southern California Academy of Sciences, 1994 Occurrence and Habitat Use of Marine Mammals at Santa Catalina Island, California from 1983-91 Susan H. Shane West Coast Whale Research Foundation, 250 Cottini Way, Santa Cruz, California 95060 Abstract. — A nine-winter-long study (1983-91) of marine mammals at Santa Cat- alina Island, California provided data on the ecological relationships among three pinniped and nine cetacean species observed there. A dramatic reduction in the _ number of California sea lions occurred during and following the winter with the most severe effects from the 1983 El Nino. The most striking change in cetacean occurrence was a precipitous decline in pilot whale numbers followed by an increase in abundance of Risso’s dolphins. The six most often-sighted cetaceans appeared to partition the habitat according to water depth and distance from shore. Long-term data on the occurrence and habitat use of several marine mammal species at one geographical location are relatively rare. Such data were accumu- lated on nine species of cetaceans and three species of pinnipeds at Santa Catalina Island, California during nine consecutive winters (1983-91). While this study originally focused on short-finned pilot whale (Globicephala macrorhynchus) so- cial organization, its other objectives were: 1) to record which species were present at the island during each winter and 2) to identify habitat use patterns for each species (Shane 1984). The severe El Nino (EN) event of 1983, one of the strongest in over four centuries (Quinn et al. 1987), had its greatest impact on the study area during the second year of the project, 1983-4 (McGowan 1985). Thus, EN served as a natural experiment with the potential for exerting a profound influence on marine mammals at Santa Catalina. The length of this study and the consistency of techniques and primary observer make the data collected particularly useful for understanding aspects of the eco- logical relationships among the species observed, as well as showing changes in their occurrence over time. The only other comprehensive data on marine mam- mals in the southern California Bight were collected opportunistically by Norris and Prescott (1961) and systematically during Outer Continental Shelf surveys in the mid-1970’s by Dohl et al. (1981) and Bonnell et al. (1981). Methods Santa Catalina Island (118°30'’W, 33°26'N), henceforth called Catalina Island, is located approximately 40 km offshore of the Los Angeles area in the southern California Bight (SCB) (Fig. 1). This 33 km-long island lies in a northwest-south- east orientation and has 86 km of shoreline. The waters surrounding the island are almost continually enriched by the Southern California Eddy (Owen 1980). Catalina is located in a boundary area south of which coastal upwelling occurs 13 14 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES West End : Arrow Point z—> Catalina Harbor Long Point Ben Weston Point f Avalon \ China Point Salta Verde Point East End Fig. 1. Santa Catalina Island, California, located 42 km south of Los Angeles. Sites #1-10 are haul-out areas used by California sea lions in 1983-91. CMSC = Catalina Marine Science Center (base port for this study). nearly year-round and north of which winds produce onshore transport and down- welling (Norton et al. 1985). The water depth at a distance of 1 km offshore varies between 55 and !83 m. Long-term (1942-81) average sea surface temperatures (SST) around Catalina range from a February low of 13.5°C to an August high of 19.4°C (NOAA 1982). All marine mammals sighted were recorded. Marine mammals were observed primarily from a 5.1 m Boston Whaler with an 85 hp or 70 hp outboard engine. Boat searches involved traveling at approximately 15-25 km/h between 0.4 and 1.6 km offshore with one observer scanning the inshore 180 degrees and a second observer scanning the offshore 180 degrees. A few sightings were made from land at the Catalina Marine Science Center (CMSC) (Fig. 1), from a single-engine, high- wing aircraft (altitude = 213-240 m, speed = 90 nm/h, 2-4 km offshore, N = 6 flights), and from a boat crossing the San Pedro Channel between the mainland and the island. The amount of time spent at Catalina each winter varied from as long as four months to as short as three days. A relative measure of search effort is indicated by the number of days and hours spent searching for marine mammals and the number of times the island was circumnavigated in the boat each year (Table 1). The abundance and location of all pinnipeds sighted were recorded. California sea lions (Zalophus californianus) were counted both in the water and on land at CATALINA ISLAND MARINE MAMMALS 15 Table 1. Marine mammal search effort at Santa Catalina Island, CA. (circum. = circumnavigations.) Time spent searching NOMSReLOuTn Dates in field Days Hours in boat 10 Jan.—21 Mar. 1983 50 145 ] 5 Dec. 1983-26 Mar. 1984 92 180 12 15-19 Nov. and 30 Nov. 1984-11 Mar. 1985 97 353 28 6-12 Feb. 1986 7 37 4 20-27 Jan. 1987 8 40 5 1-8 Feb. 1988 7 42 5 27 Jan.—3 Feb. 1989 8 46 4 15-18 Feb. 1990 3 17 3 28 Jan.—3 Feb. 1991 8 45 3 several regular haul-out sites around the island (Fig. 1). All harbor seals (Phoca vitulina) observed incidentally in the water and hauled out were counted. Addi- tionally, harbor seals were sought out and counted at all haul-out sites around the island one time in each of six years. An incomplete survey was conducted in a seventh year. Dead marine mammals were always recorded. In 1983 an unusually large num- ber of dead sea lions (51) was recorded and necropsies performed on 24 of them. Cetacean records included the date, time, location, species, total number of individuals, number of calves, water depth, distance offshore, direction of travel, and activity. To determine in an unbiased manner whether the short field seasons from 1986 onward were sufficient for sighting most cetacean species present in a given year, a random numbers table was used to randomly select days in the field each year. The number of new species seen on each day was recorded. During each of the years with short field seasons (1986-91), one hundred percent of the cetaceans were sighted within two to seven field days (mean = 4.2 days; S.D. = 1.72 days). During the two typical years with long field seasons (1983-4 and 1984- 5), 83% and 71%, respectively, of the species were seen within two to seven field days. The species missed by the random sampling procedure in these two years were rare (seen once or, in one case, seven times) during that year. Data from the long 1983 field season are not equivalent to those in other years, since most of the field time was spent at the Isthmus and the island was circumnavigated only once, possibly reducing the chances of seeing many different species. Thus, it was concluded that one week of field time was sufficient for deciding whether pilot whales, as well as the other most frequently-seen species (Risso’s dolphins, Gram- pus griseus, gray whales, Eschrichtius robustus, bottlenose dolphins, Tursiops trun- catus, and Pacific white-sided dolphins, Lagenorhynchus obliquidens) occurred in a given year. Except for 1990, no field season was shorter than seven days (Ta- ble 1). . Methods of measuring water depth varied from year to year. In 1984-5 and 1988-91 water depth was recorded using a fathometer (either a Si-Tex Honda HE-300 with a maximum depth of 480 ft. [146 m] or a Humminbird LCR400 with a maximum depth of 600 ft. [183 m]). Depth values are missing from sightings made from land, air, and from occasional sightings made from the boat. In 1983- 16 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 4 depth was taken from a nautical chart based upon triangulation from the sighting location. No depth data were collected in 1986 or 1987. Distance from shore was estimated according to the following seven categories: less than 0.1 km, 0.1-0.4 km, 0.4—-0.8 km, 0.8-1.6 km, 1.6-—2.4 km, 2.4—3.2 km, and over 3.2 km. Distance estimates were calibrated using known distances be- tween landmarks. Cetacean activity was recorded upon first encountering a group. Activities in- cluded traveling, feeding, resting, socializing, social traveling, and bowriding. Traveling involved forward progress in one direction. Feeding was recorded when animals dove repeatedly in one area, facing in varying directions when surfacing. Resting animals either floated at the surface or swam very slowly in one direction. Socializing involved frequent body contact between animals and, often, surface behavior such as leaping and slapping. Photographs were taken of pilot whales, bottlenose dolphins, and Risso’s dol- phins for individual identification. This paper includes only the results of the bottlenose dolphin photo-identification effort. Kodachrome 64, Kodachrome 200 color transparency and Tri-X black and white films were used in a Canon AE-1 camera equipped with a 70-210 mm, 80-300 mm or 70-200 mm lens. Results The results of this study need to be viewed with reference to the 1983 EN event which exerted a strong influence on oceanographic conditions and marine fauna off southern California. Satellite-derived sea surface temperatures (SST) at Cat- alina Island during this study are plotted with reference to normal SST recorded by NOAA (1982) in Fig. 2. The SST during the period of this study were generally warmer than normal, as was found by Strong (1989). However, this apparent warming trend is attributed to biases in satellite data by Reynolds et al. (1989). The 1983 EN clearly had the strongest effect on SST at Catalina in 1983-4, and the marine mammal occurrence data reflect that. A second, moderate EN occurred in 1987 (Quinn et al. 1987). Pinnipeds The abundance of California sea lions at Catalina changed during the study period (Table 2). Counts of over 800 sea lions in 1983 dropped to about 200 or less in ensuing years, starting in 1983-4 when EN’s impact in the area was greatest. Sea lion distribution varied somewhat over the years of this study (Table 2). While sea lions in varying numbers always hauled out at Catalina’s East End, additional large numbers hauled out at several other sites which usually, though not always, coincided with the area where commercial squid boats were fishing (Fig. 1). Sea lion haul-outs typically were small rocky islands, large boulders or rocky outcrops along shore. The sole exception was a sandy beach at the East End used only in 1983, 1983-4, and 1991. While sea lion age class and gender were not consistently recorded, subadult males, yearlings, juveniles and adult females all occurred at Catalina throughout the study period. California sea lions do not produce pups on Catalina. In January—March 1983 squid fisherman were observed shooting at California sea lions, because they considered the animals a threat to their livelihoods. Nec- ropsies were performed on 24 of 51 dead sea lions observed. Sixty-three percent CATALINA ISLAND MARINE MAMMALS 17 Jan 1985-6 1986-7 1987-8 Jan 1988-9 1989-30 1990-1 Fig. 2. Sea surface temperatures (SST) (solid line with filled triangles) in °C at Catalina Island, California, in nine winters from 1983 to 1991 (NOAA 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991). For comparison, each graph shows the normal monthly SST (dashed line with filled squares) which is an average of data from 1942-81 (NOAA 1982). (15/24) of these showed positive or probable evidence of gunshot wounds: shat- tered bones or skulls, shredded internal organs, and bullet holes. Sightings of dead sea lions were rare in the ensuing eight winters, probably because there were fewer sea lions at the island to conflict with squid fishing and because squid fishing was never again concentrated near the base port (where Gee sea lions were readily found) as it was in 1983. California sea lions were observed swimming with cetaceans, most commonly bottlenose dolphins, pilot whales, and Risso’s dolphins. While these associations sometimes occurred in the prime squid fishing area for a given year, such asso- ciations, especially with bottlenose dolphins, also occurred in areas apart from the squid fishing fleet. Harbor seals hauled out in small groups (< 10) at several sites around Catalina and also were seen in the water. The most consistently-used haul-out area was the East End where boulders along the shore were used. Adult females hauled out on Catalina’s southwestern beaches to bear pups beginning in February each year. Most of these beaches are small, sandy, secluded, surrounded by high cliffs, and located between Ben Weston Point and Salta Verde Point (Fig. 1). The results of 18 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 2. Maximum counts of California sea lions during the winters of 1983-91. The primary haul-out areas for each year refer to sites labeled with numbers on Fig. 1. (* = in water near commercial squid boats.) Year Max. count Date of count Primary haulouts 1983 898 14 Feb. 1, 8, 95-10 1983-84 240 24 Jan. 9 1984-85 108 7 Feb. aS 1986 113 11 Feb. 7 1987 135 26 Jan. 6 1988 250 4 Feb. 6; 10, * 1989 249 3 Feb. fi 1990 204 5) Feb: 6, 7, 10 1991 220 31 Jan. 6; 79210 the annual harbor seal counts varied depending upon the timing of pup production for that year and the timing of the count (Table 3). Although northern elephant seals (Mirounga angustirostris) were not found regularly at Catalina, a total of five elephant seals were observed there during the study. Weanling-sized pups were seen in 1983, 1983-4, and 1985. One hauled out just north of Ben Weston Point for one month. Another weanling hauled out with a 23 cm-diameter fresh shark bite on its body. Yearling-sized seals were seen twice in December, 1984. Cetaceans Nine species of cetaceans were sighted around Catalina during 1983-91 (Tables 4-5). Gray whales and bottlenose dolphins were observed every year, and Risso’s dolphins, Pacific white-sided dolphins and common dolphins (Delphinus delphis) were sighted in most years. Pilot whale sightings became rarer as the study pro- gressed (Table 5). Sperm whales (Physeter catodon) and northern right whale dolphins (Lissodelphis borealis) were seen once each, and Dall’s porpoises (Pho- coenoides dalli) were seen three times. Changes in occurrence and relative abun- dance of the five most frequently-sighted species (excluding pilot whales) can be seen by looking at the number of sightings per hour for each species in each year (Fig. 3). Group size.—The average group size varied considerably among species with Table 3. Total counts of harbor seals in the water and hauled out around Catalina Island, CA, during winter in 1984-91. No counts were made in 1983 or 1987. Tidal state during the count is described with the relative tidal height given in parentheses. (int. = intermediate; * = incomplete count.) 3/4/84 3/9/85 2/11/86 2/2/88 2/1/89 2/15/90 1/30/91 # Adults 91 144 37 109 — 211 52 # Pups 57 64 7 12 — 56 l Total # 148 208 44* 121 79 267 53 Tide falling high rising falling falling falling falling (high) (high) (low) (low) (int.) (int.) CATALINA ISLAND MARINE MAMMALS 19 Table 4. Total number of sightings of cetaceans (except pilot whales) at Catalina Island, CA, in 1983-91. Year Species 83 83-84 84-85 86 87 88 89 90 91 Gray whale 17 44 88 14 14 1 8 D q Bottlenose dolphin DD 10 74 6 6 5 15 1 10 Risso’s dolphin 0 3 2 3 30 7 18 1 8 Pacific white-sided dolphin 2 13 24 3 0 1 0 0 0. Common dolphin 2 8 7 l 2 3 1 0 0) Dall’s porpoise 0 0 1 0) 0) 1 0) 0) 1 Northern right whale dolphin 0 0 0) 0) 0) 1 0 0 0 Sperm whale 1 0) 0) 0 0) 0 0 0 0) common dolphins having the largest groups (X¥ = 67.1) and gray whales having the smallest groups (x = 1.8) of those cetaceans seen regularly (Table 6). Water depth. —While there was considerable overlap in the depths occupied by different species, certain patterns were apparent. Common dolphins were seen consistently in the deepest water, while pilot whales were found in the shallowest water (Table 7). Bottlenose dolphins frequented the greatest range of depths. Because the fathometers used had limits of 146 m and 183 m in range, occasions on which cetaceans were in deeper waters are excluded from this analysis, except in 1983-4 when depth was calculated using a nautical chart and triangulation. Thus, although there is a bias toward shallower water in the mean values presented in Table 7, it is a bias which applies to all species, so the depths are an accurate representation of relative cetacean distribution by depth. Distance offshore. — As Fig. 4 shows, the distribution of the six most frequently- seen species with respect to distance offshore closely followed the pattern estab- lished with relation to water depth. Common dolphins were sighted farthest off- shore, while pilot whales were restricted to less than 1.6 km from shore. Both Pacific white-sided dolphins and Risso’s dolphins were more frequently seen less than 1.6 km out, while bottlenose dolphins and gray whales were observed over the entire range of distances surveyed. Activity. —Traveling was the most frequently-recorded activity for each of the five most often-sighted species (excluding pilot whales whose behavior was an- alyzed separately), accounting for 68-93% of all activities recorded. Bottlenose dolphins and Risso’s dolphins exhibited the widest range of activities, each per- forming each recorded activity at least once. Generally, there were too few records of each activity to adequately describe the behavior of the five species considered. Table 5. Highest daily counts of short-finned pilot whales sighted at Catalina Island, CA, and the number of days on which pilot whales were seen in 1983-91. Year 83 83-84 84-85 86 87 88 89 90 91 # Whales 100 17 20 33 O 0) 16 0 0) # Days Dei 1 30 2 0 0 ] 0 0 20 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Eas ER Yl TT ES] GG rae LO DD Sightings/Hour ISASAASSAASSSASY INASAASSASSASSASSY KAASAASSAAASAASASAAASASSASAI DS SASAASSASSSASSSSSSY Fig. 3. Number of sightings per hour of field time for frequently-sighted species of cetaceans at Catalina Island, CA, in 1983-91. Species abbreviations: ER = gray whale; TT = bottlenose dolphin; GG = Risso’s dolphin; LO = Pacific white-sided dolphin; DD = common dolphin. The only other cetacean activity of note occurred when gray whales were social- izing and exhibiting surface behavior. On seven of the nine such occasions other species, including bottlenose dolphins (N = 7), pilot whales (N = 1), Risso’s dolphins (N = 1), and California sea lions (N = 2), joined the socializing gray whales, often abandoning their previous behavior to do so. These attendant species usually exhibited a high level of arousal (leaping, rapid swimming) that corre- sponded to the activity of the large whales. Table 6. Group size for nine species of cetaceans seen at Catalina Island, CA, in 1983-91. (N = number of groups sighted.) Species Mean Std Median Min Max N Common dolphin 67.1 91.37 30 2 300 24 Pilot whale 14.0 6.20 15 2 33 62 Risso’s dolphin 13.1 13.60 10 l 100 72 Pacific white-sided dolphin 10.3 7.64 8 l 30 43 Bottlenose dolphin 8.3 6.85 6 l 30 149 Dall’s porpoise 4.7 belS 4 4 6 3 Northern right whale dolphin 2 _ — — — 1 Gray whale 1.8 1.05 1 1 7 195 Sperm whale l — = = = 1 CATALINA ISLAND MARINE MAMMALS 21 Table 7. Mean water depth (in meters) in which six species of cetaceans were seen at Catalina Island, CA, in 1983-91. No water depth data are available for the other cetaceans sighted. (N = number of sightings with depth recorded.) Species Mean Std N Common dolphin 176.0 107.05 10 Pacific white-sided dolphin 98.3 SoS 25 Bottlenose dolphin 92.8 125.31 86 Gray whale 83.5 65.15 82 Risso’s dolphin 69.6 23.38 22 Pilot whale 39.6 19.47 Dy Direction of travel: gray whales.—Gray whales were observed en route to and from Mexican waters during their annual migration. Generally, whales moved southward before 15 February and northward after that. For instance, during the three long seasons, 100% (1983), 91% (1983-4) and 97% (1984-5) of the gray 16 a , fig ER (N=177) 60 50 40 30 No. of Sightings No. of Sightings No. of Sightings ) oN Ff DD @ AUTISTIC S DIEU ae EG Ay iu Bel Cia OLE ORE Distance Offshore Distance Offshore Fig. 4. Frequency of sightings of six cetaceans at varying distances from shore around Catalina Island, CA, in 1983-91. Species abbreviations are as in Fig. 3 (also GM = pilot whale). Distance offshore: A = 0-0.1 km; B = 0.1-0.4 km; C = 0.4—0.8 km; D = 0.8-1.6 km; E = 1.6-2.4 km; F = 2.4-3.2 km; G = over 3.2 km. N N SOUTHERN CALIFORNIA ACADEMY OF SCIENCES whales sighted traveling southward were seen before 15 February, and 100% (1983), 100% (1983-4) and 76% (1984-5) of the northward traveling whales were seen after that date. Of the 170 records for which direction of travel was recorded, the earliest record of southward movement was 31 December (1984) and the latest record of southward travel was 4 March (1984). The earliest northward traveling gray whale was seen on 31 December (1984), while the latest northward migrator was observed on 20 March (1984) (note that the field seasons always ended by 26 March). Bottlenose dolphin association with other species.—Bottlenose dolphins were associated with other cetaceans on 81 of 149 sightings (54%). These associations involved pilot whales (N = 57), Risso’s dolphins (N = 14), gray whales (N = 8), pilot whales and gray whales together (N = 1), and the lone sperm whale (N = 1). In winter 1984-5 the association between bottlenose dolphins and a single pod of 20 pilot whales monitored for 30 days was observed closely. Dolphins accom- panied the whales on 24 of those 30 days. Most often, the dolphins intermingled with the pilot whales when the latter were feeding. Frequently, dolphins appeared suddenly when the whales began to feed. Whenever the two species initially were observed separately and later seen joining together, it was clearly the dolphins which joined the pilot whales and not vice versa. On six occasions (five days), the pilot whales formed a tight group, moved closer to shore than previously (ending up 50—200 m offshore five times), and occasionally changed direction, when bottlenose dolphins appeared in the vicinity. The whales’ behavior was interpreted to represent an attempt to avoid discovery by the dolphins. The dolphins never joined the whales on three of these occasions. They did join together twice, and one occasion was inconclusive. The dolphins usually left the pilot whales when the latter stopped feeding. Bottlenose dolphin photo-identification project. —Bottlenose dolphins are far more difficult to photograph at Catalina than in Texas or Florida where other studies were conducted (Shane 1980, 1987, 1990a). This difficulty arises from the fact that the dolphins at Catalina move faster, form less cohesive groups, and change direction more often and more erratically than the dolphins studied in the Gulf of Mexico. These characteristics, plus the fact that bottlenose dolphins were not the focal study species at Catalina, account for the relatively small number of photo-identified dolphins (Table 8). Of the 50 recognizable individuals, 36 were seen only once. Seven individuals were identified in two winters and one in three winters. Six dolphins were seen two to three times during a single year. Discussion Pinnipeds The annual study period coincided with different periods in the reproductive cycles of the three pinniped species encountered. It was the non-breeding period for California sea lions, whereas it was the breeding time for harbor seals and northern elephant seals (Bartholomew and Boolootian 1960; Odell 1971). While most adult and subadult male California sea lions typically move north- ward from the California Channel Islands in the non-breeding season (Barthol- omew and Boolootian 1960; Orr and Poulter 1965), the sightings at Catalina show that some may stay in the relative vicinity of the breeding areas. Catalina is only CATALINA ISLAND MARINE MAMMALS 23 Table 8. Sightings of 14 photo-identified bottlenose dolphins seen on more than one day at Catalina Island, CA, in 1983-91. The numbers under each year indicate the number of days that individual was seen that year. The other 36 photo-identified dolphins were each seen once. ID # 83 83-84 84-85 86 87 88 89 90 91 l 2 5 1 a 1 2 3 1 1 4 1 6 1 1 7 2 8 3 9 2 10 1 1 11 3 14 1 1 17 1 1 18 2 23 2 35-40 km from two breeding islands, San Clemente and Santa Barbara. Con- ceivably, some males also may move to Catalina from Mexico during the winter (Bartholomew and Boolootian 1960). The presence of adult female and young Zalophus at Catalina in winter corresponds with the hypothesis that these animals either remain at the breeding sites or move southward in fall through spring (Bartholomew and Boolootian 1960; Orr and Poulter 1965). The largest change in counts of California sea lions occurred after the first year of the study. In seven of the nine years many sea lions aggregated where com- mercial squid fishermen were catching squid, suggesting that market squid (Loligo opalescens) is an important prey item at Catalina. Market squid was the sixth most abundant prey item in terms of percent occurrence for California sea lions at San Clemente Island in 1981-6 (Lowry et al. 1990), and it was the fifth most abundant prey for sea lions at San Nicolas Island in 1981-6 (Lowry et al. 1991). Antonelis et al. (1984) also identified market squid as one of the four most important prey items for sea lions at San Miguel Island. EN had its most severe effect on market squid catches around Catalina in 1984 (Table 9). The lowest sea lion counts at Catalina were just above 100 in 1984-5, 1986, and 1987. Residual EN effects also were found by DeLong et al. (1991) who reported that pup numbers in the Channel Islands were still below 1982 levels in. 1986. While Francis and Heath (1991) noted no significant change in numbers of adult and subadult males at San Nicolas Island from 1981 through 1984, the number of adult females there did decline during that period. DeLong et al. (1991), noting this decrease in female abundance, could not determine whether females died or moved to other sites in the SCB or in Mexico. Thus, the smaller number of sea lions at Catalina may have been a reflection of the large-scale population effects of the 1983 EN event. A longer study by Lowry et al. (1992) recorded a steady increase in California sea lion pup numbers during censuses at several Channel Islands from 1984-92. The fact that sea lion counts at Catalina in 1991 were still at one-quarter of their 1983 levels suggests that either there was an unusual influx of sea lions to Catalina in 1983 or that EN caused a long-term shift in winter distribution away from Cat- 24 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 9. Landings of market squid (Loligo opalescens) in the Los Angeles area, much of which is caught around Catalina Island, CA (California Dept. of Fish and Game, Statistics, Long Beach, CA 90802, pers. comm.). Year Total in tons 1977-1981 (avg.) 8235 1982 4729 1983 941 1984 73 1985 3414 1986 8956 1987 5976 1988 16,634 1989 18,027 1990 10,797 1991 13,566 alina. The latter hypothesis seems more likely in light of the fact that, according to McGowan (1985), “‘the biological response [to EN in the SCB as of March 1983] was quite modest’? despite increased SST, a depressed thermocline and decreased salinity. Whole-island harbor seal counts varied from 53 (1991) to 267 (1990). The counts were made prior to peak pupping in 1988, 1989, and 1991, possibly accounting for lower counts in those years. Pupping apparently occurred quite early in 1990, and the 1984 and 1985 counts, both made in March, may have been lower than the 1990 total as a consequence of EN. However, variation in haul-out patterns according to time of day and other factors may make interannual comparisons invalid (LeBoeuf and Bonnell 1980). Tidal state did not correlate with year-to-year fluctuations in seal numbers at Catalina (Table 3), but the small number of seal counts and lack of actual tidal heights at the seal haul-outs prohibit any definitive conclusion about tidal effects. The location of harbor seal breeding sites was the same in this study as those reported by Bonnell et al. (1981). During that study the highest count was of 183 harbor seals in April 1977. Cetaceans The data collected on the most frequently-seen species of cetaceans are generally indicative of some degree of habitat partitioning. Habitat partitioning is largely a reflection of diet differences between the species. Group sizes are determined, at least partially, by prey type and method of feeding. Common dolphins were found in large groups farthest offshore in deep water; they feed primarily on anchovies and squids during winter off southern California (Leatherwood and Reeves 1983). Pilot whales and Risso’s dolphins, both primarily squid eaters (Leatherwood and Reeves 1983), formed groups of approximately 15, and both were found in the shallowest waters on average. Pacific white-sided dolphins formed smaller groups in water of intermediate depth; they consume both epi- pelagic and mesopelagic schooling fishes and squids (Kajimura and Loughlin 1988). Bottlenose dolphins, renowned for their catholic diet (Leatherwood 1975), formed relatively small groups and were found in the widest range of depths compared with the other species observed. In the Gulf of California, Silber (1990) CATALINA ISLAND MARINE MAMMALS 25 postulated some degree of habitat partitioning between bottlenose dolphins, com- mon dolphins, and the vaquita (Phocoena sinus) based on diet, water depth, and distance from shore. The vaquita was intermediate between the other two species. The number of sightings of each species per hour of field time (Fig. 3) is the best indication of trends in the occurrence and relative abundance of the most often-sighted cetaceans. The most noteworthy changes in sighting frequency oc- curred for gray whales, Risso’s dolphins, and pilot whales (Table 5). From 1983- 4 through 1987 gray whales were seen quite frequently, and then from 1988 through 1991 the sighting rate dropped by 50%. Schulberg et al. (1991) and Sumich and Show (1991) reported that during this same period most gray whales used corridors offshore of Catalina Island and San Clemente Island during migration. Schulberg et al. (1991) specifically noted that use of the inshore corridor decreased between 1987 and 1990. Data from the Catalina study suggest a shift farther offshore than Catalina during this time period. Risso’s dolphins were seen rarely prior to 1987. In that year approximately 100 Risso’s dolphins remained in nearshore Catalina waters throughout the field sea- son, thus accounting for the extraordinarily high sighting rate of 0.75/hr. Risso’s dolphins were seen regularly at Catalina during 1988-91, and the sighting rate averaged six times higher than during 1983-6. A dramatic increase in shoreline observations of live Risso’s dolphins was reported throughout the southern Cal- ifornia Bight during the late 1980’s (A. Schulman, American Cetacean Society, San Pedro, California 90731, pers. comm.; D. Beeninga and G. Hoffman, Newport Beach, California 92661, pers. comm.) and strandings increased, as well (J. Heyn- ing, Los Angeles County Museum, Los Angeles, California 90007, pers. comm.). In their summary of Risso’s dolphin sightings in the eastern North Pacific, Leath- erwood et al. (1980) reported a large proportion of sightings in the area offshore of southern California, with movements onto the continental shelf occurring in 1974-5 when SST were high due to an EN. Despite this increase in sightings, Dohl et al. (1981) found that Risso’s dolphins represented less than 3% of all cetaceans seen in the SCB from 1975-8. Norris and Prescott (1961) recorded no sightings of Risso’s dolphins during five years of cetacean observations in southern California. Kruse (1989) summarized historic fluctuations in Risso’s dolphin abundance in Monterey Bay, California. She concluded that Risso’s dolphins may have become more common in Monterey Bay “over the last few decades”’ and that the 1983 EN may have caused this species to shift northward. The increase in Risso’s dolphin sightings at Catalina followed this same EN and may have been associated with the corresponding increase in SST. In general, winter SST around Catalina Island have remained at least slightly above normal in every year except 1988-9 since the 1983 EN (NOAA 1983-1991). More importantly, the explosion in numbers of Risso’s dolphins corresponded with a striking decline in abundance of pilot whales at Catalina (Table 5). Risso’s dolphins may have filled the medium-sized, squid-eating cetacean niche that was vacated by pilot whales when market squid vanished temporarily in 1983-4 just after EN. The association between bottlenose dolphins and other species of cetaceans is striking. Norris and Prescott (1961) also noted the strong affiliation between bottlenose dolphins and pilot whales. In 50% of the bottlenose dolphin sightings recorded by Dohl et al. (1981), this species was associated with other cetaceans. In most cases (72%) the associated cetaceans were pilot whales. More recently, 26 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Scott and Chivers (1990) reported frequent associations between bottlenose dol- phins in the eastern tropical Pacific and other cetaceans, especially pilot whales. The associations between bottlenose dolphins and other species observed in this study seemed to be based on shared prey items (as with pilot whales and Risso’s dolphins) and on curiosity (as with socializing gray whales and the sperm whale). Bottlenose dolphins are opportunistic feeders which frequently take advantage of human fisheries to improve their access to food (Busnel 1973; Leatherwood 1975; Shane 1990b; Corkeron et ai. 1990; Pryor et al. 1990). Because the dolphins appeared to initiate contact with other species, especially feeding pilot whales, such associations may improve the dolphins’ chances of acquiring prey. The curiosity-driven associations reflect the dolphins’ sociability and interest in un- usual phenomena. When attracted to socializing gray whales, the dolphins’ activity level increased (i.e., more leaping and rapid swimming), and socializing between dolphins appeared to increase as well. Such a reaction fits Wilson’s (1975:51) definition of the ‘‘audience effect,’ one form of social facilitation. The fact that 36 of the 50 photo-identified bottlenose dolphins were sighted only once indicates that many animals may be transients rather than residents of Catalina. However, some dolphins return to or remain at Catalina in different years, and some dolphins are seen repeatedly during a single winter. The prepon- derance of resightings of identifiable dolphins in 1984—5 (Table 8) is a reflection of the fact that most of the time that year was spent with a single pod of pilot whales, and the bottlenose dolphins were associated with those whales. Therefore, given a sufficient attraction (e.g., abundant squid and another cetacean adept at finding that prey), bottlenose dolphins do appear to remain in one area for an extended period of time. The major unanswered questions are: 1) Are any bot- tlenose dolphins year-round residents at Catalina? 2) When dolphins leave Cat- alina, where do they go? Analysis by Shultz et al. (1988) found no matches between 41 dolphins with distinctive markings at Catalina.and 421 dolphins photo-iden- tified along the southern California coast as of 1988. Thus, photographic data support Walker’s (1981) conclusion, based upon parasite loads and cranial mea- surements, that the coastal and island populations of bottlenose dolphins are separate. ; Acknowledgments Chip Deutsch and Jim Estes provided helpful comments on an earlier draft of this paper. Craig Strang, Sallie Beavers, Michael Poole, Jan Ostman, Becky Rum- sey, Sara Heimlich-Boran, and other short-term field assistants, too numerous to name, helped with the field work. Partial funding for this study was received from the National Marine Fisheries Service (Southwest Fisheries Center), the U.S. Marine Mammal Commission, the Theodore Roosevelt Memorial Fund of the American Museum of Natural History, the Monterey Bay Chapter of the American Cetacean Society, and the Biology Board of the University of California at Santa Cruz. This work was conducted under Marine Mammal Protection Act permit #624. Literature Cited Antonelis, G. A., C. H. Fiscus, and R. L. DeLong. 1984. Spring and summer prey of California sea lions, Zalophus californianus, at San Miguel Island, California 1978-1979. Fish. Bull., U.S., 82:67-76. CATALINA ISLAND MARINE MAMMALS ay Bartholomew, G. A., and R. A. Boolootian. 1960. Numbers and population structure of the pinnipeds on the California Channel Islands. 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Pinnipeds of the California Islands: abundance and dis- tribution. Pp. 475-493 in The California Islands. (D. M. Power, ed.), Santa Barbara Museum of Natural History, Santa Barbara. Lowry, M. S., C. W. Oliver, C. Macky, and J. B. Wexler. 1990. Food habits of California sea lions Zalophus californianus at San Clemente Island, California, 1981-86. Fish. Bull., U.S., 88:509- SDiNe : , B. S. Stewart, C. B. Heath, P. K. Yochem, and J. M. Francis. 1991. Seasonal and annual variability in the diet of California sea lions Zalophus californianus at San Nicolas Island, California, 1981-86. Fish. Bull., U.S., 89:331-336. , P. Boveng, R. J. DeLong, C. W. Oliver, B. S. Stewart, H. Deanda, and J. Barlow. 1992. Status of the California sea lion (Zalophus californianus californianus) population in 1992. National Marine Fisheries Service— Southwest Fisheries Center Administrative Report LJ-92- 32. SWFC, P.O. Box 271, La Jolla, CA 92038. McGowan, J. A. 1985. El Nino in 1983 in the Southern California Bight. Pp. 166-184 in El Nino north: Nino effects in the eastern subarctic Pacific Ocean. (W. S. Wooster and D. L. Fluharty, eds.), Washington Sea Grant Program, Univ. Washington. NOAA. 1982. Oceanographic monthly summary 2(4). National Weather Service, National Envi- ronmental, Satellite, Data and Information Service. 1983. Oceanographic monthly summary 3. National Weather Service, National Environ- mental, Satellite, Data and Information Service. 28 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES —. 1984. Oceanographic monthly summary 4. National Weather Service, National Environ- mental, Satellite, Data and Information Service. 1985. Oceanographic monthly summary 5. National Weather Service, National Environ- mental, Satellite, Data and Information Service. —. 1986. Oceanographic monthly summary 6. National Weather Service, National Environ- mental, Satellite, Data and Information Service. 1987. Oceanographic monthly summary 7. 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Pp. 44-72 in El Nino north: Nino effects in the eastern subarctic Pacific Ocean. (W. S. Wooster and D. L. Fluharty, eds.), Washington Sea Grant Program, Univ. Washington. Odell, D. K. 1971. Censuses of pinnipeds breeding on the California Channel Islands. J. Mamm., 52:187-190. Orr, R. T., and T. C. Poulter. 1965. The pinniped population of Ano Nuevo Island, California. Proc. California Acad. Sci. 4th series 32:377—404. Owen, R. W. 1980. Eddies of the California Current System: physical and ecological characteristics. Pp. 237-263 in The California Islands. (D. M. Power, ed.), Santa Barbara Museum of Natural History, Santa Barbara. Pryor, K., J. Lindbergh, S. Lindbergh, and R. Milano. 1990. A dolphin-human fishing cooperative in Brazil. Mar. Mamm. Sci., 6:77-82. Quinn, W. H., V. T. Neal, and S. E. Antunez de Mayolo. 1987. El Nino occurrences over the past four and a half centuries. J. of Geophys. Res., 92:14,449-14,461. Reynolds, R. W., C. K. Folland, and D. E. Parker. 1989. 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Sci. 93(1), 1994, pp. 30-37 © Southern California Academy of Sciences, 1994 Denning Characteristics of Black Bears in the San Gabriel Mountains of Southern California Cynthia H. Stubblefield and Gerald T. Braden California State Polytechnic University Pomona, Department of Biology, 3801 W. Temple Avenue, Pomona, California 91768 Abstract.—Denning habits of San Gabriel Mountain black bears were studied during the winters of 1987 through 1990. Mean denning period of five male bears was mid-November to mid-March. Denning periods for all bears ranged from late October to late March. Bears entered dens significantly later in 1988 than in 1987, 1989, and 1990 (P < .05). We speculate that fluctuations in food item availability might have affected the onset of denning. Exit dates (x? = 1.2, P = 0.758) and denning duration (x? = 4.79, P = 0.187) were not significantly different between years. Dens were located primarily in tree cavities (Pseudotsuga macro- carpa and Quercus chrysolepis) or under large boulders. All bears with more than one known den site reused a previous den. No incidents of winter activity were observed. The San Gabriel and San Bernardino Mountains are home to the southernmost populations of black bear (Ursus americanus) in California. Black bears were introduced into both ranges in 1933 after the extirpation of Ursus arctos, formerly the only ursid inhabitant (Burghduff 1935; Grinnel et al. 1937). San Bernardino black bears have been extensively studied (Boyer 1976; Siperek 1979; Novick 1981; Hogan 1984): with the exception of a reconnaissance study by Moss (1972) which did not include information on denning, the San Gabriel Mountain pop- ulation was not described prior to 1991 (Braden 1991). Objectives of this four year black bear study (1987 through 1990) were to determine mean annual home range, habitat use, food preferences, and denning habits. Presented here are the results of our study on denning habits. Specifically, we sought to determine a mean denning period for San Gabriel Mountain black bears and a general description of their den sites. We expected similarities in denning habits between this population and those of black bears throughout the southwest. However, due to incidents of winter- active male bears in central and southern California (Sequoia National Park [Graber 1991], San Bernardino Mountains [Novick 1981]) we speculated that some bears in this population might also be winter active. Methods Study area.—The study area was a 200 km? section of the San Gabriel Moun- tains (34°15’N, 117°45’W) approximately 32 km from downtown Los Angeles. Elevations ranged from 450 m to 1890 m and average annual temperature was 13.1°C. Average annual precipitation was 858 mm (January—December), of which more than 70% fell mainly as rain between January and May. Precipitation during 30 BLACK BEAR DENNING CHARACTERISTICS 31 the study years was approximately half the annual average (United States De- partment of Commerce, Climatological Data California 1987-1990). The cool (average minimum February temperature = 0.84°C), moist winters, and hot (av- erage maximum July temperature = 28.6°C), dry summers, and abruptly varying topography strongly influenced the distribution of vegetation, resulting in a mosaic of habitat types. Chaparral consisting of Adenostoma fasiculatum, Arctostaphylos sp., Ceanothus sp., Cercocarpus sp., and Quercus dumosa was the most extensive vegetation type. Other vegetation types included oak woodland (pure stands of Q. chrysolepis or mixed with Q. wislizenii), oak in association with conifer (pri- marily Pseudotsuga macrocarpa and Pinus coulteri), and pure stands of conifer (Pinus ponderosa, P. jeffreyi, and P. lambertiana). Riparian consisting of Alnus rhombifolia, Acer macrophyllum, and Salix sp. comprised less than 5% of the study area (Weislander 1934). Winter weather conditions were relatively mild during the study. However, a series of snow storms during December of 1988 and March of 1991 resulted in several road closures within the study area. The area is heavily used for recreation, including hunting. Bear season usually runs from mid-October through the end of December. The ten year average for Los Angeles County is three bears per year (Department of Fish and Game 1990 Bear Take Report). In 1987, one collared bear (15M) was legally killed. Bears have unrestricted access to the dumpster contents of several camps and residences within the area. Trapping and tracking. —Between July 1986 and August 1990 eight bears (one adult female, one juvenile female, and six adult males) were captured using culvert traps or Aldrich foot snares. Bears were immobilized with a 2:1 mixture of ke- tamine hydrochloride and zylazine hydrochloride and fitted with radiotransmitter collars (Telonics; Mesa, Arizona). Age, weight, dimensions, and general condition were also noted. Collars were motion-sensing and broadcasted at either of two pulse rates depending on the activity of the bear. Bears were located from the ground by triangulation using a Yagi three-element antenna. Each triangulation consisted of at least three compass bearings. The maximum angle between any two of the three bearings was as close to 90° as was physically possible given the terrain. Most ground locations were obtained 0.5 km io 1.0 km from the bear. When bears were widely dispersed or ground location attempts failed, a fixed wing aircraft was used to obtain location. Den entry dates were defined as the midpoint between the last recorded move- ment and the first of a series of stationary signals. Den emergence dates were defined as a midpoint between the last denning location and the first location away from the den (O’Pezio et al. 1983). Length of hibernation was defined as the interval between the entrance and exit dates. Dens were located approximately one month after bear entry and revisited later for characterization. Den entrance, exit, and duration were compared across all four years with the SAS Kruskal-Wallis NPAR1IWAY procedure (SAS 1985). Post hoc comparisons were made using Tukey’s LSD test for nonparametric data (Conover 1980). Steep terrain prevented the location of every den. Bears whose dens were found and characterized included: 15F (N = 3), 34M (N = 3), 55F (N = 1), and 00M (N = 2). At least one year’s worth of entrance and exit dates were available for most other bears (14M, 80M, 15M). 32 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 1. Summary of den site characteristics. Ele- En- Slope Habitat Cover vation Den trance Bear Year! (%) type (%) (m) aspect aspect Site 34M 87 46 Oak 90 1384 ENE NE Boulder 34M 89 53 Oak 90 989 ENE NE Boulder 34M 90* 46 Oak 90 1384 ENE NE Boulder OOM 87 80 Conifer 85 927 NNW SE P. macrocarpa OOM 88** 80 Conifer 85 927 NNW SE P. macrocarpa 15F 88 34 Oak 40 1274 NNE up O. chrysolepis 1S5F 89 iB) Oak/ 65 1500 WNW E P. macrocarpa Conifer 1SF 90** 1) Conifer 65 1500 WNW E P. macrocarpa 55F 87 67 Conifer 70 1317 ESE up O. chrysolepis ' Year of entrance. : * Same den site as 1987, no data on 1988 den. ** Same den site as previous year. Results Den characteristics.— All bears with at least two known den sites reused a previous den (34M, 1987 and 1990; 15F, 1989 and 1990). All dens were found in tree cavities (base, limb, or mid trunk of Quercus chrysolepis or Pseudotsuga macrocarpa) or under boulders and all dens were located among stands of oak or conifer (Table 1). Two of the eight dens we located contained bedding (34M’s 1989 den, uniden- tified leaves and small branches; 15F’s 1988 den, Yucca whipplei leaves). Exca- vated dens were not observed during this study. Dens of San Gabriel Mountain black bears were generally located on north facing slopes. Entrance and duration.—Male bears entered their dens significantly later in 1988 than all other years (x* = 8.33, P = .04 for Kruskal Wallis and P < .05 for each pairwise comparison). Length of denning ranged from early September to late March (Table 2) and was not significantly different between years (x? = 4.8, P = .19; based on Kruskal Wallis tests). During 1988, 1989, and 1990 bear 80M disappeared without trace of radio signal from ground or air (each spring he reappeared). Period of disappearance, which ranged from early September to late December, was treated as a denning period. All bears remained at their den sites even on warm winter days. Exit. — Bears consistently (x? = 1.18, P= .76) emerged from their dens in March despite variations in den entrance dates (between years and between bears). Spring- like weather conditions usually prevailed during this time however, bears emerged from their (1990) dens in March of 1991 during a rare storm with heavy rains and snow. Discussion Den entrance, exit, and duration. —Denning behavior has been associated with several variables. In general, these include food availability (Rogers 1987; O’Pezio 33 BLACK BEAR DENNING CHARACTERISTICS "286 JO se (S194) O8V - ‘skep /-| = powea pur ajeurrxoidde oie saiep [TV | See ee eee — oo = = = C8 = = = 9C/T ae = 97/TI 9C/TI ¢ ASS L8 v9 TZ ie OI/E I/€ 8/E = €1/CI LT/Cl LC/Cl = Cl ASI OIT €cl 6L cel OI/€ CI/E 6/€ O£/E 17/11 8/TI LI/TI 07/01 uBsUl [BI =z 6L OL = = v/E 87/7 Se 1/01 CI/TI vI/Tl es 9 Wr Oc! 807 v6 ILI OI/t 6C/E 61/€ LT/E T¢/01 67/6 CI/Cl 8/01 9 WO08 r= = 89 TOI = = v/t €/T = = 9C/TI ¢c/Ol at WO00 68 £8 re 6c1 OI/E I/€ aa 8C/T O/T 8/TI = CT/Ol 9 We = = = 6£1 = a = 6/t = an = TC/OI ¢ WSI 16/06 06/68 68/88 88/L8 16 06 68 88 06 68 88 L8 c08V Ievogq sevseeeenenenneneettens (JO STOYUIM) SICO Ao wnennnnennencecee ceecececcececceneececeeeecenetnetnes ITBQ J cteeserseneneeceneenenneneeneneenee seeeeneeneneenenerneneneeneneenetnenn, UIQ) JL coseercneaneneneencneneensnensersns uoneing So1ep 1IXq solep souenUuq ee SS — E==_=_=—_=_—_______—_—EEEEE~E~yaEEEEEEEEEeEeEeEeEe—eeeEeEeEeEeEeEeEeEEe————— ee ———————————————————eeeeoOOOoeeeeeeeeeeeeeoeoqoeoeoeoaoaoaoaoaoaoooqoaeeeeeeee——————— SS qa (OE ‘0661 YZNoIM) 1/86] ZULINP suIeJUNO|Y [ALIQeyH URS dy} Ul SIvaq YoRTG JO ,sa1ep BulUUsq “7 IIQUL SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Table 3. Comparison of approximate denning dates for black bears across North America. Location Begin End Duration Reference East-central early Oct.—early early April 171 Tietje and Ruff (1980) Alberta Nov. Southwest late Oct.—late late March 125 Lindzey and Meslow Washington Nov. (1976) West-central mid Oct.—late mid April 171 Amstrup and Beecham Idaho Nov. (1976) Montana late Oct. mid April—mid 192 Jonkel and Cowan May (1971) Coastal North mid Dec. late April 125 Hamilton and Mar- Carolina chinton (1980) Central Arizona early Nov. mid March—mid 141 LeCount (1983) April Central California mid Dec. late March 104 Graber (1990) Southern Califor- mid-late Dec. early March-—late 100 Novick et al. (1981) nia April Southern Califor- mid Oct.—mid early March 112 This study nia Dec. et al. 1983) weather (Jonkel and Cowan 1971), circannual rhythm (Johnson and Pelton 1980), bear condition (Lindzey and Meslow 1976), photoperiod (LeCount 1983), or combinations of the above (Schwartz et al. 1987). The importance of these individual factors and how they influence denning behavior may vary from year to year and between bears within a region (O’Pezio et al. 1983). Bears in this study denned for about the same length of time as bears in the San Bernardino Mountains (Novick et al. 1981), and similarly mild climates (Lindzey and Meslow 1976; Hamilton and Marchinton 1980; Graber 1991), and for a shorter period of time than bears in colder climates (Amstrup and Beecham 1976; Tietje and Ruff 1980; Jonkel and Cowan 1971). Den emergence dates were similar to those found in the San Bernardino Moun- tains (Novick et al. 1981) and Sierra Nevada range (Graber 1991) of California (Table 3). A small sample size precludes an effective evaluation of the influence of age and sex on denning behavior of San Gabriel Mountain black bears. Two females (S5F and 15F, both with no sign of pregnancy or cubs) observed during this study entered their dens later than male bears (approximately one month later than male bear mean) but emerged around the same time. These observations are consistent with those of Beecham et al. (1983) who found adult males den sig- nificantly earlier than non-pregnant females. Novick et al. (1981) and Schwartz et al. (1987) have reported that pregnant females den earlier and longer than males and non-pregnant females. It has been suggested that food availability and the acquisition of body fat may be the initial elements triggering den entrance (Rogers 1987). When body fat is low and food is available, bears have postponed denning by feeding later in the year until food resources were unavailable (Jonkel and Cowan 1971; Herrero 1978; Johnson and Pelton 1980; Tietje and Ruff 1980). Conversely, bears have denned early after reaching optimum fat levels when food resources were abundant as well as when nutritious foods were in short supply (Rogers 1987). BLACK BEAR DENNING CHARACTERISTICS 35 We suggest fluctuations in food item availability may play a large role in the onset of denning in San Gabriel Mountain black bears. In 1986, the acorn crop was prolific and acorns were available throughout the spring, summer, and early fall of 1987. Entrance dates (late October of 1987), which coincided with the disappearance of acorns, may have been the result of bears having reached op- timum hibernation weight after feeding heavily on such a high calorie item for most of the year. The following fall acorns were absent but holly-leaf cherries (Prunus ilicifolia) were abundant and persisted well into January of 1989 (bears denned in late December of 1988). Scat contents from 1988 indicated bears were foraging late in the year on this readily available but possibly less preferred item. Our observations from 1989 and 1990, when bears entered dens at approxi- mately the same time (mid November), indicated that several natural foods were available to bears. There were no obvious fluctuations in food item availability; bears were eating the same items in similar proportions during both years. Acorns and coffeeberries (Rhamnus ilicifolia) dominated fall scats, and although the holly- leaf cherry crop was plentiful in the field, they were found in less than 2% of the scats (Stubblefield 1993). Several researchers have reported winter-active male bears which did not den at all (Hamilton and Marchinton 1980, Novick 1981, Graber 1991). Graber (1991) suggested, after observations of winter-active male bears in Sequoia National Park, foraging especially at aggregate clumps (natural or anthropogenic), may be more energy efficient than hibernating. Despite availability of natural foods and access to anthropogenic foods, all bears observed during this study denned. We observed that bears cease their camp visits in late September and October. Abandonment of camps appeared to coincide with the initiation of deer season in late September followed by bear season in late October. Hunting may curtail the quantity of time spent foraging on anthropogenic foods thus increasing the importance of natural foods during this time of the year. Although availability or nutritive contribution of food resources (natural or anthropogenic) were not measured directly during our study, our observations tend to support the hy- pothesis that food availability may influence the onset of denning especially during extreme years. Weather may not be the most important factor triggering the onset or duration of denning in San Gabriel Mountain black bears. Other researchers suggest the relationship between temperature or weather and den entrance (Novick et al. 1981) and den emergence are weak (O’Pezio 1983). Novick et al. (1981) felt that in regions with mild climates the severity of the winter influences the time of emergence and the duration, but not the onset, of denning. Although an increase in temperature is reported to influence den emergence and duration (Novick et al. 1981), bears in the San Gabriel Mountains consistently exit their dens at approximately the same time each year despite variations in weather (heavy rain and snow during 1991 emergence) or their individual den entrance dates. Den characteristics and reuse. —Den location, presence or absence of bedding, and excavation vary between regions. The use of rocks (LeCount 1983; Novick 1981; Beecham et al. 1983) and trees, cavity or base, (Jonkel and Cowan 1971; Hamilton and Marchinton 1980; Johnson and Pelton 1981) as dens is well doc- umented, but the presence of nesting materials varies considerably and appears 36 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES independent of winter weather conditions. In southern California, use of bedding materials appears limited. Novick et al. (1981) reports a small amount of bedding material was found in San Bernardino Mountain dens (no mention of the actual number of dens containing bedding) while within the San Gabriel Mountains, only two of the nine dens we found (55F, 1987; 34M 1989) contained nesting material. Den excavation by black bears has been observed in most regions (Johnson and Pelton 1981, Tennessee; LeCount 1983, Arizona; Beecham et al. 1983, Idaho) including the San Bernardino Mountains (Novick et al. 1981). San Bernardino Mountain black bears (Novick et al. 1981) “construct” their dens by excavating under standing trees or large boulders whereas San Gabriel Mountain black bears appear to be making use of natural cavities in trees or openings between boulders. However, the cavity under one boulder den (34M, 1989) might have been the result of a previous (bear or year) excavation. Most black bear studies, even in the nearby San Bernardino Mountains (Novick et al. 1981), indicate that bears seldom reuse dens. LeCount (1983) suggested reuse may indicate a shortage of quality dens. Since logging pressure is minimal and estimated bear density moderate to low, this explanation does not seem likely for the San Gabriel Mountain population. Perhaps bears associate a previous den site with safety and available foods upon emergence. Due to the small sample size of individuals observed, generalized statements concerning denning habits of San Gabriel Mountain black bears are limited. Additional research is needed before the factors affecting the timing of denning as well as the characteristics of den sites can be accurately assessed within this population. Acknowledgments We would like to thank Curtis Clark, David Moriarty, and Glenn Stewart for their guidance. Permission to trap and collar bears was granted by the California Department of Fish and Game. Financial support was provided by Alan Neal and the Los Angeles County Fish and Game Commission. A special thanks to Rob Martens and Ken Watanabe for their assistance in locating dens. Literature Cited Amstrup, S. C., and J. J. Beecham. 1976. Activity patterns of radio-collared black bears in Idaho. J. Wiidl. Mgmt., 40:340-348. Beecham, J. J., D. G. Reynolds, and M. G. Hornocker. 1983. Black bear denning activities and den characteristics in west-central Idaho. 5th Internat. Conf. Bear Res. and Mgmt., 5:79-86. Boyer, K. B. 1976. Food habits of black bears (Ursus americanus) in the Banning Canyon area of San Bernardino National Forest. Unpubl. Master’s Thesis. California State Polytechnic Uni- versity, Pomona, California, 53 pp. Braden, G. T. 1991. Home ranges, habitat use, and denning characteristics of black bears (Ursus americanus) in the San Gabriel Mountains of southern California. Unpubl. Masters Thesis. California State Polytechnic University, Pomona, California, 80 pp. Burgduff, A. E. 1935. Black bears released in southern California. California Fish and Game, 21: 83-84. Conover, W. J. 1980. Practical nonparametric statistics. Second edition. John Wiley and Sons, New York, New York, 493 pp. Department of Fish and Game. 1990. California Bear Take Report. BLACK BEAR DENNING CHARACTERISTICS 37 Graber, D. M. 1991. Winter behavior of black bears in the Sierra Nevada, California. 8th Internat. Conf. Bear Res. and Mgmt., 8:269-272. Grinnel, J., J. S. Dixon, and J. M. Linsdale. 1937. Furbearing mammals of California. Vol. 1. University of California Press, Berkeley, California, 375 pp. Hamilton, R. J., and R. L. Marchinton. 1980. Denning and related activities of black bears in the coastal plain of North Carolina. 4th Internat. Conf. Bear Res. and Mgmt., 4:121-126. Herrero, S. 1978. A comparison of some features of the evolution, ecology, and behavior of black and brown/grizzly bears. Carnivore, 1:7-17. Hogan, N. F. 1984. Home range and habitat preferences of female black bears (Ursus americanus) in the San Bernardino Mountains of southern California. Unpubl. Masters Thesis. California State Polytechnic University, Pomona, California, 48 pp. Johnson, K. G., and M. R. Pelton. 1980. Environmental relationships and the denning period of black bears in Tennessee. J. Mamm., 61:653-660. Jonkel, C. J.,and McT. Cowan. 1971. The black bear in the spruce-fir forest. Wildlife Monographs, 27:1-57. LeCount, A. L. 1983. Denning ecology of black bears in Central Arizona. 5th Internat. Conf. Bear Res. and Mgmt., 5:71-78. Lindzey, F.G.,and E.C. Meslow. 1976. Winter dormancy in black bears in southwestern Washington. J. Wildl. Mgmt., 40:408-425. Moss, H. H. 1972. A study of the black bear in the San Gabriel Mountains. Unpubl. Masters Thesis. California State Polytechnic University, Pomona, California, 63 pp. Novick, H. J., J. M. Siperek, and G. R. Stewart. 1981. Denning characteristics of black bears (Ursus americanus) in the San Bernardino Mountains of southern California. California Fish and Game, 67:52-61. O’Pezio, J., S. H. Clarke, and C. Hackford. 1983. Chronology of black bear dennirig in the Catskill region of New York. Sth Internat. Conf. Bear Res. and Mgmt., 5:87-93. Rogers, L.L. 1987. Effects of food supply and kinship on social behavior, movements, and population growth of black bears in northeastern Minnesota. Wildlife Monographs, 97:1—72. SAS Institute. 1985. SAS user’s guide: basics, version 5. Schwartz, C. C., S. D. Miller, and A. W. Franzmann. 1987. Denning ecology of three black bear populations is Alaska. 7th Internat. Conf. Bear Res. and Mgmt., 7:281-292. Siperek, J. M. 1979. Physical characteristics and blood analysis of black bears (Ursus americanus) in the San Bernardino Mountains of southern California. Unpubl. Masters Thesis. California State of Polytechnic University, Pomona, California, 63 pp. Stubblefield, C. H. 1993. Food habits of black bears in the San Gabriel Mountains of southern California. Southwestern Nat. Jn press. Tietje, W. D. and R. L. Ruff. 1980. Denning behavior of black bears in the boreal forest of Alberta. J. Wildl. Mgmt., 44:858-870. United States Department of Commerce. 1987-1990. Record of river and climatological observa- tions. Mount Wilson Station. Asheville, North Carolina. Wieslander, A. E. 1934. Vegetation types of California. Pasadena, Pomona, and Tujunga Quadran- gles. United States Forest Service, Arcadia, California. Accepted for publication 25 June 1993. Bull. Southern California Acad. Sci. 93(1), 1994, pp. 38-41 © Southern California Academy of Scierices, 1994 RESEARCH NOTES Additional Archaeological Evidence for Colorado River Fishes in the Salton Basin of Southern California Kenneth W. Gobalet Department of Biology, California State University, Bakersfield, California 93311 Fish remains recovered from archaeological sites in the Salton Basin of south- eastern California have attracted considerable attention, in part, because most fishes represented are endangered and are normally associated with the lower Colorado River or the Sea of Cortez. They also capture the imagination because their habitat was the huge prehistoric Lake Cahuilla fed by the Colorado River where now only stark desert vegetation or the saline Salton Sea exist. In a previous survey of the fishes represented by remains recovered from archaeological sites of the Salton Basin, Gobalet (1992) reported the remains of razorback sucker, Xyrauchen texanus, Colorado squawfish, Ptychocheilus lucius, bonytail, Gila ele- gans, striped mullet, Mugil cephalus, and machete, Elops affinis. He also suggested that more species might have been present in Lake Cahuilla than have been previously reported or that hybrids may have been present. That summary omitted numerous unpublished archaeological site reports that quantified the recovered fish remains. The fish remains recovered from archaeological sites CA-IMP-6427 (Elmore site), CA-RIV-1331, CA-RIV-1349, and CA-RIV-4128 have recently been stud- ied. Results of those projects, along with findings of other researchers overlooked in the prior study, are reported here. Site CA-IMP-6427 is located adjacent to State Route 86, 2 miles east of Kane Spring in western Imperial County, California. It was occupied around A.D. 1663 (Don Laylander, pers. comm., January 1993). Sites CA-RIV-1331 and CA-RIV-1349 are located at the mouth of Toro Canyon, south of Indian Wells in Riverside County, California. Radiocarbon dates for these two sites are 320 + 90 y.b.p. for CA-RIV-1331 and 110 + 88 y.b.p. for CA-RIV-1349 (Jerry Schaefer, personal communication, April 1993). CA-RIV- 4128 is located north of Coachella on the Cabazon Indian Reservation. Specific objectives of this study have been to comprehensively evaluate the new material to determine whether or not humpback chub (Gila cypha), roundtail chub (G. robusta) or flannelmouth sucker (Catostomus latipinnis) were present as suggested previously by Gobalet (1992) and to determine whether or not evidence for hybridization could be found. These findings and the data missed by Gobalet (1992) give a more complete and accurate picture of the fishes that occupied Lake Cahuilla. The fish identifications were determined by comparison with the skeletons at California State University, Bakersfield, supplemented with the comparative ma- terials indicated in the materials examined section. The precaudal vertebrae of minnows (Cyprinidae) can be distinguished from those of suckers (Catostomidae) by the presence of a narrow strut interconnecting the socket of the parapophysis 38 RESEARCH NOTES 39 Table 1. Summary of fish remains recovered from archaeological sites in the Salton Basin of Southern California. Indicated below are the number of elements identified. Ptycho- cheilus lucius, Xyrauchen Colo- Mugil Gila texanus, rado cephalus, —_Elops elegans, razorback squaw- striped affinis, bonytail sucker fish mullet machete Reference RIV-1331 16 8 ] — ] This report RIV-1349 337 33 1 — — This report RIV-2937 5 30 1 — — Salls 1985 RIV-2997 83 10 1 2 _ Salls 1985 RIV-2998 46 — _ — — Salls 1985 RIV-2999 54 2 — 1 _ Salls 1985 RIV-3000 33 1 1 1 _ Salls 1985 RIV-4128 20 310 —_ — _ This report IMP 4434 45 gm 310 gm — 6 gm — Follett 1985a IMP 5204 3420 194 2 43 5 Roeder & Salls 1986 IMP 1141 8 14 — — — Salls & Roeder 1987 IMP 5428 8 5 _ — — Salls & Roeder 1987 4-IMP-1049 3 — _— — — Salls & Roeder 1988 4-IMP-5270 — 16 — — — Salls & Roeder 1988 IMP-3688 35 31 = l — Follett 1985b IMP-4926 — 53 — — _— Roeder 1982 IMP-6427 3 35 — — 1 This report SDI-4443 65 12 _ 1 1 Findley 1977 14 sites 2666 1582 110 62 2 Gobalet 1992 Total 6802 2335 117 111 10 with the neural spine. The caudal vertebrae of minnows have a ventrally projecting spine on the posteroventral portion of the centrum that is lacking in suckers. All catostomid elements are probably razorback sucker. The remains identified as bonytail might possibly be another member of the genus Gi/a, but this seems increasingly unlikely. The tally of fish remains recovered from archaeological sites CA-IMP-6427, CA-RIV-1331, CA-RIV-1349, and CA-RIV-4128 are found in Table | along with the findings of fish remains from 28 other widely separated sites within the Salton Basin. Bonytail and razor back sucker were clearly the dominant large species captured by the Cahuilla Native Americans and were probably the dominant species in the lake with the piscivorous squawfish and machete, and bottom feeding mullet, minor in importance. The biology of these fishes and the methods of aboriginal capture have been reviewed extensively by Gobalet (1992). No remains of the flannelmouth sucker, roundtail or humpback chubs have been found. It appears that the only member of the Gi/a robusta complex present in Lake Cahuilla or its Salton Basin tributaries was the bonytail and the only sucker, the razorback sucker. Without the presence of additional chubs or suckers, hybridization would not have occurred. Sampling techniques that do not lead to the microscopic evaluation of midden material still leave doubt as to whether the small desert pupfish (Cyprinodon macularius), Gila topminnow (Poeciliopsis oc- cidentalis), or woundfish (Plagopterus argentissimus), were present as Gobalet 40 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES (1992) suggested. No such sampling was undertaken in these projects. These studies collectively suggest that bonytail and razorback suckers were the dominant large species in Lake Cahuiulla and that the predatory Colorado squawfish, diad- romous striped mullet, and machete. were rare. Acknowledgments The following individuals have my thanks for contributing to this study: David Catania, Michael E. Douglas, Lloyd T. Findley, Paul Langenwalter, W. L. Minck- ley, Douglas W. Nelson, Mark A. Roeder, Jerry Schaefer, Don Laylander, Julie Gunn, Aggie Arvizu, and Traci Alexander. Materials Examined Institutional abbreviations are as listed by Leviton et al. (1985) except those designated KWG are in the collection at California State University, Bakersfield. Catostomus latipinnis: ASU 13844, UMMZ 179561: C. macrocheilus: KWG 353: C. occidentalis: KWG 240: C. tahoensis: KWG 545; C. fumeiventris: KWG 536: Chasmistes cujus: KWG 488: Xyvrauchen texanus: ASU 14882; Gila bicolor: KWG 358, KWG 377, KWG 357; G. cypha: UMMZ 178667-S, 179577-S, ASU 14156: G. elegans: CAS 25865, CAS 66037, CAS 66038; UMMZ 179581, UMMZ 176972-S, UMMZ 179580-S, ASU (uncataloged, 360 mm S.L.): G. robusta: ASU 10509, CAS 25850, UMMZ 182502-S; Ptychocheilus grandis: KWG 539, KWG 540, KWG 548; P. lucius: ASU 13866, CAS 26210; P. oregonensis: KWG 347, KWG 404, KWG 454. Literature Cited Findley, L. T. 1977. Archeoichthyology of the Barrel Springs site (CA-SDI-4443) with notes on adjacent areas of the Colorado Desert, California. Unpublished manuscript. Follett, W. I. 1985a. Fishbone analysis. Pp. C-1 to C-8 im Lake Cahuilla prehistoric occupation at IMP-4434 and IMP-5167 Imperial Valley, California. (D..Gallegos, ed.), Manuscript on file, WESTEC Services, Inc., 5510 Morehouse Drive, San Diego, CA 92121-1709. —. 1985b. Analysis of fish remains from six localities adjacent to State Route 86, Imperial County, California. Pp. 175-182 im Report of archaeological test excavations at five sites located along Highway 86 in Imperial County, California: CA-IMP-3675, CA-IMP-3676, CA-IMP- 3678. CA-IMP-5099 and CA-IMP-5101, 11-IMP-86, 60.9, 67.8, 11208-182641.(M. D. Rosen, ed.), Manuscripts on file. Environmental Planning Branch Caltrans District 11, P.O. Box 85406, San Diego, CA 92138-5406. Gobalet, K. W. 1992. Colorado River fishes of Lake Cahuilla, Salton Basin, southern California: a cautionary tale for zooarchaeologists. Bull. Southern California Acad. of Sci., 91(2):70-83. Leviton, A. E., R. H. Gibbs Jr.. E. Heal, and C. E. Dawson. 1985. Standards in herpetology and ichthyology: part I. Standard symbolic codes for institutional resource collections in herpetology and ichthyology. Copeia, 1985(3):802-832. Roeder. M. A. 1982. An analysis of column samples from archaeological sites (IMP-4926), western Imperial County, California. Pp. D-1 to D-4 in Archaeological data recovery program: northern portion of IT Corporation Imperial Valley site. (R. Philips, ed.), Manuscript on file, WESTEC Services Inc., 5510 Morehouse Drive, San Diego, CA 92103. ,and R. A. Salls. 1986. Fish remains from the late prehistoric Dunaway Road site, Imperial County, California. Pp. 105-118 in Late prehistoric adaptations during the final recessions of Lake Cahuilla: fish camps and quarries on West Mesa, Imperial County, California. (J. Schaefer, ed.), Manuscript on file. USDI, Bureau of Land Management, 333 South Waterman Avenue, El Centro, CA 92243. Salls,R. A. 1985. Fish remains from the Oak Tree West sites (CA-RIV-2937-3000), Coachella Valley Riverside County, California. Unpublished manuscript. RESEARCH NOTES 41 , and M. A. Roeder. 1987. Fish remains. Pp. 145-149 in Settlement and subsistence at San Sebastian: a desert oasis on San Felipe Creek, Imperial County, California. (J. Schaefer, L. J. Bean, and C. M. Elling, eds.), Manuscript on file, USDI, Bureau of Reclamation, 400 Railroad Avenue, P.O. Box 427, Boulder City, NV 89005. , and . 1988. Fish remains. Pp. 160-163 in Lowland Patayan adaptations to ephemeral alkali pans at Superstition Mountain, West Mesa, Imperial County, California. (J. Schaefer, ed.), Manuscript on file, USDI, Bureau of Land Management, El Centro Resource Area Office, 333 S. Waterman Avenue, El Centro, CA 92243. Accepted for publication 5 August 1993. Bull. Southern California Acad. Sct. 93(1), 1994, pp. 42-44 © Southern California Academy of Sciences, 1994 Occurrence of the Swallow Damselfish, Azurina hirundo, from Islands off Southern California Robert N. Lea! and Florence McAlary” ‘California Department of Fish and Game, Marine Resources Division, 20 Lower Ragsdale Drive, Monterey, California 93940 ?University of Southern California, Wrigley Marine Science Center, P.O. Box 398, Avalon, California 90704 The damselfish genus Azurina is comprised of two species restricted to the eastern Pacific Ocean (Allen 1991). Azurina hirundo Jordan and McGregor [in Jordan and Evermann 1898], the swallow damselfish, is known from several island groups off the coast of Mexico: Isla Guadalupe (type locality), Islas San Benito (RNL, pers. observation), Rocas Alijos, and Islas Revillagigedo. Gotshall (1989) speculated that it ““may occur as far north as the Coronado Islands, Baja California and San Clemente Island, California.’ Its occurrence at Clipperton, Las Tres Marias, and the islands within the Sea of Cortez is unknown. Azurina eupalama Heller and Snodgrass 1903, the Galapagos damselfish, is considered a Galapagos Archipelago endemic; the type locality is Hood Island (also known as Espanola). It has not been collected or observed at either Cocos Island (R. J. Lavenberg, Natural History Museum of Los Angeles County and W. A. Bussing, University of Costa Rica; pers. comm.) or at Malpelo Island (McCosker and Rosenblatt 1975). The most notable character in distinguishing these two taxa is color: A. hirundo is metallic blue to black while A. eupalama is olive and gray. Allen (1991) gives meristic characters (pectoral rays and gill rakers on lower limb) which are non- overlapping and which also serve to differentiate these species. Heller and Snod- grass (1903) mention morphometric differences between hirundo and eupalama: however, after examining specimens of both forms at the Marine Vertebrates Collection, Scripps Institution of Oceanography, it appears that morphometry is not dependable for separating these species. On 4 March 1991, while diving at Big Fisherman Cove, Santa Catalina Island (lat 33°26.8'N, long 118°29.0’'W), the junior author (FM) observed two unusual damselfish which were schooling with the locally common damselfish, the black- smith, Chromis punctipinnis. The two fish were estimated at 5 to 6 inches in length and were at a depth of ca. 8 m; water temperature at 10 m was 14.9°C. These damselfish were recognized as Azurina, having been seen by FM at Isla Guadalupe, Mexico in 1983. Azurina hirundo is generally similar in color to Chromis punctipinnis but is much more elongate and possesses a strongly forked caudal fin; A. eupalama is olive and gray in color. Unfortunately, these fish were not photographed or collected, hence this record must remain anecdotal. Five months later, on 1 August 1991, near Pyramid Cove, San Clemente Island (ca. lat 32°50'N, long 118°22'W), Larry Naylor, an underwater photographer, observed and photographed three individuals at two locations at this island (Fig. 1). The length of these damselfish was estimated as between 5 and 6 inches. Two of these fish were at ca. 8 m and the third at 16 m, all in close association with the bottom. 42 RESEARCH NOTES 43 Fig. 1. Swallow damselfish, Azurina hirundo, at Pyramid Cove, San Clemente Island, 1 August 1991. Photo by Larry Naylor. On 23 July 1992, a single Azurina was observed at Big Fisherman Cove (by FM), essentially the same location as the 1991 observation. These three observations, one corroborated by underwater photography, rep- resent the first documented occurrences of the swallow damselfish from Califor- nian waters. The addition of Azurina hirundo to the California ichthyofauna is yet another example of a tropical organism occurring in the warm-temperate Marine environment off southern California (Radovich 1961; Hobson 1969; Swift 1986; Brooks 1987; Lea et al. 1989; etc.). New records of tropical species from California can be expected in the future, especially during and immediately fol- lowing periods of oceanic warming such as the El Nino events of 1957-59, 1982- 84, and 1992-93. The majority of these occurrences constitute expatriated indi- viduals or minor populational movements and under most circumstances rep- resent dead-end or waif populations in terms of their reproductive potential. Literature Cited Allen, G. R. 1991. Damselfishes of the worid. Mergus Publ., Melle, Germany. 271 pp. Brooks, A. J. 1987. Two species of Kyphosidae seen in King Harbor, Redondo Beach, California. Calif. Fish and Game, 73(1):49-50. Gotshall, D. W. 1989. Pacific Coast inshore fishes. Third Ed. Sea Challengers, Monterey, Calif. 96 pp. Heller, E., and R. E. Snodgrass. 1903. Papers from the Hopkins Stanford Galapagos Expedition, 1898-1899. XV. New fishes. Proc. Washington Acad. Sci., 5:189-229, plates 11—xx. Hobson, E. S. 1969. First California record of the Guadalupe cardinalfish, dpogon guadalupensis (Osburn and Nichols). Calif. Fish and Game, 55(2):149-151. 44 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES Jordan, D. S., and B. W. Evermann. 1898. The fishes of North and Middle America. Bull. U.S. Nat. Mus., No. 47 (pt. 2):1241-2183. Lea, R. N., J. M. Duffy, and K. C. Wilson. 1989. The Cortez angelfish, Pomacanthus zonipectus, recorded from southern California. Calif. Fish and Game, 75(1):45—47. McCosker, J. E., and R. H. Rosenblatt. 1975. Fishes collected at Malpelo Island. Pp. 91-93 in The biological investigation of Malpelo Island. (J. B. Graham, ed.), Smithsonian Contri. Zoology 176. Radovich, J. 1961. Relationships of some marine organisms of the northeast Pacific to water tem- peratures, particularly during 1957 through 1959. Calif. Dept. of Fish and Game, Fish Bull. 112:62 p. Swift, C. C. 1986. First record of the spotted scorpionfish, Scorpaena plumieri from California: The curtain falls on ‘““A comedy of errors.” Calif. Fish and Game, 72(3):176-178. Accepted for publication 12 December 1992. Contribution no. 165 of Wrigley Marine Science Center. Proceedings of the Symposium Interface Between Ecology and Land Development in California Edited by Jon E. Keeley An outstanding compilation of timely papers by researchers, conser- vationists, consultants, and policymakers, including: Peter H. Raven Ecology and Species Extinction Jonathan L. Atwood California Gnatcatcher and Coastal Sage Scrub Martin L. Cody Theoretical and Empirical Aspects of Habitat Fragmen- tation : Jim A. Bartel Endangered Species Act: Land Development, Politics, and Reauthorization Cheryl Swift et al. Habitat Linkages in an Urban Mountain Chain Wayne R. Ferren et al. Rare and Threatened Wetlands of California G. Ledyard Stebbins Conservation of California’s Rare Habitats Todd Keeler-Wolf Rare Community Conservation in California Joy B. Zedler Restoring Biodiversity to Coastal Marshes Ted V. St. John et al. Use of Mycorrhizal Plants in Revegetation and Restora- tion Marylee Guinon Habitat Valuation and Restoration Costing Jim Jokerst An Alternative Approach to Vernal Pool Mitigation Plan- ning and twenty-nine other papers dealing with land mangement, biodiversity, habitat corridors, buffer zones, rare species, and community restoration. Price, $26.00 (soft cover, includes tax and shipping) Available from: Southern California Academy of Sciences 900 Exposition Blvd. Los Angeles, CA 90007 With this issue, the BULLETIN bids farewell to its two long-time editors: Tech- nical Editor, Jon Kelley, and Managing Editor, Gretchen Sibley. 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All changes in galley proof attributable to the author (misspellings, inconsistent abbreviations, deviations from style, ete. ) will be charged to the author. Reprint orders are placed with the printer, not the Editor. CON NTENTS - The Bi AOE ad Current Situs of the Long-cared Owl i in Coaste q S California. ‘By Peter He Bloom Occurrence and Habitat Use. of ree Mammals at Santa Cat California from 1 ots By pason ee slhaae BEAL SSE Denning Gharictersies of Binek Bears in the San Gabriel Southern California. By rence Hi: Stubblefield and Gera d Research Notes! Additional ecnacoloricnlk Pyaeace for Colorado River ReneS int Basin of Southern California. By Kenneth W. Cove! Occurrence of the Swallow Damselfish, Azurina hirundo, from Is Southern California. By Robert N. Lea and Florence McAl a0! pate AL me: COVER: Swallow damselfish 4zurina hirundo at Pyramid Cove, San Clemente Island, Photo by Larry Naylor. ;