Vot. 22, No. 1, 1991 WESTERN BIRDS Quarterly Journal of Western Field Ornithologists President : Narca A. Moore-Craig, 3532 Winston Way, Carmichael, CA 95608 Vice-President : Peter Gent, 55 South 35th, Boulder, CO 80303 Treasurer/Membership Secretary Howard L. Cogswell, 1548 East Avenue, Hayward, CA 94541 Recording Secretary: Jean-Marie Spoelman, 4629 Diaz Drive, Fremont, CA 94536 Orculation Manager: William E Haas, 10601-A Tierrasanta Blvd., Suite 127, San Diego, CA 92124 Directors: Bruce Deuei, Peter Gent, Ron LeVailey, John S. Luther, Guy McCaskie, Robert McKernan, Narca Moore-Craig, Janet Witzeman, David Yee Editor: Philip Unitt, 3411 Felton Street, San Diego, CA 92104 Associate Editors: Cameron Barrows, Tim Manolis, Thomas W. Keeney Graphics Manager: Virginia P. Johnson, 4637 Del Mar Ave., San Diego, CA 92107 Photo Editor: Bruce Webb, 8204 Cantershire Way, Granite Bay, CA 95661 Secretary, California Bird Records Committee: Michael A, Patten, P, O. 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If this is not possible, extra charges for typesetting will be made as follows: $15 full page, $10 half page, $5 quarter page. Send copy with remittance to the Treasurer. Make checks payable to Western Field Ornithologists. A 15% commission is allowed for agencies. WESTERN BIRDS Volume 22, Number 1, 1991 DISTRIBUTION AND HISTORY OF CALIFORNIA GULL COLONIES IN NEVADA P. K. YOCHEM, J. R. JEHL, JR., B. S. STEWART, Hubbs Sea World Research Institute, 1700 South Shores Road, San Diego, California 92109 S. THOMPSON, Laguna Atascosa National Wildlife Refuge, P. O. Box 450, Rio Hondo, Texas 78583 L, NEEL, Nevada Department of Wildlife, 380 West B Street, Fallon, Nevada 89406 Conover (1983) reported on breeding populations of the California Gull ( Larus californicus ) in the western United States and found that the total number of nesting birds in the 1980s had nearly tripled from that in the 1920s (276,000 vs. 101,000). The species’ status in Nevada is not well documented, even though rookeries are restricted to a few localities in the western part of that state. For example, Power (1980) presented low and high estimates for the number of breeding adults of 1800 and 7512, respectively, whereas surveys conducted by U.S. Fish and Wildlife Service (USFWS) and Nevada Department of Wildlife (NDOW) biologists during the late 1980s suggest there may be more than 15,000. In this paper we review what little is known about the status of the California Gull in Nevada, with emphasis on recent population estimates from Stillwater National Wildlife Refuge (NWR) , Pyramid Lake (Anaho Island NWR) , Fallon NWR, and Lahontan Dam and Reservoir (Figure 1) . Our survey is based on the literature, communication with wildlife managers and knowledgeable local biol- ogists, and on Annual Narrative Reports and other documents in USFWS and NDOW files. We report counts by management areas (e.g., wildlife refuges) because data were often presented that way in the unpublished reports we con- sulted; this occasionally gives the misleading impression that areas are widely separated when they are in fact adjacent. Indeed, these areas were often com- bined in the reports we reviewed (e.g., Stillwater Wildlife Management Area [WMA] Annual Narrative Reports included Stillwater NWR and parts of Fallon NWR) . HISTORY OF GULL COLONIES Pyramid Lake (Anaho Island and Gull Rock) California Gulls on Anaho Island (a 100- ha National Wildlife Refuge estab- lished in 1913) in Pyramid Lake now nest on a sandy beach on the south end of Western Birds 22:1-12, 1991 1 CALIFORNIA GULL COLONIES IN NEVADA the island and among the greasewood ( Sarcobatus vermiculatus) and saltgrass (Distichiis spicata ) flats along the west side of the island (Figure 2) . Historically, gulls nested in rocky habitat on the northern shore (e.g., figure 3 in Ridgway 1877, figure 17 in Woodbury 1966) . Data on the Pyramid Lake colony from 1868 through 1990 are given in Table 1. Ridgway (1877:637) described the gull colony in May 1868 as “immense,” spreading over “several acres of ground.” As the densest nesting areas for this species (at Mono Lake, Califor- nia, and Great Salt Lake, Utah) contain up to 1000 pairs/ acre, we infer that the colony seen by Ridgway numbered 4000-6000 birds. There were still “many” on Anaho Island in 1879 (Henshaw 1879), but by 1917 gulls had abandoned the island for Gull Rock, a group of small pinnacles (18 x 27 rn, elevation 18-21 m) at the northern end of the lake. Evermann (1923, cited by Hall 1926) Figure 1. Location of California Gull colonies in Nevada. 2 CALIFORNIA GULL COLONIES IN NEVADA estimated about 300 nests on Gull Rock in 1917, similar to Hall’s (1926) estimates of 600 adults and young in 1924 (Hall [1929:2] later stated that his estimate of 600 was “far too low” but did not clarify this) . Hall also observed large numbers of gulls near the American White Pelican ( Pelecanus erythro- rhynchos) colony on Anaho Island in 1924 but saw only one nest that was later abandoned. Ridgway (1877:638) reported that “many bushels of eggs were gathered for food,” and it might be that human disturbance and egging prompted a popula- tion decline and shift in nesting location, although the record is not sufficient to confirm causality. In any event, Hall (1929), in a letter to H. P. Sheldon (U.S. Game Conservation Officer), urged that Pyramid Lake be designated a bird reservation, primarily because of disturbance to American White Pelican col- onies, but he also noted that California Gulls and Double -crested Cormorants ( Phatacrocorax ouritus ) “[have] of late years suffered great destruction of eggs and young in the same way as has the White Pelican on Anaho Island.” Native Americans continued to collect eggs after the gull colony moved to Gull Rock, as Hall (1924:3) reported: “I learned that three days previous to my arrival at the lake [15 May 1924], an Indian fisherman had visited the rock and taken all the eggs for food. That they laid again was indicated by my count of three hundred (300) young gulls made on June 28 when I visited the rock.” California Gulls had resumed nesting on Anaho Island by 1927, when Gromme (1930) reported seven nests there; by 1940 there were 200 nests Figure 2. California Gull rookery at Anaho Island National Wildlife Refuge, Pyramid Lake, Nevada, 23 July 1990. Photo by Frank S. Todd 3 CALIFORNIA GULL COLONIES IN NEVADA Table 1 Numbers of California Gulls at Anaho Island, Pyramid Lake, Nevada Estimated Estimated Estimated Total or Counted or Counted or Counted Estimated Date Adults Nests Young Population Source 1868 U* yyn immense Ridgway 1877 1879 “many” Henshaw 1879 1924 l b Hall 1924 1927 7 Gromme 1930 1929 0 C Hall 1929 1940 200 Bond 1940 1942 504 G. Alcorn, cited in Marshall and Giles 1953 1948 1000 V. Mowbray, cited in Marshall and Giles 1953 1950 2000 400 d ANR, SWMA e 1951 1800 1706 684 4000 Marshall and Giles 1953 1952 1500 1400 4500 ANR, SWMA 1953 1500 900 4000 ANR, SWMA 1954 1500 ANR, SWMA 1955 2000 / ANR, SWMA 1956 2600 1750 ANR, SWMA 1957 1950 ANR, SWMA 1958 3000 1700 3000 ANR, SWMA 1959 2000 3500 ANR, SWMA 1960 2000 9 ANR, SWMA 1961 2150 2000 ANR, SWMA 1962 2550 3500 ANR, SWMA 1963 2500 ANR, SWMA 1964 1000 2100 4000 ANR, SWMA 1965 1200 2500 4500 ANR, SWMA 1966 1200 2500 5000 ANR, SWMA 1967 3000 4500 8000 ANR, SWMA 1968 2800 4200 9000 ANR, SWMA 1969 2200 4000 7500 ANR, SWMA 1970 2500 4625 10,000 ANR, SWMA 1971 1931 2895 h 6900 ANR, SWMA 1972 2100 2950 7000 ANR, SWMA 1975 3500 ANR. SWMA 1977 3000 H. Kingery. cited in Alcorn 1988 1978 800 ANR, SWMA 1979 2975 900 3875 ANR, Anaho, 1. NWR 1980 3400 750 4150 ANR. Anaho, 4 CALIFORNIA GULL COLONIES IN NEVADA Table 1 (Continued) Date Estimated or Counted Adults Estimated or Counted Nests Estimated or Counted Young Total Estimated Population Source 1981 4000 1750 600' ANR, Anaho 1. NWR 1982 1900 ANR, Anaho 1. NWR 1983 2150 1100 ANR. Anaho 1. NWR 1986 3550 2660 > Thompson 1987 1987 2800 2100 Bill Henry, pers, comm. 1988 2500 Bill Henry, pers. comm. 1989 1900 Bill Henry, pers. comm. 1990 1680 Bill Henry, pers. comm. Q 4000 - 6000: see text. ^One nest with one egg observed on south shore: nest later deserted. Hall (1924) noted large numbers of adults near pelican colony, to prey on eggs and chicks. Most nests were on Gull Rock; Hall estimated 600 adults and immatures but later felt this number to be “far too low" (Hall 1929) . c Author stated “at present and for many years past, the California Gulls . . . have nested many miles away from Anaho Island in the northern end of Pyramid Lake,” presumably on Gull Rock. ^ Mortality of juveniles very high due to banding operations e Annual Narrative Report, Stillwater Wildlife Management Area. f High mortality of juveniles; no numbers given. 3 Lowering lake level threatened to connect island to mainland. Authors noted production down 38% from 1970. ' Number fledged. j 13 May estimate; on 12 June, when most young had fledged recently, estimate was 4500 adults on 4500 nests. present (Bond 1940). During the 1950s the colony fluctuated between 1500 and 2000 nests (Marshall and Giles 1953, Stillwater WMA Ann. Narr. Repts.) . Data for the 1960s are difficult to interpret because of unequal censusing effort and inconsistent methods of censusing and reporting data, the precision of which is unstated. From 1964 through 1966 annual estimates of nests by USFWS personnel ranged from 1000 to 1200, but in 1967 and 1968, 2800-3000 nests were reported. From 1969 through 1977 counts were similar to 1950s levels, with two exceptions: 2500 in 1970 and 3000 in 1977. Nest counts resumed in 1981 after a lapse of several years and again were similar to 1950s levels; in two years, however, counts were higher (2660 in 1986, 2500 in 1988; Thompson 1987). There were 1680 nests present in 1990 (B. Henry pers. comm.). These counts are based on aerial surveys and ground counts from elevated observation points, and nest estimates are believed to be accurate to within 20% . Note that recent counts are similar to the probable size of the col- ony described by Ridgway (1877) in the 1860s. 5 CALIFORNIA GULL COLONIES IN NEVADA Stillwater National Wildlife Refuge Stillwater WMA, which includes Stillwater NWR, was established in 1948 and currently covers about 200,000 acres. Thompson and Merritt (1988) noted that the quality and quantity of its water has been steadily declining, as its source is return flow from irrigated land; for example, estimated wetland acreage de- clined from over 23,971 in 1986 to 4,388 in 1988 (Thompson and Neel 1989) . California Gulls nest, or have nested, at two sites within Stillwater NWR; Still- water Point Reservoir and Stillwater Marsh. In most years data are available only for the WMA as a whole, rather than by site, but in Table 2 we have in- Table 2 Numbers of California Gulls in the Stillwater National Wildlife Refuge, Nevada Date Estimated or Counted Adults Estimated or Counted Nests Estimated or Counted Young Source 1950 15 32 ANR, SWMA q 1951 100 128 ANR, SWMA Q 1952 100 100 ANR, SWMA 0 1953 15 20 ANR, SWMA 0 1954 20 25 ANR, SWMA 0 1955 80 100 ANR, SWMA 0 1967 300 b ANR, SWMA a 1972 100 b ANR, SWMA a 1977 1700 H. Kingery, cited in Alcorn 1988 1986 1200 NDOW Rept. 1987 1350 c NDOW Rept. 1988 0 Thompson and Neel 1989 1989 0 NDOW Rept. 1990 0 NDOW Rept, Stillwater Point Reservoir^ 1950 13 20 e Marshall 1951; ANR, SWMA 1951 100 ANR.SWMA 1954^ ANR. SWMA 19559 426 ANR, SWMA 1956 37 h ANR, SWMA 1957 49' ANR, SWMA a Annual Narrative Report, Stillwater Wildlife Management Area. b No nesting: see text. c Breeding pairs. d Small bare island, used for first time in 1950, abandoned several years later. e Estimated 6 reached maturity. f Nesting gulls still present. 9 Colony on island “overflowed,” some adults moved to shoreline of Stillwater Pt. and to Nutgrass Dike; predation was high in both areas. h Nests counted on 24 May. ' 26 of these on point of land on shoreline. 6 CALIFORNIA GULL COLONIES IN NEVADA eluded the few counts we found for Stillwater Point Reservoir; two counts for Stillwater Marsh are presented below. Nest counts made in the 1950s ranged from 15 (1950, 1953), to 100 (1951, 1952) (Stillwater WMA Ann. Narr. Repts). Ten of twelve counts made by USFWS biologists in the 1960s and early 1970s combined California and Ring- billed { Larus delawarensis ) gulls and therefore could not be used. About 300 California Gulls were present in 1967 and 100 were present in 1972, but ap- parently none nested; L. Napier (in Alcorn 1988) stated that there was “no nesting at Stillwater from 1967 to 1974.” P. Schwabenland (in Alcorn 1988) also reported that California Gulls “come to feed from Anaho where they nest. Have nested at Stillwater in the past although not at present [1974].” From 1976 on, abundance is reported as “use days” with a few anecdotal comments (Stillwater WMA Ann. Narr. Repts.) and is therefore essentially uninterpretable. For example, USFWS biologists reported that in 1976 use was down 65% and production was down 85% from 1975, and that use dropped to an all-time low (about 15% of long-term averages) in 1978, There is one report of 1700 nests in 1977 (H. Kingery, in Alcorn 1988). In 1980, gulls were considered “more abundant’ than in 1979, but no numbers were presented (Stillwater WMA Ann. Narr. Repts.). In 1986, 1200 nests were reported, and 1350 breeding pairs were observed in 1987 (NDOW Repts.). No California Gulls nested in the refuge in 1988, 1989, or 1990 (NDOW Repts.; Thompson and Neel 1989). The few counts reported for individual sites within Stillwater WMA are sum- marized below. Stillwater Point Reservoir. Stillwater Point Reservoir was first used by nesting California Gulls in 1950, when the refuge biologist recorded 13 nests with 20 young on a small bare island (Stillwater WMA Ann. Narr. Repts.; Marshall 1951) . The next report of nesting was in 1955, when 426 adults were counted and the colony “overflowed” to the shoreline of the reservoir and Nutgrass Dike (where predation was high) ; in 1957 approximately half of the 49 nests counted were on the shoreline and half were on the island within the reservoir (Stillwater WMA Ann. Narr. Repts.). There are no other reports of nesting on the reservoir. Stillwater Marsh. Only two counts are reported for Stillwater Marsh: “total estimated populations” of 200 and 250 in 1951 and 1952, respectively (Stillwater WMA Ann. Narr. Repts.). Lahontan Dam and Reservoir California Gulls nest on two rocky islets (Gull Island and Walleye Island, each approximately 2.4 m above water level) within Lahontan Reservoir (Table 3) . The colony at Gull Island (0.52 ha) apparently was not active before 1930 (Conover 1983) , but its exact date of establishment is unknown. Alcorn (1988) reported that over 60 chicks were banded there in 1939 and 1940, with nest counts in the early 1940s ranging from 172 to 380. The next counts were made about 40 years later, when Gubanich and Judd (1988) reported that 4000 pairs nested there from 1983 through 1985; they have since revised this estimate downward to 3000 pairs (Gubanich pers. comm.). In 1989, Gubanich and Judd counted 2710 nests on Gull Island in mid-May, and in 1990 counted 2986 nests in 12 May (an additional 30 nests were completed later; Gubanich pers. comm.). The colony on Walleye Island (actually a small group of Califor- 7 CALIFORNIA GULL COLONIES IN NEVADA Table 3 Numbers of California Gulls at the Lahontan Dam and Reservoir, Nevada Date Estimated or Counted Adults Estimated or Counted Nests Estimated or Counted Young Source 1939 65 a Alcorn 1988 1940 61 a Alcorn 1988 1941 172 Alcorn 1988 1942 380 Alcorn 1988 1943 246 Alcorn 1988 1944 364 Alcorn 1988 1946 342 Alcorn 1988 1983-85 3000 b A. Gubanich, pers. comm. 1989 2710 A. Gubanich, pers. comm. 1990 3016 A. Gubanich, pers. comm. a Number of young banded. b Gull Island. nia Gulls nesting among ca. 2000 pairs of Ring-billed Gulls) was established in 1986, when it consisted of 100 nesting pairs; approximately the same number nested there from 1987 through 1989, with a slight increase to about 150 pairs in 1990 (Gubanich pers. comm.). Gubanich and Judd (1988:126) reported that disturbance (including shooting by humans and nest destruction by dogs) is "a constant threat” at Lake Lahontan, which is a Nevada State Recreation Area. Fallon National Wildlife Refuge Fallon NWR (Table 4) was established in 1931, but Thompson and Meritt (1988) reported that a permanent marsh no longer exists because the inflow of water has been sporadic since 1967. Nesting has been reported at three sites within the refuge: Battleground Point, Gull Island, and Pelican Island. Two large islands (Battleground Point and Gull Island), isolated in the Car- son Sink by floods, were used by hundreds of gulls in the mid-1980s. Carson Sink, normally an alkaline playa, was transformed into a 30,000-ha lake with water up to 4 m deep. The lake was quickly pioneered by dense populations of fish (e.g., Tui Chub [G//a bicolor] and carp); gull nesting apparently was in- itiated in 1984. These two colonies produced approximately 2000 young an- nually before disappearing after 1987 because of low water, although few ac- curate counts are available (NDOW Repts.; Stillwater WMA Ann. Narr. Repts.) . The “total estimated population” of California Gulls at Pelican Island was 50 in 1952 and 260 in 1956; there were no gulls present in 1951 or 1957 (Still- water WMA Ann. Narr. Repts.) . The next count was in 1987, when 450 pairs were present; there was no nesting in 1988, 1989, or 1990 (NDOW Repts.). 8 CALIFORNIA GULL COLONIES IN NEVADA Table 4 Numbers of California Gulls in the Fallon National Wildlife Refuge, Nevada Estimated or Counted Date Adults Estimated or Counted Nests Total Estimated Population Source Pelican Island 1951 0 Ann. Narr. Rept., Stillwater WMA 1952 50 Ann. Narr. Rept., Stillwater WMA 1956 260 Ann. Narr. Rept., Stillwater WMA 1957 1987 900° 0 Ann. Narr. Rept., Stillwater WMA NDOW Rept. 1989 0 NDOW Rept. 1990 0 NDOW Rept. Gull Island 1986 3000 1987 1800° 1200 NDOW Rept. NDOW Rept. 1988 c 0 Thompson and Neel 1989 1989 0 NDOW Rept. 1990 0 NDOW Rept. Battleground Point 1986 300 b NDOW Rept. 1988 c 0 Thompson and Neel 1989 1989 0 NDOW Rept. 1990 0 NDOW Rept. a Nesting pairs. b Displaced by American White Pelicans by 15 May, c Unsuccessful nesting attempt. Other Nevada Colonies According to N. Saake (pers. comm.) approximately 500 pairs nested on islands in Washoe Lake (Figure 1) from at least the 1960s through 1975. However, because the gulls’ activities increased erosion rates of the islands, which were designed mainly as waterfowl habitat, attempts were made to eradicate the colony. In recent years up to 50 pairs have bred there, but nesting has been sporadic. Approximately 150 pairs attempted nesting on Artesia Lake, Smith Valley (Figure 1), in 1987, but evidently failed to fledge young (NDOW Repts ). The area has been dry in subsequent years. Conover (1983), citing G. Herron (pers. comm.) , reported breeding gulls at Reno city parks, Truckee River, and Wild Horse Reservoir, but did not include the year(s) observed or population size. Power (1980), citing a personal com- munication from G. Herron to D. Babb, also reported nesting within Reno city 9 CALIFORNIA GULL COLONIES IN NEVADA limits. Power (1980) also listed Walker Lake, Carson Lake, Humboldt Lake, and Riptor Reservoir as possible breeding sites, but could not obtain written substantiation for them and so did not include them in his summation. N. Saake (pers. comm.) reported that no California Gulls currently nest at Humboldt, Walker, or Carson lakes, and the biologists and refuge managers we talked to were unfamiliar with Riptor Reservoir. S. Faraisl (pers. comm.) reported that approximately 600-700 pairs nested in the Reno - Sparks urban area in 1989 and 1990: 250 pairs at Highland Reservoir, 250 pairs at Virginia Lake, and several small colonies along the Truckee River. The chicks at Highland Reser- voir, which supplies drinking water to Reno, were removed when the colony was determined to be a human health hazard. DISCUSSION The breeding distribution of California Gulls in Nevada is highly localized in the western part of the state (Figure 1). Because it is constrained by the availability of secure nesting sites, which vary with water conditions, major col- onies can persist only at permanent bodies of water (e.g., Lahontan Reservoir, Pyramid Lake) . Other colonies in this desert landscape are small and ephem- eral, and form or vanish as quickly as water conditions change (e.g., Carson Sink) . While it is not possible to reconstruct the history of the Nevada colonies in any detail, it is evident that the state population numbered several thousand birds in the 1870s, decreased to a few hundred breeding pairs in the 1920s, then in- creased to approximately 7500 pairs in the 1980s. The maximum increase ap- pears to have occurred between 1940 and 1970. Note, however, that much of the recent growth seems attributable to the Lahontan Reservoir area, because the Pyramid Lake colony seems to have stabilized at roughly 4000-6000 breeding adults in the past two decades. Population trends at Pyramid Lake parallel those at the nearby Mono Lake, California, where the colony grew rapidly in the middle decades of this century but then remained stable in the 1970s and 1980s (Jehl et al. 1984, 1988; for data on Great Salt Lake, Utah, see Paul et al. 1990). We suspect that these changes and the increase in the species’ population in the mid -20th century (Conover 1983) , as well as the increase of other large gull species in the North- ern Hemisphere (e.g., Herring Gull, Larus argentatus; Chabrzyk and Coulson 1976), were due largely to enhanced winter survivorship. It remains to be determined why growth seems to have ceased at Pyramid Lake, where over the past two decades numbers have been similar to those we infer for the 1860s. This correspondence is surprising, because there have been important local changes in factors that might affect gull numbers, e.g., increased protection from human disturbance via formation of a wildlife refuge, law en- forcement and education efforts, changes in the ecology of Pyramid Lake, and declines in some fish species (Buchanan and Coleman 1977) . Perhaps the lim- iting factors affecting that colony — although different from those of the last cen- tury — still, fortuitously, sum to the same carrying capacity. The alternative is that the same factors operate unchanged; if so, they remain to be identified. 10 CALIFORNIA GULL COLONIES IN NEVADA SUMMARY Californa Gull ( Larus californicus) rookeries in Nevada are concentrated in the western portion of the state. There are a few permanent colonies (e.g., Pyramid Lake), but others, whose status depends on water conditions (e.g., Carson Sink), are ephemeral. Here we review the history and current status of California Gulls in Nevada. Surveys suggest that the breeding populations there may be larger (ca. 15,000 breeding adults in 1985 and 1986) than previously reported . ACKNOWLEDGMENTS We thank R. Anglin, S. Faraisl, A. Gubanich, B. Henry, and N. Saake for providing unpublished data, and M. Conover and A. Gubanich for commenting on the manuscript. LITERATURE CITED Alcorn, J. R. 1988. The Birds of Nevada. Fairview West Publishing, Fallon, NV. Bond, R. M. 1940. Birds of Anaho Island, Pyramid Lake, Nevada. Condor 42:246- 250. Buchanan, C. C.. and Coleman, M. E. 1987. The Cui-ui, in Audubon Wildlife Report 1987 (R. DiSilvestro, ed.), pp. 425-436. Academic Press, Orlando, FL. Chabrzyk, G.. and Coulson, J. C. 1976. Survival and recruitment in the Herring Gull Larus argentatus. J. Animal Ecol. 45:187-203. Conover, M. R. 1983. Recent changes in Ring-billed and California gull populations in the western United States. Wilson Buli. 95:362-383. Evermann, B. W. 1923. The pelicans of Pyramid Lake. Overland Monthly, May, pp. 16-18,45. Gromme, O. J. 1930. A sojourn among the wild fowl of Pyramid Lake, Nevada. Public Museum of Milwaukee Yearbook 10:268- 303. Gubanich. A. A. , and Judd, H, 1988. First report of nesting Ring-billed Gulls in Nevada. W. Birds 19:125-127. Hall. E. R. 1924. Birds of Pyramid Lake. May 15 - Aug, 3, 1924. Smithsonian Institution Archives, Record Unit 7176, U.S. Fish and Wildlife Service, 1860-1961, Field Reports. Box 70, Folder 1. Hall, E. R. 1926. Notes on the water birds nesting at Pyramid Lake, Nevada. Condor 28:87-91. Hall, E. R. 1929. Letter to H. P. Sheldon, 17 October 1929. Smithsonian Institution Archives, Record Unit 7176, U.S. Fish and Wildlife Service, 1860-1961, Field Reports. Box 70, Folder 1. Henshaw, H. W. 1879. Ornithological report from observations and collections made in portions of California, Nevada and Oregon. Appendix L, Annual Report Chief Engineers for 1879, Annual Report Geog. Surv. West 100th Meridian, by George M. Wheeler, pp. 282-335. Jehl, J. R., Jr., Babb, D. E., and Power, D. M. 1984. History of the California Gull colony at Mono Lake, California. Colonial Waterbirds 7:94-104. Jehl, J. R , Jr., Babb, D. E., and Power, D. M. 1988. On the interpretation of historical data, with reference to the California Gull colony at Mono Lake. California. Colonial Waterbirds 11:322-327. 11 CALIFORNIA GULL COLONIES IN NEVADA Marshall, D, B. 1951. New bird records for western Nevada. Condor 53:157-158. Marshall, D. B., and Giles, L. W, 1953. Recent observations on birds of Anaho Island, Pyramid Lake, Nevada. Condor 55:105-116. Nevada Department of Wildlife Reports. Nevada Department of Wildlife, 380 West B Street, Fallon, NV 89406. Paul, D. S., Jehl, J. R., Jr., and Yochem, P. K. 1990. California Gull populations nesting at Great Salt Lake, Utah. Great Basin Naturalist, 50:299- 302. Power, D. M. (ed.J 1980. The biology of certain water and shore birds at Mono Lake, California. D. M. Power and Associates, 2559 Puesta del Sol, Santa Barbara, CA 93105. Ridgway, R. 1877. United States Geological Exploration of the 40th Parallel, Clarence King (Geologist-in-Charge) . Part III, Ornithology, pp. 303-669. Stillwater Wildlife Management Area Annual Narrative Reports, Stillwater National Wild- life Refuge, P. O. Box 1236, Fallon, NV 89406. Thompson, S. P. 1987. Results of population estimates for Anaho Island NWR. U.S. Fish and Wildlife Service Memorandum, Stillwater Wildlife Management Area, Anaho Island National Wildlife Refuge. Stillwater National Wildlife Refuge, P. O. Box 1236, Fallon, NV 89406. Thompson, S., and Merrit, K. 1988. Western Nevada wetlands: History and current status. Nevada Public Affairs Review 1:40-45. Thompson, S,, and Neel, L. 1986. Aerial survey of colonial nesting migratory birds within the Lahontan Valley. U.S. Fish and Wildlife Service Memorandum, Stillwater Wild- life Management Area. Stillwater National Wildlife Refuge, P. O. Box 1236, Fallon, NV 89406. Thompson, S. , and Neel, L. 1989. Summary of colonial nesting bird counts in Lahontan Valley, 1987 and 1988. U.S. Fish and Wildlife Service Memorandum to Stillwater Wildlife Management Area Refuge Manager, Fallon, Nevada. Stillwater National Wildlife Refuge, P. O. Box 1236, Fallon, NV 89406. Woodbury, W. V. 1966. The history and present status of biota of Anaho Island, Pryamid Lake, Nevada. M.S. Thesis, University of Nevada, Reno. Accepted 27 November 1990 12 EFFECTS OF BROOD PARASITISM BY BROWN-HEADED COWBIRDS ON WILLOW FLYCATCHER NESTING SUCCESS ALONG THE KERN RIVER, CALIFORNIA JOHN H. HARRIS. Biology Department, Mills College, 5000 MacArthur Blvd., Oakland, California 94613 Alteration and loss of riparian habitat have played a central role in the decline of riparian bird species (Gaines 1974, Rernsen 1978, Laymon et al. 1987). However, the absence of certain species from seemingly suitable habitat (Gaines 1974) suggests that other factors may also be important. In his review of the historical riparian avifauna of the Sacramento Valley, Gaines (1974) suggested that 9 of 12 of the declining species, including the Willow Flycatcher ( Empidonax traiflii), were susceptible to and had prob- ably been adversely affected by Brown-headed Cowbird ( Molothrus ater) brood parasitism. Brood parasitism by Brown-headed Cowbirds has been implicated in the decline of songbirds in eastern deciduous forests (Mayfield 1965, 1977a, Brittingham and Temple 1983) and in western riparian habitats (Gaines 1974. 1977, Goldwasser et al. 1980, Laymon 1987). Brown-headed Cowbirds increased their range with the clearing of forests and spread of intensive grazing and agriculture. These changes increased the amount of suitable foraging habitat available to cowbirds and rendered their host populations more vulnerable by reducing their numbers and fragmenting their habitat (Mayfield 1977a, Rothstein et al. 1980, Brittingham and Temple 1983. Laymon 1987). Riparian birds are especially susceptible to brood parasitism because their habitat is linear, ecotonal, often patchy, and frequently near pastures, stockyards, or agricultural fields. Thus the cowbird s favored feeding areas (heavily grazed pasture, Stubblefields, live- stock concentrations) are near its potential hosts in the riparian vegetation. Brown-headed Cowbirds commute from feeding areas to habitats with high host density (Rothstein et al, 1980, 1984, Stafford and Valentine 1985). The Willow Flycatcher is one of many riparian bird species that have suffered serious declines in the southwestern United States (Gaines 1974, Serena 1982, Harris et al. 1987a, b). In recent years the Willow Flycatcher has been included on the Audubon Blue List (Arbib 1979, Tate 1981, 1986, Tate and Tate 1982), the U.S. Forest Service’s Region 5 (California) Sensitive Species List, the LJ.S. Fish and Wildlife Service’s Region 1 (California. Oregon, Washington, Idaho, Nevada) Sensitive Species List, and it was considered a Species of Special Concern by the California Department of Fish and Game beginning in 1978 (Rernsen 1978). In California, where all Willow Flycatchers occur in isolated remnant popula- tions (Serena 1982, Harris et al. 1987b, Unitt 1987), the species was recently listed as endangered by the California Fish and Game Commission. The Willow Flycatcher also is listed as an endangered species in Arizona. The southwestern subspecies (£. t. extimus ) has been reduced to an esti- mated 500-1000 pairs in California, Arizona, New Mexico, Utah, Nevada and Baja California (Unitt 1987). Western Birds 22:13-26, 1991 13 WILLOW FLYCATCHER NESTING SUCCESS Early studies in lowland southern California showed that the Willow Flycatcher is a host for Brown-headed Cowbirds (Hanna 1928, Rowley 1930, Friedmann 1963). Friedmann (1963) reported 150 instances of parasitism of Willow Flycatchers, 41 of them in southern California. Hanna (1928) found more parasitized nests of Willow Flycatchers than of any other species, and commented on the difficulty of finding an unparasitized Willow Flycatcher nest. The decline of the Willow Flycatcher in central and coastal California coincided with the cowbird’s range expansion in the 1920s and 1930s (as summarized by Gaines 1974, Garrett and Dunn 1981, Laymon 1987). Unfortunately, early studies did not report parasitism rates for Willow Flycatchers, nor did they follow nests through the breeding season; thus the responses of Willow Flycatchers to parasitism and the fledging success rate under parasitism remain poorly known for southwestern riparian habitats (Brown 1988). The incidence of parasitism observed in recently studied California montane meadow populations is low (Stafford and Valentine 1985, Valentine et al. 1988, Sanders and Flett 1989), suggesting that parasitism rate could be related to elevation or habitat differences. The purpose of this investigation was to study the characteristics and success rate of Willow Flycatcher nests in a habitat representative of the former core, and remaining lowland portions, of the flycatcher’s range in California. The study population (on the Kern River, Kern County, Cali- fornia), is the largest remaining Willow Flycatcher population documented in California (Harris et al. 1987b) and is one of the largest populations in the total range of the subspecies E. t. extimus (Unitt 1987). METHODS I conducted the study from 1 June through 15 August 1987 on The Nature Conservancy’s Kern River Preserve, on the south fork of the Kern River upstream from Lake Isabella, Kern County, California. It includes a large area of mature riparian forest dominated by cottonwoods ( Populus fremontii ) and willows ( Salix laevigata and S. gooddingii). I studied nesting success of Willow Flycatchers at two locations on the preserve: Mariposa Marsh, a marsh and willow thicket draining into the Kern River, and Slough Channel No. 4, a willow-lined slough near the preserve headquarters. Both sites are at 822 m (2630 feet)' elevation. At both sites the home ranges of singing males were searched for females and nests daily. I identified 12 territories based on daily observations of locations of singing males and the consistent use of specific singing perches throughout the breeding season. I checked nests three or four times weekly, minimizing the duration of nest checks. I noted the activities of the nesting pair (nest construction, brooding, response to parasitism, feeding of young) and observed the nest contents by using a small automobile side-mirror mounted on a pole. If an adult was sitting on a nest, I did not disturb the nest. I noted the plant species in which each nest was located, nest construction material, height of the nest over ground or water, distance to the edge of the willow clump, distance to the canopy top, and the per- centage of ground covered with standing water in the pair’s home range. I 14 WILLOW FLYCATCHER NESTING SUCCESS collected these data after nesting was completed or the nest was aban- doned. RESULTS Nests Moist, low-lying areas and sloughs with dense willow thickets were the Willow Flycatcher's preferred nesting habitat. Many nests were around the ponds created by beaver dams. The nesting and foraging activities of Willow Flycatchers were frequently concentrated in openings within the canopy of willow thickets. I located nests on 8 of the 12 territories. On three of the other territories, no nests or females were located despite repeated, intensive searching. Males in these territories also disappeared from the area earlier in the season than did males with nests, suggesting that the former were unmated. On the remaining territory, movements and vocalizations of the male suggested the presence of a female, but no nest was found. In addition to the nests at my two principal sites, I located another nest adjacent to the main river channel near the preserve headquarters and monitored the nest for the final three weeks of the study. Table 1 Characteristics of Willow Flycatcher Nests Subspecies 0 Location Nest Substrate Mean and Range of Nest Height (m) N Source E.t. traillii Michigan Dogwood (48%) Willow (15%) Elderberry (12%) 1.33 (0.61-2.82) 93 Walkinshaw (1966) E.t. traillii Ohio/ Nebraska Dogwood (39%) Hawthorn (18%) Willow (12%) 1.37 (0.72-2.78) 80 Holcomb (1972) E.t. brewsteri British Columbia Willow. Rose. Dogwood 5 1.14 (0.68-2.62) 26 Stein (1963) E.t. brewsteri California Willow (100%) 1.14(0.70-1.75) 20 Sanders and Flett (1989) E.t. brewsteri California Willow. Dogwood, Azalea 5 1.49 (0.77-2.18) 22 Valentine et al. (1988, pers. comm.) E.t. extimus Entire range 0 Willow (86%) 2.3 (0.60-5.50) 172 Unitt (1987) E.t. extimus Arizona Tamarisk (100%) 3.3 d (1.50-4.50) 12 Brown (1988) E.t. extimus California Willow (100%) 2.52 (1.00-6.40) 19 This study “Subspecific identity where not provided by the source was determined with reference to the review of Unitt (1987). b Listed- in order of importance from most frequently used to least frequently used. c Review of nest characteristics from egg collection data throughout the subspecies' range in the southwestern U.S. d Median nest height. 15 Table 2 Rates of Brood Parasitism and Acceptance of Cowbird Eggs by Willow Flycatchers ' 3 Subspecies 6 Location Habitat Parasitism Rate Acceptance Rate Source WILLOW FLYCATCHER NESTING SUCCESS cn C o 0 } JD 0 ) _c V) -o -c 3 CD IS U C (13 JD O O x: D 0 ) JC c o "D -o O C co c D 3 CD > i- ^ CO c t* Cl o o CD O ^ c jc CD u CD n3 _c U. •5 5 5 _o CD x: u 15 u CD T3 "D C Cb CO CD JT CD X) - “D u D i- O CD co 44 CD ^ ■£ ^ >> 3 -D C T3 CD CD co "O CD > °Z a ° ° O 5 C +-> CD C -5 CD ^ (5 * 8 . a fa i-i O (D O i- CD co 5 CD > CD cs a a) ^ c CD ~o w — CO u co 4C CD "G -a CD ^ Cl 3 co 3 -D £ D O CO O 16 WILLOW FLYCATCHER NESTING SUCCESS I found 19 nests on the 8 territories, an average of 2,4 (range 1-6) nests per territory. Incidences of multiple nests within territories were all due to renesting attempts. All nests were in willows, mostly between forked branches (nesting has been reported recently in other plant species on the preserve, M. Whitfield pers. comm.). Nests were constructed of thistle fibers, strands of dried willow bark, grasses, animal hair, and the fluffy “cotton" borne by willow seeds. The average nest height was 2.52 m (±1.39 standard deviation, range 1.0-6. 4 m). The average distance from the nest to the top of the canopy above the nest was 4.82 m (±2.89 s.d., range 1.0-10.5 m). The average distance to the outer perimeter of the willow clump containing the nest was 7.03 m (±4.27 s.d., range 1.0-15 m). Seventy-four percent (14 of 19) of the nests were over water or mud. The summer of 1987 was very dry; all nests would have been over water during the previous year. All nests but one were near beaver ponds; the exception was the only nest more than 4 meters from water. The percentage of each territory covered by standing water at the beginning of the summer ranged from 70 to 100%. Cowbird Parasitism Thirteen of the nineteen nests (68%) were parasitized on seven of eight (88%) territories (Table 3). Three nests (16%) were unparasitized. Three (16%) were abandoned for unknown causes. Of these three nests with unknown fates, one loss coincided with heavy winds that apparently knocked down the nest. Two of the nests could have been parasitized; one of these was dismantled to construct a new nest, a behavior frequently observed with parasitized nests. Thus up to 80% of nests may have been parasitized. Parasitized nests suffered a variety of fates (Table 3). Seven of the 13 parasitized nests (53%) were abandoned, with abandonment occurring on four of eight territories. In at least five of these cases the female dismantled the abandoned nest, using the material to build the next nest. The extreme case was exemplified by a pair at Mariposa Marsh that constructed six successive nests, finally fledging three young from the sixth nest. Three parasitized nests each fledged one cowbird and no flycatchers. One para- sitized nest had two cowbirds near fledging when it was destroyed by an owl. Two nests parasitized late in the season successfully fledged Willow Flycatchers and no cowbirds. In one of these cases, a single cowbird egg was laid in a nest with four healthy nestling flycatchers (about 1 week old); one Willow Flycatcher nestling disappeared at this time, but three were fledged on 8 July. This was probably the first nesting attempt by this pair of Willow Flycatchers. In the other case, a second nesting attempt, a single cowbird egg was laid at about the flycatcher’s hatching date (30 June). In this nest, one flycatcher egg was apparently removed at the time of parasitism, one nestling flycatcher was unusually small and died, the third nestling fledged on 15 July, and the cowbird egg did not hatch. The three unparasitized nests were all successful. All of these nests were renesting attempts (second, third, and sixth attempts), fledging one, two, and three young, respectively. The sixth nest of a pair at Mariposa Marsh 17 WILLOW FLYCATCHER NESTING SUCCESS Table 3 Fates of Willow Flycatcher Nests in the Kern River Preserve, 1987 Territory Nest Number 0 Flycatcher Eggs Cowbird Eggs Nest Fate (Fledge Date) Slough Channel B 1 1 2 Abandoned (14 July) 6 2 2 1 Abandoned 3 3 0 Fledged two flycatchers (13 August) Slough Channel D 1 2 2 Lost to predator 9 July 2 2 1 Fledged one cowbird (8 August) Mariposa Marsh A 1 3 1 Abandoned (5 JulyP 2 1 1 Abandoned 3 4 1 Abandoned 4 ? ? Abandoned 5 ? 1 Abandoned 6 3 0 Fledged 3 flycatchers (9 August) Mariposa Marsh C 1 3 7 Abandoned 2 1 0 Fledged 1 flycatcher (22 July) Mariposa Marsh E 1 ? 1 Abandoned 2 3 1 Fledged 1 flycatcher (15 July) Mariposa Marsh G 1 4 1 Fledged 3 flycatchers (8 July) 2 2 1 Fledged 1 cowbird (10 August ) bx Mariposa Marsh F 1 4 0 Probably knocked down by wind River Channel A 1 1 1 Fledged 1 cowbird (30 July) a In sequence of construction. b Estimated date when young would have fledged from initial nests had nest not been abandoned. c As the adults were not banded, the two successful broods in this territory may have had different parents. 18 WILLOW FLYCATCHER NESTING SUCCESS fledged three young on 9 August. The young from their first nest would have fledged on 3 or 4 July. The second nest of a pair at Mariposa Marsh never had more than one egg. The single young fledged on 22 July. The young from this pair's first nest would have fledged on 7 or 8 July. The third successful unparasitized nest was along the Slough Channel and was the pair’s third nesting attempt. This nest had three eggs, one of which did not hatch. The two young fledged on 13 August. Young from the first nest would have fledged on 12 or 13 July. Three young cowbirds fledged from the 13 parasitized nests, an egg success rate of 20% (3 of 15 eggs). DISCUSSION Nests Willow Flycatcher nests in this study were similar in their mode of construction and supporting plant species to those previously described in the literature (Table 1). Throughout its range, the Willow Flycatcher uses a variety of riparian shrubs and trees, principally willows ( Salix spp.) and dogwoods ( Cornus spp.). Nests are open cups supported by slender branches. Some nest characteristics measured on the Kern River Preserve differ from those in other habitats (Table 1). The nest heights I observed in this study were within the range for the species, but higher than those in California montane meadow habitats (Table 1). The differences in nest height between my results and those of Sanders and Flett (1989) ( t =4.31, df = 37, p < 0.05) and Valentine et al. (1988) (f = 3.32, df = 39, p < 0.05) are both significant, reflecting the difference in height between the short, shrubby willows of montane meadows and the larger willows characteristic of a mature riparian forest. The distance from the nest to the top of the willow canopy above the nest also differed from that reported in the literature, apparently for similar reasons. In my study, this distance (4.82 m, range 1-10.5 m) was sub- stantially larger than that reported in montane meadows of the Little Truckee River (0.96 m, range 0.5-1. 5 m. Sanders and Flett 1989) or the Shaver Lake region (1.19 m, range 0.51-1.85 m, Valentine et al. 1988). These differences are significant for both the Little Truckee River ( t = 6.03, df = 37, p < 0.01) and the Shaver Lake region ( t = 5.29, df = 35, p < 0.01). Another interesting contrast is provided by measurements of the distance from the nest to the outer perimeter of the willow clump. Willow Flycatch- ers construct their nests near the edge of willow clumps or near streams (King 1955, Kings River Conservation District 1985, Flett and Sanders 1987, Valentine et al. 1988). In my study, the distance to the nearest willow clump edge was greater (7.03 m, range 1-15 m), than that observed on the Little Truckee River (2.3 m, range 0.6-7. 5 m, t = 4.64, df = 37, p < 0.01, Sanders and Flett 1989). This difference also reflects habitat differences; on the Kern River, Willow Flycatcher nests were in large openings under the willow canopy, thus they could be near an edge within the canopy but far from the outer edge of the willow clump. Therefore a different nest microhabitat results from similar behavior in structurally different habitats. 19 WILLOW FLYCATCHER NESTING SUCCESS In montane meadows, the habit of constructing nests near the edges of willow clumps or near cattle trails (Sanders and Flett 1989) places Willow Flycatcher nests at risk from destruction by browsing livestock or by wind (Stafford and Valentine 1985, Taylor and Littlefield 1986, Valentine et al. 1988, Sanders and Flett 1989). On the Kern River and in similar riparian habitats, the placement of nests in spaces within the canopy may reduce the risk of knockdown, particularly if the depth of water beneath the nests discourages cattle use of the habitat. Nest Success and Cowbird Parasitism The Willow Flycatcher is subject to severe brood-parasitism by Brown- headed Cowbirds on the Kern River. The rate of nest parasitism, at least 68%, was higher than any previously reported (Table 2), but is similar in magnitude to rates observed along the Colorado River (Brown 1988) and in montane riparian habitat in Colorado (Sedgwick and Knopf 1988). These studies and my results refute the suggestion by Friedman et al. (1977) that western Willow Flycatchers are parasitized at rates lower than are eastern populations. High parasitism rates for Willow Flycatchers nesting in lowland southwestern riparian habitats are also supported by anecdotal historical data and egg collections (Hanna 1928, Rowley 1930, Friedman 1963), and by the coincidence of the species’ decline with the spread of cowbirds in California (Gaines 1974, Laymon 1987). Brood parasitism was the leading cause of nest failure during my study. Six young flycatchers fledged from three unparasitized nests, while four fledged from two of 13 parasitized nests. Thus ten Willow Flycatchers fledged on the eight territories with nests: a rate of 1.25 young per nesting pair or 0.83 per singing male detected in my study area. Forty-one Willow Flycatcher eggs were found in the study areas; thus the egg success rate was 24.4%. However, other eggs were probably removed, because unparasitized Willow Flycatcher clutches usually contain three or four eggs (King 1955, Walkinshaw 1966, Holcomb 1972, Kings River Conservation District 1985). I estimate that a minimum of eight additional eggs may have been removed, so the actual egg success rate was probably closer to 20%. This egg success rate is lower than that in midwestern populations parasit- ized at lower rates. Egg-to-fledging success rates of 81.4% (Berger 1967) and 65.6% (Walkinshaw 1966) have been reported from populations with parasitism rates of 10.1% and 5.3%, respectively. King (1955) reported a fledging success rate of 44,6% of hatched eggs from a population with a 4.5% parasitism rate. The percentage of nests fledging young from the heavily parasitized population (40.7%) in Colorado was a surprisingly high 40.7%. Successful renesting following abandonment of parasitized nests was responsible for this success rate (Sedgwick and Knopf 1988), but the overall egg success rate may have been lower, as renesting attempts usually result in smaller clutches (Holcomb 1974). Successful Willow Flycatcher broods may have been negatively affected by the delays in fledging date caused by abandonment and renesting. Fledging dates ranged from 11 July to 13 August. Estimated or actual fledging dates of initial nesting attempts were from 1 to 15 July. Cowbird 20 WILLOW FLYCATCHER NESTING SUCCESS parasitism resulted in fledging dates for renesting attempts of 1 to 15 August. Thus successful nesting of parasitized Willow Flycatchers was delayed by 2-4 weeks. Delay in fledging date could result in poor prepara- tion for migration. Alternatively, late fledging may be an indication that Willow Flycatchers could produce two broods within a season if unparasitized (M. Whitfield, pers. comm.), although double broods have not been reported previously. Other causes of nest failure may lower nest success rates to levels similar to that of this study. On the Little Truckee River, a mid-July snow storm was the primary cause of mortality during 1987, a year in which only 19% egg- to-fledging success was achieved (Flett and Sanders 1987, Sanders and Flett 1989). During the previous year, the success rate was 45%. Stafford and Valentine (1985). and Valentine et al. (1988) reported egg-to-fledging rates of 25% and 38% in two different years in the Shaver Lake area, Fresno County. Primary sources of egg failure were livestock knocking down nests and egg inviability. Clearly Willow Flycatcher populations may be limited by different factors depending on location and habitat. Brown- headed Cowbird brood parasitism may often be the most important limiting factor in low-elevation riparian habitats like the Kern River Preserve. The most common response by Willow Flycatchers to brood parasitism in this study was abandonment of parasitized nests, followed by attempts to renest (7 of 13 parasitized nests). Nest abandonment in response to brood parasitism has also been reported in most other studies of cowbird-parasit- ized Willow Flycatchers (King 1955, Berger 1967, Holcomb 1972, 1974, Brown 1988, Sedgwick and Knopf 1988). Abandonment appears to be a beneficial strategy in that renesting attempts may eventually avoid parasit- ism (Sedgwick and Knopf 1988, this study), but the effects of the delay in fledging date are unknown. Some studies have reported burial of the cowbird eggs or construction of a new nest bottom over cowbird eggs (Walkinshaw 1966, Berger 1967, Holcomb 1972, Brown 1988, Sedgwick and Knopf 1988), although this response is never as frequent as nest abandonment or acceptance of cowbird eggs. Brown (1988) reported possible rejection of cowbird eggs based on discovery of cowbird egg fragments below a Willow Flycatcher nest. Comparison of reported accep- tance rates is difficult because of differences between studies in the fre- quency of nest observation and because of small sample sizes in some studies (Table 2). Populations parasitized at a higher rate (>15%), however, accept cowbird eggs less often (8 of 28 nests, 28.6%) than those parasitized at a lower rate (31 of 48 nests, 64.6%). This difference is significant (X 2 = 8.15, df = 1, p < .005), suggesting that abandonment and other responses may become more likely as the parasitism rate in a population increases. Proximate mechanisms for such behavior remain unknown for this host species. This study supports the hypothesis that parasitism in the Sierra Nevada may be indirectly related to elevation (Rothstein et al. 1980, Stafford and Valentine 1985). The parasitism rate observed on the Kern River Preserve differed sharply (Table 2) from that observed during two years of study in the Little Truckee River region (elevation 2010 m, Flett and Sanders 1987, Sanders and Flett 1989), and several years in the Shaver Lake region 21 WILLOW FLYCATCHER NESTING SUCCESS (elevation 1731-2097 m, Kings River Conservation District 1985, Stafford and Valentine 1985, Valentine et al. 1988). Only a single parasitized nest was found during these two studies. This low parasitism rate has been hypothesized to result from the mid-July exodus of Brown-headed Cowbirds from high elevations combined with mid-summer breeding of the Willow Flycatcher in California (Rothstein et al. 1980, Verner and Ritter 1983, Stafford and Valentine 1985). The studies near Shaver Lake indicated that Brown-headed Cowbird egg-laying preceded the arrival and nesting of most Willow Flycatchers. Farther south and at lower elevations, cowbirds may be resident for longer periods and have more extended breeding seasons (Rothstein et al. 1980, Layman 1987), and Willow Flycatchers arrive earlier in the spring (Garrett and Dunn 1981). Along the Kern River, Brown- headed Cowbirds decrease by the end of July (S. Laymon pers. comm.). Cowbird egg-laying took place from 9 to 20 July during my study, over- lapping the flycatcher’s initial nesting attempts. Management Implications The very high rate of Brown-headed Cowbird parasitism and low egg success rate of Willow Flycatchers at the Kern River Preserve during 1987 suggests that brood parasitism may affect the ability of Willow Flycatchers to recolonize or increase in lowland riparian habitat, even if efforts are made to restore suitable habitat. The population at the Kern River Preserve seems not to have fully occupied the suitable habitat present. Such a high parasitism rate is of great concern because of the endangered status of the species in California and of the subspecies E. t. extimus throughout its range (Unitt 1987). Possible management strategies to reduce Brown-headed Cowbird para- sitism include trapping of cowbirds and managing habitat to reduce cowbird feeding opportunities and success rate. Trapping of cowbirds may be an effective short-term strategy where cowbirds concentrate (Mayfield 1977b, Goldwasser et al. 1980, Laymon 1987). Willow Flycatchers increased from 5 to 17 singing males from 1981 to 1986 during a cowbird removal program designed to benefit the Least Bell’s Vireo ( Vireo bellii pusillus ) on the Santa Margarita River, San Diego County (Unitt 1987). Because of the intensive effort and cost of such a program, this strategy should be applied where conditions contribute to success of trapping and where there are key populations of threatened species. At the Kern River Preserve the cowbird’ s feeding and nesting areas are adjacent, concentrating the cowbirds in a relatively small area and favoring trapping success. On the other hand, the surrounding habitat is arid and probably the density of hosts in it is much lower, so cowbirds may travel from a considerable distance (Rothstein et al. 1984) to search for hosts in the high-quality riparian habitat of the preserve. It might be difficult to remove enough cowbirds to reduce parasitism rates if the cowbirds are traveling to the preserve from great distances. In the short run, cowbird trapping and egg removal should be implemented to relieve Willow Flycatcher populations and evaluate the effect of Brown-headed Cowbirds on fledging success and population density. Habitat management represents the best long-term strategy for cowbird control. Fragmentation and disturbance of habitat are associated with 22 WILLOW FLYCATCHER NESTING SUCCESS higher parasitism rates (Rothstein et al. 1980, Brittingham and Temple 1983, Airola 1986). The linear nature of riparian habitat patches make the nests of riparian birds especially vulnerable to cowbirds (Bleitz 1956, Laymon 1987). Most willow thickets at the Kern River Preserve are close to very short grazed grassland or Stubblefields. Increasing the width of riparian corridors by revegetation and reducing grazing in the vicinity of the riparian strip is an ongoing process at the preserve that will allow the usefulness of riparian habitat modification in reducing parasitism to be evaluated. Re- duction of grazing intensity would allow grasses to grow to a height that inhibits the cowbird’s foraging. Further benefits in areas where low willows provide nesting habitat (M. Whitfield pers. comm.) would include reduction of browsing and disturbance of foliage at the height of Willow Flycatcher’s nests (Stafford and Valentine 1985, Flett and Sanders 1987, Valentine et al. 1988). SUMMARY This study shows that the Willow Flycatcher’s nesting microhabitat and nest characteristics in lowland riparian forests differ from those in montane meadows. Nests on my study area were higher and tended to be located within the willow canopy, on the edge of within-canopy spaces. These differences are probably due to the difference between my study area and montane meadow sites in height and canopy structure of willows. Willow Flycatchers on the Kern River are subject to a high rate of brood parasitism by Brown-headed Cowbird. Brood parasitism occurred in at least 68% of nests and was the leading cause of nest failure during my study. As a result, the overall egg success rate was low (at most 24.4%). The most common response of Willow Flycatchers to parasitism was abandonment of the nest followed by renesting attempts. This strategy was often successful, but fledging dates for some pairs were delayed two to four weeks. My study supports the hypothesis that Brown-headed Cowbird brood parasitism rate is indirectly related to elevation. Overlap between the breeding seasons of Brown-headed Cowbirds and Willow Flycatchers is greater on the Kern River than at higher-elevation montane meadows, where cowbirds tend to depart near the beginning of flycatcher nesting. The high rate of cowbird parasitism observed in my study is of concern because of the endangered status of the Willow Flycatcher. Possible man- agement strategies to alleviate this situation include habitat restoration, reduction of grazing to reduce cowbird feeding habitat and nest destruction, and cowbird trapping. Flabitat restoration and reduction of grazing are preferred long-term strategies, because they reduce the suitability of habitats for cowbird feeding near riparian areas and because they hinder the ability of cowbirds to locate hosts by reducing the amount of habitat edge relative to habitat area. Trapping of cowbirds or egg removal may be useful short- term strategies to provide immediate relief to critical populations of Willow Flycatchers, Questions remaining for future study include the effect on parasitism rate of habitat differences within lowland riparian forests, differences in para- sitism rates between natural and artificial revegetation sites, and the extent 23 WILLOW FLYCATCHER NESTING SUCCESS of year-to-year variation in parasitism. These issues, which could influence management strategies for the species, may be clarified by ongoing studies at the Kern River Preserve (M. Whitfield, pers. comm.). ACKNOWLEDGMENTS This study was supported in part by a Mills College Faculty Development Grant. Susan Martinez and Minh Kelly assisted with field work. Advice, encouragement, and companionship in the field were kindly provided by Mary Halterman, Chuck Hunter, Steve Laymon, Ronald Schlorff, Reed Tollefson, and Mary Whitfield. Rick Hewett provided access and support at The Nature Conservancy Kern River Preserve. 1 am grateful to reviewers Bryan Brown, Steve Laymon, and Philip Unitt, and to the following persons who commented on earlier drafts of this manuscript: Dan Airola, Ted Beedy, Steve Laymon, Ron Schlorff, Susan Sanders, Jamie Uyehara, Mary Whitfield, and Brad Valentine. LITERATURE CITED Airola, D. A. 1986. Brown-headed Cowbird parasitism and habitat disturbance in the Sierra Nevada. J. Wildlife Mgmt. 50:571-575. Arbib, R. 1979 The Blue List for 1980. Am. Birds 33:830-835. Berger, A. J. 1967. Traill’s Flycatcher in Washtenaw County, Michigan. Jack-Pine Warbler 45:117-123. Bleitz. D. 1956. Heavy parasitism of Blue Grosbeaks by Cowbirds in California. Condor 58:236-238. Brittingham, M. C.. and Temple, S. A. 1983. Have cowbirds caused forest songbirds to decline? BioScience 33:31-35. Brown, B. T. 1988. Breeding ecology of a Willow Flycatcher population in Grand Canyon, Arizona. W. Birds 19:25-33. Flett, M. A., and Sanders, S. D. 1987. Ecology of a Sierra Nevada population of Willow Flycatchers. W. Birds 18:37-42. Friedmann, H. 1963. Host relations of the parasitic cowbirds. U.S. Natl. Mus. Bull. 233. Friedmann, H., Kiff, L. F., and Rothstein, S. I. 1977. A further contribution to knowledge of the host relations of the parasitic cowbirds. Smithsonian Contr. Zool. 235. Gaines, D. 1974. A new look at the nesting riparian avifauna of the Sacramento Valley, California. W. Birds 5:61-80. Gaines, D. 1977. Birds of the Yosemite Sierra. California Syllabus, Oakland. Garrett, K., and Dunn, J. 1981. Birds of Southern California: Status and Distribution. Los Angeles Audubon Soc., Los Angeles. Goldwasser, S., Gaines, D. A., and Wilbur, S. 1980. The Least Bell’s Vireo in California: A de facto endangered race. Am. Birds 34:742-745. Hanna, W. C. 1928. Notes on the Dwarf Cowbird in southern California. Condor 30:161-162. Harris, J. H Sanders, S. D., and Flett, M. A. 1987a. Willow Flycatcher surveys in the Sierra Nevada. W. Birds 18:27-36. 24 WILLOW FLYCATCHER NESTING SUCCESS Harris. J. H., Sanders, S. D.„ and Flett, M. A. 1987b. The status and distribution of the Willow Flycatcher in the Sierra Nevada: Results of the 1986 survey. Wildlife Mgrnt. Div., Admin. Rep. 87-2, Calif. Dept. Fish and Game. Holcomb, L. C. 1972. Traill's Flycatcher breeding biology. Nebr. Bird Rev. 40:50-68. Holcomb, L. C. 1974. The influence of nest building and egg laying behavior on clutch size in renests of the Willow Flycatcher. Bird-Banding 45:320-325. King, J. R. 1955. Notes on the life history of Traill’s Flycatcher ( Empidonax traillii) in southeastern Washington. Auk 72:148-173. Kings River Conservation District. 1985. Studies of the Willow Flycatcher in the central Sierra Nevada conducted during 1983 and 1984. Research Rep. 85- 017, Kings River Conservation District. Laymon, S. A. 1987. Brown-headed Cow'birds in California: Historical perspectives and management opportunities in riparian habitats. W. Birds 18:63-70. Laymon, S. A., Beedy, E. C., Franzreb, K., and Gustafson, J., eds. 1987. Manage- ment and preservation of endangered birds in riparian ecosystems. Proceedings of a symposium. Cooper Ornithological Society. W. Birds 18:1-96. Mayfield. H, F. 1965. The Brown-headed Cowbird, with old and new hosts. Living ' Bird 4:13-28. Mayfield, H. F. 1977a. Brown-headed Cowbird: Agent of extermination? Am. Birds 31:107-113. Mayfield, H. F. 1977b. Brood parasitism: Reducing interaction between Kirtland’s Warbler and Brown-headed Cowbird, in Endangered Birds: Management Tech- niques for Preserving Threatened Species (S. A. Temple, ed.), pp. 85-91. Univ. of Wise. Press, Madison. Rernsen, J. V., Jr. 1978. Bird species of special concern in California. Nongame Wildlife Investigations Rep. 78-1, Calif. Dept. Fish and Game. Rothstein, S. I., Verner, J., and Stevens, E. 1980. Range expansion and diurnal changes in dispersion of the Brown-headed Cowbird in the Sierra Nevada. Auk 97:253-267. Rothstein, S. I., Verner, J.. and Stevens, E. 1984. Radio-tracking confirms a unique diurnal pattern of spatial occurrence in the parasitic Brown-headed Cowbird. Ecology 65:77-89. Rowley, J. S. 1930. Observations on the Dwarf Cowbird. Condor 32:130. Sanders, S. D,, and Flett, M. A. 1989. Ecology of a Sierra Nevada population of Willow Flycatchers ( Empidonax traillii), 1986-87. Wildlife Mgmt. Div., Admin. Rep. 88-3, Calif. Dept. Fish and Game, Sedgwick. J. A., and Knopf, F. L. 1988. A high incidence of Brown-headed Cowbird parasitism of Willow Flycatchers. Condor 90:253-256. Serena, M. 1982. The status and distribution of the Willow Flycatcher (Empidonax traillii ) in selected portions of the Sierra Nevada, 1982. Wildlife Mgmt. Branch Admin. Rep. 82-5, Calif. Dept. Fish and Game. Stafford, M. D,, and Valentine, B. E. 1985. A preliminary report on the biology of the Willow Flycatcher in the central Sierra Nevada. Cal-Neva Wildlife Trans., pp. 66-77. Stein, R. C. 1963. Isolating mechanisms between populations of Traill’s Flycatcher. Proc. Am. Philos. Soc. 107:21-50. Tate, J. 1981. The Blue List for 1981. Am. Birds 35:3-10. Tate, J. 1986. The Blue List for 1986. Am. Birds 40:227-236. 25 WILLOW FLYCATCHER NESTING SUCCESS Tate, J., and Tate, D. J. 1982. The Blue List for 1982. Am. Birds 36:126-135. Taylor, D. ML, and Littlefield, C. D. 1986. Willow Flycatcher and Yellow Warbler response to cattle grazing. Am. Birds 40:1169-1173. Unitt, P. 1987. Empidonax traillii extimus : An endangered subspecies. W. Birds 18:137-162. Valentine, B. E., Roberts, T. A., Boland, S. P., and Woodman, A. P. 1988. Livestock management and productivity of Willow Flycatchers in the central Sierra Ne- vada. Trans. W. Section, Wildlife Soc. 24:105-114. Verner, J., and Ritter, L. V. 1983. Current status of the Brown-headed Cowbird in the Sierra National Forest. Auk 100:355-368. Walkinshaw, L. H. 1966. Summer biology of Traill’s Flycatcher. Wilson Bull. 78:31- 46. Accepted 11 January 1991 Willow Flycatcher Sketch by Eric Lichtwardt 26 BREEDING BIRDS OF LAGUNA FIGUEROA AND LA PINTA POND, BAJA CALIFORNIA, MEXICO EDUARDO PALACIOS and LUCIA ALFARO, Centro de Investigacion Cientifica y Educacion Superior de Ensenada (CISESE), P. O. Box 434844, San Diego, California 92143-4844 (USA mailing address) Coastal lagoons, with their adjacent beaches, salt marshes, and mudflats, are important habitats for numerous birds, including terns and shorebirds. These habitats are used by both migratory and resident species, the former including not only those present during the winter, but also those that reproduce in the area. The future of these habitats is threatened by the ever-increasing impacts of residential and recreational development. In California, two of the bird species that have been most directly affected by the loss or reduction of these habitats are the Snowy Plover ( Charadrius alexandrinus nivosus) and the California Least Tern ( Sterna antillarium browni). In Baja California, coastal lagoons har- bor important breeding populations of these species, but, even here, the col- onies are being directly affected by the off-road vehicles and pets of tourists. As indicated by Atwood (1987), their habitat, besides these individual species, should be considered endangered. Accordingly, it is important to inventory the present extent and utilization of these habitats before additional plans to develop them are approved and carried out. We present here a survey of the breeding birds of two such coastal wetlands, Laguna Figueroa and La Pinta Pond, Baja California. Laguna Figueroa, also known as Laguna Mormona, is located 163 km south of Ensenada, between Colonia Guerrero and San Quintin. It is a long, closed, hypersaline lagoon, separated from the ocean by a barrier dune ridge 20 km long, 100 - 150 m wide, and 8- 12 m high. The lagoon extends inland 0.5- 2.5 km from this barrier dune (Horodyski 1977, Horodisky et al. 1977, Margulis et al. 1983) . The wetland includes a narrow band of marsh and a large salt flat (Figure 1) . The northern part of the marsh consists of two types of habitats: an inundated area of relatively tall intermediate marsh composed of annual pickleweed ( Sa/icornia bigelouii) and saltwort (Batis maritime), and a non- inundated area of relatively low upper marsh composed of shoregrass ( Monan - thochloe littoralis), saltgrass [Distichlis spicata) , and pickleweed ( Salicornia subterminalis ) . Although the tides are the primary influence on the lagoon’s water level, the variations are largely damped out by percolation through the barrier dune. There are both permanent and ephemeral ponds, varying in diameter from a few meters to several hundred meters, and in depth from a few centimeters to several decimeters (Horodyski 1977) . Runoff rain water also contributes to this lagoon during the November- March rainy season. There are, in Baja California, several other small largely unstudied lagoons. La Pinta Pond is one such small closed lagoon approximately 53 km south of Laguna Figueroa, in the northeastern part of Bahia de Santa Maria, and 500 m north of Hotel La Pinta -San Quintin (Figure 1). This lagoon is bordered by middle marsh species, mainly pickleweed (S. uirginica), and includes a small island 9.5 m long and 6.3 m wide, also covered by this vegetation. Western Birds 22:27-32, 1991 27 BIRDS OF LAGUNA FIGUEROA AND LA PINTA POND We surveyed both lagoons on 13 and 14 June and from 4 to 6 July 1990 as part of our study of nesting Least Terns. During these visits we also recorded nesting by other species, described below. Figure 1. Locations of Laguna Figueroa (Laguna Mormona) and La Pinta Pond, Baja California, Mexico. 28 BIRDS OF LAGUNA FIGUEROA AND LA PINTA POND SPECIES ACCOUNTS Snowy Plover ( Charadrius alexandrinus): We found 15 pairs at Laguna Figueroa, During our first visit one pair on the northern pond had three chicks. There were four active nests in the area between the salt flat and the open marsh, together with nesting Least Terns. The plover nests were widely separated, with an average distance between them of about 100 m. The average clutch was 2.75 eggs. By our second visit, all the eggs recorded on the first visit had presumably hatched, as we found four empty nests plus one active nest with three eggs, and four egg shells. We did not detect any chicks. This breeding population, of at least 30 individuals, is probably augmented by the ar- rival of migrants during the winter, as at Estero de Punta Banda, Baja California (Palacios et al. in press), Bolinas Lagoon, California (Page et ai 1979), and elsewhere along the Pacific coast. In La Pinta Pond we observed two pairs of these plovers, one of them running before us in a distraction display. We found also an empty nest on the dry mud flat. The Snowy Plover also nests along the sandy beach of Punta Azufre (Figure 1) in Bahia San Quintin, and it was previously recorded breeding at Laguna Figueroa by Anderson and Kelly (1980). Killdeer ( Charadrius uociferus ): At each of the two sites we found one pair, both performing the broken-wing distraction display. We didn’t find any nests, eggs, or chicks. Black-necked Stilt ( Himantopus mexicanus) : We saw three pairs in the area of closed marsh at each site. They exhibited typical distraction behavior, crying and flying near us, landing about 20 m from us and vigorously flapping their winds, and feigning incubation w'hile others foraged nervously at the side of the pond. We found two empty nests during our first visit to Laguna Figueroa. These were built of dry branches of pickleweed and formed floating rafts. In La Pinta Pond we found one pair with three chicks not yet fledged, two empty nests, and an egg shell. Here the nests were built in depressions in dry mud, lightly lined and covered with plant material. By mid-June any young would have fledged. American Avocet ( Recuruirostra americana) : In Laguna Figueroa we found only three pairs of avocets but six active nests. One had two recently hatched chicks, and the others contained eggs. The average nest diameter was 150 mm (range 120-150 mm, n = 5) and the average clutch size was 2.5 eggs (range 1-4 eggs, n = 5) . The measurements of four eggs averaged 52.1 by 33.9 mm; the eggs showing the four extremes measured 53.6 by 33.5, 52.0 by 34 . 6 , 51.0 by 33.4, and 51.0 by 33.4 mm. The nests were located on floating rafts of dry vegetation, in the channels of the closed marsh. During the second visit we found that 9 out of 11 eggs in five marked nests had hatched. One active nest still had four eggs; we also found two broken eggs. Anderson and Kelly (1980) also recorded avocets breeding at Laguna Figueroa. In La Pinta Pond we found one nest with three eggs in a depression in the dry mud flat. It had dry branches in the bottom and around the edges. We also found one empty nest and three pairs of adults in breeding plumage, one near the active nest and the other two feeding in the lagoon. Forster’s Tern (Sterna forsteri) : We saw 15 pairs, 10 active nests, and 7 emp- ty nests at Laguna Figueroa. During the first visit we found one one-day-old 29 BIRDS OF LAGUNA FIGUEROA AND LA PINTA POND chick in a nest, probably one of the first of the season. The average clutch size was two (range 1-3 eggs, n = 10) . The colony was in the area of closed marsh, together with the avocets and stilts. The nests were made out of dry branches, placed on vegetated islets (from 1 to 3 m in diameter) , and almost completely surrounded by water. The average diameter of the nests was 120 mm (range 100-130 mm, n - 10). The distance between nests averaged 6.55 m (range 2.0 - 12 mm, n — 8). Thirteen of the 18 eggs in nests recorded on the first visit hatched. We found five eggs broken by predators, probably birds. Western Gulls (Larus occidental is) were the only avian predator seen; both tern species mobbed them vigorously. There were also Coyote (Canis latrans) tracks near the nests. During the first visit to La Pinta Pond we found 15 breeding pairs and 11 ac- tive nests: one with one egg, five with two, and five with three. We collected three eggs that had rolled out of their nests, next to the islet. A pair was ob- served copulating on the side of the lagoon. By the second visit, 12 of the 26 eggs in the nests recorded on the first visit had hatched, while 14 were still in the nests, probably still viable Moreover, four nests were built after the first visit, two with two eggs and two with three. The nest that had lost two eggs out of three, at the time of the first visit, had two new eggs. Nine eggs that were measured averaged 42.89 by 30.11 mm; the eggs show- ing the four extremes measured 44,5 by 30.4, 39.4 by 29.6, 44.0 by 30 . 5 , and 42.5 by 29.0 mm. The nests were well defined and round, and consisted of a depression in the bare ground, lined and covered with dry branches. All but one of the nests were located around the islet on the beach between the vegeta- tion and the water; a single nest was in an open space in the middle of the islet. The average distance between nests was 2 m (range 1.8 -3.0 m, n = 11). We also collected five juvenile perch ( Hyperprosopon argenteum) , measur- ing 76 mm long, that were on the ground in the midst of the nesting area. Such dropped fish indicate the diet of terns during their reproductive season (Atwood and Kelly 1984). Although there are summer records of Forster’s Terns at San Quintin and El Rosario (Grinnell 1928, Wilbur 1987), our observations are the first of breeding for this species in the peninsula of Baja California, and con- stitute a southward extension of its breeding range of about 300 km (3 °) from San Diego Bay, California. So La Pinta Pond becomes the southernmost known colony of the species on the Pacific coast. Least Tern ( Sterna antillarum) . In Laguna Figueroa we found 10 pairs behaving aggressively and feeding young. During the first visit we found a nest with an egg that had been broken by an off- road vehicle, as well as three chicks (estimated ages 7,7, and 11 days) in the open marsh area. During the second visit we found one active nest with one egg, and two chicks (estimated ages 5 and 8 days). Approximately 70% of the colony area was marked by recent tracks of off-road vehicles. The second nest probably represented a second nesting attempt of an unsuccessful pair, because the composition of a second nesting wave at a given colony could depend upon the success of the first wave, both there and at nearby sites (Massey and Atwood 1981). This colony represents an addition to the list of known colonies of the Least Tern in Baja California (Palacios and Mendoza, unpubl. data). At La Pinta Pond we did not find any Least Terns, although they nest about 6.8 km to the west, on Punta Azufre (Figure 1) (Massey 1977, Palacios and 30 BIRDS OF LAGUNA FIGUEROA AND LA PINTA POND Escofet 1990) . The absence of the species at this site can be explained by the lack of suitable habitat. DISCUSSION In addition to the endangered California Least Tern and the troubled Snowy Plover, Laguna Figueroa has also a population of Belding’s Savannah Sparrow (Passerculus sandwichensis beldingi ) , endangered to the north in California. No attempt was made to census this population as it was well past the peak of the breeding season. The presence of these three species, in addition to the other nesting species we recorded, make this area an important target for any conser- vation project. We agree with Anderson (1988) and Ibarra-Obando (1990) that it must be included in any conservation program involving the larger San Quin- tin area to the south. La Pinta Pond, being a nesting site for coastal birds, shows that more effort should be spent in the inventory, study, and protection of even small and seemingly unimportant coastal lagoons. ACKNOWLEDGMENTS We thank A. Escofet, E. Mellink, C. T. Collins, and B. W. Massey who assisted us in different ways. CICESE and Pro Esteros financed this work. LITERATURE CITED Anderson, E. N. 1988. Birds, Bird Habitats and People in Northern Baja California. Report prepared for the CICESE conference on land and resource management in Baja California. Available from Dr. Joaquin Sosa, CICESE, P. O. Box 434844, San Diego, CA 92143, USA. Anderson, G., and Kelly, D. 1980. Btrding in nearer Baja. Western Tanager 47(4) : 1-3. Atwood, J. L. 1987. To save a tern. Newsletter, Manomet Bird Observatory, April. Atwood, J. L. , and Kelly. P. R. 1984. Fish dropped on breeding colonies as indicators of Least Tern food habits, Wilson Bull. 96:34-47. Grinnell, J. 1928. A distributional summation of the ornithology of Lower California. Univ. Calif. Publ. Zool. 32 :1- 300. Horodyski, R. J. 1977. Lyngbya mats at Laguna Mormona, Baja California, Mexico: Comparison with Proterozoic stromatolites. J. Sed. Petrology 47:1305-1320. Horodyski, R. J., Bloeser, B., and Vonder Haar, S. 1977. Laminated algal mats from a coastal lagoon. Laguna Mormona, Baja California, Mexico. J. Sed. Petrology 47: 680-696. Ibarra-Obando, S. E. 1990. Lagunas costeras de Baja California. Ciencia v Desarrollo 16 (92): 39 -49. Margulis, L., Grosobsky, B. D. D., Stolz, J. F., Gong-Collins, E. J., Lenk, S., Read, D., and Lopez- Cortez, A. 1983. Distinctive microbial structures and the pre- Phanerozoic fossil record. Precambrian Res. 20:443-477. Massey, B. W. 1977. Occurrence and nesting of the Least Tern and other endangered species in Baja California, Mexico. W. Birds 8:67-70. Massey, B. W. , and Atwood, J. L. 1981. Second- wave nesting of the California Least Tern: Age composition and reproductive success. Auk 98:596-605. 31 BIRDS OF LAGUNA FIGUEROA AND LA PINTA POND Page, G. W., Stenzel, L. E., and Wolfe, C. M. 1979. Aspects of the occurrence of shore - birds on a central California estuary. Studies Avian Biol. 2:15-32. Palacios, E., and Escofet, A. 1990. Anidaeion del gallito marino californiano ( Sterna antillarum browni ) en tres lagunas costeras de Baja California, y sus implicaciones en la conservacion. Programa y resumenes del VIII Simposium de Biologfa Marina, 8-12 June 1990, Ensenada, Baja California. Palacios, E , Loya-Salinas, D. H., and Escofet, A. In press. The Punta Banda Estuary (B.C., Mexico) as a link in the “Pacific Flyway”: Shorebird abundance. Ciencias Marinas. Wilbur, S. M. 1987. Birds of Baja California. Univ. Calif. Press, Berkeley. Accepted 12 February 1991 California Least Terns Sketch by Narca Moore -Craig 32 NOTES A SHORT-TAILED ALBATROSS OBSERVED NEAR SAN BENEDICTO ISLAND, REVILLAGIGEDO ISLANDS, MEXICO LUIS SANTAELLA, P. O. Box 50, Rancho Santa Fe, California 92067 ANDRES M. SADA, Apartado Postal 1124, Monterrey, Nuevo Leon 64000, Mexico On 29 April 1990, at 1500, while on a 73-foot motor yacht cruising the eastern Pacific Ocean at 19°26'N, 110°44 / W (approximately 6 nautical miles north of San Benedicto Island, the northernmost of the Revillagigedo Islands of Mexico), Santaella spotted a large albatross about 200 meters from the boat. He immediately pointed out the bird to his companions, all experienced observers: Andres and Pilar Sada, Eugenio Clariond, Miguel A. Gomez, Barbara M. Montes, and Mario A. Ramos. Having just seen two Laysan Albatrosses (Diomedea immutabilis ) , he initially thought that the approaching bird would be another Laysan. When clearly seen, however, the bird was unmistakably an adult Short-tailed Albatross (Diomedea albatrus). We all saw the bird well with binoc- ulars for about three minutes as it flew north low over the water in a leisurely but pur- poseful manner and disappeared into the distance. The weather was fair with light wind and swell and water temperature of 78°F The albatross was larger than the two Laysan Albatrosses we had just seen and had a huge pink bill. The head and body were white with a distinct yellow crown and nape. The wings above were black distally and proximally with black primaries and secondaries separated by a large white patch with irregular borders. The mantle and rump were pure white and the tail was black, with the pale feet projecting beyond it. The massive bill im- parted to the bird a front-heavy appearance, as if it were prone to keel forward. The plumage and appearance of the adult Short-tailed Albatross are unique and quite distinct from those of any other of the world’s albatrosses (Harrison 1983, 1987) . The other two species of the northern Pacific Ocean, the Laysan and the Black-footed ( D . nigripes), both found in Mexican waters, differ completely, the former having entirely blackish up- per wings and mantle, and the latter being entirely dusky brown with black bill and feet. (The juvenile Short-tailed Albaross is entirely brown but retains the pink bill and pale feet.) Our observation of a Short-tailed Albatross is the first reported for the Revillagigedo Islands. The only other albatross recently recorded from these islands is the Laysan, a re- cent colonizer (Howell and Webb 1990). Between 29 April and 6 May 1990 we ob- served two Laysan Albatrosses at sea off San Benedicto, one flying past Roca Partida, and four on landing on Clarion. There is a very old record of a Black -footed Albatross off Clarion Island (Anthony 1898). As far as we are aware, the only other record this cen- tury of a Short-tailed Albatross from Mexico is of an adult seen in November 1986 by David Ainleyand Larry Spear 230 miles off Manzanillo, Colima (L. Spear pers. comm.). There are no recent reports for Baja California (Wilbur 1987), from where the species was regularly recorded prior to 1900 (Grinnell 1928). This albatross was formerly abun- dant in the North Pacific, breeding between October and May on numerous small islands off Japan and dispersing north to the Bering Sea and east to the coasts of California and Baja California (Harrison 1983). After the species was nearly exterminated by Japanese Western Birds 22:33-34, 1991 33 NOTES plume-hunters in the late 19th and early 20th centuries, there are now approximately 250 birds breeding only on Torishima, off Japan (Hasegawa 1984) , with a total popula- tion of about 400 (Ackerman 1990). There are about a dozen recent records from western North America, ranging from Alaska to California (Hasegawa and DeGange 1982, Everett 1983, Campbell et al. 1986) . The only records since 1946 of adult Short- tailed Albatrosses off western North America south of Alaska are the two from Mexico reported here. Presumably, if the population continues to increase, the species should become more frequent off the Pacific coast of North America, including Mexico, W. T. Everett and G. McCaskie reviewed this paper and provided many useful com- ments. LITERATURE CITED Ackerman, D. 1990. A reporter at large (Albatrosses) . New Yorker, 24 Sept., pp. 61- 88. Anthony, A. W. 1898. Avifauna of the Revillagigedo Islands, Auk 15:311-318. Campbell, K. F., Bailey, S. F., Barron, A. D., and Erickson, R. A .1986. The autumn migration. Middle Pacific Coast region. Am. Birds 40:329. Everett, W. T. 1983. A Short-tailed Albatross record for Alaska in 1981. Pacific Seabird Group Bull 13:23. Grinnell, J, 1928. A distributional summation of the ornithology of Lower California. Univ. Calif. Pub. Zool. 32:1-300. Harrison, P. 1983. Seabirds: An Identification Guide. Houghton Mifflin, Boston. Harrison, P. 1987. A Field Guide to Seabirds of the World. Stephen Greene, Lexington, MA. Hasegawa, H., and DeGange, A. R. 1982. The Short-tailed Albatross, Diomedea alba- trus , its status, distribution, and natural history. Am. Birds 36:806-814 Hasegawa, H. 1984. Status and conservation of seabirds in Japan, with special attention to the Short-tailed Albatross, in Status and Conservation of the World’s Seabirds ( J. P. Croxall, P. G. H. Evans, and R. W. Schreiber, eds.), pp. 487-500. ICBPTech. Publ. 2. Howell, S. N., and Webb, S. 1990. The seabirds of Las Islas Revillagigedo, Mexico. Wilson Bull. 102:140-146. Wilbur, S. R. 1987. Birds of Baja California. Univ. of Calif. Press, Berkeley. Accepted 25 January 1991 34 NOTES TWO NEW RECORDS OF THE FLAMMULATED OWL (OTUS FLAMMEOLUS) IN THE SACRAMENTO VALLEY, CALIFORNIA TERRY A. SCHULZ, University of California Davis Raptor Center, School of Veterinary Medicine, Davis, California 95616 Information on the migration of the Flammulated Owl (Otus flammeolus) in California is minimal (Bloom 1983, Winter 1974, Collins et aL 1986). This paucity of data is per- haps due to the species’ strictly nocturnal habits and its habit of not calling during the fall, making detection very difficult (Winter 1974). The Flammulated Owl is found mainly in the Transition Zone of California, most often in forests of Ponderosa Pine ( Pinus ponder- osa), Sugar Pine ( Pinus lambertiana) , Douglas Fir ( Pseudotsuga menziesii), White Fir {Abies concoior), Incense Cedar (Calocedrus decurrens) , and Black Oak (Quercus kelloggii) (Winter 1974, 1979, Marcot and Hill 1980). The Flammulated Owl is almost exclusively insectivorous (Marshall 1957, Ross 1969, Goggans 1985) but rarely takes small vertebrates (Johnsgard 1988). The Flammulated Owl is now known to be a long-distance migrant, wintering in Mex- ico and Central America (Baida et al. 1975, Collins et al. 1986, Winter 1974). There is only one winter record for California (Stephens 1902) and two for Arizona (Simpson and Werner 1958, Monson and Phillips 1981), In California the earliest spring record is 23 March (Marcot and Hill 1980) and the latest fall record is 31 October (Winter 1974). In addition, there is a number of records of vagrant Flammulated Owls occurring far out- side their normal range (Collins et al. 1986). There are two previous fall records for the California Central Valley and here I report an additional two. Both previous lowland (elevation 4 feet) occurrences have been at Davis, Yolo County, in October. The first was of an adult female found on the University of California at Davis campus on 31 October 1936 (Emlen 1936; wing chord 135.8 mm, tail 63.5 mm, weight unknown). This specimen is deposited in the Vertebrate Museum, Department of Zoology, University of California, Davis. The second Flammulated Owl was found near Road 25A and Highway 113, Woodland, Yolo County, on 16 October 1974 (anonymous 1979). The owl was alive and taken to the School of Veterinary Medicine where it was examined and diagnosed as having bilateral cataracts of unknown etiology. The two new records are also from Yolo County. One was of an adult found trapped inside a large storage building along Hutchinson Drive, University of California campus, on 11 October 1984. I caught the owl with a net and held it overnight for observation. All remiges and rectrices were complete and unworn; the wing chord measured 134 mm, the tail measured 57.6 mm, and the body weight was 78 grams. This weight suggests the owl was a female (Johnson and Russell 1962, Reynolds and Linkart 1984) . I placed the owl in a flight chamber to evaluate its flight ability and fed it live crickets ad libitum. It was photographed (see cover), banded (U.S.F. W. NO. 1363-80789), and released in the evening of 12 October 1984 near South Putah Creek, Davis. The fourth Flammulated Owl was found by a concerned citizen on 3 October 1988 in Woodland. The owl had been caught by the family cat and was treated for shock at the University of California Davis Raptor Center and Veterinary Medical Teaching Hospital. In spite of this care the owl died the following day. Postmorten diagnosis revealed a depression fracture of the left side of the skull, focal contusion of the left cerebral hemis- phere, and pulmonary hemorrhage. The bird was hatching-year female weighing 60 grams, wing chord 133 mm, tail 55 mm. The specimen is deposited in the Department of Wildlife and Fisheries Biology Museum, University of California Davis, catalogue number MWFB 3227. Western Birds 22:35-36, 1991 35 NOTES Notably, all four records of the Flammulated Owl for California’s Central Valley are for October, suggesting that the species is a regular if rarely detected migrant during that month. LITERATURE CITED Anonymous. 1979. The early bird. Burrowing Owl [Davis Audubon Society Newsletter] 8 (9) :3. Baida, R. P. , McKnight, B. C. and Johnson, C. D. 1975. Flammulated Owl migration in the southwestern United States. Wilson Bull. 87.520-533. Bloom, P. H. 1983. Notes on the distribution and biology of the Flammulated Owl in California. W. Birds 14:49-52. Collins, P. W. , Drost, C. R. and Fellers, G. M. 1986. Migratory status of Flammulated Owls in California, with recent records from the California Channel Islands. W. Birds 17:21-31. Emlen, J. T. 1936. Flammulated Screech Owl in the Sacramento Valley. Condor 38:43. Goggans, R. 1985. Flammulated Owl habitat use in northeast Oregon. M. S. Thesis, Oregon State University, Corvallis. Johnson, N. K,, and Russell, W. C. 1962. Distributional data on certain owls in the west- ern Great Basin. Condor 64:513-515. Johnsgard, P. A. 1988. North American Owls, Biology and Natural History. Smith- sonian Inst. Press, Washington, D.C. Marcot, B. G. and Hill, R. 1980. Flammulated Owls in northwestern California. W. Birds 11:141-149. Marshall, J. R., Jr. 1957. Birds of pine-oak woodland in southern Arizona and adjacent Mexico. Pac. Coast Avifauna 31. Monson, G,, and Phillips, A. R. 1981. Annotated Checklist of the Birds of Arizona. 2nd. ed. Univ. of Ariz. Press, Tucson. Reynolds, R. T., and Linkart, B. D. 1984. Methods and materials for capturing and monitoring Flammulated Owls. Great Basin Nat. 44:49-51. Ross, A. 1969. Ecological aspects of the food habits of insectivorous screech owls. Proc. W. Foundation Vert. Zool. 1:301-344. Stephens, F. 1902. Owl notes from southern California. Condor 4:40. Simpson, J. M., and Werner, J. R. 1958. Some recent bird records from the Salt River Valley, central Arizona. Condor 60:68-70. Winter, J. 1974. The distribution of the Flammulated Owl in California. W. Birds 5.25-43. Winter, J. 1979. The status and distribution of the Great Gray Owl and the Flammulated Owl in California, In Owls of the West: Their Ecology and Conservation (P. P. Schaef- fer and S. M. Ehlers, eds.), pp. 60- 85. Natl. Audubon Soc., W. Education Center, Tiburon, CA. Accepted 22 January 1991 36 NOTES A FALL RECORD OF THE SHARP -TAILED SPARROW FOR INTERIOR CALIFORNIA MICHAEL A. PATTEN, P, O. Box 8561, Riverside, California 92515-8561 KURT RADAMAKER, 1183 Caswell Avenue, Pomona, California 91767 In the early morning of 22 September 1990 we, along with Thomas E. Wurster, ob- served a Sharp-tailed Sparrow ( Ammodramus caudocutus) at Furnace Creek Ranch, Death Valley National Monument, Inyo County, California. It was seen feeding in the weeds and resting in the scrubby tamarisks surrounding a small pond in the northwestern corner of the golf course. The lack of wind and the warm and clear conditions allowed us to study the bird closely through binoculars for 20 minutes. In size and shape the bird was like a Grasshopper Sparrow (A, souannarum) , being small and chunky with a flat crown, having a short tail with pointed retrices, and flying weakly on short wings. The bill was mostly dark, conical, and rather fine. The most strik- ing feature was the bright orange on the face and breast. The face was boldly patterned with a wide orange supercilium, which tapered to a point behind the eye, a distinctly con- trasting mouse-gray auricular patch, orange lores, and a blackish postocular stripe that thickened as it approached the nape. Pale orange on the throat contrasted slightly with the brighter orange across the breast. Fine black streaks crossed the breast, although the center of the breast appeared to be unstreaked. Black streaking on the flanks was bolder and a bit heavier. The belly looked clean white; we never obtained a clear view of the undertail coverts. The crown was very dark, with a gray central stripe and black lateral crown stripes, although this gray central stripe was difficult to see since it was nearly as dark as the lateral crown stripes The nape was unmarked mouse-gray, sharply offsetting the dark crown and back and the orange face. The back was deep blackish with bold white stripes. The wings were wholly warm grayish-brown with a trace of wingbars and darker tertials edged whitish. We never saw the rump well. All specimens from the Pacific Coast have been reported as A. c. nelsoni from central North America; our bird showed the indistinct breast streaks and the very bold back stripes characteristic of this subspecies. The similar race A. c. altera, which breeds around James Bay and winters along the Atlantic coast and the Gulf of Mexico, cannot be eliminated, however, although it is less likely to reach California. The Sharp-tailed Sparrow breeds east of the Rocky Mountains throughout the prairie provinces of Canada and the north-central Great Plains of the United States, south to southeastern South Dakota. Disjunct breeding populations inhabit the Atlantic seaboard from southeastern Quebec south to North Carolina (A.O.U. 1983). The Atlantic popula- tions are essentially resident, particularly from New York south. However, the popula- tions breeding inland and around Fludson Bay migrate south to the Gulf of Mexico, wintering along the coast from Texas to southern Florida (A.O.U. 1983) . In tidal marshes along the Pacific coast, small numbers have been found wintering annually in recent years, with records extending from Humboldt Bay, California (Morlan and Erickson 1988) south to Bahia de San Quintin, Baja California Norte (Northern 1962), and from 17 October to 6 May (Roberson 1980). Since the Sharp-tailed Sparrow has proved regular in California, the species was recently removed from the California Bird Records Committee (CBRC) review list (Dunn 1988). Despite its extensive seasonal movements through the central United States, the species is seldom detected during migration. Even though it winters regularly in Califor- nia, the Sharp-tailed Sparrow is “virtually unrecorded in the west away from coastal areas” (A.O.U. 1983). West of the Rocky Mountains, there are records only for Califor- nia and Baja California. Montana and Colorado are the only other states west of the species’ normal migration route for which there are valid records (DeSante and Pyle 1986). Western Birds 22:37-38, 1991 37 NOTES In California, vagrants have been noted along the coast away from wintering localities on occasion, with the earliest being 29-30 September 1988 at the Santa Clara River estuary, Ventura County (McCaskie 1989). Inland, there are four records of spring vagrants, all from the deserts. Two of these records are for 1976, when single birds were observed at Oasis, Mono County, 25-26 May and at Furnace Creek Ranch 27-29 May (Garrett and Dunn 1981). The other two occurrences took place in Kern County during the spring of 1990: one was observed at Mojave 13 May and one was seen and photo- graphed at Galileo Hill 20 - 24 May (McCaskie 1990) . The only other record for the inte- rior of California is unreviewed by the CBRC: one was reported on the Colorado River at Imperial Dam, Imperial County, 29 March 1975 (Garrett and Dunn 1981). This in- dividual most probably wintered at this location. There are no previous fall records away from the coast. Thus, the 22 September sighting we report here is not only the first fall record for interior California, it is also the earliest for the state by a week. We thank Philip Unitt and Jon Dunn for commenting on a draft of this note. LITERATURE CITED American Ornithologists’ Union. 1983. Check-List of North American Birds. 6th ed. A.O.U., Washington, D. C. DeSante, D., and Pyle, P. 1986. Distributional Checklist of North American Birds, Vol. I. Artemisia Press, Lee Vining, CA. Dunn, J. L. 1988. Tenth report of the California Bird Records Committee. W. Birds 19:130. Garrett, K., and Dunn, J. 1981. Birds of Southern California: Status and Distribution. Los Angeles Audubon Soc., Los Angeles. McCaskie, G. 1989. The autumn migration. Southern Pacific Coast region. Am. Birds 43:166-171. McCaskie, G. 1990. The spring season. Southern Pacific Coast region. Am. Birds 44:495-499. Morlan, J., and Erickson, R. 1988. Supplement to the Birds of Northern California, in McCaskie, G., DeBenedictis, P. , Erickson, R., and Morlan, J. 1979. Birds of Northern California: An Annotated Field List. 2nd ed, pp. 85-97, Golden Gate Audubon Society, Berkeley. Northern, J. R. 1962. Noteworthy bird records from Baja California. Condor 64:240. Roberson, D. 1980. Rare Birds of the West Coast. Woodcock Publ., Pacific Grove, CA. Accepted 4 February 1991 38 NOTES GOLDEN EAGLES NEST ON CENTER -PIVOT IRRIGATION SYSTEM NEAL D. N1EMUTH, Department of Zoology and Physiology, Box 3166, University of Wyoming, Laramie, Wyoming, 82071 On 10 June 1990, Ken and Phil Luepke, Keith Merkel, and I observed a Golden Eagle (Aquila chrysaetos) nest on an unused center-pivot irrigation system in central Albany County, approximately 39 km north of Laramie, Wyoming. One adult was at the nest, which was occupied by one unfledged juvenile. The nest, built primarily of sagebrush (Artemisia spp.), was placed 2.5 m above the ground on a crossarm of the irrigation system. The area surrounding the nest had been cultivated but was later overgrown with foxtail barley (Hordeum spp ), rabbitbrush (Chrysothamnus spp.), thistles (Cirsium spp.), and dandelions (Taraxacum spp.). Non- cultivated lands adjacent to the nest site are dominated by sagebrush. The site is level and treeless, at 2180 m elevation, and is 2 km from the nearest public road. Golden Eagles traditionally nest in trees or on cliffs (Palmer 1988), but have been known to nest on man-made structures as well. Camenzind (1969) noted a nest on an abandoned gunnery tower at an army base, and Bohm (1988) mentioned Golden Eagles nesting on transmission line structures. Menkens (1982) noted several instances of Golden Eagles nesting on windmills. Also, in several cases Golden Eagles have used ar- tificial nesting platforms provided for their use (Fala et al. 1985, Postovit et al. 1982). I thank Ken Luepke, Phil Luepke, and Keith Merkel for their assistance. 1 also thank Mike Morrison of the Farmer’s Home Administration for permitting access to the property and Clayton White and Richard Knight for reviewing an early draft of this note. LITERATURE CITED Bohm, R. T. 1988. Three Bald Eagle nests on a Minnesota transmission line. J. Raptor Res. 22:34. Camenzind, F. J. 1969. Nesting ecology and behavior of the Golden Eagle, Aquila chrysaetos. Brigham Young Univ. Sci, Bull., Biol. Series 10 (4) : 5 - 15. Fala, R. A.. Anderson, A., and Ward, J. P. 1985. Highwall-to-pole Golden Eagle nest relocations. J. Raptor Res. 19:1-7. Menkens, G. E. 1982. Characterization of Golden Eagle nesting habitat in northeastern Wyoming. M. S. Thesis, Univ. Wyoming, Laramie. Palmer, R. S., ed. 1988. Flandbook of North American Birds, vol 5. Yale Univ. Press, New Haven, CT. Postovit, HR., Grier, J. W., Lockhart, J. M., and Tate, J. 1982. Directed relocation of a Golden Eagle nest site. J. Wildlife Mgmt. 46:1045-1048. Accepted 10 February 1991 Western Birds 22:39, 1991 39 Volume 22, Number 1, 1991 Distribution and History of California Gull Colonies in Nevada P.K. Yochem, J.R. Jehi, Jr., R.S. Stewart, S. Thompson, and L. Neel 1 Effects of Brood Parasitism by Brown- headed Cowbirds on Willow Flycatcher Nesting Success Along the Kern River, California John H. Harris 13 Breeding Birds of Laguna Figueroa and La Pinta Pond, Baja Cali- fornia, Mexico Eduardo Palacios and Lucia Alfaro 27 NOTES A Short-tailed Albatross Observed Near San Benedicto Island, Revillagigedo Islands, Mexico Luis Santaella and. Andres M. Sada 33 Two New Records of the Flammulated Owl (Otus flammeolus) in the Sacramento Valley, California Terry A. Schulz 35 A Fall Record of the Sharp-tailed Sparrow for Interior California Michael A. Patten and Kurt Radamaker 37 Golden Eagles Nest on Center-Pivot Irrigation System Neal D. Niemuth 39 Bulletin Board 40 Cover photo © by Terry A. Schulz of U.C, Davis Raptor Center: Flammulated Owl (Otus flammeolus). University of California Davis campus, Yolo County, California, 11 October 1984. Western Birds solicits papers that are both useful to and understandable by amateur field ornithologists and also contribute significantly to scientific litera- ture. The journal welcomes contributions from both professionals and amateurs. Appropriate topics include distribution, migration, status, identifica- tion, geographic variation, conservation, behavior, ecology, population dynamics, habitat requirements, the effects of pollution, and techniques for censusing, sound recording, and photographing birds in the field. Papers of general interest will be considered regardless of their geographic origin, but particularly desired are reports of studies done in or bearing on the Rocky Mountain and Pacific states and provinces, including Alaska and Hawaii, western Texas, northwestern Mexico, and the northeastern Pacific Ocean. Send manuscripts to Philip Unitt, 3411 Felton Street, San Diego, CA 92104. For matter of style consult the Suggestions to Contributors to Western Birds (8 pages available at no cost from the editor) and the Council of Biology Editors Style Manual (available for $24 from the Council of Biology Editors, Inc. , 9650 Rockville Pike, Bethesda, MD 20814. Reprints can be ordered at author’s expense from the Editor when proof is returned or earlier. Good photographs of rare and unusual birds, unaccompanied by an article but with caption including species, date, locality and other pertinent information, are wanted for publication in Western Birds. Submit photos and captions to Photo Editor. WESTERN BIRDS Quarterly Journal of Western Field Ornithologists President: Peter Gent, 55 South 35th, Boulder, CO 80303 Vice-President : Robert McKeman, 1230 Friar Lane, Redlands, CA 92373 Treasurer/Membership Secretary: Howard L. Cogswell, 1548 East Avenue, Hayward, CA 94541 Recording Secretary: Jean-Marie Spoelman, 4629 Diaz Drive, Fremont, CA 94536 Circulation Manager: William E. Haas, 10601- A Tierrasanta Blvd., Suite 127, San Diego, CA 92124 Directors: Peter Gent, Ron LeValley, John S. Luther, Guy McCaskie, Robert McKeman, Steve Summers, Janet Witzeman, David Yee Editor: Philip Unitt, 3411 Felton Street, San Diego, CA 92104 Associate Editors: Cameron Barrows, Tim Manolis, Thomas W. Keeney Graphics Manager: Virginia P. Johnson, 4637 Del Mar Ave., San Diego, CA 92107 Photo Editor: Bruce Webb, 8204 Cantershire Way, Granite Bay, CA 95661 Secretary, California Bird Records Committee: Michael A. Patten, P. O. Box 8612, Riverside, CA 92515 Editorial Board : Robert Andrews, Alan Baldridge, Andrew J. Berger, Laurence C. Binford, David F. DeSante, Jon L. Dunn, Richard Erickson, Kimball L. Garrett, Joseph R. Jehl, Jr., Ned K. Johnson, Virginia P. Johnson, Brina Kessel, Stephen A. Laymon, Paul Lehman, John S. Luther, Guy McCaskie, Joseph Morlan, Harry B. Nehls, Dennis R. Paulson, Oliver K. Scott, Ella Sorensen, Richard W. Stalkup, Charles Trost, Terence R. Wahl, Roland H. Wauer, Bruce Webb, Wayne C. Weber, Richard E. Webster Membership dues, for individuals and institutions, including subscription to Western Birds: Patron, $1000; Life, $250; Supporting, $50 annually; Contributing, $30 annually; Family, $22; Regular, U.S. , $18 for one year, $35 for two years, $50 for three years; outside U.S. , $23 for one year, $45 for two years, $65 for three years. Dues and contributions are tax- deductible to the extent allowed by law. Send membership dues, changes of address, correspondence regarding missing issues, and orders for back issues and special publications to the Treasurer Make checks payable to Western Field Ornithologists, Back issues of California Birds/ Western Birds: $20 per volume, $5.00 for single issues. Xerox copies of out of print issues (Vol. 1, No. 1; Vol. 2, Nos. 1 and 4; Vol. 6, No. 2) : $5.50 each. Checklist of the Birds of California: $2.00 each, 10 or more $1.50 each. Pelagic Birds of Monterey Bay, California: $2.50 each, 10 or more $2.00 each, 40 or more $1.50 each. All postpaid. Published July 20, 1991 ISSN 0045-3897 WESTERN BIRDS ADVERTISING RATES AND SPECIFICATIONS Full page 4 x 6 3 /4 inches $60 per issue $200 per year Half Page 4x3% inches $40 per issue $130 per year Quarter Page 4 x l l X 6 inches $30 per issue $110 per year Offset printing, one column per page, 4 inches wide. Glossy, black and white photos are ac- ceptable; half-tone screen size: 133 line. Photo-ready copy is requested. If this is not possible, extra charges for typesetting will be made as follows: $15 full page, $10 half page, $5 quarter page. Send copy with remittance to the Treasurer. Make checks payable to Western Field Ornithologists. A 15% commission is allowed for agencies. WESTERN BIRDS Volume 22, Number 2, 1991 THE BIRDS OF SOUTHEAST FARALLON ISLAND: OCCURRENCE AND SEASONAL DISTRIBUTION OF MIGRATORY SPECIES PETER PYLE and R. PHILIP HENDERSON, Point Reyes Bird Observatory, 4990 Shoreline Highway, Stinson Beach, California 94970 The small size and open terrain of Southeast Farallon Island, located 42 km west of San Francisco, provide ideal conditions for monitoring bird migration (DeSante and Ainley 1980, DeSante 1983). Recognizing this, ornithologists from the Point Reyes Bird Observatory (PRBO) have con- ducted standardized censuses of all migrant bird species daily since 3 April 1968. DeSante and Ainley (1980) summarized the occurrence patterns of the 331 species recorded on the island from 1854 to 2 April 1976 and noted an additional 15 species observed through 2 October 1979. Here we update DeSante and Ainley, noting a total of 375 species recorded on Southeast Farallon Island through 31 December 1989, and summarizing the occurrence patterns of 359 migratory species, 20 intraspecific forms, and four interspecific hybrids recorded from 3 April 1968 through 31 December 1989. For each migratory species we provide seasonal arrival data for both spring and fall, which should reflect movement patterns along the adjacent California coast. This “2 2-year” data set will provide the basis for future analyses on the climatic factors that influence migrants’ arrival at the island and trends in the occurrence of species and biogeographical groups. STUDY AREA AND CENSUSING METHODS The location, topographical features, and vegetation structure of South- east Farallon Island (Figure 1) and methods of censusing migratory birds there were described by DeSante and Ainley (1980) and DeSante (1983). Each day PRBO personnel censused all migrant individuals; for landbirds this was facilitated by most individuals’ congregating at four or five veg- etated or prominent areas on the island. An attempt was made either to band or, if possible, to determine the age and sex of landbirds in the field so Western Birds 22:41-84, 1991 41 BIRDS OF SOUTHEAST FARALLON ISLAND that turnover rates could be assessed. Shorebird roosts and freshwater seepages were censused daily at high tide in all months except from April through July, when coastal access was restricted to prevent disturbance to breeding seabirds. Visibility permitting, five-minute counts of migrating seabirds were conducted each morning, which were used to help determine daily arrivals. Roosting Brown Pelicans ( Pelecanus occidentalis) were also counted each morning, visibility permitting. The environmental conditions and censusing procedures varied little during the 22-year period of data collection. The two 8-m-high Monterey Cypresses ( Cupressus macrocarpa) adjacent to the southeastern living quarters (see map in Coulter 1972), which had been one of the primary focal points of migratory lanbirds (DeSante and Ainley 1980), blew over in a storm on 13 November 1981 . These were replaced by two saplings of the same species in 1982, at which time a third sapling cypress was planted adjacent to the northwestern living quarters. These three cypresses grew in height from about 3 to 5 m between their planting and December 1989. The bush mallow Lavatera arborea, a flowering biennial that grows to a height of 2.5 m, increased in abundance from a few plants in 1975 to three cultivated patches of approximately 100 m 2 each from 1980 through 1989. Two of these patches surrounded the Monterey Cypresses adjacent to each living quarters, and the third patch was located about 200 m southeast of the living quarters, in an area previously occupied only by annuals less than 0.5 m tall. The overall vegetation structure otherwise remained virtually unchanged from that described by DeSante and Ainley (1980). An increase in the annual totals of hummingbirds detected on the island since the late 1970s is probably related to the expansion of bush mallow, which has induced hummingbirds to stay longer (PRBO, unpub- lished data). Otherwise, because habitat considerations are inconsequential in determining the abundance of migrant landbirds on the island (DeSante and Ainley, 1980, p. 71), we assume that changes in the status of the Monterey Cypress and the bush mallow have altered neither the number of landbirds attracted to the island nor their detectability on daily censuses. TERMINOLOGY AND METHODS OF ANALYSIS Table 1 lists and summarizes the seasonal occurrence patterns of the 359 migratory species recorded on the island from 3 April 1968 through 31 December 1989. Five hypothetical species and three escaped cagebirds recorded during the 22-year period are listed separately, following the table. The notes, also following the table, describe anomalous occurrence pat- terns, unusual individual records, all breeding activity by landbirds, and other observations of interest. Sixteen of the 375 species recorded on the island are not included in the table. Twelve of these are breeding seabirds, which were not censused daily: Leach’s Storm-Petrel ( Oceanodroma leucorhoa), Ashy Storm-Petrel (O. homochroa), Double-crested Cormorant ( Phalacrocorax auritus), Brandt’s Cormorant (P. pencil latus), Pelagic Cormorant (P. pelagicus), American Black Oystercatcher (Haematopus bachmani), Western Gull ( Larus occidentalis ), Common Murre ( Uria aalge), Pigeon Guillemot (Cepphus 42 BIRDS OF SOUTHEAST FARALLON ISLAND columba), Cassin’s Auklet ( Ptychoramphus aleuticus), Rhinoceros Auklet (Cerorhinca monocerata ), and Tufted Puffin ( Fratercula cirrhata). Ainley and Boekelheide (1990) and Carter et al. (1990) have provided detailed information on occurrence patterns and population status of these species on the island. The remaining four species, Short-tailed Albatross ( Diomedea albatrus ), White-faced Ibis ( Plegadis chihi), Black Rail ( Laterallus jamaicensis ), and Clapper Rail (Rallus longirostris), were recorded on the island prior to 1968 but not during the period on which we report. DeSante and Ainley (1980) provided details on these species and others reported from the island prior to 1968. Table 1 includes the following categories: Species. All migratory species identified with confidence on or within 2 km of the island during the 22-year census period are listed. For rare and vagrant species we follow the evaluations of the California Bird Records Committee (CBRC), which has reviewed or is in the process of reviewing records of all species included in Table 1 that meet their criteria for assessment (see Bevier 1990). Records of species not accepted by the CBRC are, at best, considered hypothetical by us. Also included in Table 1 are additional subentries for 17 subspecific taxa, three intergrades of subspecies, four interspecific hybrids, and two species pairs, grebes of the genus Aechmophorus and hummingbirds of the genus Selasphorus, in which a substantial portion of the individuals were identified to the pair but not to species. Figure 1. Southeast Farallon Island. Photo by Peter Pyle 43 BIRDS OF SOUTHEAST FARALLON ISLAND Total. The total number of arrivals of each species recorded during the 22-year period is presented here. For landbirds, we used the same algorithim employed by DeSante and Ainley (1980, pp. 6-7) to calculate the minimal number of arrivals when similar unbanded individuals of a species occurred on successive days: arrivals = total minus total from the day before. By incorporating information on banded birds and distinctive plumage characteristics, well over 95% of arriving landbirds were recorded by means of this algorithim (DeSante and Ainley 1980). Arrivals of waterbirds were carefully estimated with variations of the above algorithim, depending on our ability to census each species accu- rately. Our criteria for waterbirds are those employed by DeSante and Ainley (1980, p. 7) with the exception that, in our analysis, higher turnover during the late fall and winter was assumed for 11 species frequenting inaccessible portions of the island during this period and higher turnover throughout the year was assumed for Brown Pelicans. These assumptions were based on a reassessment of the data from the full 22-year period and on careful censuses we made of these species during the winters of 1988 through 1990. Totals for these species during the period covered by DeSante and Ainley were recalculated and differences can be found in the notes following the table. We have also reassessed in light of additional information the identification or arrival status of six individuals of five other species reported by DeSante and Ainley. Not included in the totals are individuals not confidently identified to species or species-pair and rare or unseasonal species that were not adequately described by the observer. This latter group includes eight records of seven CBRC-review species that were either not accepted by the CBRC or have not yet been submitted to the committee owing to lack of a description. Dates of these records are listed in the notes following the table. Spring, Fall, and Winter Totals. The total numbers of arrivals for each season are presented here. Seasonal definition follows DeSante and Ainley (1980) for the most part; for all species except shorebirds we define the three seasons of occurrence as follows: spring, 1 March-14 July; fall, 15 July-19 December; winter, 20 December-28 (or 29) February. For shore- birds (suborder Charadrii) we define spring as 1 March-20 June and fall as 21 June-19 December. The data presented in Table 1 rigorously follow these seasonal definitions, with the exception of 33 records of 16 species of landbirds that we reclassified after a careful examination of occurrence patterns (see DeSante and Ainley 1980, p. 6). The notes following the table specify these records and present additional data for 1 7 waterbird species whose arrival patterns appear to overlap two or more seasons significantly. We have included 18 known immature dispersants of four landbird species in the spring totals, along with other adults and birds of unknown age recorded in the same time period; records of these are also listed in the notes following the table. In addition, we have not distinguished fall visitants from winter residents that arrived in the fall, as did DeSante and Ainley, and our fall-to-winter cutoff date is 1 1 days earlier than that of DeSante and Ainley (as based on a reevaluation of landbird occurrence patterns over 22 44 BIRDS OF SOUTHEAST FARALLON ISLAND years). Those wishing to compare the results of the two analyses, therefore, should sum fall and winter arrival totals. Date Ranges. Ranges of arrival dates within the spring and fall seasons, as defined above, are listed under this category. Anomalously late or early arrivals within seasons, along with the closest seasonal records during the 22-year period, are pointed out in notes following the table. Mean Dates and Standard Deviations. The mean dates of arrival and the standard deviations (in days) around the means are presented for both spring and fall. The standard deviation indicates how extended or concen- trated the peaks of occurrence are within each season; 68% of the arrivals fall within one standard deviation and 95% of the arrivals fall within two standard deviations of the mean. Generally, deviations of <10 days indicate a concentrated peak, those of 10-20 days indicate a moderately concen- trated peak, and those of >20 days indicate extended arrival. High Counts and Dates. The 22-year high count and date on which the high count was established are given for each species for both spring and fall. The high count refers to the total present on the island regardless of when the individuals arrived; note that in many cases this total includes birds that had arrived on previous dates and occasionally in previous seasons. If the high count was recorded on more than one date, the most recent chronological date is given. If the high count for the island fell during the winter it is listed in the notes following the table. Winter Residents. We follow DeSante and Ainley (1980) in defining winter residents as individuals that remained on the island for >21 days, at least part of which was within the winter season. For each species the total number of residents occurring during the 21 winters of the data set is given. Bonaparte’s Gull Sketch by Sven Achtermann 45 Table 1 Occurrence and Seasonal Distribution of the Birds of Southeast Farallon Island 0) C § ,3 Uu C/5 *55 "c $ s CC nj |2 0) c 3 . O 3 CJ Q -c "2 .gi g S d co +1 CD .3 cn (C 3 C CC 10 c o u> 10 0) CO £ CO _c p a co £ CD CJ -t — i 0 10 U O ■S'S 1 10 § Q ■S co 2. +i ai to C Q CC (0 c o l/) (TD CD C /5 cO (2 cO (2 i« 05 '0 0) Q. CO if If CM 00 CM CM CO 00 CM u LO it ON t" o VO ■o LO LO o CM co CO T 3 CO LO o CO o ■cf s 6 z oo LO O' o v £5 co 00 T-H CT> 00 r- o oo o oo 00 oo 00 LO r^ CO CO oo > o > CM 0 » 05 u CO u > o If o o 3 o CD CD o o o z; z 2 < o a a o o t-h lO LO ON ON ON CM 1—1 CM CM 1 — i t-h CM CM > o z: 00 CM > o z o> > o 2 LD 1—1 Q. 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QJ VJ 3 CD & CD -C = 1 -c a> o zo o ^ B. S £•§ tf) 3 e ;e O -= V5 -c 5 J2 ■“SO •c 2 u i'll •5 ^ a a <5 .£ E ^ I < U 5 o fc Q. § 1/5 s si ■u s « •c -a 0) Q. E "5 < I & to 5 o t to Cl tO -O w 22 T3 tO £ O fc a $ S> o 5 t o 2J g. .5 CQ to X 03 « CO c a c 'a o, ‘a S-rx & Ic W j= „ O -o to _ ^ g* GO | GO -§ GO _g Lark Sparrow 257 26 9 Mar- 26 Apr 2 230 29 Jul- 14 Sep 8 Chondestes grammacus 28 Jun ±26 9 Apr 82 c 13 Dec ±21 1 Oct 74 Black-throated Sparrow 23 7 17 Apr- 21 May 2 16 18 Aug- 14 Sep 2 Amphispiza bilineata 18 Jun ±20 22 May 77 10 Oct ±13 8 Sep 84 Table 1 ( Cont .) 0 ) -*— < C (JL •JL °° 'in ^ s Cl. 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( 0 < < < s < -3 < s s ”3 s 00 rH 00 t-H CM LO CM H* co LO 00 t-H LO CM 00 Lr a < co a < 0 c 3 LO i- O. < Tj> S' O Q. LO >v f a Tf CL ^ >. ^3 CM C D O . C — i CO J-H CL Mt* 1 — i H “3 t-H rH s rH < rH s CM < r— 1 CM co , — 1 t-h < CM av t-H ±1 t-H CM +1 00 rH +1 co t-H +1 av +1 lO +1 t-H +1 lO +1 r-H co +1 O CM +1 1 00 ±1 LO CM +1 I -g I :x I -g Jp ^ 3 S 00 00 SU rH co C I >■ 3 >v ra «g ^ & 2 00 CM csj LO i <0 i 3 i nj rtJ 2i-S CM CM § l CM LO iv§ 2 o O p' CO CM P~ I (0 Q. 00 -o 3 CO CO av LO o OV ov o La V -Si IE £ U 5 - 3, cC L. L>- -C k 5 - O, t/> 8 "53 3 -o -Si E (0 N O i 5 0 lot t .C S t 03 Q. (B HH CL Q. C o §> t o CO o Tf Vj- 00 o o c 3 "3 3 3 Q. if "O — *r — CO « QJ a 3 cs N 2iPvj -S cr V t£ c - ‘ •* ia I N <0 Q o o .2 3 1 3 !| •c o 8 S “3 CO a 3 P CO co 03 o 03 O. _o co "a E 3S. -c JC vO av co vO a 3 2 CO LO a; o a JS 3 v> £ c c a 3 g> “=» o c O -C CO 2 ^ VD «3 3 O E ~ o 3 Q. a. S ^ a cn -~ c O 3 a t/> co c o *0 0) JS a .2 c x ^ a V5 13 -o c fO a ^ ^ ^ 03 -C CJ S*° J3 c C 1 ■§. t> J o VO LO c/) K ^ lo 0 ra ^cc c -a o c^l U -L. C o -c a CQ go, co LC u I CD C/) - 3 cn — c ^ S, I CO "O C £ ,"§ £ " § d “ c/i £ +i §> CO Q (S ra c -= o 49 <2 o ph O' 0 CM CO t-" CO CM CO r- lO CO CM 03 pH ON LO CO T-H rn 0 CM 00 00 LO 10 00 r-~ 00 00 r- t-h r- r-' LO t-p CT) > n CO a. cn cr» n. a CO a CM 3 3 < O z V O 3 < 3 < a < <% $ 3 < O C'. M3 CO M3 \o t-H ON r- On 03 CM CM CM r-l CM CM t-h a $ £3 rH +| O ^ O 2 - 00 00 >, L; L. >, £- k. c rt3 Q. Q. (O H O. <3 I o o vO t-H CM 00 CO pH CM O CO M3 E <3 X £ O C/D CQ ~§ 3 c T% sS « J g)C0 O to *§■ §j LU tj Kh OQ « -g -i § - 5 o s Cx-O 0 p) « « o o "S 3 ’ c § no Si-S a "S u § ^ js OQ O VJ 3 ’C 03 §.5 » O 11 ^ o I cy § O 5 c J 2 O o ■c O v> lx o — =§ ■ 8 -fj «2 O J x CD ‘ a Q) "B cd 3 0^0 iS^E 2 2S.-S 1"S <8 LO M3 M3 a 3 o Wh CD in a> 'G CD CL -§ O £ JJ ^1-8 |£° Jr? co 3 ^ t3 £ r-* ON V) 3 fi 3 B- 3 cl I -C 3 ill 3 j*! B* 5&<3 £5l Cassin’s Finch 7 3 12 Apr- 6 May 1 4 5 Oct- 1 Nov 1 C. cassinii 14 Jun ±34 21 Apr 87 c 11 Dec ±29 11 Dec 89 House Finch 586 325 9 Mar- 21 Apr 23 251 19 Jul— 15 Oct 12 C. mexicanus 1 Jul ±24 26 Apr 83 15 Dec ±23 26 Oct 72 VO co esa r- o CM o OV VO \D i-H cjn ov ' 00 o t^- LO r^- H oo 00 > o o. -♦— < -M— 1 ±1 I LO +1 N H N ^ ^ CO M CT) O 00 -3 l— D u (D Q -3 ■™D u 01 a is2 i S 5 < 'sD o> lO a\ H i-H l-H r-H ov CO i-H CM CM CM VO CO oo CO i-H cn 00 l-H a ) 0 lo 00 C' IT" r— 00 L-* k— k. >— o. to O. to a < 2 < 2 s < r"~ Ov 00 LO 1^ o n l-H CM r-H 2-vo S-r- to < CO ^ CO ± co ±1 t — ±1 ^ CM CM ^ CM 2 S 2 +1 oo +1 r-~ CM r - ra ' ' d * lo ' S N 2 H (0 -3 2 > .1 tO c >• 3 <0 J r ~- CM 00 CM OO ^ VO LO CO o CO e-r- < 1-1 CM +1 CM J C v- — 1 « -5 'V ,—1 CM © OV CM VO LD 00 00 VO vO r-- V) C J= .= o Cu C ^ 3 c ~ 15 U5 U ^ Si ,2 2 o ui 2 (5 ^ 8 *2 1 It 13 -J c <-> a CC CX -J S — 5 5 3 C — -« — a > _Q _C o .S o .2 <3 i: 10 a cj £ c u, CD u c 32 o O c 3 c CD a C/J (6 , u a ^ to •SJi ? 1 — d c w on 1 - § B. if Si If - P ® ai m E g S flOA (/)(/) «o 50 cm dbh (diameter at breast height), at least two canopy layers (canopy closure >50%), and standing dead trees. To locate nests, we watched 74 potential nest trees in July for 10--15 minutes each in five of the eight stands. We considered a tree a potential nest site if it had a hollow interior and a Pileated Woodpecker entrance hole or a broken-off top. If a swift was seen entering a tree, we climbed the tree to determine if there was a nest. We used a periscope to look for nests in trees with intact tops. If we could see a nest, we recorded the number and size of young and the distance from the entrance hole to the nest. We measured diameter, depth, and height of the hollow chamber (both up and down) from the entrance hole, as well as the height, width, and exposure of the entrance hole, the outside tree diameter at the entrance hole, and the thickness of the shell at the entrance. For the nest tree, species, condition (live or dead), Western Birds 22:85-91, 1991 85 VAUX’S SWIFT NESTS dbh, tree height, height of entrance hole above ground, number of entrance holes, presence of decay, and condition of the tree top {intact or broken) also were recorded. In the 1 hectare surrounding the tree, we recorded forest type, succes- sional stage, logging activity, canopy closure, and slope gradient and exposure. Successional stage was classified as mature or old growth. Old- growth stands were multi-layered, had >50% canopy closure, and had >10 trees/ha that were >50 cm dbh. Stands that contained trees >30 cm dbh but did not have any trees >50 cm dbh or did not have enough to qualify as old growth were considered mature. Logging activity was classified as {1) no logging or high-graded stands logged >20 yrs ago when only the valuable large-diameter serai species Ponderosa Pine ( Pinus ponderosa), Western Larch ( Larix occidentalis ), and Douglas-fir were harvested, (2) partial overstory removal where 20-40% of the basal area had been removed within the last 20 years, or (3) shelterwood cut, which is the gradual removal of an entire stand in a series of cuts. Canopy closure was determined in percentage with a densiometer. Slope gradient was measured in percentage with a clinometer. We recorded feeding interval by sitting below nest trees and recording the time an adult entered and left the entrance hole during the day. RESULTS Twenty-one Vaux’s Swift nests were located in 20 trees; one tree contained two nests. All the nests were in trees with their heartwood cores decayed and hollowed out by Indian paint fungus (Echinodontium tinctoriurn), and all had entrance holes excavated by Pileated Woodpeckers for roosts (Figure 1). We located the first nest on 20 June when we saw a swift breaking tiny branches off a small (15 cm dbh) dead Douglas-fir and flying into a hole excavated by a Pileated Woodpecker in a large (94 cm dbh) dead Grand Fir. The second nest was located 12 July and contained 6 or 7 eggs; on 17 July this nest contained 5 or 6 young. The nest was a semicircle of small sticks cemented together with saliva (Figure 2). The other 19 nests were located between 20 July and 2 August, and all contained young. Young swifts were observed out of the nest but clinging to the wall of the nest cavity at three nests on 1, 2, and 6 August. Adults were still entering one of the nest trees on 20 August. We observed Vaux’s Swifts apparently copulating in the air on 1 1 June 200 m from a nest. On 27 June we observed one of a pair of Vaux’s Swift in the V-glide aerial display described by Stokes (1983) as part of the courtship of the Chimney Swift ( Chaetura pelagica). This behavior has not been previously reported for the Vaux’s Swift. To record foraging intervals, we watched seven nests from 20 July to 3 August for a total of 7.2 hours. The average interval between trips to feed young at a nest was 12.1 minutes (SD = 16.61, range = 0.5-90 minutes, N = 27).' The amount of time the adult stayed in the nest averaged 178 seconds (SD - 340.47, range = 30-1800 sec, N - 28). 86 VAUX’S SWIFT NESTS All the swifts entered their nest trees through the woodpecker holes. Three of the 20 nest trees had their tops broken off, and we observed swifts Figure 1. Live Grand Fir with Pileated Woodpecker holes used by Vaux’s Swifts as a nest tree. Photo by Evelyn L. Bull 87 VAUX’S SWIFT NESTS leave the tree through the hollow top at two of them. We never saw them enter the trees through the top. Nineteen of the holes excavated by Pileated Woodpeckers and used by the swifts were full-sized {approximately 11x8 cm, Table 1), while two of Figure 2. Vaux’s Swift nest constructed on the inside of a hollow tree. Photo by Evelyn L. Bull 88 VAUX’S SWIFT NESTS them were only partially completed. One of the incomplete holes must have been about the minimum size (5.1 x 4.4 cm) the swifts could use, because we saw an adult swift get stuck in the hole on its way out. After about 2 minutes of struggling, it got a wing out of the hole, then the second, and used the wings as leverage to pull the rest of the body through. This happened only once in seven observed feedings at this nest. Sixty-five percent of the swifts’ nest chambers were accessible through one hole made by a Pileated Woodpecker; the remainder were accessible through two. Typically the swifts went into the lower of the two holes. Forty-three percent of the holes faced north, 34% faced east, 14% faced south, and 10% faced west. Nineteen of the nests were an average of 2.05 m below the entrance hole used for access and 1.6 m up from the bottom of the chamber. Two nests were 0.4 and 2.5 m above the entrance hole. The tree containing the two swift nests had a partition separating them, so each pair had its own entrance and its own chamber. The pair in the lower hole had their nest below the entrance hole, whereas the pair in the upper hole had their nest above the hole. All of the nests were in Grand Firs, of which 17 were live and 3 were dead. Trees used by the swifts for nesting were large in diameter (mean = 67 cm dbh). The entrance hole averaged 12 m above the ground and ranged in height from 8 to 18.3 m (Table 1). The forest type surrounding all nest trees was Grand Fir. Seventeen of the nests were in old-growth stands that had no cutting or had been high- graded, two were in mature stands that had been high-graded, and one was in a shelterwood cut where large-diameter {>80 cm dbh) dead Grand Fir had been retained. Seventy-five percent of the nests were on slopes gentler Table 1 Characteristics of 21 Vaux’s Swift Nests in Hollow Trees in Northeastern Oregon, 1990 Characteristic Mean Standard Deviation Range Tree characteristics Diameter at breast height (cm) 67.5 14.6 45-96 Height (m) 25.4 6.7 15-37 Canopy closure (%) 70.8 18.7 5-91 Height of hole above ground (m) 12.0 2.6 8-18 Cavity characteristics Entrance hole height (cm) 10.9 2.0 5.1-12.7 Entrance hole width (cm) 8.1 1.2 9. 8-4. 4 Diameter inside cavity (cm) 28.4 5.1 19.7-39.1 Outside diameter at hole (cm) 48.8 10.2 32-66 Width of surrounding wood (cm) 7.8 2.9 3.2-13.7 Cavity depth below hole (m) 3.6 2.5 0.6-7. 7 Cavity depth above hole (m) 2.1 1.7 0. 1-7.6 89 VAUX’S SWIFT NESTS than 10%; the remainder were on steeper slopes. Slope aspect was north- facing or east-facing at 80% of the nests. Several nests were in close proximity in three of the stands. Eight nests were found within 2 ha in an old-growth stand in Umatilla County; the distance between these nests ranged from 30 to 94 m. Four nests were within 8 ha in an old-growth stand in Union County; distance between these nests ranged from 200 to 350 m. Another four nests were situated 70-400 m apart in another stand in Union County. The last four nests were all in separate stands. We doubt that we located all the Vaux’s Swift nests in any of these stands. DISCUSSION In northeastern Oregon, the chronology of the Vaux’s Swift nesting appeared to be nest building and incubation in June, nestlings from mid- July to mid- August, and fledglings (out of nest but in tree) from early to late August. These dates compare with other nesting dates reported in the literature for Oregon {Griff ee 1961, Thompson 1977) and Montana (Baldwin and Hunter 1963, Baldwin and Zaczkowski 1963). Davis (1937) reported feeding trips to the nest every 1-21 minutes; Finley and Finley (1924) observed feeding every 15-20 minutes at a nest. Our average foraging interval fell within these times; however, we observed a wider range of intervals than reported previously. The longest foraging interval (90 minutes) was recorded on a very hot afternoon. Both adults fed the young and remained in the cavity for 30 minutes or more. Vaux’s Swift nests were in old-growth Grand Fir and in trees used by Pileated Woodpeckers for roosting. Eighty-five percent of the nests were in old growth, and all nests were in Pileated Woodpecker roosts. We do not know if the association resulted because the potential nest sites were in old growth or because the swifts selected the old-growth habitat and then searched for nest sites there. Pileated Woodpeckers typically roost in old- growth Grand Fir because the large diameter of these trees accomodates a hollow chamber large enough for the woodpeckers to enter, 8-18 meters above the ground. In addition, the larger and older trees typically have more decay, which creates the hollow interior. In northeast Oregon, the majority of hollow trees are Grand Fir because of the prevalence of the Indian paint fungus that decays the heartwood. The swifts cannot enter these hollow trees unless the top is broken off or there is a hole in them. For this reason, we suspect Pileated Woodpeckers create the majority of nest sites for Vaux’s Swifts, because broken-topped hollow trees are scarce in most stands. Broken-topped trees are, however, important communal roost sites for Vaux’s Swifts (Bull, unpublished data). Hofslund (1958) reported a Chimney Swift nest in an abandoned nesting hole of a Pileated Woodpecker. In northeastern Oregon, it appears that Vaux’s Swifts depend on Pileated Woodpeckers to provide access to suitable nest sites, and Pileated Wood- peckers, in turn, depend on old-growth forests to provide large-diameter trees with hollow interiors for their roost sites. These important habitat components need to be considered in habitat management decisions and to 90 VAUX’S SWIFT NESTS be maintained in forests if nesting habitat for these birds is to be conserved. Our hypothesis that Vaux’s Swifts require old-growth forests now needs testing to determine if the species is also found in second growth or logged stands with appropriate nest trees retained. SUMMARY Twenty-one Vaux’s Swift nests were found in 20 hollow Grand Fir trees; one tree contained two nests. All 20 trees were Pileated Woodpecker roost trees, and the swifts entered these trees through holes created by the woodpeckers. Eighty-five percent of the nest trees were in old-growth forests. Nest building was observed in June; young were in the nest from mid-July to early August; young were out of the nest but in the tree from early to late August. Foraging interval at nests averaged 12 minutes. Eight nests were found within a 2-ha area. ACKNOWLEDGMENTS We are grateful to Charles Collins for his advice and assistance. The USDA Forest Service, Pacific Northwest Research Station, provided funds. This manuscript was reviewed by C. T, Collins, R. S. Holthausen, W. F. Laudenslayer, M. G. Raphael, and J. W. Thomas. LITERATURE CITED Baldwin, P. H., and Hunter, W. F. 1963. Nesting and nest visitors of the Vaux’s Swift in Montana. Auk 80:81-85. Baldwin, P. H., and Zaczkowski, N. K. 1963. Breeding biology of the Vaux’s Swift. Condor 65:400-406. Bent, A. C. 1940. Life histories of North American cuckoos, goatsuckers, humming- birds, and their allies. Bull. U.S. Natl. Mus. 176. Davis, W. B. 1937. A Vaux Swift and its young. Condor 39:222-223. Finley, W. L., and Finley, 1. 1924. Changing habits of Vaux Swift and Western Martin. Condor 26:6-9. Gabrielson, I. N., and Jewett, S. G. 1970. Birds of the Pacific Northwest. Dover, New York. Griff ee, W. E. 1961. Nesting of the northern Vaux Swift in the Willamette Valley. Murrelet 42:25-26. Hofslund, P. B. 1958. Chimney Swift nesting in an abandoned Pileated Woodpecker hole. Wilson Bull. 70:192. Manuwal, D. A., and Huff, M. H. 1987. Spring and winter bird populations in a Douglas-fir forest sere. J. Wildlife Mgint, 51:586-595. Stokes, D. W. 1983. A Guide to Bird Behavior. Little, Brown, Boston. Taylor, H. R. 1905. The nest and eggs of the Vaux Swift. Condor 7:17179. Thompson, B. C. 1977. Behavior of Vaux’s Swifts nesting and roosting in a chimney. Murrelet 58:73-77. Accepted 6 March 1991 91 ATLASING CALIFORNIA’S BREEDING BIRDS — COUNTY BY COUNTY TIM MANOL1S, 808 El Encino Way, Sacramento, California 95864 Projects to map the distributions of breeding bird species in a given area by means of a grid-based system have grown in popularity worldwide since the first of these breeding bird atlases (as they have come to be known) began in Great Britain in the 1960s (e. g., see Laughlin et al. , Am. Birds 36:6, 1982). In Europe and elsewhere atlas projects have often been national in scope. When atlasing hit North American shores, however, it fragmented into a state-by-state effort, and, as it made its way westward, into a county-by-county proposition. The first California atlas project began in Marin County as early as 1976. Western Field Ornithologists’ annual meeting has emerged since as a major forum for the discussion of atlasing efforts on the West Coast. At the 1985 meeting in San Rafael, David Shuford spoke about the Marin County atlas, one of only two (the other was Orange County’s) then in progress within the state. The first of what was to become a series of workshops on atlasing was held at the 1986 meeting in Sacramento. A conference room filled to overflowing with inter- ested WFO members bore witness to a big upswing in atlas enthusiasm and activity. There were now three active California county atlas projects — Sonoma joined the list — and San Bernardino and Sacramento counties were preparing to start atlas work in 1987. Compilers of an atlas for Lane County, Oregon, presented a report on the status of their project. By 1988, when a second atlas workshop was held at the WFO meeting in Monterey, eight California atlas projects were underway (Monterey, Santa Clara, and Santa Cruz were new additions). At the most recent WFO meeting, in San Diego in September 1990, representa- tives of most of California’s ongoing county atlas projects gathered for a third biennial workshop. Including Orange and Marin counties, which had completed field work, there were now 11 active county atlas projects (Napa, San Luis Obispo, and Riverside having been added to the list). Six individuals representing seven atlas projects spoke at the San Diego meeting. Barbara Carlson (San Bernardino and Riverside counties) discussed some of the problems encountered in beginning an atlas project (e. g., raising funds, producing a project newsletter on a regular basis, developing database and mapping programs) but focused on encouraging atlasers to expand into neighboring counties, as her team of San Bernardino atlasers did in 1990 with the addition of Riverside County to the project. She pointed out that taking on a new county in this fashion, as an offshoot of an established project, was considerably easier than starting from the ground up. Sylvia Ranney Gallagher (Orange County) shared experiences from her group’s six years of field work. Among key points she mentioned were (1) the need to encourage community involvement in the project, using media coverage, (2) establishing a database management system before beginning the project, (3) collecting data on habitat distribution and changes during the course of the project, and (4) anticipating the final product (the published atlas) when formatting data collection. Speaking next, I noted the current status of the Sacramento County project and described a graphical method for presenting information on breeding phenology collected during atlas work. Paul Noble (Santa Clara County) presented maps of the preliminary distributions of certain species documented by Santa Clara County atlasers. He discussed aspects of atlasing in a county that contains rugged and isolated as well as heavily urbanized blocks. 92 Western Birds 22:92-94, 1991 Speaking for Santa Cruz County, David Suddjian discussed the status of the county’s project, presenting data on patterns of distribution of some breeding species and describing the involvement of local organizations and some methods of fund- raising in support of atlas work. Suddjian also discussed the collection and graphical representation of data on breeding phenology. Mildred Comar (San Luis Obispo County) concluded the county reports with a brief overview of progress on her county’s project The workshop ended with an open discussion involving all participants. By consensus, those present encouraged WFO to establish a committee to evaluate the potential for further statewide cooperation and coordination of atlas work in Califor- nia. The day following, I presented a summary of the workshop to the WFO general membership, describing the current status of each project, discussing the value of these activities to the understanding and conservation of California's birdlife, and encouraging others to expand the work throughout the state. Some interest was expressed at the WFO meeting on establishing atlas projects in other counties, and I hope such interest will bear fruit and continue to spread. With the exception of Marin, which was atlased by means of a grid of blocks approximately 2.5 km on a side (derived from directly subdividing USGS 7.5-minute topo maps), California county atlas projects have all used blocks 5 km on a side derived from the Universal Transverse Mercator Grid. All grid blocks are being covered in most counties (Marin, Napa, Orange, Sacramento, San Mateo, Santa Clara, Santa Cruz, Solano, and Sonoma). Larger counties, however, have not found such a course feasible. The Monterey and San Luis Obispo projects are covering all blocks in accessible areas (priority blocks) and quads (each with one priority and three non-priority blocks) in more remote areas. The San Bernardino and Riverside projects are conducting stratified random sampling, selecting one block out of six in areas with diverse habitats and one block out of twelve in areas with essentially monotypic vegetation, as well as covering specialty blocks with unique biological features. The present status of all California county atlas projects is described below, including names and addresses of individuals who can be contacted for further information. All involved are eager to help other atlas projects get started (and deserve thanks for providing information for this summary). In addition, 1 urge anyone interested in working with or providing advice or assistance to the WFO committee to evaluate possibilities for statewide coordination of atlas work to contact me at the address shown. CALIFORNIA COUNTY ATLAS PROJECTS MARIN — Field work was conducted from 1976 to 1982. Results are in the final phases of preparation for publication. Contact: David Shuford, Point Reyes Bird Observatory, 4990 Shoreline Highway, Stinson Beach, CA 94970. MONTEREY — Completion of field work, begun in 1988, is anticipated in 1992. Contact: Becca Serdehely, 280 Hidden Valley Road, Watsonville, CA 95076. NAPA — Field work began in 1988 (pilot year). Completion of field work is antici- pated in 1993. Contact: Bill Grummer, 3801 N. St Helena Highway, Calistoga, CA 94515, or Mike Rippey, Rural Route 1, Box 694, Vallejo, CA 94589. ORANGE — Field work was conducted from 1985 to 1990. Results are being prepared for eventual publication. Contact: Sylvia Ranney Gallagher, 21562 Kaneohe Lane, Huntington Beach, CA 92646. 93 RIVERSIDE — Field work began in 1990. Contact: Barbara Carlson, P. O. Box 55419, Riverside, CA 92517. SACRAMENTO — Field work began in 1987 (pilot year); completion is expected by 1992. Contact: Tim Manolis, 808 El Encino Way, Sacramento, CA 95864. SAN BERNARDINO — Completion of field work, begun in 1987, is anticipated in 1992. Contact: Barbara Carlson (see above). SAN FRANCISCO — Scheduled to begin in 1991. Contact: Stephen F. Bailey, Dept, of Ornithology and Mammalogy, California Academy of Sciences, Golden Gate Park, San Francisco, CA 94118. SAN LUIS OBISPO — Field work began in 1989; completion is anticipated in 1993. Contact: Mildred Comar, 5525 Cascabel, Atascadero, CA 93422. SAN MATEO — Scheduled to begin in 1991, but incorporating information gathered for the Santa Cruz and Santa Clara projects dating back to 1987; the project will be completed in 1994. Contact: David Suddjian, 1136 Callas Lane #1, Capitola, CA 95010. SANTA CLARA — Scheduled for completion in 1992, field work began with a pilot year in 1987. Contact: William Bousman, 321 Arlington Way, Menlo Park, CA 94025. SANTA CRUZ — Begun in 1988 (but incorporating some data collected in 1987), the project is scheduled for completion in 1991. Contact: David Suddjian (see under San Mateo County). SOLANO — Began in 1988 (pilot year), but put on hold until completion of field work in Napa County. Completion anticipated in 1998. Contact: Robin Leong, 336 Benson Avenue, Vallejo, CA 94590. SONOMA — Field work was conducted from 1986 to 1990. Results are being prepared for publication. Contact: Betty Burridge, 1653 Arroyo Sierra, Santa Rosa, CA 95404, or Ruth Rudesill, P.O. Box 371, Kenwood, CA 95452. 94 AN UPDATE FROM THE CALIFORNIA BIRD RECORDS COMMITTEE MICHAEL A. PATTEN, Secretary, P. O. Box 8612, Riverside, California 92515-8612 The California Bird Records Committee (CBRC) received 221 records in 1990. A similar number (213) of records was received in 1989, and this will probably be close to the annual average. The CBRC has reviewed about 2860 of the 3110 “published records” (as defined by Roberson, “News from the California Bird Records Commit- tee,” W Birds 20:269-271, 1989) through May 1990, which represents a review percentage of close to 92%. The twelfth report of the CBRC is now in press (next issue of Western Birds ) and a draft of the thirteenth report has been completed. These reports will publish all Committee decisions for bird records received through 1988. A fourteenth report is also in preparation. It will cover all pre-1986 records for which documentation has been obtained and recently reviewed. A list of “unresolved” records will also be published soon, either separately or as an appendix to the fourteenth report. This publication will list all published records for which little or no documentation has been received by the CBRC. Roberson (1989) reported that as of January 1990 the California state list stood at 572 species. The CBRC has since reviewed and accepted three additional species: Murphy’s Petrel ( Pterodroma ultima ), Common Pochard (Aythya ferina), and Gray Wagtail (Motacilla cinerea). Also, the Introduced Birds Subcommittee submitted the Sierra Nevada population of White-tailed Ptarmigan ( Lagopus leucurus ) for review, and the species was formally accepted. Thus, the current (April 1991) state list stands at 576 species. A number of species that would represent first state records are currently under review: Solander’s Petrel ( Pterodroma solandri), Crested Caracara ( Polyborus plancus ), Band-tailed Gull ( Larus belcheri), Iceland Gull (L. glaucoides), Swallow-tailed Gull ( Creagrus furcatus ), Oriental (Rufous) Turtle-Dove ( Streptopelia orientalis), Green Kingfisher ( Chloroceryle americana), Cave Swallow ( Hirundo fulva), Red-flanked Bluetail ( Tarsiger cyanurus), Eyebrowed Thrush (Turdus obscurus), Smith’s Longspur ( Calcarius pictus), Eastern Meadowlark ( Sturnella magna), and Oriental Greenfinch ( Carduelis sinica). The current members of the CBRC are Stephen F. Bailey, Jon L. Dunn, Richard A. Erickson, Kimball L. Garrett, Matt T. Heindel. Paul E. Lehman, Michael J. Lippsmeyer, Guy McCaskie, Joseph Morlan, and Michael A. Patten. After serving five years as Secretary, Don Roberson retired in January 1991. All documentation and correspondence should now be sent to me at the above address. The annual CBRC meeting was held on 12 January 1991 at the Los Angeles County Museum of Natural History. At this meeting, no changes were made to the bylaws or the Review List, last given by Roberson (1989). As in the past, copies of the CBRC bylaws and Review List can be obtained from the Secretary at no charge, but please include a self-addressed stamped envelope. 95 Volume 22, Number 2, 1991 The Birds of Southeast Farallon Island: Occurrence and Seasonal Distribution of Migratory Species Peter Pyle and R. Philip Henderson 41 Vaux’s Swift Nests in Hollow Trees Evelyn L. Bull and Howard D. Cooper 85 Atlasing California’s Breeding Birds - County by County Tim Manolis 92 An Update from the California Bird Records Committee Michael A. Patten 95 Bulletin Board 96 Cover photo by © David A. Leatherman of Fort Collins, Colorado: Least Bittern (Ixobrychus exltis), Riverbend Ponds along Poudre River, Fort Collins, Colorado. June 1983. Western Birds solicits papers that are both useful to and understandable by amateur field ornithologists and also contribute significantly to scientific litera- ture. The journal welcomes contributions from both professionals and amateurs. Appropriate topics include distribution, migration, status, identifica- tion, geographic variation, conservation, behavior, ecology, population dynamics, habitat requirements, the effects of pollution, and techniques for censusing, sound recording, and photographing birds in the field. Papers of general interest will be considered regardless of their geographic origin, but particularly desired are reports of studies done in or bearing on the Rocky Mountain and Pacific states and provinces, including Alaska and Hawaii, western Texas, northwestern Mexico, and the northeastern Pacific Ocean. Send manuscripts to Philip Unitt, 3411 Felton Street, San Diego, CA 92104. For matter of style consult the Suggestions to Contributors to Western Birds (8 pages available at no cost from the editor) and the Council of Biology Editors Style Manual (available for $24 from the Council of Biology Editors, Inc., 9650 Rockville Pike, Bethesda, MD 20814. Reprints can be ordered at author’s expense from the Editor when proof is returned or earlier. Good photographs of rare and unusual birds, unaccompanied by an article but with caption including species, date, locality and other pertinent information, are wanted for publication in Western Birds. Submit photos and captions to Photo Editor. - jp- -m JT IP 1, I rT Vol. 22, No. 3, 1991 WESTERN BIRDS Quarterly Journal of Western Field Ornithologists President: Peter Gent, 55 South 35th, Boulder, CO 80303 Vice-President: Robert McKeman, 1230 Friar Lane, Redlands, CA 92373 Treasurer/Membership Secretary: Howard L. Cogswell, 1548 East Avenue, Hayward, CA 94541 Recording Secretary: Jean-Marie Spoelman, 4629 Diaz Drive, Fremont, CA 94536 Circulation Manager: William E. Haas, 10601-A Tierrasanta Blvd., Suite 127, San Diego, CA 92124 Directors: Bruce Deuel, Peter Gent, Ron LeValley, John S. Luther, Guy McCaskie, Robert McKeman, Steve Summers, Janet Witzeman, David Yee Editor: Philip Unitt, 3411 Felton Street, San Diego, CA 92104 Associate Editors: Cameron Barrows, Tim Manolis, Thomas W. Keeney Graphics Manager: Virginia P. Johnson, 4637 Del Mar Ave., San Diego, CA 92107 Photo Editor: Bruce Webb, 8204 Cantershire Way, Granite Bay, CA 95661 Secretary, California Bird Records Committee: Michael A. Patten, P. O. Box 8612, Riverside, CA 92515 Editorial Board: Robert Andrews, Alan Baldridge, Andrew J. Berger, Laurence C. Binford, David F. DeSante, Jon L. Dunn, Richard Erickson, Kimball L. Garrett, Joseph R, Jehl, Jr., Ned K. Johnson, Virginia P, Johnson, Brina Kessel, Stephen A. Laymon, Paul Lehman, John S. Luther, Guy McCaskie, Joseph Morlan, Harry B. Nehls, Dennis R. Paulson, Oliver K. Scott, Ella Sorensen, Richard W. Stallcup, Charles Trost, Terence R. Wahl, Roland H. Wauer, Bruce Webb, Wayne C. Weber, Richard E. Webster Membership dues, for individuals and institutions, including subscription to Western Birds: Patron, $1000; Life, $250; Supporting, $50 annually; Contributing, $30 annually; Family, $22; Regular, U S. , $18 for one year, $35 for two years, $50 for three years; outside U.S. , $23 for one year, $45 for two years, $65 for three years. Dues and contributions are tax- deductible to the extent allowed by law. Send membership dues, changes of address, correspondence regarding missing issues, and orders for back issues and special publications to the Treasurer. Make checks payable to Western Field Ornithologists. Back issues of California Birds/Western Birds: $20 per volume, $5.00 for single issues. Xerox copies of out of print issues (Vol. 1 , No. 1 ; Vol. 2, Nos. 1 and 4; Vol. 6, No. 2) : $5.50 each. Checklist of the Birds of California: $2.00 each, 10 or more $1.50 each. Pelagic Birds of Monterey Bay, California: $2.50 each, 10 or more $2.00 each, 40 or more $1.50 each. All postpaid. Published September 15, 1991 ISSN 0045-3897 WESTERN BIRDS ADVERTISING RATES AND SPECIFICATIONS Full page 4 x 6 3 A inches $60 per issue $200 per year Half Page 4x3% inches $40 per issue $130 per year Quarter Page 4 x l n / 16 inches $30 per issue $110 per year Offset printing, one column per page, 4 inches wide. Glossy, black and white photos are ac- ceptable; half-tone screen size: 133 line. Photo-ready copy is requested. If this is not possible, extra charges for typesetting will be made as follows: $15 full page, $10 half page, $5 quarter page. Send copy with remittance to the Treasurer. Make checks payable to Western Field Ornithologists, A 15% commission is allowed for agencies. WESTERN BIRDS Volume 22, Number 3, 1991 TWELFTH REPORT OF THE CALIFORNIA BIRD RECORDS COMMITTEE JERI M. LANGHAM, Biology Department, California State University, Sacramento, California 95819 Western Field Ornithologists and the California Bird Records Com- mittee are again pleased to thank Bushnell, a division of Bauch & Lomb, for its continued generous support in helping to sponsor the publication of these reports. This report contains 244 reviewed records of 70 species plus one hybrid. The 206 accepted records of 58 species and 38 unaccepted records of 25 species plus one hybrid represent an 84.8% acceptance rate. The California Bird Records Committee (hereafter, the CBRC or the Committee) is very grateful to the 183 observers who took time to contrib- ute descriptions and/or photographs of birds on our Review List that they encountered in California. Although this report includes records from more observers than any previous report, we still encourage additional birders and ornithologists to support the CBRC process by submitting reports and/ or photographs to Michael A. Patten, CBRC Secretary, P.O. Box 8612, Riverside, CA 92515. The Western Foundation of Vertebrate Zoology (1100 Glendon Avenue, Los Angeles, CA 90024) and its director Lloyd Kiff continue to maintain the archive of all records published in CBRC reports. All voice recordings are kept at the California Academy of Sci- ences, Department of Ornithology and Mammalogy, Golden Gate Park, San Francisco, CA 94118. The Committee has accelerated its progress of reviewing older records while continuing to review current ones. The former include some speci- men records as well as old records from the files of both the Middle and the Southern Pacific Coast regions of American Birds (hereafter abbreviated AB) and its predecessor Audubon Field Notes (hereafter AFN). Many of these reports have long been considered valid by other authors; their publication in this report marks their CBRC acceptance or unacceptance Western Birds 22:97-130, 1991 97 CALIFORNIA BIRD RECORDS under a formal record number. With the publication of our upcoming summary of old records in the fourteenth report, the CBRC will have evaluated about 91% of all published records of Review List species. We welcome all documentation of unreviewed past records, published or not. State List. As of the eleventh report {Bevier 1990), the California list stood at 572. Since then, three additional species, the White-tailed Ptarmi- gan ( Lagopus leucurus), Murphy’s Petrel ( Pterodroma ultima), and Gray Wagtail { Motacilla cinerea) have been accepted, bringing the list to 575. Details of these recent decisions will appear in the thirteenth and fourteenth reports. In addition, reported here is the earliest acceptable California record of the Anhinga ( Anhinga anhinga). The most recently published state checklist (Field List of California Birds, 1987) contains 565 species and is available from Western Birds’ circula- tion manager for $1.00 postpaid. Reuiew List. The list of species and species complexes we review has remained fairly stable over recent years and was recently published by Roberson (1990). In general, our Review List includes species that average four or fewer records per year over the most recent 10-year period and any species not yet on the California list. The Tricolored Heron (Egretta tricolor ) was recently added to this list (Bevier 1990), and documentation is desired only for observations since 1990. Cook’s Petrel ( Pterodroma cookii), Wilson's Storm-Petrel ( Oceanites oceanicus), Barred Owl (Sfrix uaria), and Prothonotary Warbler ( Protonotaria citrea) were deleted (Bevier 1990), but we still desire documentation for records prior to 1990 of these four species. Format. The format is very similar to that of the tenth (Dunn 1988) and eleventh (Bevier 1990) reports. The accepted and unaccepted records are listed separately by species in the order of the Check-list of North Ameri- can Birds, 6th ed. (AOU 1983), and its supplements (AOU 1985, 1987, 1989). Within each species account, the records are usually listed chrono- logically according to first known date of occurrence. On rare occasions, to facilitate understanding of CBRC decisions, the order has been changed. Names preceded by an asterisk are of species no longer on the Review List. The number of CBRC-accepted records, in parentheses, follows the species name. For species we no longer review, this number reflects only CBRC- accepted records during the period in which the species was on our Review List. Two asterisks following this number denote that the period of years for which the species has been reviewed is restricted or that some older reports not formally accepted have been included (Roberson 1986). Each record includes the locality, a standard abbreviation for the county (see below), and full date spans. In most cases, the dates are from the seasonal reports in AB and AFN. Dates differing from those listed in these publications are itali- cized, indicating that ours are correct. Enclosed in parentheses are the initials of the reporting observer(s), listed in alphabetical sequence by last name and followed by the CBRC record number. If the observer(s) who initially found or identified the bird provided documentation, their initials are listed first, followed by a semicolon. If an observer submitted a photo- graph, a dagger follows the initials. Many photographers also submitted 98 CALIFORNIA BIRD RECORDS written descriptions with their photos, a practice we strongly encourage. A specimen is indicated by an acronym {see below) for the museum that houses it and the specimen number (if available). Unless indicated by “t” or all reports are sight records. When individual birds return for additional years, each annual occurrence is reviewed under a separate record number, and Committee members indicate if they believe the bird is the same individual as one previously accepted. If a majority agrees it is the same, it is treated as additional dates of a previous record and does not add to the number following this species’ name. If a majority thinks it is different, it is considered a new individual. Individuals judged probably the same are considered the same individual, but those judged only possibly the same are considered new birds. All annotations are mine, although the information usually is derived from the Committee’s files. The CBRC does not review the sex or age of rarities. Such designations here are my opinions based on what I consider clear evidence. Likewise, the Committee generally does not assign rarities to any particular race. However, I include subspecific information on specimens where the identification was made by an ornithologist who examined a specimen or when other evidence was compelling. Abbreviations. The Committee has adopted standard county abbrevia- tions, with only the abbreviation for Monterey being changed (MNT to MTY) since the tenth report (Dunn 1988). California’s counties are ALA, Alameda; ALP, Alpine; AMA, Amador; BUT, Butte; CLV, Calaveras; COL, Colusa; CC, Contra Costa; DN, Del Norte; ED, El Dorado; FRE, Fresno; GLE, Glenn; HUM, Humboldt; IMP, Imperial; INY, Inyo; KER, Kern; KIN, Kings; LAK, Lake; LAS, Lassen; LA, Los Angeles; MAD, Madera; MRN, Marin; MRP, Mariposa; MEN, Mendocino; MER, Merced; MOD, Modoc; MNO, Mono; MTY, Monterey; NAP, Napa; NEV, Nevada; ORA, Orange; PLA, Placer; PLU, Plumas; RIV, Riverside; SAC, Sacramento; SBT, San Benito; SBE, San Bernardino; SD, San Diego; SF, San Francisco; SJ, San Joaquin; SLO, San Luis Obispo; SM, San Mateo; SBA, Santa Barbara; SCL, Santa Clara; SCZ, Santa Cruz; SHA, Shasta; SIE, Sierra; SIS, Siskiyou; SOL, Solano; SON, Sonoma; STA, Stanislaus; SUT, Sutter; TEH, Tehama; TR1, Trinity; TUL, Tulare; TUO, Tuolumne; VEN, Ventura; YOL, Yolo; and YUB, Yuba. This report contains records received from 31 of the state’s 58 counties. Museums that house specimens reported herein, and have permitted CBRC members access to their specimens or are otherwise cited are abbreviated as follows: AMNFI, American Museum of Natural History, New York; CAS, California Academy of Sciences, San Francisco; IACM, Los Angeles County Museum of Natural History; MVZ, Museum of Vertebrate Zoology, University of California, Berkeley; PGMNH, Pacific Grove Mu- seum of Natural History; HSU, Humboldt State University, Areata; SDNHM, San Diego Natural History Museum; and USNM, United States National Museum of Natural History, Washington, D.C. Other abbreviations include NM, National Monument; NP, National Park; NS, National Seashore; and NWR, National Wildlife Refuge. 99 CALIFORNIA BIRD RECORDS ACCEPTED RECORDS YELLOW-BILLED LOON Gauia adamsii (36). One was at Crescent City harbor, DN, 28-30 Oct 1986 (GSL, LPL, JARf; 1-1987). One was at Woodly Island marina, Eureka, HUM, 10-11 Mar 1987 (GSL, LPL; 126-1987). One was photographed about 4 miles out from Monterey harbor, MTV', 28 Mar 1987 (BAf, MPart, DEQ; 151-1987). Those submitting reports of this species should read Phillips (1990), who cautioned that only adults in alternate plumage are readily distinguishable from the more widespread Common Loon (G. immer). Since most of California’s records are not in this plumage, see Binford and Remsen (1974), Burn and Mather (1974), Appleby et al. (1986), Godfrey (1986). and Kaufman (1990) for other important field marks. SHORT-TAILED ALBATROSS Diomedea alhatrus (4**). A first-year bird was seen during a seabird census 20 miles west of Cypress Point in outer Monterey Canyon, MTY, 18 Apr 1987 (DGA; 97-1987). ‘WILSON’S STORM-PETREL Oceanites oceanicus (78). One was 13 miles west of the Eel River mouth, HUM, 6 Oct 1979 (RLeV; 324-1986). One was on Monterey Bay, MTY, 15 Oct -13 Nov 1983 (SFB; 222-1986). One was just beyond the Cordell Bank, MRN, 13 Jul 1986 (JM; SFB, RS; 291 1986). Up to two birds were seen on Monterey Bay, MTY, 31 Aug-12 Nov 1986 (RAE, JML, DLS; 387- 1986). The 6 Oct 1979 sighting becomes the northernmost accepted record for Califor- nia, although there is a 31 May 1976 report from the south jetty of the Columbia River mouth in Oregon Schmidt (1989). The 13 Jul 1986 individual establishes the earliest accepted fall California record for this species, with the earliest previous accepted records falling in the last week of August. However, the CBRC is reviewing a report of 16 individuals seen 15 Aug 1987 just a few miles from the Cordell Bank location. California’s only spring record is 1 May 1978, Monterey Bay (Roberson 1985, 1986). RED-FOOTED BOOBY Sula sula (3). One adult (or close to it) was seen at Morro Rock, Morro Bay, SLO, 27 May 1985 (JSc; DT; Figure 1; 76-1985). This record was almost rejected by the CBRC with a 1-9 vote on the first round and 2-8 vote on the second. Harrison’s (1983) Red-footed Booby text and figure captions for wingspan are incorrect. Murphy’s (1936) wingspan data of 147-150 cm for males and 146-158 cm for females are more reasonable. Harrison’s error (pointed out by Bailey) had caused several members to reject on the first round because of the report’s drawn wingspan comparison to Western Gulls (Larus occidentalis) . It was Garrett, however, whose persistent positive comments from March 1986 until August 1988 eventually caused the 9-1 vote. The omission from the drawings of the diagnostic underwing black carpal patch was partially responsible for some original negative votes, but this mark was later pointed out by three members to be sometimes indistinct or difficult to see. The black and white tail pattern, which had also caused problems for several members, was shown to be possible in this species by LACM specimen #18948 and is not typical of other booby species. While reports of very rare birds (in this case, two previously accepted records) should be scrutinized carefully by records committees, I believe this episode serves as an excellent example of how valuable committee interaction can be. Having ten members on a committee usually ensures that several will have field experience with most rarities, that one or more work for museums or have easy access to collections, that some have excellent libraries or access to university libraries, that in any given group of records several members will have time to research difficult reports closely, 100 CALIFORNIA BIRD RECORDS and that at least one member will know or be able to learn about the person(s) submitting the report. One of the most useful functions of state records committees, not mentioned in Bevier’s (1990) comments on Committee procedures, is to document the ability and integrity of our contemporaries for future researchers who may wish to evaluate the records themselves. Immaculate descriptions can easily be copied out of books by anyone, and we all know observers who are prone to report rarities that can seldom be refound for verification. ANHINGA Anhinga anhinga (3). An adult male was at Lake Merced, SF, 2 Jun- 16 Jul 1939 (not 2-29 Jun 1939 as in Grinnell and Miller 1944 and Roberson 1980) (GB; 2-1979). This record, submitted to the CBRC in 1978 by David DeSante, is based on Grinnell and Miller’s (1944) references to Bolander’s (1939) comments and brief description and to a comment in AFN ( Gull 21:81) naming five observers who last saw the bird on 16 Jul 1939. The brief description by Bolander (1939) would probably not be accepted if submitted for a modern sighting, but the CBRC is usually more lenient with old records of easily identified species. This record was originally rejected 2-8 (Binford 1985) at the end of its second round, primarily on the basis of questionable natural occurrence. Whether accepted or rejected, all records submitted to the CBRC are archived at the Western Founda- tion of Vertebrate Zoology in Los Angeles and can, by majority vote at any annual meeting, be recirculated again. Such was the case with this record, after two subsequent Anhinga records had been accepted from southern California (Roberson’ 1980, Bevier 1990). Some CBRC members prefer to wait for development of clear patterns of vagrancy between California and a bird’s normal range before accepting first state records. An Anhinga reported from Searsville Lake, SM, 28-30 May 1939, and cited in the Gull 21:70 as “undoubtedly” the same bird as seen on Lake Merced was not voted on by the Committee because no description accompanied the published report. Ccvr/OQfi scm a t~ tcotkj r a X/&J/ Figure 1. Three illustrations of the Red-footed Booby ( Sula sula ) with a Western Gull ( Larus occidentaiis ) near Morro Rock, Morro Bay, San Luis Obispo County, California, 27 May 1986. Sketch by John Schmitt 101 CALIFORNIA BIRD RECORDS REDDISH EGRET Egretta rufescens (20). One immature was present at Seal Beach, ORA, 8 Nov 1980-1 6 Jan 1981 (SFB, HSt; 223-1986) This might possibly be the same as 9-1985 (Bevier 1990). A subadult was at the mouth of the Santa Margarita River, SD, 17 Apr-3 May 1981 (LSal; 23-1987). An adult at Gunpowder Point near the Sweetwater River mouth, Chula Vista, San Diego Bay, SD, 13 Oct 1986 -31 Jan 1987 (BDP, GMcC; 437-1986), is the same individual (with a slightly deformed bill) returning here for its fifth winter (records 49-1984, 45-1984, Roberson 1986; 50-1985, Dunn 1988; and 69-1986, Bevier 1990). An immature was observed at the Tiiuana River mouth, SD, 4 Sep 1986-7 Mar 1987 (JLD, GMcC; 441-1986). Although the CBRC received descriptions to support only two Reddish Egrets in San Diego Bay in fall 1986, up to four were reported (AB 41:143). We encourage all observers to submit descriptions of Review List species seen in California, YELLOW-CROWNED NIGHT-HERON Nyctanassa uiolacea (12). An adult was at Scripps Institute of Oceanography, La Jolla, SD, 9-25 Apr 1987 (GMcC; 186- 1987). This is considered to be the same bird originally found at nearby San Elijo Lagoon 25 Oct 1981 and irregularly present there and at La Jolla since that time (previously accepted 88-1981, Binford 1985; 81-1982 and 36-1983, Morlan 1985; 237- 1984, Dunn 1988; and 18-1986, Bevier 1990). Roberson (1986) and Dunn (1988) mistakenly published the 1983 record as 37-1983. TRUMPETER SWAN Cygnus buccinator (11). An adult with a green neck band was seen at Tule Lake NWR, SIS, 23 Dec 1984 (RE; 28-1985). Another adult without a neck band was present the same day at the opposite end of Tule Lake NWR, MOD (MRo; 196-1985). Two adults were at King Island in the San Joaquin River delta, SJ, 1 Feb 1986 (DGY; 340-1986). Two adults were seen in flight at Tule Lake NWR, SIS, 18 Jan 1987 (PR; 78-1987). There appears to be some confusion in the birding community about the meaning of green neck collars on swans. In a letter to the CBRC in June 1986, Harold H. Burgess (president of the Trumpeter Swan Society) informed us that green collars indicate only that the swan was banded in the Pacific Hyway. Green collars with white markings have been placed on Trumpeter Swans as follows: 01AA-19AA at Malheur NWR, 01MA-58MA at Red Rock Lakes NWR, 01PA-13PA at Turnbull NWR, and, since 1983, 01-99 by the Wyoming Game and Fish Department. Humboldt State University has used green collars (series R001-25) for the Tundra Swan (Cygnus columbianus) and, therefore, both species have been fitted with green collars. Burgess also mentioned that a thousand Trumpeter Swans are being found in Washington and Oregon where only a hundred were being found prior to surveys begun in 1983. He challenges us to find the hundred or so he believes to be in California each winter. The CBRC urges utmost caution to those accepting this challenge, since to date such numbers have not been documented here. Records of swans identified largely or solely on calls, including the first two listed above, have caused difficulties in Committee review. Observers looking at any individual bird at the same time often perceive and describe colors differently, and it should come as no surprise that individually we hear and describe calls differently. One must also be aware of the range in calls of the Tundra Swan. Regardless, typical Trumpeter Swan calls are diagnostic (Banko 1960), and, if clearly heard by an observer with much experience with the Tundra Swan, should support a claimed identification. Observers should take care to express their concept of heard calls accurately and also attempt to use differences in the shape and size of bill and body to support their identification. See Jordan (1988) for ways to distinguish these two species. 102 CALIFORNIA BIRD RECORDS The latter two records mentioned above passed (10-0) on the first round, owing mainly to excellent extended comparative descriptions in one case and to both call and size comparisons in the other. EMPEROR GOOSE Chen canagica {39**). An immature was present at Tule Lake NWR, SIS, 1-28 Nov 1981 (REf; 295-1986). An immature was south of the mouth of Tillas Slough in the Smith River estuary, DN, 9 Jan-19 Feb 1982 (RAE; 209- 1986). One adult was at Prince Island, north of Crescent City, DN, 25 Feb 1984 (RST; 79-1987). At least eight Emperor Geese (many actually taken by hunters) were in Del Norte and Humboldt counties during the first week of January 1982(AB 36:326), with one remaining at the Smith River mouth through the end of February. The CBRC requests details from anyone who saw any of the other seven, for which we received no descriptions. TUFTED DUCK Aythya fuligula (37). An adult male at Mallard Reservoir, north of Concord, CC, 27 Dec 1986-10 Jan 1987 (BRi; JG, JM; 48-1987), was the first for Contra Costa County. A female observed variously at Elk Glen Lake in Golden Gate Park and the nearby San Francisco Zoo, SF, 19 Dec 1986-20 Mar 1987 (ASHf, DM, DR, DLS, RSf; 22-1987 and PG; 80-1987), was considered to be the same as 161-1986 (Bevier 1990), returning for its second winter. An adult male at Garretson Point on the east side of San Leandro Bay, Oakland, ALA, 11-12 Jan 1987 (JM+; 49-1987), was possibly the same adult male seen at Lake Merritt, Oakland, ALA, 19 Mar-5 Apr 1987 (SEF, JML, PEL, MJL, BDP, DEQ; 92-1987). An adult male was observed on Richardson Bay, MRN, 19 Jan 1987 (DAH; GC; 155-1987). A majority of the Committee believes this individual was different from the one that wintered here for six years from 1976 to 1982 (see Luther 1980, Binford 1985, and Morlan 1985) as four winters had passed without any reports. A detailed discussion of these records with corrections will appear in our fourteenth report. An adult male photo- graphed on a pond near Grenada, SIS, 15 Feb-13 Apr 1987 (REf; 260-1987), was first found in each of the previous two years on the same pond but the record was circulated and accepted under two different numbers (93-1985 and 294-1986, Dunn 1988). As discussed by Dunn (1988), individual Tufted Ducks often return in successive years, but because they sometimes move around either in the same or successive years, it is quite difficult to determine the exact number of individuals involved. Although not reported here, records from Point Reyes NS have been particularly troublesome and will be dealt with in our fourteenth report. Careful details on tuft length and other morphological characters, as well as dates, can be very helpful to Committee members and should be submitted by all observers. KING EIDER Somateria spectabilis (22). A female was at the south end of Crescent City harbor, Crescent City, DN, 21 Nov-21 Dec 1986 (ADB, RE, WEHf, GSL, LPL, GMcC, JARt; 46-1987). STELLER’S EIDER Polysticta stelleri (2). An immature male was at the south spit of Humboldt Bay, HLJM, 1 9 Nov 1983 (DBf; 292-1986). This bird was shot by Todd Pearl, later identified by him, and given to a friend who had Mike Reynolds, an amateur taxidermist, prepare the specimen. Photos taken by Reynold’s friend Don Brewer now constitute the documentation for this record, as the specimen is in private hands. MISSISSIPPI KITE Ictinia mississippiensis (18). A first-summer bird was at Furnace Creek, Death Valley NM, INY, 28-30 May 1983 (CC; JAJ; 226-1986). An immature was found at Oasis, MNO, 30 Aug 1986 (GMcC; 378-1986). The latter is only the fourth fall record for California. 103 CAUFORNIA BIRD RECORDS Clark and Wheeler (1987) and Dunne et al. (1988) discussed identification of kite species recorded north of Mexico. Although the Plumbeous Kite (1. plumbea) is unrecorded here, kites should be described well enough to eliminate this species. ZONE-TAILED HAWK Buteo albonotatus (20). An immature flew over Lake Henshaw, SD, 25 Feb 1984 (BF; 71-1984). An adult was seen at Cuyamaca Rancho State Park, SD, 3 Sep 1984 (MRR; 260-1986). A pair at Hot Springs Mountain, SD, 6-12 Jul 1986 (GMcC; 332-1986) fledged one young from a nest in July (AB 40:1255). This same pair returned to their nesting area 13 Jun-7 Jul 1987 (GMcC; MJL, CM; 162-1987) and again had young in the nest in July (AB 41:1487). An adult on the Plano Trabuco, ORA, 28 Nov-7 Dec 1986 (JLD; 442-1986), was considered to be the same bird present there in winter 1985-86 (17-1986, Bevier 1990). Before finally being accepted on a 9-1 vote, the Lake Henshaw bird was subjected to five rounds of voting and to discussion at the January 1988 CBRC annual meeting. Much of the problem dealt with elimination of the Harlan’s Red-tailed Hawk (B, jamaicensis hariani) as well as dark morphs of three other Buteo species, the Rough-legged (B. lagopus), Swainson’s (B. swainsoni), and Short-tailed (B. brachyurus) hawks. Had they been published earlier, Clark and Wheeler (1987) and Dunne et al. (1988) might have been useful. The description of the tail pattern created problems, until compared with the juvenile on Plate II in Meyer de Schauensee and Phelps (1978). The observed dihedral wing character, similar to that of Turkey Vulture ( Cathartes aura), was the deciding factor in helping the record to be accepted, along with a recently discovered nesting site on nearby Hot Springs Mountain. The Lake Henshaw bird was published (AB 38:357) as an adult., but details support its being in immature plumage. The Cuyamaca Rancho bird was published (AB 39:102) as an immature, but details support adult plumage. YELLOW RAIL Coturnicops noveboracensis (57). One adult at Alameda, San Leandro Bay, ALA, 12 Dec 1985 (DRi, MPe; 160-1986), represents the first northern California record since 1970. One was seen at Tomales Bay, MRN, 3 Dec 1986 (JE; 156-1987). An adult was found dead at the Salt River mouth, Eel River slough, HUM, 2 Jan 1987 (GSLt, HSU #1098; 89-1987). The recent records for this very secretive species indicate that it may be present more often as a wintering species in coastal California marshes than previously thought. Birders going to these areas during very high tides in hopes of seeing Yellow and Black (Laterallus jamaicensis ) rails should be aware that the presence of humans may make these small rails vulnerable to predation. Observers have seen Great Blue Herons ( Ardea herodias), Great Egrets ( Casmerodius albus ), and Black- crowned Night-Herons (Nycticorax nycticorax ) eat small rails that are forced out of their concealed areas by very high tides. It is possible that birders standing around marsh edges may sometimes discourage these rails from flying to safer shrubby edge- cover. Before finally being accepted on its third round with a 9-1 vote, the Alameda bird created much interesting discussion concerning the dates by which Soras ( Porzana Carolina ) have molted out of juvenal plumage. It appears, however, that most Soras have lost much or all of their Yellow Rail-like juvenal plumage by early December, and, therefore, misidentifying a juvenile Sora as a Yellow Rail after that time is much less likely than previously believed. CBRC members searching through four different museums were unable to find any Sora specimens collected after early November that still resembled Yellow Rails. One member, however, noted that Cramp et al. (1980) said first alternate plumage is gained Nov-Feb and thus some, even if few, Soras may be in juvenal plumage after December. The best field mark on a flying bird is the diagnostic rectangular white secondary wing patches. 104 CALIFORNIA BIRD RECORDS PURPLE GALLINULE Porphyrula martinica (2). An immature (Figure 2) was at Lake Elizabeth, Fremont, ALA, 17-27 Oct 1986 (AH; HLC, JLD, RAE, HG, DGr, KeH, JML, PLat, MJL, CM, GMcC, JM, BDP, DRt, RSt; 388-1986). In a reclamation project, the Fremont City Park Department recently destroyed the habitat where this bird was found. The Purple Gallinule is famous for extralimital vagrancy, having occurred in 42 of the contiguous 48 states (DeSante and Pyle 1986, Johnson 1989), five Canadian provinces (Godfrey 1986), South Africa (Urban et al. 1986), the British Isles, and continental Europe (Cramp et al. 1980). See Remsen and Parker (1990) for additional comments on gallinule vagrancy. MONGOLIAN PLOVER Charadrius mongolus (2). An adult in alternate plumage was at the Santa Clara River mouth, VEN, 12-17 Jul 1986 (JSR; JLDt, SEF, MJL, VKf; 300-1986). This bird was probably the same as one present at this location in 1982 (74-1982, Morlan 1985) and 1983 (65-1983, Roberson 1986). Because there was only one previous state record, a majority of the Committee suspected that this bird was more likely missed in 1984 and 1985 rather than a different individual. Figure 2. California’s second recorded Purple Gallinule ( Porphyrula martinica ) at Lake Elizabeth, Fremont, Alameda County, 17-27 Oct 1986. Photo by Peter La Tourrette 105 CALIFORNIA BIRD RECORDS Figure 3. California’s first Barred Owl ( Strix varia) recorded east of the Coast Ranges at Tule Lake Northwest Reserve, Siskiyou County, 28 Nov 1986-21 Feb 1987. Photo by John R. Silliman Figure 4. Sprague’s Pipit ( Anthus spragueii) on Southeast Farallon Island, San Francisco County, California, 10-11 Oct 1986. 106 Photo by Oddvin Lund CALIFORNIA BIRD RECORDS We also suspect that a successful vagrant is likely to repeat its migration stops in succeeding years. EURASIAN DOTTEREL Charadrius morinelSus (2). A juvenile was at Point Reyes NS, MRN, 6-9 Sep 1986 (DAH, DDK; SFB+, JC+, JLD, AG+, HG, MBG, KeH, RAHt, JML, PLaf, MJL, GMcC, JM, BDP, DRf, JTrf; 365-1986). K(z Lao j a S cfi\s r£ pj S LPiri&iM, J - f.'SV AM r2 , VT PM JS; IQS’} OurfT- rteei'i 70 f> Of <&\ Lj_ Lus-nr OCWM- E>A.cr.V;V "Tip »>•*. <2 - 1. iiir.i-7 ft.-vu.ifV- THflAt 0 ,\i C.i rMC»C SiCiE OnF IT't o~ vJ 1 6 1 Gut O^'S to L.i (Jit r f h‘G C pJ t/\ sYl p.trocosw o:'U)^- \ HctiE - 6-rrrwt utin f&L nAVAA-D a WV, f'4tP dUre-iUAu^ft ArOlAI lU.AJ* t)4/C/c(f Jf 6^1' fefA-s fjp r~ Jirr &lAci c TltlrJ f? !*,£, £>lP - fALC 0AU>' n^icu 6 'Kit elf C(2dW/V AJ.4ft lAfVWi 0/1 Cic eAitsr f/wtt cr Awfc LwWet p/f-Cic (3/i(Jw’(0oC. U I TH p^iCt-Cri. f [ ii /i'l . 4 1 t£0S fJOT otZ'Yl^fJ f'V. T7-ri,)L=S went uotrw x t> vs.* i?jcT v'--t_C cOCri 'V(5- v\ \ X'h, \ X *^S\ iCu/m? U&.'uio A* uric KePiWr-/ 7 7->f*-/V LcV^ev^ AHCk_ v> J— j Cjl4 [ (P'lK- Ir'Ji'- 0,0 FtAA'IEO' ■l t 0 c-£ LCCs WcT £tf 6Aru. e ‘Vt'Wi j ;j 'is' lAVOeflTAt/cv £ ! •■» Lt v 7 op All.- |Tfc &//l 0 tv'AA; w>c ,,76 Ait' n/-g- 8/ierti'r ^tfOVtAQ A iu ov'Tc'i 6 waeO uTFcrcf A^cvc, T>ftr»x a BdXtfvv D+A-r, f,4v^Ui5 6 A THC CwV.Z-ia/G FN ■+ FlAaJ)oX 7Aw_ mA-? 7/f f/v iltlcA/ , U-U-^vlix-i i r tv A A fV.Hi’ev} N «l J A/'v'.'i DO V/v /|,r ^ iiftw/v jiffcgtr — 7 >, J J J' C i A0'L»4 (_t-7 reue .+|tre*i me x)- 6 •<>' ^ irn>i > j . /✓ eti ^ / r j- Ac rt C w . T ui iCt T / j: FAvv tTt-f T/Vil U'A6 /A7 AaV /H_.-vn3>rr pf^AKCcT £i 6 'HT Figure 5. California’s second recorded Brown Shrike ( Lanius cristatus) at Whitehouse Pool near Point Reyes Station, Marin County, 28 Nov 1986-26 Apr 1987. Sketch by Jeri M. Langham 107 CALIFORNIA BIRD RECORDS This exceptionally well-documented record is the second for California, the state’s first Eurasian Dotterel having been photographed on Southeast Farallon Island, SF, 12-20 Sep 1974 (Henderson 1979). Photographs of the Point Reyes bird were published in Western Birds 17:95, AB 41:42 and 139, and on the cover of Birding 18, no. 6. There are only two other west-coast records south of Alaska: Westport, Washington, 3 Sep 1934 (Brown 1935), and Ocean Shores, Washington, 8 Sep 1979 (Paulson 1979). All four of the above and one collected on Kure Atoll, Hawaiian Islands, 9 Sep 1964 (Clapp and Woodward 1968) occurred within the first two weeks of September and within the correct range of latitude for wintering of the Eurasian Dotterel (Cramp et al. 1983, Hayman et al. 1986, Urban et al. 1986). The species is considered rare but possibly a local summer breeder in Alaska (Kessel and Gibson 1978). RUFOUS-NECKED STINT Calidris ruficollis (5). One in alternate plumage was found at Vigo Street marsh, Eureka, HUM, 20-22 Jul 1984 (KVR+, JSt; RLeVt; 430-1986). WHITE-RUMPED SANDPIPER Calidris fuscicollis (9). One in alternate plumage was at Stockton sewage ponds, SJ, 17 May 1986 (DGY; KFH; 341-1986). This is the only Central Valley record and also the earliest for California. BUFF-BREASTED SANDPIPER Tryngites subruficollis (42). One was at Aho Nuevo State Reserve, SM, 1-4 Sep 1978 (EB; 197-1986). One was at Areata marsh, HUM, 25 Aug-2 Sep 1979 (RLeV; 325-1986). Up to five birds were at Areata bottoms, HUM, 15-25 Sep 1982 (RAE; 165-1986). Two birds were at Salinas sewage ponds, MTY, 28 Aug-2 Sep 1986 (SFB, JC, MaDt, MDat, SEF, Figure 6. Female Blue-winged Warbler (Vermivora pinus) at Butterbredt Springs, Kern County, California, 29-30 May 1987. 108 Photo by John Wilson CALIFORNIA BIRD RECORDS Figure 7. First Worm-eating Warbler (Helmitheros uermiuorus ) recorded in the Central Valley at Merced National Wildlife Refuge, Merced County, California, 31 Oct 1978. Sketch by Robby J. Bacon Figure 8. One Mourning Warbler ( Oporornis Philadelphia ) and one Connecticut Warbler (O. agilis ) on Southeast Farallon Island, San Francisco County, California, 12 Sep 1986. Photo by Peter Pyle 109 CALIFORNIA BIRD RECORDS PJM, MCM, JM, DR, DLS; 362-1986). One was at Asilomar State Beach, Pacific Grove, MTY, 6-8 Sep 1986 (DR, BT+; 364-1986). One was in the Tijuana River valley, SD, 11 Oct 1986 (PEL, GMcC; 466-1986). As expected, all appeared to be juveniles. The 11 Oct individual was rather late. LITTLE GULL Larus minutus (31). An adult was at Areata oxidation ponds, HUM, 11-13 Nov 1982 (KVRt; 477-1986). An immature was at Areata oxidation ponds, HUM, 31 Jul-14 Sep 1986 (RAE, LPL; 334-1986). An adult at Stockton sewage ponds, SJ, 16 Oct 1986 - 22 Apr 1987 (SW+; GMcC, DGY; 77-1987), is considered the same one here each winter since Mar 1979 (previously accepted as 21-1979, Luther et al. 1983; 85-1983, 93-1983, 1-1984, 42-1984, Roberson 1986; 269-1984, Dunn 1988; and 165-1985 Bevier 1990). A first year bird was at the north end of the Salton Sea, RIV, 18 Apr-9 May 1987 (GMcC; PEL, MAP; 157- 1987). With the appearance of the Jul 1986 Areata bird, there are now California records for every month of the year. According to David Yee (pers. comm.), the returning adult at Stockton sewage ponds (first reported 16 Oct 1986) was joined sometime in Mar 1987 by another adult that had been wintering at the Lodi sewage ponds since Dec 1986, and by a third adult from 1 to 13 Apr 1987. Two of the three were still present 17 Apr 1987, after which most Bonaparte’s Gulls ( Larus Philadelphia ) departed as well. LESSER BLACK-BACKED GULL Larus fuscus (4). An adult was at the north end of the Salton Sea, RIV, 14 Sep-5 Oct 1986 (RH+; JLDf, GMcC, MAP; 379-1986). One was at Malibu Lagoon, LA, 19 Jan 1987 (TKf; 177-1987). The Salton Sea bird was only the third for California. The first was an adult photographed in Seaside, MTY, 14 Jan 1978 (Binford 1978), and the second was an adult at the south end of the Salton Sea, IMP, 18 Dec 1984-5 Jan 1985 (Dunn 1988). By an 8-1 vote (one abstention), the individual (379-1986) seen at the north end of the Salton Sea was considered to be probably different from the individual (278-1984 Dunn 1988) seen the previous year at the south end. The Los Angeles County bird (177-1987) was the first for the southern California coast. Unfortunately, it was seen only by its finder, but excellent photographs taken that day clearly show a near-adult Lesser Black-backed Gull with some black smudg- ing through the red mark on the mandible. Bevier (pers. comm.) saw an adult on the east coast that kept a black mark next to the red one on the lower mandible for as many as three years. In their voting comments, Dunn and Lehman mentioned an adult also possessing this dark smudge that returned for many winters to a beach north of Corpus Christi, Texas. Interestingly, Grant (1986) did not mention that adults can still show this mark after their fourth winter. Because of two additional records of this species at the Salton Sea (thirteenth report), the Malibu Lagoon individual actually represented California’s sixth record, SANDWICH TERN Sterna sandvicensis (1). An adult returned to the Elegant Tern (S. elegans ) breeding colony in the saltworks at the south end of San Diego Bay, SD, 18 Apr-16 May 1987 (JML, GMcC; 137-1987). This is considered to be the same individual first seen here in May 1980 (Schaffner 1981 and previously accepted as 80-1980, Luther et al. 1983). It returned in 1982 (58-1982, Morlan 1985) and again in 1985 (9-1986, Bevier 1990) and is the only record for the west coast of North America north of Mexico. BLACK-BILLED CUCKOO Coccyzus erythropthalmus (9). An immature was at Mono Lake County Park, MNO, 29 Aug 1986 (DS; 440-1986). An immature was at Big Sur River mouth. MTY, 2-4 Oct 1986 (DEG; SEF, MJL, CM, DR; 381-1986). Zimmer (1985) pointed out that juvenile Yellow-billed Cuckoos (C. americanus) may lack the yellow lower mandible base and instead have a dusky mandible. Other 110 CALIFORNIA BIRD RECORDS field marks that clearly separate the species should be noted. The Mono County bird represents the second accepted inland record for California, the first being one at Brock Ranch, IMP, 12-13 Sep 1981 (Binford 1985). GROOVE-BILLED ANI Crotophaga sulcirostris (3). One was 2 miles north- northwest of Seeley, IMP, 25 Oct 1986 (PU; RH ; 40-1987). *BARRED OWL Strix uaria (5). One heard along Horse Linto Road near Willow Creek, HUM, 16 Apr 1985 (JSt; 435-1986), is the same bird first discovered 30 Apr 1983 (48-1983, Morlan 1985) and now a resident here. One (Figure 3 and AB 41:325) found at Tule Lake NWR, SIS, 28 Nov 1986-21 Feb 1987 (REt, RAE, JRSt, SS+; 85-1987), was the first found in California east of the Coast Ranges. CHUCK-WILL’S-WIDOW Caprimulgus carolinensis (1). One found injured at Half Moon Bay. SM, 16 Oct 1986, was taken to the Peninsula Humane Society, where it subsequently died on 20 Oct 1986 (CAS #83955; 3-1987). Full details with photographs were published by Bailey (1989). The only other record for the far West involved a specimen picked up on the road leading into Corn Springs on the Desert Wildlife Range of southwestern Nevada, 12 Jun 1984 (AB 38:1046). BROAD-BILLED HUMMINGBIRD Cynanthus latirostris (28). One was at Ano Nuevo State Reserve, SM, 19 Oct 1986 (MCM; 424-1986). This bird was published (AB 41:140) as an adult, but the five Committee members who commented on its age all agreed that the description indicated an immature male. GREATER PEWEE Contopus pertinax (20). One was at Earp, SBE, 22 Dec 1983 (JSt; 90-1986). One at Montecito, SBA, 28 Dec 1985 (JEL; 189-1986), is consid- ered to be the same bird present there the previous winter (265-1984, Dunn 1988). i Figure 9. Cassin’s Sparrow ( Aimophila cassinii ) on Southeast Farallon Island, San Francisco County, California, 22 Sep 1986. Photo by Peter Pyle 111 CALIFORNIA BIRD RECORDS SCISSOR-TAILED FLYCATCHER Tyrannus forficatus (45). A male was near Clovis, FRE, 8 Jul 1978 (KFH; 320-1986). One was in the Tijuana River valley, SD, 27 Oct 1978 (JEM; 230-1986). One was at Tecopa, INY, 31 Aug-7 Sep 1981 (KSt; 299-1986). One was at Point Loma, SD, 1 Oct 1984 (REW; 243-1984), One was at the Mad River mouth, HUM, 30 Oct-1 Nov 1985 (JStt; 391-1986). One on San Clemente Island, LA, 2 Jun 1986 (DW; 328-1986), is not previously published. One was at Goleta, SBA, 10 Jul 1986 (HPR; 467-986). One was photographed (AB 41:211) at Point Reyes NS, MRN, 30 Jan- 21 Feb 1987 (PEL, GMcC, JMt, BDP, RSt; 74-1987). The Point Reyes NS bird is noteworthy in that there is only one other accepted California record for January and February (6 Jan-3 Feb 1980, Bevier 1990), one for February and April (22 Feb-early April, Bevier 1990), and none for December. SEDGE WREN Cistothorus platensis (3). One was at Fort Funston, San Fran- cisco, SF, 23-24 Oct 1986 (DDK; SFBt, JLD, DAH, JM; 443-1986). This repre- sents only the third record for the state and is supported by excellent documentation, including the published (AB 41:140) photo. GRAY-CHEEKED THRUSH Catharus minimus (9). One was on Southeast Farallon Island, SF, 26 Sep 1986 (PP; SH; 10-1987). One at Point Loma, SD, 1 Oct 1986 (REW; 38-1987), is the first record for southern California. WOOD THRUSH Hylocichla mustelina (7). One found at Furnace Creek, Death Valley NM, INY, 15 Nov 1986 (GMcC; DRWt; 24-1987), established California’s first inland record. GRAY CATBIRD Dumetella carolinensis (32). One was at Deep Springs, INY, 6 Oct 1975 (PRS; 254-1986). Another was at Scotty’s Castle, INY, 9 Sept 1981 (JSt; Figure 10. Juvenile Le Conte’s Sparrow (Ammodramus leconteii) on Southeast Farallon Island, San Francisco County, California, 11-12 Sep 1986. Photo by Peter Pyle 112 CALIFORNIA BIRD RECORDS 428-1986). One was at Baker, SBE, 12-14 Oct 1984 (BED; JLDf; 298-1986). One was photographed at China Ranch near Tecopa, INY, 3-8 Oct 1986 (JTaf; 39- 1987). One was at Point Loma, SD, 16-23 Oct 1986 (PEL, GMcC, BDP; 438- 1986) . One at Oasis, MNO, 24 May 1987 (PJM; 239-1987), was considered only possibly the same bird as a singing male there 30 May 1987 (CM; JML, MJL, GMcC; 147-1987). One was at Mojave, KER, 5 Jun 1987 (RSat; JWt; 168-1987). RED-THROATED PIPIT Anthus ceruinus (41). One was at Prairie Creek Red- woods State Park, HLIM, 10 Oct 1982 (GJS; 200-1986). One was heard but not visually singled out of the American Pipit (A. rubescens) flock flying overhead at Goleta, SBA, 6 Nov 1982 (PEL; 238-1986). One was photographed on Southeast Farallon Island, SF, 24-27 Sep 1986 (PPf; 55-1987). One was west of Santa Maria, SBA, 5-6 Oct 1986 (PEL; 469-1986). One bird at Point Reyes NS, MRN, 6 Oct, was joined by a second on 7 Oct with one still present until 1 1 Oct 1986 (DDK; RAE, DAH; 19-1987). One heard at Bolinas, MRN, 7 Oct 1986 (PP; 8-1987), and previously unpublished is considered only possibly the same as the second bird from record 19-1987. One was at Moss Landing, MTY, 12 - 18 Oct 1986 (MDa; DR; 385- 1987) . Up to three birds were seen in the Tijuana River valley, SD, 14 Oct-2 Nov 1986 (PEL, GMcC; 470-1986), with three reported on 19 Oct and two still present 23 Oct. One was at Goleta, SBA, 14-15 Oct 1986 (JLD, PEL; 445-1986). Another one at Goleta, SBA, 4-15 Nov 1986 (PEL; JLD, CM; 444-1986), established California’s latest record for this species. SPRAGUE S PIPIT Anthus spragueii (17). One (Figure 4) was on Southeast Farallon Island, SF, 10-11 Oct 1986 (KFH; OLf; 57-1987). Up to five were along Old River Road north of Needles, SBE, 2 Nov, with three still present 27 Nov 1986 (PEL, GMcC; 468-1986). One was seen and heard calling in flight over Brawley, IMP, 29 Nov 1986 (RH, GMcC; 25-1987). Prior to the fall of 1974, Sprague’s Pipit was unrecorded in California, but now it appears to be a rare fall vagrant and winter visitor, especially along the southeastern border of the state. The Brawley bird is the first for the Imperial Valley, although it should be expected there in the many alfalfa fields, as suggested by other southeast- ern California records. BROWN SHRIKE Lanius cristatus (2). An immature (Figure 5) was at Whitehouse Pool near Point Reyes Station, MRN, 28 Nov 1986-26 April 1987 (MDe, MMf; LA, SFB, BBa, DC, JC+, JLD, AG+, CHK, THK, JML, PEL, TM, GMcC, CM, JMf, BDP, DRt, RS; 20-1987). California’s second Brown Shrike was found and identified by Oregonians Merrylynn Messinger (first to spot the bird) and Mike Denny while birding near Point Reyes Station. On the 29th, they had better looks and returned to Oregon on the 30th knowing it was a shrike but not which one. A positive identification was made 20 Dec 1986 when Mike checked Armstrong (1983). He then wrote to Peter Pyle and to the American Birding Association to inform them of the sighting, and both forwarded the information to the CBRC secretary. In the meantime, the bird was seen and misidentified by several observers as a Northern Shrike ( Lanius excubitor) until Kevin Hintsa correctly identified it on 14 Jan 1987. Although we have written documentation from many birders and at least four good sketches, no close photos are included with the record. If anyone has good photos, please send them to the CBRC secretary for inclusion in a possible upcoming publication in Western Birds of details of this individual. From the documentation and the excellent research work done by several current or former Committee members, all similar species have been adequately eliminated. Medway (1970), however, believed that immature Brown Shrikes are not identifiable to race even in the hand; the Point Reyes bird was described only before it molted into adult plumage, and so the Committee did not feel it could be assigned to a 113 CALIFORNIA BIRD RECORDS specific race, although several members believed it to be of the nominate race (L. c. cristatus). The brief description of the adult-plumaged bird (AB 41:325) as having a bright rufous crown and a relatively indistinct supercilium and some distant photos added to the record after circulation suggest the nominate race, discussed by Dean (1982). WHITE-EYED VIREO Vireo griseus (12). One at Deep Springs, INY, 21 May 1987 (CDB; PEL; 131-1987) is the first for Inyo County. YELLOW-THROATED VIREO Vireo flauifrons (25). One was at Elk Head, Trinidad State Beach, HUM, 28 Apr 1983 (GSL; SWH; 421-1986). One was at Huntington Beach, ORA, 23 Oct-1 Nov 1986 (DRW; SFB+, JLD+, RAE, PEL, CM, GMcC; 446-1986). One was at Goleta, SBA, 30 Apr 1987 (CDB; JLD, PEL; 130-1987). PHILADELPHIA VIREO Vireo philadelphicus (58). One was in the Tijuana River valley, SD, 12-14 Oct 1979 (CGE; GMcC; 370-1986). One was banded and photographed on Southeast Farallon Island, SF, 26 Sep 1983 (KFHf, PP; 319- 1986). One was at California City, KER, 22 Oct 1983 (MH; 333-1986). One was on Southeast Farallon Island, SF, 12-15 Sep 1986 (PP+; 60-1987). One was at Fairhaven, HUM, 13-14 Sep 1986 (JSt, LPL; 433-1986). Another on Southeast Farallon Island, SF, 19-22 Sep 1986 (PPf; 61-1987), was found weakened and died on the later date (CAS #84371). One at Carpinteria, SBA, 1 Oct 1986 (TEW; JLD, PEL; 447-1986), is the first for Santa Barbara County. YELLOW-GREEN VIREO Vireo flavoviridis (16). One was at Goleta, SBA, 11- 12 Oct 1982 (PEL; 302-1986). One was at Fairhaven, HUM, 9-10 Oct 1984 (JSt; 347-1986). One was near Little Sur River mouth. MTY, 3 Oct 1986 (JML; EG, LKL; 475-1986). This species was split from the Red-eyed Vireo in the AOU’s 36th supplement (AOU 1987). The finder of the Goleta bird actually reported seeing two birds together (AB 37:225). However, he did not send in descriptions of either bird, and thus the Committee had no choice but to accept only the individual described by one of the six other birders who were there. We cannot stress enough the importance of all observers seeing a bird on the Review List sending in reports. Several of the accepted records listed thus far would have been rejected had there not been multiple descriptions to clinch the identification. BLUE-WINGED WARBLER Vermivora pinus (7). A male was at Butterbredt Springs, KER, 9 May 1987 (MOC; JW; 167- 1987). A female (Figure 6 and AB 41:380) was at the same location 29-30 May 1987 (JLD; NBB. MOC, JML, PEL, MJL, CM, GMcC, DR, LSanf, JWt; 146-1987). There are now three records of this very rare species for Kern County, but a male and female less than three weeks apart at the tiny Butterbredt Springs oasis is remarkable. GOLDEN-WINGED WARBLER Vermivora chrysoptera (28). A male was at Oasis, MNO, 23 May 1987 (SFBf, JML, PEL, MJL, GMcC, MAP, DRf; 139-1987). A male photographed (AB 41:489) at Butterbredt Springs, KER. 29-30 May 1987 {JWt; NBB, MOC, JLD, JML, PEL, MJL, CM, GMcC, DR, LSanf; 145-1987), was sometimes seen foraging with the female Blue-winged Warbler (146-1987) that was present at the same time. YELLOW-THROATED WARBLER Dendroica domirrica (50). One was in the Santa Ynez Mountains, SBA, 10 May 1981 (LRB; 323-1986). A singing male was tape-recorded at Hawkins Bar, TRI, 14 Jun 1982 (MRa; 248-1986). A male was singing at Fairhaven, HLJM, 25 May 1985 (GSL; BRo; 422-1986). One was at Montana de Oro State Park, SLO, 7-8 Sep 1986 (TME; CM, GPS; 16-1987). One 114 CALIFORNIA BIRD RECORDS was at Torrey Pines State Park, SD, 8-9 Oct 1986 (JO’B; GMcC; 33-1987). One was on Southeast Farallon Island, SF, 21 Oct 1986 (SH; 9-1987). One was photographed (AB 41:489) at California City, KER, 14 May 1987 (NBB; 136- 1987). All of the above records were of the expected white-lored race (D. d. albilora ) except possibly of the bird whose song was taped but whose plumage was not described. There are only two California records (both from mid to late fall) of individuals showing characteristics of the two yellow-lored races (D. d. dominica and D, d. stoddardi). The bird at Hawkins Bar may represent the first CBRC-accepted record based on a taped recording without any accompanying written description. GRACE’S WARBLER Dendroica graciae (18). A male returned for its eighth winter to Montecito, SBA, 13 Oct 1986-19 Mar 1987 (PEL, DR; 451-1986). This bird has previously been accepted as 23-1980 (Binford 1983), 114-1984 (Roberson 1986) , 3-1985 and 221-1984 (Dunn 1988), and 77-1986 (Bevier 1990). One thought to be a female returned for its third winter to another locality in Montecito, SBA, 19 Oct 1986-11 Jan 1987 (PEL; 69-1987). This bird has previously been accepted as 5-1985 (Dunn 1988) and 20-1986 (Bevier 1990). A male was at Irvine, ORA, 21 Feb-27 Mar 1987 (BED, JLD; 169-1987). An adult returned for its third winter to Ventura, VEN, 28 Dec 1986-25 Mar 1987 (CDB, JSR; 175-1987). This bird has previously been accepted as 6-1985 (Dunn 1988) and 22-1986 (Bevier 1990). A second wintering individual was at Ventura, VEN, 14 Mar-4 Apr 1987 (RJM; 181-1987), only about 1 mile away from the other wintering bird. The Irvine bird was published (AB 41:331) as having been at Newport Beach, but Irvine is the correct location. It is identified as a male because it was singing. If the list of singing female birds in Ritchison (1983) is complete, no female paruline warblers are known to sing. PINE WARBLER Dendroica pinus (22). One was in the Tijuana River valley, SD, 15 Oct 1986 (GMcC; 32-1987). An immature female was at Montana de Oro State Park, SLO, 26-27 Oct 1986 (TME; JH, KAH, GPS; 27-1987). An immature male was at Gaviota State Beach, SBA, 30 Oct 1986 (PEL; 472-1986). An immature female was at Gaviota State Beach, SBA, 1 Nov 1986 (TEW; 473-1986). An immature female in the Tijuana River valley, SD, 8 Nov 1986 (GMcC; 237-1987), was accompanied by an immature male (GMcC; 30-1987). One was at Point Dume, LA, 21 Dec 1986 (KLG; 4-1987). A singing male was at Torrey Pines State Park, SD, 5-6 Jun 1987 (GMcC; 188-1987). ^ The six Pine Warblers found in southern California in fall 1986 were unprec- edented, as this species had formerly been very rare. Even more unusual were the immature male and female found together in the Tijuana River valley. The Torrey Pines individual is only the third found in California in spring. *PROTHONOTARY WARBLER Protonotaria citrea (65). One was at Point Loma, SD, 10 Oct 1979 (CGE; 369-1986). One was at Samoa, HUM, 18-19 Sep 1982 (RAE; 167-1986). One was at San Diego, SD, 9 Oct 1982 (VPJ; 267-1986). One was in the Loleta bottoms, HUM, 24 Nov 1982-6 Mar 1983 (JSt; 427-1986). One was at Lanphere Dunes, west of Areata, HUM, 23 Sep 1983 (RRf; 476-1986). One was at Point Fermin, LA, 19 Sep 1984 (BED; 297-1986). One was at McKinleyville, HUM, 11-14 Sep 1986 (JSt; 434-1986). One was at Pacific Grove, MTY, 13-20 Sep 1986 (JML, GMcC, DR; 367-1986). One was at Point Reyes NS, MRN, 18-21 Sep 1986 (BDP; MWt; 380-1986). One was near San Pedro, LA, 16- 25 Oct 1986 (JLD, ALHf, PEL, CM, GMcC; 439-1986). A male was at Oceano Campground, Pismo State Beach, SLO, 17-22 Oct 1986 (KJZ; JLD, CM, RER; 423-1986). A male was at Butterbredt Springs, KER, 10 May 1987 (SEF, PEL; 135- 1987) . A female was at California City, KER, 28 May 1987 (NBB, JLD, JW; 144- 115 CALIFORNIA BIRD RECORDS 1987). A male was at Oceano Campqround, Pismo State Beach, SLO, 28 May 1987 (CM; 161-1987). The bird at Loleta bottoms established the second California winter record for the Prothonotary Warbler. WORM-EATING WARBLER Helmitheros uermiuorus (37). One was at Merced NWR, MER, 31 Oct 1978 (RJB; 350-1986). One was on Southeast Farallon Island, SF, 30 May-1 Jun 1986 (PPf; 383-1986). One photographed on Southeast Farallon Island, SF, 12-13 Oct 1986 (KFH|; fide PP; 205-1987), has not been previously published. One was at Morongo Valley, SBE, 30 Apr 1987 (NBB; 132- 1987). One was at Butterbredt Springs, KER, 10 May 1987 (PEL; SEF, JWt; 133- 1987). One was on Southeast Farallon Island, SF, 13 Jun 1987 (PP; SFBt; 149- 19 87). The Merced bird (Figure 7) established the single record for the Central Valley. KENTUCKY WARBLER Oporornis formosus (36). A male was on Southeast Farallon Island, SF, 10 Jun 1986 (PPf; 384-1987). A female was at La Crescenta, LA, 11 Sep-18 Oct 1986 (JLDt, KLG, CM, 448-1986). A male was at Los Osos, SLO, 7 Dec 1986-1 Feb 1987 (ELB; JLDt, PEL, CM, JEM, GPSf; 13-1987). One was at Point Loma, SD, 5-7 May 1987 (GMcC; 187-1987). A female on Southeast Farallon Island, SF, 9 May 1987 (PPt; 206-1987), furnished the earliest spring record for this locale. A male was at Mojave, KER, 10 May 1987 (SEF, PEL; 134- 1987). A male was at Galileo Park, KER, 15 May 1987 (JW; CM; 160-1987). A singing male was at Kern River Preserve, KER, 16 May 1987 (WCH; 166-1987). A singing male at Morongo Valley, SBE, 17 May 1987 (DRW; 183-1987), was judged to probably be the same one still there 24 May 1987 (DGo; 184-1987); in AB 41 :490, however, these were considered separate individuals. A bird at Oasis, MNO, 25 May 1987 (BL; SFB, MAP; 141-1987) was judged to be the same as one there 27 May (JML; 256-1987), although they were previously published (AB 41:490) as separate individuals. A male was at Deep Springs, INY, 25-27 May 1987 (MJL; SFB, JML; 142-1987). A male was at Butterbredt Springs, KER, 27-29 May 1987 (JSR; JLD, JW; 165-1987). A male was at Furnace Creek, Death Valley NM, INY, 30 May 1987 (MAP; 182-1987). This normally very rare vagrant to California had an unprecedented invasion in spring 1987 with 11 individuals being reported for the state (one still under review). Vagrant eastern warblers that visit our state appear to have definite wave years, which I believe may correlate with exceptionally successful breeding and/or wintering seasons. Several Committee members mentioned the difficulty in sexing first-year male and female Kentucky Warblers. The 25-27 May 1987 Oasis bird illustrates this problem. For additional information see Pyle et al. (1987). CONNECTICUT WARBLER Oporornis agilis (31). Two were on Southeast Farallon Island, SF, 12 Sep 1986 (both PPt; 62-1987 and 63-1987). One of these birds (62-1987) died when a Western Gull ( Larus occidentalis) was found trying to pull it from a mist net. It is now CAS #84370. Hand-held Connecticut (62-1987) and Mourning (64-1987) warblers are shown together in Figure 8. MOURNING WARBLER Oporornis Philadelphia (40). A male was at California City, KER, 16 May 1986 (JW; TME; 331-1986). An amazing five were on Southeast Farallon Island, SF, in fall 1986; one 3 Sep (PPt, 66-1987), one 10 Sep (PPt: 67- 1987), two 12 Sep (both PPt; 64-1987 and 65-1987), and one 20 Oct (PPt; 6- 1987). One at Carmel River mouth, MTY, 4 Nov 1986 (DR; 436-1986), established the latest fall record by two weeks. A male was on Southeast Farallon Island, SF, 7 Jun 1987 (SFB; PPt; 148-1987). 116 CALIFORNIA BIRD RECORDS Six Mourning Warblers in 1986 accounted for northern California’s best fall ever, although there were five in fall 1974. Two Connecticut and two Mourning warblers on Southeast Farallon Island 12 Sep 1986 were certainly noteworthy. Variations in characters distinguishing spring male Mourning and MacGillivray’s (O. tolmiei ) warblers were discussed by Lanyon and Bull (1967), Hall (1979), and Pitocchelli (1990). Although four adult male Mourning Warbler specimens examined by Hall had eye-arcs when examined with a magnifying glass, lack of eye-arcs seems quite reliable for Mourning Warblers seen well in the field. He considered the black lore to be of no value and the black apron to be of little value for distinguishing the two species. Pitocchelli found that MacGillivray’s Warblers all have eye-arcs and dark lores but that plumage of Mourning Warblers is more variable with some having eye- arcs and others having dark lores. Although Cox (1973) questioned the specific status of these two species, Pitocchelli believed they should remain separate. In his comments on one of the fall records, Bevier mentioned examining some fall adult female Mourning Warbler specimens from the Isle of Shoals, Maine, that have creamy-whitish eye-arcs, no supra-loral line, and whitish-buff throats. All, however, have Mourning Warbler measurements! For an excellent discussion of female and immature Oporornis warblers see Pyle and Henderson (1990). SCARLET TANAGER Piranga oliuacea (48). A female was at Morro Bay, SLO, 11 Nov 1984 (KLG; 459-1986). A male was at San Juan Capistrano, ORA, 5 Jun 1986 (MPtr; 330-1986). A singing male was at Lopez Lake, SLO, 14 Jun 1986 (CM; 269-1986). An immature male was at Thousand Palms Oasis, RIV, 3 Oct 1986 (JLD; 449-1986), An immature male was at Palos Verdes, LA, 30 Oct-2 Nov 1986 (BED; RAE, DRW; 41-1987). A female at Coronado, SD, 7 May 1987 (EC; 176- 1987), represents the earliest date for a California spring vagrant by almost two weeks. A singing male was at Fairhaven, HUM, 7 Jun 1987 (GSL; LPL; 219-1987). See Kaufman (1988) for a discussion of female tanager identification and representa- tive photographs. PAINTED BUNTING Passerina ciris (16). An immature was at Gaviota State Beach, SBA, 1-2 Sep 1986 (CDB; GSL, HPR; 474-1986). A first-year female was on Southeast Farallon Island, SF, 23 Sep 1986 (PPt; 58-1987). An adult male at Scotty’s Castle, 1NY, 22 May 1987 (PEL; JLD, SEF, JML, MJL; 138-1987), represents only the second accepted spring record for southern California. CASSIN’S SPARROW Aimophila cassinii (16). One (Figure 9) was on Southeast Farallon Island, SF, 22 Sep 1986 (PPt; 59-1987). For separating Cassin’s from Botteri’s Sparrow, see Kaufman’s (1990) excellent text, which includes the chapter that appeared earlier in Birding (Kaufman 1989). LE CONTE’S SPARROW Ammodramus leconteii (10). A juvenile wason South- east Farallon Island, SF, 11-12 Sep 1986 (PPt; 54-1987). Another on Southeast Farallon Island, SF, 1 1-12 Oct 1986 (KFHt, fide PP; 212-1987), had already molted into first basic (winter) plumage. The September 1986 bird (Figures 10 and 11) was remarkable because of its early date and even more impressive because it was apparently in juvenal plumage. There are, however, two additional September records (thirteenth report). Bevier (in voting comments) mentioned that Le Conte’s Sparrows typically do not leave their breeding grounds until September, with 5 and 14 September being the earliest dates for Iowa (Dinsmore et al. 1984) and 8 October being the earliest for Texas (Oberholser 1974). Pyle (in voting comments) suggested that Le Conte’s Sparrows may have a supple- mental (pre-first basic) plumage as do Indigo Buntings (Passerina cyanea) (Rohwer 1986), Cassin’s (Aimophila cassinii ) and Bachman’s (A. aestivalis) sparrows (Willoughby 1986), and some other passerine species. 117 CALIFORNIA BIRD RECORDS ‘SHARP-TAILED SPARROW Ammodramus caudacutus (34). An immature at Areata marsh, HUM, 22 Oct 1986-27 Jan 1987 (LPL, DR, JSt; 431-1986), established the first record for that county. One was at Bolinas Lagoon, MRN, 28 Nov 1986 (BDP; 452-1986). One at Morro Bay State Park, SLO, 2 Nov 1986 (KAH, CM, GPSt;14-l987), is previously unpublished. Three were at Palo Alto Baylands, SCL, 4 Nov 1986-29 Jan 1987 (SEF; WGB, GH, JM, DLS; 21-1987). This is the last CBRC report that will include records of the Sharp-tailed Sparrow because the species has been off the Review List since the tenth report (Dunn 1988). Therefore, a few closing comments seem appropriate for Bolinas Lagoon and Palo Alto Baylands, where it has been difficult to determine which records represent returning individuals. With the exception of the winter periods 1979-80 and 1981-82, for which the Committee received no w'ritten reports, Bolinas Lagoon has had as many as three wintering Sharp-tailed Sparrows since Feb 1977 (14-1977, Luther 1980; 222- 1980, Binford 1985; 38-1982 and 120-1982, Morlan 1985; 121-1983, Roberson 1986; 255-1984, Dunn 1988; 160-1985, Bevier, 1990; and 452-1986 reported above). AB 33:804 reported four in winter 1978-79. The banded bird in winter 1980- 81 (222-1980, Binford 1985) was not reported again. Records previously reported and accepted from Palo Alto Baylands begin with one bird 8 Feb 1978 (79-1978, Luther et al. 1983) and end with the three reported above for winter 1986-87. At this location, there were several winters (1979-80, 1981- 82, 1984-85, and 1985-86) for which the Committee received no reports but AB sometimes did. Morlan (1985) discussed these in more detail. Any additional information about birds seen during these years would be welcome. Figure 11. Juvenile Le Conte’s Sparrow ( Ammodramus leconteii) on Southeast Farallon Island, San Francisco County, California, 11-12 Sep 1986. Photo by Peter Pyle 118 CALIFORNIA BIRD RECORDS SNOW BUNTING Plectrophenax nivalis (24). One was on Southeast Farallon Island, SF, 10 Nov 1986 (PP+; 7-1987). One was at Bodega Head, SON, 30 Nov 1986 (JCt; 75-1987). One was at King Salmon, HUM, 6-8 Dec 1986 (LPL, JM+, DRt; 453-1986). COMMON GRACKLE Quiscalus quiscula (14). One was at Furnace Creek, Death Valley NM, INY, 23 May 1983 (JSt; 429-1986). UNACCEPTED RECORDS, identification questionable YELLOW-BILLED LOON Gavia adamsii. One in Monterey Harbor, MTY, in early Nov 1980 (162-1986). One at Point Lobos State Reserve, MTY, 29 Dec 1986 (17- 1987). Both reports received 0-10 first-round votes. For identification tips, see references listed under accepted records. TOWNSEND’S SHEARWATER Puffinus auricularis. One west of the Cordell Bank, MRN, 16 Jun 1985 (69-1985).' Although this report was published (AB 39:957), it was a very difficult one for CBRC members, beginning with its first round in Dec 1985 and ending in Mar 1988 with a fourth round, prior to which it was discussed at the Jan 1987 annual CBRC meeting. Of the fifteen Committee members who eventually voted on this report, only three (who were able to vote more than once) kept their “accept” vote throughout and only three kept their “unaccept” vote throughout. This very contro- versial report finally received a 5-5 vote. Had it not represented the first record for the state as well as for North America north of Mexico, this report might have been accepted. Most members who did not accept it commented that they believed the observers were capable of identifying Puffinus auricularis and may have seen one. A few members thought that Townsend’s Shearwater proper (P. a. auricularis), which breeds on the Revillagigedo Islands off western Mexico, had not been definitively separated from Newell’s Shearwater (P. a. newetli), which breeds on the Hawaiian Islands. The three observers who submitted this report are experienced seabird observers. However, they rarely have to describe the birds they census with the thoroughness and detail that is required to document first state records. I believe that if one or more records of Townsend’s Shearwater are accepted for the state, this report will be reviewed again and accepted. A 28 Oct 1990 sighting from Cordell Bank is currently under review. It is important to restate that all CBRC reports that are not accepted can be reevaluated if new and substantial information concerning that species or that sighting surfaces. All researchers have access to unaccepted as well as accepted reports. Many interesting comments on field marks for this difficult seabird group are part of the 62-page record. Jehl’s (1982) paper on Townsend’s Shearwater is certainly worth reading, as is Stallcup’s (1990) book on ocean birds, Harrison’s (1983) text, and Dunn’s (1988) discussion of the unaccepted 27 Aug 1977 Manx Shearwater (P puffinus) report. TRISTRAM’S STORM-PETREL Oceanodroma tristrami. One described but poorly photographed on Monterey Bay, MTY, 9 Oct 1977 (411-1986). One west of Santa Cruz, SCZ, 11 Oct 1986 (412-1986). Both of these reports were not accepted (0-10) on their first round. The October 1977 bird was not accepted even by two Committee members who saw it. These reports serve primarily to alert Pacific-coast birders to study the literature on Tristram’s (called Sooty Storm-Petrel in AOU 1983 but changed in AOU 1989), 119 CALIFORNIA BIRD RECORDS UNACCEPTED RECORDS, identification questionable (Cont.) Markham’s (O. markhami), and Matsudaira’s (O. matsudairae ) storm-petrels. Pratt et al. (1987) noted that Tristram’s has a paler rump than the other three species. This feature shows up nicely in one of the photos in Harrison (1987), which also shows a bluish-gray sheen to the rump. Pratt et al. (1987) suggested that the white bases of the primary shafts of Matsudaira’s Storm-Petrel is often difficult to see at any distance, but both photos in Harrison (1987) show it clearly. However, Dunn (pers. comm.) has seen white at the base of Black Storm-Petrel (O. melania) primaries when the birds were extremely close, so caution with this field mark is recommended. Brown (1980) said that shallow wing beats and much gliding are the best way to separate Markham’s from Black Storm-Petrel. From recent experience, Roberson (pers. comm.) says gliding is just one of several good characters, which include differences in tail length, shape, and carpal bar prominence, CHINESE POND HERON Ardeola bacchus. One at Brawley, IMP, 21 Jan 1987 (87-1987), In comments on the 0-10 vote, most of the seven members who questioned the identification mentioned that even if it had been properly identified they would have questioned its natural occurrence. Some thought that a Cattle Egret (Bubulcus ibis ) in alternate plumage was not eliminated. BLACK-BELLIED WHISTLING-DUCK Dendrocygna autumnahs. Two at Border Field State Park, SD, 24 May 1986 (36-1987), received a 2-8 vote. Although this report was published (AB 40:523), it wassuggested that these birds were probably escapees. Most CBRC members who questioned the identification indicated also they would not accept because of a questionable origin. So far the CBRC has not accepted any coastal reports of this species, but all coastal sightings should be submitted to the Committee as numbers of this species are increasing in Arizona and it is a casual visitor to the Salton Sea. A sighting from there in 1912 has not been submitted to the CBRC for review. The earliest accepted record dates back to June 1951 at Calipatria. TRUMPETER SWAN Cygnus buccinator. One at Lower Klamath NWR, SIS, 4 Feb 1979 (195-1986). Twenty birds near Clear Lake NWR, MOD, 6 Jan 1984 (68- 1987). One at Diaz Lake, near Lone Pine, INY, 15 Dec 1984 (29-1985). The main problem with the Lower Klamath report was the very brief description from only one of the six observers. The Clear Lake report was of 20 birds identified from a plane. Although the reporter has considerable experience identifying swans from plane surveys in Alaska, the race of the Canada Geese ( Branta canadensis) with which these were observed for size comparison was not determined, and the birds were never relocated and studied from the ground. The Lone Pine bird was published (AB 39:785), but not accepted (4-6) on its third circulation. Those supporting this report believe the calls were properly identified because the observer had considerable experience with Tundra Swans (Cygnus columbianus ) wintering in the Sacramento Valley. Most of those not accepting the report believe that Trumpeter and Tundra swan voices are so variable that voice alone cannot be used to separate these species. See comments under accepted records of Trumpeter Swan for various problems faced by sightings of this species reported in California. TUFTED DUCK Aythya fuligula. A female at Lopez Lake, SLO, 27 Jan 1986 (204-1986), Two males also reported from here in early 1986 were previously accepted (Bevier 1990). The change from the 6-4 first-round to the 2-8 final-round vote reflects the Committee’s increased caution with females of this species in which al! the appropriate field marks are not seen. In this case, not only was the bird never refound, but the wing pattern was not observed as the bird did not fly or flap its wings, the described bill pattern did not seem correct, and there was only the hint of a tuft. 120 CALIFORNIA BIRD RECORDS UNACCEPTED RECORDS, identification questionable (Cont.) The increased number of male Ay thy a hybrids found in the state in recent years has made many aware of the possibility of female hybrids and increased the need for more caution with reports of this species. Interesting comments on hybrids by Gillham et al. (1966), Gillham (1988), and Harris et al. (1989) should be examined by those who report this species. MISSISSIPPI KITE Ictinia mississippiensis. One at Pigeon Point, SM, 5 Apr 1984 (211-1986). One at Sepulveda Basin, Encino, LA, 14 Jan 1987 (44-1987). Votes on the Pigeon Point report went from 7-3 in the first round (based on the description) to 4-6 in the second round. Concern arose over the very early date, the observer’s distance from the bird, and the angle of the sun. In the second round some members mentioned interesting early dates apparently unknown to others who did not accept primarily because of the 5 Apr date. Bevier’s first-round comments mentioned dates ranging from 26 Dec to 17 Feb (Oberholser 1974), a 15 Mar record from northern Texas (AB 37 : 886), and a flock of 250 birds on 23 Mar at Santa Ana NWR in Texas (AB 38:932). In second-round comments, Roberson mentioned a 9 Apr record from Cape May (Leek 1984) and a 12 Apr record from Iowa (Dinsmore et al. 1984). The 0-10 vote on the Jan 1987 Encino report reflects the report’s winter date as well as an unconvincing description. ZONE-TAILED HAWK Buteo albonotatus. One seen without binoculars at Tor- rance, LA, 20 Oct 1984 (24-1985), was not accepted (6-4) after four rounds of voting and discussion at an annual CBRC meeting. WILSON’S PLOVER Charadrius wilsonia. Five at the south end ofthe Salton Sea, IMP, 31 Aug 1986 (88-1987). At a time of year when the Salton Sea area is so heavily birded, five adults by a single observer who was unaware of the species’ status in California (three records) expectedly received a 1-9 vote. However, the species has nested once at the Salton Sea (Garrett and Dunn 1981), a report currently under review. BAR-TAILED GODW1T Limosa lapponica. One at Los Penasquitos Lagoon, SD, 19 Dec 1982 (168-1986) was not accepted (3-7) after two circulations. Although the report submitted ran to just over three single-spaced typed pages and most of what was decribed fit the Bar-tailed God wit, there were several problems. Most CBRC members were concerned that the observation took place “five to fifteen minutes after sunset” and that several key field marks such as underwings, rump, uppertail coverts, and tail patterns and colors were not described. Several members supporting the report felt the marks seen were enough to eliminate similar species. WHITE-RUMPED SANDPIPER Calidris fuscicollis. One at the Salinas River mouth, MTY, 6 Nov 1980 (164-1986). One at Wilbur, KIN, 18 Sep 1984 (286- 1986). One at the Salinas sewage ponds, MTY, 2 Oct 1986 (386-1987). Two of the descriptions were far too brief for a bird so rare. In at least one case, a Red Knot ( Calidris canutus) was suspected to account for the report. Any of the three would have represented only the third fall record for this species. Extremely good documentation is thus required for such a sighting to be accepted. THICK-BILLED MURRE Uria Iomvia. One at Crescent City harbor, HUM, 20 Jun 1987 (220-1987). While most records of this species are from late summer through early winter, a June occurrence would certainly fit in with other California records of alcids such as the Horned Puffin ( Fratercula corniculata ) and Least Auklet ( Aethia pusilla), which have similar northern breeding ranges. The incompleteness of the description, however, contributed heavily to the 3-7 vote. 121 CALIFORNIA BIRD RECORDS UNACCEPTED RECORDS, identification questionable (Cont.) BROAD-BILLED HUMMINGBIRD Cynanthus latirostris. A female present at a hummingbird feeder in Santa Cruz, SCZ, 5 Oct-8 Nov 1985 and again 15 Jun-27 Aug 1986 (360-1986) was joined by an immature on 18 Aug 1986 (361-1986). Both of these reports were previously published (AB 41:140). A very detailed description of these birds was sent in by an observer who saw both on 18 Aug 1986. Two photographs of the female taken by the homeowner in early Oct 1985 and a color slide taken 8 Nov by a visitor were both submitted with the written description. Many of the Committee’s comments centered around anomalies visible in the photographs or mentioned in the written description that suggested the female might be a hybrid. In particular, the bill color and pattern were wrong, and the green flecking seen on the throat should not occur. Females of this species have dusky-gray throats. Several CBRC members thought one of the parents in each case was probably a Broad-billed Hummingbird, but there was no consensus concerning the other parent. The immature was observed for only about 30 seconds, but compari- son of its description with specimens at both the MVZ and CAS suggested that it too might be a hybrid. The dates as well as the improbability of two individuals of this species at the same feeder so far north also contributed to first-round votes of 4-6 (female) and 2-8 (immature). ALDER FLYCATCHER Empidonax alnorum. One on Southeast Farallon Island, SF, 4 Sep 1985 (187-1985), would have been California’s first record. This report was published (AB 40:331) but with the disclaimer that the bird was identified by comparison with measurements from Stein (1963). It did not mention that the identification was also based on papers by Phillips (1948) and Aldrich (1951) plus examination of 150+ skins (from a wide range of geographic populations) at MVZ and CAS. Stein’s (1963) data have been questioned because differences among sex and age categories were studied only superficially, and geographic sampling of breeding populations was incomplete (letters from consultants N. K. Johnson, J. V. Remsen, Jr., and T. S. Schulenberg). Phillips et al. (1966, 1970) said these species are too similar for banders to try to distinguish and thus all should be listed as Traill’s Flycatchers. Several of the measurements fell outside the range known for the Willow Flycatcher (E. traiilii), and neither call notes nor song was heard from the Southeast Farallon Island bird. Descriptions and/or sonograms of the call or song are necessary to identify Alder and Willow flycatchers conclusively (Zink and Fall 1981, Whitney and Kaufman 1986). As pointed out by several consultants and Committee members, the carefully collected measurements of the bird do not rule out the Willow Flycatcher. Even if the bird had been collected, at present many specimens of these two species can not be identified. Comments about a prominent loral spot on the Southeast Farallon Island bird can also not be considered (at present) useful since specimens of both species can exhibit this loral spot, as can be seen in photographs of both species (Whitney and Kaufman 1986, Farrand 1983). In the end, the report received a 1-9 vote. SCISSOR-TAILED FLYCATCHER Tyrannus forficatus. One at Lafayette, CC, 3 May 1981 (354-1986). Although this report was published (AB 35:860), it was not acccepted (1-9) by the Committee because the description and observation were both too brief. CURVE-BILLED THRASHER Toxostoma curuirostre. One at Fort Piute, SBE, 16 May 1987 (180-1987), was published as possibly that species but more likely the similar Bendire’s Thrasher (T bendirei), which breeds at this location (AB 41:489). The report received a 0-10 vote primarily because of the unusual date, the brevity of the view, and the lack of a description of the underparts, which therefore did not eliminate Bendire’s Thrasher. 122 CALIFORNIA BIRD RECORDS UNACCEPTED RECORDS, identification questionable (Cont.) RED-THROATED PIPIT An thus cervinus. One at Westley, STA, 6 Nov 1980 (166-1986). One at Tennessee Valley Cove, MRN, 17 Apr 1987 (128-1987). The Westley bird would have represented the first Central Valley record. The Tennessee Valley Cove bird would have constituted the first spring record for California. PHILADELPHIA VIREO Vireo philadelphicus. One at Big Sycamore Canyon, VEN, 14 Oct 1978 (36-1981). One at Point Reyes NS, MRN, 21-27 Sep 1986 (50- 1987). The Big Sycamore Canyon report was published (Garrett and Dunn 1981 and AB 33:216). This report was very difficult for the Committee (6-4 after four circulations and discussion at an annual meeting) because most members believe the bird was correctly identified. The observer is one of the best in North America and certainly well qualified to identify this species, but the description (not written for the CBRC and not submitted to it by the observer) was considered inadequate to separate this species from similar ones. The observer, although believing the sighting was correct, asked for the report to be withdrawn after its second circulation. However, CBRC rules do not permit a report to be withdrawn after it has begun circulation, and a few members later voted against it because of this request. The Point Reyes sighting was published (AB 41:140-141), but only with the latter date. The extremely brief description and the fact that only this observer reported the bird (on both weekends) from an area so heavily birded in fall contributed to the 2-8 vote. BLUE-WINGED WARBLER Vermiuora pinus. One at Lafayette, CC, 29 Sep 1984 (44-1985) was published (AB 39:100). BLUE-WINGED x GOLDEN-WINGED WARBLER Vermiuora pinus x chrysoptera. One at Moss Landing, MTY, 27 Nov 1986 (463-1986). “Lawrence’s” Warbler (the hybrid form described) is the rarest of the hybrids produced by these two species (Parkes 1951). Moreover, the bird’s flying up to a telephone wire and sitting with blackbirds and House Finches ( Carpodacus mexicanus ) seemed behavior very unusual for a Vermiuora warbler. The sighting was brief, by a single observer, and there were problems with the description, so the record was not accepted (1-9). There are only two accepted California records for hybrids of these two species (Winter and McCaskie 1975, Dunn 1988). CERULEAN WARBLER Dendroica cerulea. One at Tapia Park, Malibu Canyon, LA, 17 Nov 1986 (464-1986). After publication by Lehman (1987) of an article on problems associated with immature Blackburnian and Cerulean warblers, and be- cause of the presence of a dull Blackburnian 15-23 Nov 1986 foraging high in the same trees, the initial finder requested this report be withdrawn. As mentioned previously, however, once a report begins circulation, it cannot be withdrawn. The report was not accepted (2-8) because of the very poor viewing conditions (overcast and drizzly), the presence of a dull female Blackburnian Warbler in the same trees, and there being only nine Cerulean Warbler records for California. CONNECTICUT WARBLER Oporornis agilis. One at Carpinteria Creek, SBA, 25 Sep 1983 (133-1983), was published (AB 38:248). One at Point Reyes NS, MRN, 20 Sep 1984 (212-1984), was also published (AB 39:100). Both of these reports generated much lively and informative discussion on Oporornis identification. The Carpinteria bird received a 5-5 vote after four circula- tions and discussion at an annual CBRC meeting. Five expert consultants reviewed the report and hundreds of specimens were checked in seven museum collections. It seems clear that the Connecticut Warbler has a distinctive walk similar to the 123 CALIFORNIA BIRD RECORDS UNACCEPTED RECORDS, identification questionable (Cont.) Ovenbird’s ( Seiurus aurocapillus), whereas the Mourning Warbler hops (Lehman 1984,, Pyle and Henderson 1990). However, one Committee member and one consultant have seen a Mourning Warbler walk briefly, but not at such length and as deliberately as the Connecticut Warbler and Ovenbird. Because plumage can be so variable, several members place much emphasis on walking by the Connecticut Warbler. According to Clark (1975), most bird species move either asynchronously (by walking) or synchronously (by hopping). The birds involved in both of these unaccepted reports were observed to walk repeatedly, and this was the main reason for the votes to accept the sightings. Several other Connecticut Warbler traits were exhibited by the Carpinteria individual. In the end, however, the reports were not accepted primarily because both birds were described as having distinctly yellow throats and no one could find a Connecticut Warbler specimen showing distinct yellow on the throat or even a small break in the breast band that creates the hooded effect in this species. There is a photograph of a Connecticut Warbler with a yellow throat in Pyle and Henderson’s (1990) article on separating female and immature Oporornis warblers in fall. For both reports, the idea of a hybrid was dismissed for lack of any known hybrids involving a Connecticut Warbler (Cockrum 1952). The lack of hybridization with Mourning Warbler is especially interesting since there is about a 90% overlap in the breeding ranges of these two species (Godfrey 1986). The Point Reyes bird also was subjected to four circulations and discussion at one annual CBRC meeting. There is a published sighting (AB 39:100) of a Mourning Warbler on the same date (21 Sep 1984) from the same Point Reyes location that remains unreviewed by the CBRC and may have contributed some confusion for both the observers and Committee members. MOURNING WARBLER Oporornis Philadelphia . One at Furnace Creek, Death Valley NM, INY, 25 May 1987 (179-1987), was published (AB 41:490). The CBRC did not accept this report primarily because of the extremely brief description and an inappropriate statement about the entire head, neck, and bib being black. See Pitocchelli (1990) and Pyle and Henderson (1990) for the most recent discussion of field marks used to identify difficult Mourning Warbler plumages. *SHARP-TAILED SPARROW Ammodramus caudacutus. One at Limantour Estero, Point Reyes NS, MRN, 21 Dec 1984 (396-1986). COMMON GRACKLE Quiscalus quiscula. One near Los Banos, MER, 4 Aug 1980 (335-1986). UNACCEPTED RECORDS, natural occurrence questionable (identification accepted) KITTLITZ’S SANDPLOVER Charadrius pecuarius. One photographed at San Diego River mouth, SD, 26 Dec 1970 (363-1986) had been banded. The bird clearly was identified correctly. Although widely distributed in Africa (Urban et al 1986), this species is primarily sedentary, with a May 1913 record for southern Norway being the farthest one away from the African breeding grounds (Hayman et al. 1986). For unknown reasons this Norway record was not cited by Cramp et al. (1983) or Urban et al. (1986). However,Dunn and Morlan (pers. comm.) saw Israel’s second and third records of this species in November 1986, suggesting that there is more movement away from Africa than implied by these publications. 124 CALIFORNIA BIRD RECORDS CORRIGENDA TO ELEVENTH REPORT (Bevier 1990) Under Accepted Records: The final date of record 38-1985 (Yellow-billed Loon) is 26 Jan 1969, not 25 Jan 1969. The location for record 239-1986 (Scissor-tailed Flycatcher) is Prado Regional Park, SBE, not Prado Basin near Corona, RIV. The year for record 231-1986 (Blue-winged Warbler) is 1984, not 1986. CONTRIBUTORS David G. Ainley, Lynne Aldrich, Bjorn Anderson, Robby J. Bacon, Stephen F. Bailey, Larry Ballard, Bruce Barrett (BBa), Alan D. Barron, Hal Baxter (HBa), Chris D. Benesh, Louis R. Bevier, Laurence C. Binford, Gordon Bolander, William G. Bousman, Eilleen L. Bowen, Bob Bradley (BBr), Jean Brandt (JBr), Don Brewer, Ken Briggs, R. V. Britton, N. Bruce Broadbooks, Hank Brodkin (HBr), June Buntin (JBu), Elliot Burch, Chris Carpenter, Mark O. Chichester, Graham Chisholm, Herbert Clarke, Howard L. Cogswell, Mark R. Collie, John Comstock, Bruce Conant, Remain Cooper, Elizabeth Copper, Debby Cotter, Brian E. Daniels, Maryann Danielson (MaD), Mike Danzenbaker (MDa), Mike Denny (MDe), David DeSante, Ruth Doudiet, Jon L. Dunn, Tom M. Edell, Art Edwards, Claude G. Edwards, Jr., Raymond Ekstrom, Richard A. Erickson, Jules Evens, Lynn D. Farrar, Shawneen E. Finnegan, Bob Florand, Ginger Francis, David A. Gaines, Kimball L. Garrett, Douglas E. George, R. H. Gersteriberg, Albert Ghiorso, Dave Goodward (DGo), Peter Gottschling, Ed Greaves, Helen Green, Margaret D. Green, Douglas Greenberg (DGr), Jeffrey Greenhouse, Marguerite B. Gross, Kem Hainebach (KeH), Richard A. Hallowell, Keith F. Hansen, W. Edward Harper, Stanley W. Harris, Gregg Hauser, Jim Havlena, Karen A. Havlena, Matt Heindel, Roger Higson, Alice Hoch, David A. Holway, Alan S. Hopkins, Bambi Hopkins, Arthur L. Howe, Steve Howell, William C. Hunter, Lin Jensen, Jerome A. Johnson, Virginia P. Johnson, Durrell D. Kapan, Virgil Ketner, Ted Kinchloe, David B. King, Jr,, Christine H, Koundakjian, Ted H. Koundakjian, Bruce LaBar, Jeri M. Langham, Laurie K. Langham, Peter La Tourrette (PLa), Paul E. Lehman, Joan E. Lentz, Gary S. Lester, Lauren P. Lester, Ron LeValley (RLeV), Michael J. Lippsmeyer, W. June Ludlow, Oddvin Lund, Tim Manolis, Curtis Marantz, Guy McCaskie (GMcC), John E. McDonald, Merrylynn Messinger, Peter J. Metropulos, Mark C. Miller, Randy J. Moore, Joseph Morlan, Bert Mull, Robert E. Munsey, Dan Murphy, Dan Nelson, Charles Newell, Ella Newell, John O’Brien (JO’B), Max Parker (MPar), Benjamin D. Parmeter, Michael A. Patten, Robert Patton, Marie Patterson (MPtr), Jay Penniman, Michael Perrone (MPe), Peter Pyle, David E. Quady, Marty Raphael (MRa), Hugh P. Ranson, Rick Reynolds, David Rice (DRi), Bob Richmond (BRi), Mark R. Robbins, Michael Robbins (MRo), Don Roberson (DR), Robin E. Roberson, Bill Rodstrom (BRo), James A. Rooney, Kenneth V. Rosenberg, Philip Rostron, Jim S. Royer, Larry Salata (LSal), Larry Sansone (LSan), Barry Sauppe (BSa), Rick Saval (RSa), Phillip R. Sayre, John Schmitt (JSc), Brad Schram (BSc), Rusty Scalf (RSc), Dave Shuford, John R. Silliman, Laurens Silver (LSi), Arnold Small, Gregory P. Smith, Kenneth Smith, Hal Spear, Larry Spear (LSp), Rich Stallcup, John Sterling (JSt), Gary J. Strachan, David L. Suddjian, Steven Summers, Jan Tarble (JTa), Michael Taylor, Dean Thompson, Ronald S. Thorn, Bob Tintle, Gerald Tolman, John Trochet (JTr), Louis Tucker, Philip Unitt, Vitaly Volmenski, Richard E. Webster, Mike Wihler, David Willey, Douglas R. Willick, John Wilson, Summer Wilson, Thomas E. Wurster, David G. Yee, Kevin J. Zimmer, R. D. Zirker. 125 CAUFORNIA BIRD RECORDS ACKNOWLEDGMENTS The Committee is most grateful to the 183 contributors listed above, without whom this report would not have been possible. Increased use of photography to document rarities has made the CBRC’s job much easier, and thus we thank the 49 photographers who submitted transparencies or prints for our review and permanent archival in our files. Non-CBRC member photographers who deserve special men- tion for the extent of their contributions are Raymond Ekstrom, Keith F. Hansen, Peter La Tourrette, John Trochet, John Wilson, and especially former CBRC member Peter Pyle. The Committee also appreciates the review of certain difficult records by the following experts: R. G. B. Brown, Harold H. Burgess, David DeSante, Kim Eckert, Joseph R. Jehl Jr., Ned K. Johnson, Bruce Peterjohn, J. Van Remsen, Jr., Thomas Schulenberg, Rich Stallcup, and Alan Wormington. The continued help of the Point Reyes Bird Observatory in obtaining and compil- ing records from Southeast Farallon Island is greatly appreciated. Don Roberson deserves special mention for digging through Guy McCaskie’s Southern Pacific Coast Region AB files and submitting many records, especially those of John Sterling. Because voting on some of the records treated in this report took so many years to complete {four rounds plus discussion at an annual meeting), almost all previous CBRC members contributed a vote in at least one of the rounds of the 244 reviewed records. Former members who voted on a substantial number of records are Laurence C. Binford, Benjamin D. Parmeter, and Richard Stallcup. Current or recent members who reviewed an earlier draft of this manuscript and made many useful contributions and corrections are Stephen F. Bailey, Louis R. Bevier, Jon L. Dunn, Richard A. Erickson, Kimball L. Garrett, Paul E. Lehman, Michael J. Lippsmeyer, Curtis Marantz, Guy McCaskie, Joseph Morlan, Michael A. Patten, Peter Pyle, and Don Roberson. The following curators or collections managers graciously provided members access to their collections: Luis F. Baptista and Stephen F. Bailey (CAS), Eugene A. Cardiff (SBCM), George A. Clark, Jr. (Connecticut State Museum of Natural History), Kimball L. Garrett and the late Ralph W. Schreiber (LACM), Stanley W. Harris (Humboldt State University), Ned K. Johnson and Anne Jacobberger (MVZ), James R. Northern (Univ. of Calif., Los Angeles), Dennis M. Power and Paul Collins (SBMNH), Amadeo M. Rea and Susan Breisch (SDNHM), J. V. Remsen, Jr. and Steven Cardiff (Museum of Natural Science, LSU), Vernal L. Yadon (PGMNH), and Richard L. Zusi (USNM). I also thank my wife, Laurie K. Langham, for entering the original data into our word processor, for helping me double-check all record dates and locations with those in AB, and for providing support throughout the project. LITERATURE CITED Aldrich, J. W. 1951. A review of the races of Traill’s Flycatcher. Wilson Bull. 63:192-197. American Ornithologists’ Union. 1983. Check-list of North American Birds. 6th ed. Allen Press, Lawrence, KS. American Ornithologists’ Union. 1985, Thirty-fifth supplement to the A. O.U. Check- list of North American Birds. Auk 102:680-686. American Ornithologists’ Union. 1987. Thirty-sixth supplement to the A. O.U. Check-list of North American Birds. Auk 104:591-596. American Ornithologists’ Union. 1989. Thirty-seventh supplement to the A.O.U. Check-list of North American Birds. Auk 106:532-538. 126 CALIFORNIA BIRD RECORDS Appleby, R. H., Madge, S. C., Mullarney, K. 1986. Identification of divers in immature and winter plumages. Br. Birds 79: 365-391. Armstrong, R. H. 1983. A Guide to the Birds of Alaska. Alaska Northwest Publ. Co., Anchorage. Bailey, S. F. 1989. First record of Chuck-will’s-widow in California. W. Birds 20:93- 95. Banko, W. E. 1960. The Trumpeter Swan: Its history, habits, and population in the United States. N. Am. Fauna 63. Bevier, L. 1990. Eleventh report of the California Bird Records Committee. W. Birds 21:145-176. Binford, L. C. 1978. Lesser Black-backed Gull in California with notes on field identification. W. Birds 9:141-150. Binford, L. C. 1983. Sixth report of the California Bird Records Committee. W. Birds 14:127-145. Binford, L. C. 1985. Seventh report of the California Bird Records Committee. W. Birds 16:29-48. Binford, L. C., and Remsen, J. V., Jr. 1974. Identification of the Yellow-billed Loon (I Gavia adamsii ), W. Birds 5:111-126. Bolander, G. 1939. A second record [Anhinga] for California. Gull 21:70. Brown, D. E. 1935. Dotterel in western Washington. Condor 37:82. Brown, R. G. B. 1980. The field identification of Black and Markham’s storm-petrels Oceanodroma melania and O. markhami. Am. Birds 34:868. Burn, D. M., and Mather, J. R. 1974. The White-billed Diver in Britain. Br. Birds 67:257-296. Clapp, R. B., and Woodward, P. W. 1968. New records of birds from the Hawaiian Leeward Islands. Proc. U. S. Natl. Mus. 124:1-39. Clark, G. A., Jr. 1975. Additional records of passerine terrestrial gaits. Wilson Bull. 87:384-389. Clark, W. S., and W'heeler, B. K. 1987. A Field Guide to Hawks of North America. Houghton Mifflin, Boston. Cockrum, E. L. 1952. Check-list and bibliography of hybrid birds in North America north of Mexico. Wilson Bull. 64:140-159, Cox, G. W. 1973. Hybridization between Mourning and MacGillivray’s warblers. Auk 90:190-191. Cramp, S., and Simmons, K. E. L. (eds.) 1980. The Birds of the Western Palearctic, Vol. 2: Hawks to Bustards. Oxford Univ. Press, Oxford, England. Cramp, S.. and Simmons, K. E. L. (eds.). 1983. The Birds of the Western Palearctic, Vol. 3: Waders to Gulls. Oxford Univ. Press, Oxford, England. Dean, A. R. 1982. Field characters of Isabelline and Brown shrikes. Br. Birds 75:395-406. DeSante, D. and Pyle, P. 1986. Distributional Checklist of North American Birds. Artemisia Press, Lee Vining, CA. Dinsmore, J. J., Kent, T. H., Koenig, D., Petersen, P. C., and Roosa, D. M. 1984. Iowa Birds. Iowa State Univ. Press, Ames. Dunn, J. L. 1988. Tenth report of the California Bird Records Committee. W. Birds 19:129-163. 127 CALIFORNIA BIRD RECORDS Dunne, P., Sibley, D., and Sutton, C. 1988. Hawks in Flight. Houghton Mifflin, Boston. Farrand, J., Jr. (ed.). 1983. The Audubon Society Master Guide to Birding, Vol. 1: Loons to Sandpipers. Chanticleer Press, New York. Garrett, K., and Dunn, J. 1981. Birds of Southern California: Status and Distribu- tion. Los Angeles Audubon Soc., Los Angeles. Gillham, E. H. 1988. The identity of “Mystery photograph 97.” Br. Birds 81:650- 653. Gillham, E. H., Harrison, J. M., and Harrison, J. G. 1966. A study of certain Aythya hybrids. Wildfowl Trust Annu. Rep. 17:49-65. Godfrey, W. E. 1986. The Birds of Canada. Rev. ed. Natl. Mus. Canada, Ottawa. Grant, P. J. 1986. Gulls: A Guide to Identification. 2nd ed. Buteo Books, Vermillion, S. D. Grinnell, J., and Miller, A. H. 1944. The distribution of the birds of California. Pac. Coast Avifauna 27. Hall, G. A. 1979. Hybridization between Mourning and MacGillivray’s warblers. Bird-Banding 50:101-107. Harris, A., Tucker, L., and Vinicombe, K. 1989. The MacMillan Guide to Bird Identification. MacMillan Press, London. Harrison, P. 1983. Seabirds: An Identification Guide. Houghton Mifflin, Boston. Harrison, P. 1987. A Field Guide to Seabirds of the World. Stephen Greene, Lexington, VA. Hayman, R, Marchant, J., and Prater, T. 1986. Shorebirds: An Identification Guide to the Waders of the World. Houghton Mifflin, Boston. Henderson. P. 1979. A Dotterel on Southeast Farallon Island, California. W. Birds 10:92-94. Jehl, J. R., Jr. 1982. The biology and taxonomy of Townsend’s Shearwater. Gerfaut 72:121-135. Johnson, G. D. 1989. First record of Purple Gallinule in Wyoming. W. Birds 20: 136. Jordan, M. 1988, Distinguishing Tundra and Trumpeter swans. [Reprinted with minor changes from Ore. Birds 14:37-41], Birding 20:223-226. Kaufman, K. 1988. Practiced eye: Notes on female tanagers. Am. Birds 42:3-5. Kaufman, K. 1989. Cassin’s and Botteri’s sparrows. Birding 21:293-297. Kaufman, K. 1990. A Field Guide to Advanced Birding: Birding Challenges and How to Approach Them. Houghton Mifflin, Boston. Kessel, B., and Gibson, D. D, 1978. Status and distribution of Alaska birds. Studies Avian Biol. 1. Lanyon, W. E., and Bull, J. 1967. Identification of Connecticut, Mourning, and MacGillivray’s warblers. Bird-Banding 38:187-194. Leek, C. F. 1984. Status and Distribution of New Jersey’s Birds. Rutgers, New Brunswick, N. J. Lehman, P. E. 1984. Point-Counterpoint: Connecticut Warbler. Birding 16:15. Lehman, P. E. 1987. Immature Blackburnian and Cerulean Warblers: A cautionary note. Birding 19:22-23. Luther, J. S. 1980. Fourth report of the California Bird Records Committee. W. Birds 11:161-173. 128 CALIFORNIA BIRD RECORDS Luther, J. S., McCaskie, G., and Dunn, J. 1983. Fifth report of the California Bird Records Committee. W. Birds 14:1-16. Medway, L. 1970. A ringing study of the migratory Brown Shrike in west Malaysia. Ibis 112:184-198. Meyer de Schauensee, R., and Phelps, W. H., Jr. 1978. A Guide to the Birds of Venezuela. Princeton Univ. Press, Princeton. N. J. Morlan, J. 1985, Eighth report of the California Bird Records Committee. W. Birds 16:105-122. Murphy, R. C. 1936. Oceanic Birds of South America. Am. Mus. Nat. Hist., New York. Oberholser, H. C. 1974. The Birdlife of Texas (E. B. Kincaid, Jr., ed.). Univ. of Texas Press, Austin. Parkes, K. C. 1951. The genetics of the Golden-winged x Blue-winged warbler complex, Wilson Bull. 63:5-15. Paulson, D. 1979. Dotterel at Ocean Shores, Washington. Continental Birdlife 1:109-111. Phillips, A. R. 1948. Geographic variation in Empidonax traillii. Auk 65:507-514. Phillips, A. R. 1990. Identification and southward limits, in America, of Gavia adamsii, the Yellow-billed Loon. W. Birds 21:17-24. Phillips, A. R., Howe, M. A., and Lanyon, W. E. 1966. Identification of the flycatchers of eastern North America, with special emphasis on the genus Empidonax. Bird-Banding 37:153-171. Phillips, A. R., and Lanyon, W. E. 1970. Additional notes on the flycatchers of eastern North America. Bird-Banding 41:190-197. Pitocchelli, J. 1990. Plumage, morphometric, and song variation in Mourning ( Oporornis Philadelphia ) and MacGillivray’s (O. tolmiei) warblers. Auk 107:161-171. Pratt, H. D., Bruner, P. L., and Berrett, D. G. 1987. A Field Guide to the Birds of Hawaii and Tropical Pacific. Princeton Univ. Press, Princeton, N. J. Pyle, P., and Henderson, P. 1990. On separating female and immature Oporornis warblers in fall. Birding 22:222-229. Pyle, P., Howell, S. N. G., Yunick, R. P, and DeSante, D. F. 1987. Identification Guide to North American Passerines. Slate Creek Press, Bolinas, CA. Remsen, J. V., Jr., and Parker, T. A., III. 1990. Seasonal distribution of the Azure Gallinule ( Porphyrula flauirostris ) with comments on vagrancy in rails and gallinules. Wilson Bull. 102:380-399. Ritchison. G. 1983. The function of singing in female Black-headed Grosbeaks (Pheucticus melanocephalus ): Family-group maintenance. Auk 100:105-116. Roberson, D. 1980. Rare Birds of the West Coast. Woodcock Publ., Pacific Grove, CA. Roberson, D. 1985. Monterey Birds. Monterey Peninsula Audubon Soc., Carmel, CA. Roberson, D. 1986. Ninth report of the California Bird Records Committee. W. Birds 17:49-77. Roberson, D. 1990. News from the California Bird Records Committee. W. Birds 20:269-271. 129 CALIFORNIA BIRD RECORDS Rohwer, S. 1986. A previously unknown plumage of first-year Indigo Buntings and theories of delayed plumage maturation. Auk 103:281-292. Schaffner, F. C. 1981. A Sandwich Tern in California. W. Birds 12:181-182. Schmidt, O. (ed.). Rare birds of Oregon. Ore. Field Ornithol. Spec. Publ. 5. Stallcup, R. 1990. Ocean Birds of the Nearshore Pacific: A Guide for the Sea-going Naturalist. Point Reyes Bird Observatory, Stinson Beach, CA. Stein, R. C. 1963. Isolating mechanisms between populations of Traill’s Flycatchers. Proc. Am. Philos. Soc. 107:21-50, Urban, E. K., Fry, C. H., and Keith, S. (eds). 1986. The Birds of Africa, Vol. 2. Academic Press, London. Whitney, B., and Kaufman, K. 1986. The Empidonax challenge: Looking at Empidonax, Part III: Traill’s Flycatcher: The Alder/ Willow problem. Birding 18:153-159. Willoughby, E. J. 1986. An unusual sequence of molts and plumages in Cassin’s and Bachman’s sparrows. Condor 88:461-472. Winter, J., and McCaskie, G. 1975. 1973 report of the California Field Ornitholo- gists Records Committee. W. Birds 6:135-144. Zimmer, K. J. 1985. The Western Birdwatcher. Prentice Hall, Englewood Cliffs, N. J. Zink, R. M., and Fall, B. A. 1981. Breeding distribution, song and habitat of the Alder Flycatcher and Willow Flycatcher in Minnesota. Loon 53:208-214. Accepted 5 April 1991 130 FIRST RECORD OF THE LONG-TOED STINT IN CALIFORNIA MICHAEL A. PATTEN, P. O. Box 8561, Riverside, California 92515-8561 BRIAN E. DANIELS, 3471 Lama, Long Beach, California 90808 On 29 August 1988 we, along with Douglas R. Willick and Kurt Radamaker, identified a juvenile Long-toed Stint ( Calidris subminuta) at the sewage ponds in Salinas, Monterey County, California. At about 1230 PDT, Daniels noticed an unfamiliar small Calidris sandpiper sitting at the edge of one of the large rock-lined sewage ponds with some Least (C. minutilla ) and Western Sandpipers (C. maun); he and Willick watched it for about 20 minutes before Patten and Radamaker arrived. The weather was clear and mild with a slight breeze, so observation conditions were excellent. We studied the bird through binoculars and telescopes for the remainder of the afternoon at distances as close as 20 feet. The following description is based on our field notes, on those of various observers who sent details to the California Bird Records Committee (CBRC), and on photographs. Our bird was a small Calidris slightly larger than a Least Sandpiper. It was similar in shape to a Least, but had a longer neck, longer legs (in particular, longer tibiae), and a shorter, straighter bill (about 75% as long as the head). The crown sloped to a high point at the rear, unlike a Least’s. The middle toe seemed to be as long as the tarsus and was clearly longer than the bill. The legs and feet were straw yellow, a bit brighter than a Least’s. The bill was blackish, except for a pale base to the mandible. In flight, the toes extended beyond the tip of the tail. There was a very thin whitish trailing edge to the greater secondary coverts, but this did not create an obvious wing stripe. The tertials were long and concealed the folded primaries. The crown was black with narrow bright rufous streaks that were more prominent posteriorly. The bird had a capped appearance resulting from a distinct separation between the crown and the brownish-gray nape and bold white supercilium. The nape was finely streaked with black. The dark crown ran down through the forehead, meeting the bill and a dark trans-ocular line. This line dipped downward slightly before the eye, forming a bulbous white loral spot. Thin buffy-white lateral crown stripes were very distinct, forming a split supercilium. The supercilium was whitish and flared slightly behind the eye before stopping abruptly at the nape; it seemed somewhat broader than a Least Sandpiper’s and was cleaner white before the eye and dirtier (a bit streaked) behind the eye. The face was mostly white with a uniform dull brownish-gray ear patch that was finely streaked with black; a tinge of chestnut was visible on the posterior edge of the cheek. The chin and throat were clean white. The breast was very pale buff or whitish at the center, gradually becoming more buffy toward the sides. The breast was streaked with dusky, very finely at the center and more heavily toward the sides. The undertail coverts and belly were white. The blackish mantle feathers were thinly edged in rufous, creating a pattern of rufous and black stripes. The blackish scapulars and tertials were edged in bright mfous, with the edges on the outermost tertial duller than those of the inners. The blackish median and lesser coverts were edged with buffy white, contrasting slightly with the pale chestnut edgings on the greater coverts. The fringes of the greater wing coverts and scapulars were broken at the tip by a black shaft streak. The scapulars and wing coverts of this bird were longer and more pointed than those of a juvenile Least Sandpiper, which are shorter and more diamond-shaped. Buffy-white stripes Western Birds 22:131-138, 1991 131 LONG-TOED STINT IN CALIFORNIA on the sides of the mantle formed a prominent “V” on the back. The tail pattern was like that of a Least. The flight call, heard several times, was a mellow, rolling “chrrrup” or “prrrt,” lower pitched than that of a Least Sandpiper. The bird fed by walking jacana-like on floating vegetation and picking insects from the surface. It had a strange tumor-like growth on the right cheek that slightly raised the feathers away from the face. The bird was last reliably reported on 2 September 1988. Additional photographs were published in American Birds 42:1226 and 43:27 and by Wilds (1988). The record, the first for California and only the third for North America outside of Alaska, was unanimously accepted by the CBRC on the first round (McCaskie and Pyle in manuscript) and is now on file, with over 20 color photographs, at the Western Foundation of Vertebrate Zoology, Los Angeles. Figure 1. Long-toed Stint, Salinas sewage ponds, 31 August 1988. The extremely long toes and pale base to the mandible are visible in this photograph. In particular, note the whitish edges of the lesser and median coverts versus the bright rufous edges of the scapulars. Photo by Lawrence Sansone 132 LONG-TOED STINT IN CALIFORNIA DISTRIBUTIONAL SUMMARY The Long-toed Stint nests in disjunct populations in the forested areas of Siberia from the River Ob’ east to the Chukotski Peninsula, the Com- mander Islands, the northern Kurile Islands, and (probably) the Kamchatka Peninsula (Cramp and Simmons 1983, A.O.U. 1983, Hint et al. 1984). Display flights and similar behavior have prompted speculation that the bird may occasionally nest in Alaska (Roberson 1980, Balch 1988, Armstrong 1990). The species winters from the Philippines, Formosa, southeastern China, and eastern India south to Ceylon through Indonesia to southern Australia (A.O.U. 1983, Cramp and Simmons 1983, Blakers et al. 1984). A few may also winter regularly in eastern Africa, because small numbers pass through the Middle East (Hayman et al. 1986, Hollom et al. 1988). Long-toed Stints have occurred three times as vagrants in Europe: once in Sweden, 4 October-5 November 1977 (Pettersson et al. 1978), once in Britain, 28 August-1 September 1982 (Rogers et al. 1985), and again in Britain, 6-7 September 1990 (Nightingale and McGeehan 1990); each was a juvenile. There are at least nine records for Africa (Urban et al. 1986) and for Christmas Island and the Seychelles in the Indian Ocean (Hayman et al. Figure 2. Long-toed Stint, Salinas sewage ponds, 29 August 1988. Here the combination of the dark forehead (extending down to the bill), the bulbous white loral spot, the dark comma-shaped loral stripe, and the bold white supercilium are evident. Note the bulge of a presumed tumor on the lower cheek. Photo by Peter La Tourrette 133 LONG-TOED STINT IN CALIFORNIA 1986). Also, a juvenile was collected 26 August 1967 on Midway Atoll, Hawaiian Islands (Clapp 1968). In North America, Long-toed Stints occur regularly in the outer Aleutian Islands (east to Adak) and casually to the Pribilof Islands, St. Lawrence Island, and western mainland Alaska (A.O.U. 1983). As many as 40 were on Shemya Island 16 May 1976 (Roberson 1980). Most records from this region are from spring (mid-May to early June) and fall (late July to mid- September), but the species has been recorded in summer (Armstrong 1990). The Long-toed Stint’s occurrence in Alaska coincides with the known spring and fall migration timing of the species (Cramp and Simmons 1983). The only previous records for continental North America outside of Alaska (see DeSante and Pyle 1986) are two birds reported from Oregon: a juvenile at the south jetty of the Columbia River 2-6 September 1981 (Gilligan et al. 1987) and an adult in alternate plumage there 17 July 1983 (Schmidt 1989). An earlier report from Oregon and one from British Columbia are generally regarded as misidentified Least Sandpipers (Roberson 1980, A.O.U. 1983, Godfrey 1986). V Figure 3. Long-toed Stint, Salinas sewage ponds, 29 August 1988. This angle clearly shows the bold mantle stripes and the sharp contrast between the crown and the nape. Photo by Peter La Tourrette 134 LONG-TOED STINT IN CALIFORNIA IDENTIFICATION SUMMARY Both the Long-toed Stint and the Least Sandpiper are very small with medium-long yellowish legs (but see Carey 1987) and medium-long black bills that are slightly decurved and pointed at the tip. They are very similar to one another and field separation can be difficult. Consistent differences in shape, bare-part coloration, measurements, and vocalizations are given in standard references such as Prater et al. (1977), Grant and Jonsson (1984), Hayman et al. (1986), and Veit and Jonsson (1987). The Long-toed Stint and Least Sandpiper are much more similar in plumage than they are in shape. In juvenal plumage, each is characterized by whitish underparts with dark streaking at the sides of the breast, a rufous crown, a white throat and supercilium, grayish ear coverts, largely dark- centered feathers with rufous edgings on the upperparts, and whitish mantle stripes. However, subtle differences can be found in each of the characters mentioned here. Much has been said about the extent of streaking on the underparts and whether or not it crosses through the center of the breast. According to several sources (such as Wallace 1980), a typical Least shows a complete breast band of streaks on a buff wash whereas a typical Long-toed shows no streaking at the center of the breast and the ground color is whiter. Nevertheless, much overlap exists and this Figure 4. Long-toed Stint, Salinas sewage ponds, 29 August 1988. Note how the streaking fades toward the center of the breast and extends down the flanks. A fairly distinct lateral crown stripe is apparent at this angle. Photo by Peter La Tourrette 135 LONG-TOED STINT IN CALIFORNIA character cannot be used with complete confidence (Wilds 1988, Alstrom and Olsson 1989). A key difference exists in the wing coverts: on the Least, the wing coverts are edged with warm buff or rufous; on the Long-toed, the edgings are white or whitish-gray and broken at the tip. Thus, contrast between the wing coverts and the scapulars is significant on the Long-toed, whereas little or no contrast is present on the Least. The rufous fringe on the scapular feathers of the Long-toed is broken by black at the tip but completely encircles the tip on the Least. The pattern on the face and head provides some of the best clues to specific identification. The supercilium of the Long-toed is usually whiter, especially above and in front of the eye. Often, the supercilium of the Long- toed extends past the auriculars to the back of the head, thus creating a more capped effect. However, the Least can show a supercilium nearly this long and the Long-toed can show one much shorter, so this mark should not be. relied upon in the field. On Long-toed, the dark loral line appears to be split, as if formed by two spots that barely meet (Wilds 1988, Alstrom and Olsson 1989). The gap at the center forms a comma-shaped loral line, producing a bulbous white “drop” between the eye and the bill. This effect is further accentuated by the dark forehead of Long-toed, which extends down from the crown to meet the base of the cuimen and to connect with the loral stripe. The Least has a thicker loral line that show's no sign of being split. Also, the anterior portion of the supercilia usually meet over the bill, creating a white area on the forehead at the base of the cuimen. Bold whitish lateral crown stripes, forming a split supercilium, are often present on juvenile Long-toed Stint but usually absent or faint on the Least Sand- piper (Alstrom and Olsson 1989). The posterior edge of the auricular is usually whiter and less well defined on the Long-toed and the nape of a Long-toed is typically gray, unlike the faded buff of a Least. The nape color contributes to the more capped appearance of juvenile Long-toed Stint. In alternate plumage, the supercilium is not nearly as bold as in juveniles and the white area before the eye is less clearly defined. A split supercilium is frequent in spring Long-toed, but is also rarely present in spring Least. The loral stripe tends to be wider in alternate-plumaged Long-toed but is still narrower than on a typical Least. Thus, the two species can closely resemble one another in alternate plumage, although the Long-toed Stint tends to be brighter overall and each species still shows a head pattern similar to that described for juveniles. Basic-plumaged birds of both species are brownish-gray above, with the Long-toed slightly darker. The pattern of the mantle feathers is distinctive. These feathers are black-centered and widely edged with brownish in the Long-toed. In the Least, the feathers are mostly brownish-gray with black shafts that blend diffusely into the sur- rounding feathers. Also, the differences in facial pattern are still evident. ACKNOWLEDGMENTS We thank the many observers that supplied the CBRC with written documentation and photographs of this bird. We especially thank Joseph Morlan and Jon L. Dunn for drawing our attention to key features of juvenile Long-toed Stints of which we were previously unaware. We also are very grateful to Tim Manolis for providing the sketch and to Peter La Tourrette and Lawrence Sansone for providing the photo- 136 LONG-TOED STINT IN CALIFORNIA graphs, Robert L. Pyle supplied information concerning the Midway Atoll record. Richard A. Erickson, Joseph Morlan, Don Roberson, Philip Unitt, and Richard R. Veit read a draft of this paper and offered many valuable comments. LITERATURE CITED Alstrom, P. and Olsson, U. 1989. The identification of juvenile Red-necked and Long-toed Stints, Br. Birds 82:360-372. American Ornithologists’ Union. 1983. Check-List of North American Birds. 6th ed. A.O.U., Washington, D.C. Armstrong, R. H. 1990. A Guide to the Birds of Alaska. Alaska Northwest Books, Anchorage. Balch, L. 1988. Curling up with a good (bird) book. Birding 20:290-303. Blakers, M., Davies, S. J. J. F. and Reilly, P. N. 1984. The Atlas of Australian Birds. Melbourne Univ. Press, Melbourne. Carey, G. J. 1987. Long-toed Stint with dark legs. Br. Birds 80:242. Clapp, R. B. 1968. Three unusual shorebirds from Midway Atoll, Pacific Ocean. ‘Elepaio 28:76-77. Cramp, S., and Simmons, K. E. L. (eds.). 1983. The Birds of the Western Palearctic, voi. III. Oxford Univ. Press, Oxford, England. DeSante, D., and Pyle, P. 1986. Distributional Checklist of North American Birds, vol. L Artemisia Press, Lee Vining, CA. Flint, V. E., Boehme, R. L., Kostin, Y. V., and Kuznetsov, A. A. 1984. A Field Guide to Birds of the U.S.S.R. Princeton Univ. Press, Princeton, N.J. Gilligan, J., Schmidt, O., Nehls, H., and Irons, D. 1987. First record of Long-toed Stint in Oregon. W. Birds 18:126-128. Godfrey, W. E. 1986. The Birds of Canada. Natl. Mus. Canada, Ottawa. Grant, P. J., and Jonsson, L. 1984. Identification of stints and peeps. Br. Birds 77:293-315. Hayman, P, Marchant, J., and Prater, T. 1986. Shorebirds: An Identification Guide to Waders of the World. Houghton Mifflin, Boston. Hollom, P A. D., Porter, R. F., Christensen, S., and Willis, I. 1988. Birds of the Middle East and North Africa. Buteo Books, Vermillion, S.D. Nightingale, B,, and McGeehan, A. 1990. Recent reports. Br. Birds 83:438. Pettersson, J., Osterberg, J. and Kjellen, N. 1978. Langtasnappa Calidris subminuta funnen vid Ottenby — en ny art for Europa [Long-toed Stint at Ottenby — a species new to Europe]. Var Fagelvarld 37:333-338. Prater, A. J., Marchant, J. H., and Vuorinen, J. 1977. Guide to the Identification and Ageing of Holarctic Waders. Field Guide 17, Br. Trust for Ornithol., Tring, England. Roberson, D. 1980. Rare Birds of the West Coast. Woodcock Publ., Pacific Grove, CA. Rogers, M. J., and the Rarities Committee with comments from A. R. Dean and K. E. Vinicombe. 1985. Report on rare birds in Great Britain in 1984. Br. Birds 78:529-589. Schmidt, O. (ed.). 1989. Rare Birds of Oregon. Ore. Field Ornithol. Spec. Publ. 5. 137 LONG-TOED STINT IN CALIFORNIA Urban, E. K., Fry, C. H. and Keith, S. 1986. The Birds of Africa, vol. II. Academic Press, London. Veit, R. R., and Jonsson, L. 1987. Field identification of smaller sandpipers within the genus Calidris. Am, Birds 41:212-236. Wallace, D. I. M. 1980. Field identification of small species in the genus Calidris , in The Frontiers of Bird Identification (J. T. R. Sharrock, ed.), pp. 146-162. British Birds Ltd., Biggleswade, England. Wilds, C. 1988. Photo quiz. Birding 20:384 and 388-390. Accepted 14 March 1991 Long-Toed Stint Sketch by Tim Manolis 138 NOTES FIRST RECORD OF A GARGANEY IN IDAHO SCOTT GROTHE, Department of Biological Sciences, Idaho State University, Pocatello, Idaho 83209 At 1147 hrs, on 20 April 1990, at a distance of 50 to 75 m, I observed a male Garganey {Anas querquedula) on the Snake River, approximately 15 km west of Hammett, Idaho, 200 m east of the Flying “H” irrigation pump station. I watched the bird for about 2.5 minutes. The Garganey was feeding within a floating bed of algae along the bank with a male and female Cinnamon Teal (A. cyanoptera). From 1815 to 1833 hrs on 2 May 1990, and again at 0800 on 3 May, I saw the bird at a distance of 20 to 40 m, feeding in a similar fashion with a male and. female Cinnamon Teal, now 50 m west of the Flying “H irrigation pump station on the north side of the river. At approximately 1600 hrs on the same day, D. M. Taylor and N. Cummings observed the male Garganey at this same location displaying the same feeding behavior. The male Garganey was identified by the white head stripe starting above and in front of the eye, following a line parallel to the crown ending at the nape, and by the five long white wing feathers outlined in black. These feathers extended over the leading edge of the folded wing and down along side the body. The Garganey was also similar in size to the Cinnamon Teal with which it was seen. Observations were made with a 40-power Nikon spotting scope and 7 x 50 Bushnell binoculars. I photographed the bird with 80-210 mm zoom and 500 mm lenses on a Pentax ME Super camera with Kodachrome 64 film (Figure 1). Since all of sightings were made while the bird was in the water, no leg bands were observed. There appeared to be little wear on the plumage. I spoke with three area residents, none of whom knew of any Garganeys raised by aviculturists. These observations were accepted by the Idaho Bird Records Committee for the first record of a Garganey in Idaho. My three observations of the Garganey foraging with a pair of Cinnamon Teal not only reinforces Kaufman’s suggestion of an influx of this species during the 1989 fall migration, but is in concert with other male Garganeys sighted with Blue-winged (A. discors) or Cinnamon Teal (Spear et al. 1988). In the spring of 1990, Garganeys were also sighted in California, Colorado, Alberta, Saskatchewan, North Dakota, Virginia, Quebec, New Brunswick, and on Prince Edward Island (Kaufman 1990). Many of these birds may have previously overshot their breeding grounds in Europe or Africa, or were misoriented in their migration and ended up in Central and South America. The Garganey I observed could have arrived in this manner or via Pacific routes, pushed off its traditional course by eastward movements of storms (Spear et al. 1988). Western Birds 22:139-140, 1991 139 NOTES Figure 1. Male Garganey observed in April and May 1990 on the Snake River in southwestern Idaho. Photo by Scott Grothe LITERATURE CITED Kaufman, K. 1990. The changing seasons. Am. Birds. 44:384-387. Spear, L. B.. Lewis, M. J., Myers, M. T., and Pyle, R. L. 1988. The recent occurrence of Garganey in North America and the Hawaiian Islands. Am. Birds 42:385-392. Accepted 4 April 1991 140 NOTES PREDATION BY FERAL CATS ON BIRDS AT ISLA SOCORRO, MEXICO RICARDO RODRIGUEZ-ESTRELLA, GUSTAVO ARNAUD, SERGIO ALVAREZ CARDENAS, and ANTONIO RODRIGUEZ, Centro de Investigaciones Biologicas, Div. Biol, Terr., Apartado Postal 128, La Paz, Baja California Sur 23000, Mexico Socorro Island, the largest and biologically most diverse of the four islands of the Revillagigedo Archipelago (Brattstrom 1990), confronts serious problems related to human activities. Eight endemic taxa of land birds now breed on Socorro: Yellow- crowned Night Heron, Nyctanassa uiolacea grauirostris; Socorro Red-tailed Hawk, Buteo jamoicensis socorronensis; Socorro Ground Dove, Columbina passerina socorroensis; Green Parakeet, Aratinga holochlora brevipes ; Socorro Wren, Thryomanes sisson ii; Socorro Mockingbird, Mimodes graysoni ; Tropical Parula Warbler, Parula pitiayumi graysoni; and Socorro Towhee, Pipilo erythrophtahnus socorroensis (McLellan 1926, Jehl and Parkes 1982, Brattstrom 1990). Jehl and Parkes (1983) have proposed that domestic cats ( Felis catus ), introduced since 1957, are responsible for the extirpation of the endemic Socorro Dove, Zenaida graysoni, and reductions of other species, especially the Socorro Mockingbird. However, no quantitative data on predation by feral cats on Socorro Island have been previously reported in the literature. We present here an analysis of the diet of feral cats on Socorro Island. Socorro Island, located approximately 450 km south of the tip of the peninsula of Baja California, covers about 14,000 hectares (16 x 11 km), This island is a volcanic cone whose highest point is Mount Evermann (1050 m). Climate is arid tropical with an average annual temperature of 24.8° C and average annual precipitation of 327.7 mm. Fresh water is found in the puddles formed after tropical storms and continuously in several caves. From 16 to 28 February and from 7 to 12 May 1990 we conducted our field research on Socorro Island, intensively searching for scats, tracks, and other indirect evidence of feral cats, specially in the south portion of the island. We searched in Croton scrub (40 m elevation), disturbed grassland, and forest (650 m elevation). Presumably, the scats we found were from different individuals, as they were widely dispersed. We found and analyzed 31 scats, comparing the remains of scales, bones, feathers, and hairs with those of the collection of Centro de Investigaciones Biologicas. Table 1 shows the occurrence of items in 31 scats found during February and May 1990. Feral cats were feeding mainly on House Mice (Mus musculus), endemic lizards ( Urosaurus auriculatus ), some birds, and also crabs, insects, scorpions, and various vegetable materials (Table 1). Birds were present in 22.6% of the cat scats (February and May samples combined). The Socorro Ground Dove and Tropical Parula Warbler were the two bird species found most often in the scats, five and three times, respectively. A recent colonizer, the Mourning Dove (Zenaida macroura), was present in two of the 31 analyzed scats. Although we did not find remains of another recent colonizer, the Northern Mockingbird ( Mimus polyglottus ), in May we found feathers of one in the field, presumably eaten by a feral cat. Jehl and Parkes (1982) reported predation by cats on Townsend’s Shearwater ( Puffinus auricularis), but we did not find evidence of this perhaps because our searches were not made near the shearwater colonies. Our results suggest that predation on birds by feral cats is not very important. However, even limited predation may seriously affect a species as endangered as the Socorro Mockingbird. This species’ population may be approximately 60-70 pairs (Castellanos and Rodriguez-Estrella 1990, L. Baptista pers. comm ), and we found evidence that it is preyed upon by Socorro Red-tailed Hawks (a Socorro Mockingbird Western Birds 22:141-143, 1991 141 NOTES Table 1 Prey Remains Identified in 3 1 Scats of Feral Cats on Socorro Island, 1990 Prey February (12 samples) N° % May (19 samples) N % Mammals 11 91.7 17 89.5 Mus musculus 9 75.0 17 89.5 Felis catus 2 16.7 0 0.0 Birds 3 25.0 4 21.1 Columbina 2 16.7 3 15.8 Thryomartes 1 8.3 1 5.3 Parula 2 16.7 1 5.3 Mi modes 1 8.3 0 0.0 Zenoida rrtacroura 0 0.0 2 10.5 Reptiles 4 33.3 10 52.6 Urosaurus auriculatus 4 33.3 10 52.6 Invertebrates 9 75.0 14 73.7 Orthoptera 8 66.7 12 63.2 Lepidoptera 2 16.7 0 0.0 Coleoptera 2 16.7 4 21.1 Hymenoptera 1 8.3 1 5.3 Scorpiones 0 0.0 4 21.1 Decapoda 0 0.0 2 10.5 Miscellaneous 9 75.0 17 89.5 Seeds 1 8.3 4 21.1 Vegetable fibers 8 66.7 14 73.7 Unidentified animal matter 0 0.0 2 10.5 “Number of scats in which each species or item was identified. wing and feathers showing predation by a hawk) and cats. The endemic Red- tailed Hawk and Socorro Mockingbird have presumably long been in predatory-prey equilibrium, while cats are of recent introduction. “Alien predation” (Moors and Atkinson 1984) by cats may be a serious problem because it could lead to declines in some bird species, as has happened with other island landbirds and seabirds (Jehl 1972, Taylor 1979, Diamond 1982, Moors and Atkinson 1984, Fitzgerald and Veitch 1985, Veitch 1985, Ebenhard 1988). The population of feral cats seems to be densest in the southeast portion of the island apparently because this area is the zone most perturbed by human activities. Here water and domestic garbage are available for cats, and the food supply in human refuse may favor an increase of the cats’ population. The actual numbers of cats is hard to determine, although their distribution on the island is increasing (Arnaud et al. unpubl. data). Because feral cats take their prey mainly on the ground, birds foraging on the ground, such as the endemic ground dove and wren, are especially vulnerable. The Socorro Wren population is very dense, but such is not the case for Socorro Ground Dove, which is still fairly common in the open lowlands of the island, especially in the southeast and eastern portions near the coast (W. Wehtje pers. comm.). This species is no longer as tame as reported by Villa (1960) — “son mansas y se les captura simplemente con las manos” — but it seems that their foraging and reproductive activities are normal. However, whenever we approached 142 NOTES the ground doves, they immediately flew, suggesting that predation by cats is affecting the endemic dove’s tameness and possibly its population size. At the Centro de Investigaciones Biologicas we are studying the process of apparent extinction of some bird species, and we want to call the attention of the scientific community and organizations concerned with the conservation of biodiversity about the need to eradicate the feral cats from Socorro Island and thereby protect the endemic avifauna. Otherwise, cats may put in risk some of the land birds of the island, particularly the Socorro Mockingbird. Special thanks are due to Alfredo Ortega for encouraging our studies on Socorro Island. Philip Unitt, William T. Everett, and an anonymous reviewer made helpful suggestions on a previous draft. Luis Baptista kindly provided us the information on the 19 Socorro Mockingbirds he recorded in the north-central part of the island in November 1990. For its support on the island we thank the Mexican Navy. Economic support was provided by World Wildlife Fund, the Centro de Investigaciones Biologicas, Consejo Nacional de Ciencia y Tecnologia, Secretaria de Programacion y Preseupuesto, Secretaria de Desarrollo Urbano y Ecologia, and Fundacion Ricardo J. Zevada. LITERATURE CITED Brattstrom, B. H. 1990. Biogeography of the Islas Revillagigedo, Mexico. J. Bio- geogr. 17:177-183. Brattstrom, B. HL, and Howell, T. R, 1956. The birds of the Revilla Gigedo Islands, Mexico. Condor 58:107-120. Castellanos, A., and Rodriguez-Estrella, R. 1990. Endangered Socorro Mockingbird ( Mimodes graysoni ) on Socorro Island, Mexico. Proceedings of the 108th Stated Meeting of the American Ornithologists’ Union and 60th Annual Meet- ing of the Cooper Ornithological Society, Univ. of Calif., Los Angeles. Diamond, J. M. 1982. Man the exterminator. Nature 298:787-789. Ebenhard, T. 1988. Introduced birds and mammals and their ecological effects. Swedish Wildlife Res. 13:1-107. Fitzgerald, B. M., and Veitch, C. R. 1985. The cats of Herekopare Island, New Zealand; their history, ecology and effects on birdlife. New Zealand J. Zool. 12:319-330. Jehl, J. R. 1972. On the cold trail of an extinct petrel. Pacific Discovery 25:24-29. Jehl, J. R., and Parkes, K. C. 1982. The status of the avifauna of the Revillagigedo Islands, Mexico. Wilson Bull. 94:1-19. Jehl, J. R., and Parkes, K, C. 1983. “Replacements” of landbird species on Socorro Island, Mexico. Auk 100:551-559. McLellan, M. E. 1926. Expedition to the Revillagigedo Islands, Mexico, in 1925. VI. The birds and mammals. Proc. Calif. Acad. Sci., 4th ser., 15:297-322. Moors, P. J., and Atkinson, I. A. E. 1984. Predation on seabirds by introduced animals, and factors affecting its severity. ICBP Tech. Publ. 2:668-690. Taylor, R. H. 1979. How the Macquarie Island parakeet became extinct. New Zealand J. Ecol. 2:42-45. Veitch, C. R. 1985. Methods of eradicating feral cats from offshore islands in New Zealand. ICBP Tech. Publ. 3:125-141. Villa, B. 1960. Vertebrados terrestres. La Isla Socorro. Monogr. Inst. Geofisica. Univ. Nacional Autonoma de Mexico 2:203-216. Accepted 15 April 1991 143 PRESIDENT’S MESSAGE You may have noticed that issues of Western Birds have recently been appearing quite frequently. WFO hopes and expects that all issues of Volume 22 will appear during 1991, so that the journal will be caught up by the end of the year. Then from 1992 and Volume 23 onward, four issues will come out in the correct calendar year. This also means that the renewal notices for Volume 23 will be sent out in early 1992. Please renew promptly even though it will be less than a year since you last renewed. At its meeting in Bend, Oregon, in June 1991 the WFO board decided that Volume 23 would be the last for which the life membership is $250. Life membership will be raised to $350 for Volume 24 in 1993. If you are thinking of becoming a life member, this is the time to “just do it.” Also remember that you can pay in up to four equal installments. WFO has several new life members since the list published on page 142 of Vol. 21, No. 3. They are Dr. William A. Carter Gilmer Ewing Dr. Peter R. Gent Richard A. Hallowell Clarann Levakis Dr. Eugene I. Majerowicz John T. McBride Jr. Neil Multack Dr. Evelyn B, Myers Dr. Peder H. Svingen Carl G. Thelander Oklahoma California Colorado California California California Louisiana California California Minnesota California In addition, the following members have paid their first installment: Douglas W. Aguillard California Dr. David G. Seay California Contributors to Western Birds please note that editor Philip Unitt will be out of the country from approximately 10 November to 31 December 1991. During his absence, please send correspondence to associate editor Tim Manolis, 808 El Encino Way, Sacramento, CA 95864. Finally, the date of the WFO Seventeenth Annual Meeting has been set. The meeting will be held on the weekend of 18-20 September 1992 at the San Francisco Bay Bird Observatory, Alviso, California. It will be hosted by executive director Don Starks and other members of the observatory. They can be contacted at (408) 946- 6548. 1 hope to see you all there. Peter Gent 144 Volume 22, Number 3, 1991 Twelfth Report of the California Bird Records Committee Jeri M. Langham 97 First Record of the Long-toed Stint in California Michael A. Patten and Brian E. Daniels 131 NOTES First Record of a Garganey in Idaho Scott Grothe 139 Predation by Feral Cats on Birds at Isla Socorro, Mexico Ricardo Rodriguez-Estrella, Gustavo Arnaud, Sergio Alvarez Cardenas , and Antonio Rodriguez 141 President’s Message Peter Gent 144 Cover photo © by Lawrence Sansone of Los Angeles, California: Long-toed Stint ( Calldrls subminuta ) , Salinas sewage ponds, California. 31 August 1988. Western Birds solicits papers that are both useful to and understandable by amateur field ornithologists and also contribute significantly to scientific litera- ture. The journal welcomes contributions from both professionals and amateurs. Appropriate topics include distribution, migration, status, identifica- tion, geographic variation, conservation, behavior, ecology, population dynamics, habitat requirements, the effects of pollution, and techniques for censusing, sound recording, and photographing birds in the field. Papers of general interest will be considered regardless of their geographic origin, but particularly desired are reports of studies done in or bearing on the Rocky Mountain and Pacific states and provinces, including Alaska and Hawaii, western Texas, northwestern Mexico, and the northeastern Pacific Ocean. Send manuscripts to Philip Unitt, 3411 Felton Street, San Diego, CA 92104. For matter of style consult the Suggestions to Contributors to Western Birds (8 pages available at no cost from the editor) and the Council of Biology Editors Style Manual (available for $24 from the Council of Biology Editors, Inc. , 9650 Rockville Pike, Bethesda, MD 20814). Reprints can be ordered at author’s expense from the Editor when proof is returned or earlier. Good photographs of rare and unusual birds, unaccompanied by an article but with caption including species, date, locality and other pertinent information, are wanted for publication in Western Birds. Submit photos and captions to Photo Editor. WESTERN BIRDS Quarterly Journal of Western Field Ornithologists President: Peter Gent, 55 South 35th, Boulder, CO 80303 Vice-President: Robert McKeman, 1230 Friar Lane, Redlands, CA 92373 Treasurer/ Membership Secretary: Howard L, Cogswell, 1548 East Avenue, Hayward, CA 94541 Recording Secretary: Jean-Marie Spoelman, 4629 Diaz Drive, Fremont, CA 94536 Circulation Manager : William E. Haas, 10601-A Tierrasanta Blvd., Suite 127, San Diego, CA 92124 Directors: Bruce Deuel, Peter Gent, Ron LeValley, John S. Luther, Guy McCaskie, Robert McKeman, Steve Summers, Janet Witzeman, David Yee Editor: Philip Unitt, 3411 Felton Street, San Diego, CA 92104 Associate Editors: Cameron Barrows, Tim Manolis, Thomas W. Keeney Graphics Manager: Virginia P. Johnson, 4637 Del Mar Ave., San Diego, CA 92107 Photo Editor: Bruce Webb, 8204 Cantershire Way, Granite Bay, CA 95661 Secretary, California Bird Records Committee: Michael A. Patten, P. O. 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Send membership dues, changes of address, correspondence regarding missing issues, and orders for back issues and special publications to the Treasurer. Make checks payable to Western Field Ornithologists. Back issues of California Birds/Western Birds: $20 per volume, $5.00 for single issues. Xerox copies of out of print issues (Vol. 1, No. 1; Vol. 2, Nos. 1 and 4; Vol. 6, No. 2): $5.50 each. Checklist of the Birds of California: $2.00 each, 10 or more $1.50 each. Pelagic Birds of Monterey Bay, California: $2.50 each, 10 or more $2.00 each, 40 or more $1.50 each. All postpaid. Published November 8, 1991 ISSN 0045-3897 WESTERN BIRDS ADVERTISING RATES AND SPECIFICATIONS Full page 4 x 6 3 /4 inches $60 per issue $200 per year Half Page 4x3% inches $40 per issue $130 per year Quarter Page 4 x l n / i6 inches $30 per issue $110 per year Offset printing, one column per page, 4 inches wide. Glossy, black and white photos are ac- ceptable; half-tone screen size: 133 line. Photo-ready copy is requested. If this is not possible, extra charges for typesetting wall be made as follows: $15 full page, $10 half page, $5 quarter page. Send copy with remittance to the Treasurer. Make checks payable to Western Field Ornithologists. A 15% commission is allowed for agencies. WESTERN BIRDS Volume 22, Number 4, 1991 LONG-DISTANCE VAGRANCY OF THE ASIATIC MARBLED MURRELET IN NORTH AMERICA, 1979-1989 SPENCER G. SEALY, Department of Zoology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada HARRY R. CARTER, Point Reyes Bird Observatory, 4990 Shoreline Highway, Stinson Beach, California 94970 (present address: U.S. Fish and Wildlife Service, 6924 Tremont Road, Dixon, California 95620) W. DAVID SHUFORD, Point Reyes Bird Observatory, 4990 Shoreline Highway, Stinson Beach, California 94970 KEVIN D. POWERS, Manomet Bird Observatory, Manomet, Massachusetts 02345 (present address: Digital Equipment Corporation, 333 South Street, Shrewsbury, Massachusetts 01545) CHARLES A. CHASE III, Denver Museum of Natural History, City Park, Denver, Colorado 80205 (present address: Department of Biology, Florida State University, Tallahassee, Florida 32603) Long-distance vagrancy is common in seabirds, particularly among the petrels of the order Procellariiformes (Bourne 1967). Records of such vagrancy in the Aicidae also are numerous and have involved many species (e.g., Bent 1919, Grinnell 1938, Porsild 1943, Salomonsen 1944, Munyer 1965, Nero 1968, Sealy et al. 1971, Roberson 1980, Pitman et al. 1983). The nominate subspecies of the Marbled Murrelet ( Brachyramphus marmoratus marmoratus ) regularly occurs inland up to 75 km from the Pacific Ocean on the west coast of North America (Carter and Sealy 1986), but these occurrences represent normal use of its inland nesting areas. Long-distance vagrancy in this species was not detected until 1979, but, over the next 10 years, 10 specimens of the Asiatic subspecies (B. m. perdix) were taken and three other Marbled Murrelets were observed at widespread localities across North America. Four specimen records have been published (Jehl and Jehl 1981, Mumford 1982, Sealy et al. 1982, Hoffman and Woolfenden 1988). In this paper, we document six other inland occurrences of B. m. perdix and examine all records to attempt to explain the occurrence of these Asian birds in North America. Western Birds 22:145-155, 1991 145 ASIATIC MARBLED MURRELET IN NORTH AMERICA £ c /) co £ ■o c a j 5 cu „ J 3 CQ '3 J 3 >. < S ) £ ■g 1 1 DQ £ ^ Q) "O +± c Q o c o c*— I (0 o o _l "D o y 2 0 ) cc T3 Ctf c QJ CTv CO CO CTv CM G"v i— i , cf vD O p £ i- 1 CM O OV i-h | Oo O) i — i t — i x 3 CM CM CM i-i CM i — l CM CM CM UJ O vq^H^to c\i co cm cm lo CO CO CO CO CO CO CO LO 0 > CO Ov I-H 00 Tt 00 l> [b [b 00 00 vb CO VO LO vb oo ldgocmooo^cmloco oovbodvbcviov'vtoovr^ ^-vt l COCO'^oo>d'’^cO’d< r^. ^ cm oo lo vO vD VO vO LO vb CM l> vb vb CV 00 CM LO ■St ob VO 00 o o O oo CM CM CO CM *— i CO 00 OV Ov Cv CTVi— Ir- i CM CM CO CO CO CO VD [•"•000000000000000000 > O) o cn &-g CO CO CO o OD 4 l 3 ll)iD 33 (» 2 t /> a a a fO fi 3 fl 3 o 3 - - - "0 -ft C C C S ft .2 ^ .-3 :3 ^ <*> C 3 'P OJ2 *0 03 (T3 J2 o cyu£ u s u u u < e CJ CD JO ^ CD H CM CO rf LO vO t — 00 OV O O U o c o 2 aT J £ (0 J o c o 2 •a 0 ) 0 ) > o u 0 ) 64 pm; 18% silt) to the most inland areas of the slough (67% clay and 33% silt; C. Jong, Univ. California, Santa Cruz, unpubl. data). During this study, water depth in the main channel below mean lower low water (MLLW) was 5 m at the Figure 1. Shorebird survey area of Elkhorn Slough, indicating intertidal mudflats, salt marsh, and salt ponds. 158 SHOREBIRDS IN ELKHORN SLOUGH mouth and <1 m at the most inland station; the mean tidal range was 1.1m (Smith 1973, Broenkow 1977). About 170 ha of intertidal mudflats are exposed at MLLW (Browning 1972). Diked evaporating salt ponds (77 ha) are adjacent to Elkhorn Slough (Figure 1). An extensive salt marsh (583 ha) is located primarily on the northwest edge of the slough, and pickleweed ( Salicornia uirgmica) is the dominant plant cover. Surveys We conducted our most intensive shorebird surveys from 1 November 1977 to 27 February 1980, along the main channel of Elkhorn Slough from California State Highway 1 to Hudson’s Landing (Figure 1). At low tide, shorebirds on each intertidal mudflat and in adjacent salt marsh were identified and counted by one to four observers. Surveys were conducted from a small boat and lasted 1-4 hours. The direction of the survey route along the main channel and the state of the tides varied during each survey. All surveys were conducted between +1.2 and -0.1 m, relative to MLLW; mudflats were exposed within this range but the extent of exposure varied; see Ramer (1985) for tidal conditions during each survey. To minimize error associated with movement of birds among areas, we excluded any large flocks that likely were counted earlier. Number of shorebirds was converted to biomass by multiplying by the average weight of each species (Page et al. 1979) . Because of limited time at low tide, not all species were counted during every survey; abundance of common species, however, was deter- mined at least once a month. Number of surveys during the year, therefore, is different for each species. Only surveys that included counts of all common species were used to estimate total and seasonal abundance of shorebirds. To assess temporal patterns in abundance of shorebirds, we defined seasons as fall (July-October), winter (November-February), and spring (March-June). Summer was identified as the period (usually June) between the lowest abundance in spring and the increase in numbers in fall. Habitat Use Salt Ponds. To document shorebird use of salt ponds (Figure 1), we conducted additional surveys during October and November 1978. Num- bers of birds roosting and feeding at five ponds were recorded over 3 hours on each of 12 days. Observations focused on the most abundant species: Western Sandpiper ( Calidris mauri), Least Sandpiper (C. minutilla), and Dunlin (C. alpina). Salt Marshes. We estimated relative frequency of roosting and feeding on 9 and 26 March 1979 for 10 minutes at 1-hour intervals in each of 3 hours during high tide at seven stations throughout the marsh (Figure 1). Diet From November 1978 to December 1979, stomach contents of Western Sandpipers (N = 25), Willets ( Catoptrophorus semipalmatus ; N - 21), and Marbled Godwits ( Limosa fedoa; N = 24) were collected, primarily at one mudflat along the main channel of the slough. These were the most 159 SHOREBIRDS IN ELKHORN SLOUGH abundant species that represented a gradient in bill length and body size. Feeding birds were shot and stomachs were injected with 10% formalin in the field. Stomach contents of seven additional Western Sandpipers were collected by means of a stomach pump after feeding birds were trapped in a net in the salt ponds. Few prey items remained in the stomachs after pumping (Ramer 1985); this effective technique should be considered in place of sacrificing birds for future diet studies. All data on diet of Western Sandpipers were combined for analysis. Prey parts were identified to the lowest possible taxon; number and relative volume {%) of each prey category in a stomach were estimated. Prey identification frequently was based on recognizable parts only, such as bivalve hinge fragments, amphipod uropods, and polychaete setae. A minimum prey number of 1 was assigned to taxon represented solely by parts (e.g,, polychaete setae or pieces of algae). Prey categories in each stomach were ranked according to their index of relative importance (IRI; Pinkas et al. 1971), a function of relative frequency of occurrence (FO), relative number (N), and relative volume (V); IRI = (N + V) x (FO). RESULTS Seasonal Patterns The most abundant shorebird species along the main channel of Elkhorn Slough were (in descending order) the Western Sandpiper, Dunlin, Least Sandpiper, dowitchers (Short-billed [Limnodromus griseus] and Long- billed [L. scolopaceus]), Marbled Godwit, American Avocet ( Recurvirostra americana ), Willet, Black-bellied Plover ( Pluuialis squatarola), Long-billed Curlew ( Numenius americanus ), and Sanderling ( Calidris alba). Other shorebirds occurred irregularly, and included a maximum of 46 Ruddy Turnstones (Arenaria interpres), 32 Semipalmated Plovers ( Charadrius semipalmatus), 27 Whimbrels ( Numenius phaeopus), 1 Greater Yellow- legs ( Tringa melanoleuca), 6 Killdeers ( Charadrius vociferus), 6 Red Knots (Calidris canutus), 3 Black-necked Stilts ( Himantopus mexicanus), and 1 Lesser Yellowlegs ( Tringa flavipes) per survey. For the eight species common to each of 21 surveys along the main channel of Elkhorn Slough, total number increased during fall, from about 200 birds in June to 11,750 birds in November (Figure 2). From 6000 to 13,750 birds were counted during winter (the period of minimum migratory movement), and numbers decreased from spring to summer. Biomass similarly increased from 70 kg in June to 740 kg in November (Figure 2). From counts combined by season over all years for each species, Western Sandpipers accounted for at least 75% of shorebirds present in every season (Figure 3). Numbers of each of the other species represented less than 10% of the total in any particular season. Small species (<150 grams body weight) made up at least 90% of the total number of shorebirds in all seasons (Figure 3). Total biomass was more evenly distributed between small and large (>150 grams body weight) species; one species predomi- nated in each category. Western Sandpipers had the highest biomass of the small species, and Marbled Godwits had the highest numbers and biomass of the large species (Figure 3). 160 SHOREBIRDS IN ELKHORN SLOUGH Figure 2. Seasonal changes in mean (vertical line is range) number and biomass of shorebirds along the main channel of Elkhorn Slough from November 1977 to February 1980. Number of surveys is indicated above each bar. 161 SHOREBIRDS IN ELKHORN SLOUGH 80- % DC 60- £ “i ° i , x g 40- 1 uj | CL Z 20 - UZZL Fall (N = 5) 40- £ o 20 " 80- 2 CD 60- S| 5 I 40- CL z 20 - I 1 t w 40- cu < ° 2 £ o 20 - Winter (N = 8) I 1 80- % DC 60- ■*“ LU oi £ | 4( CL Z - 20 “ I- co 40 - Z CO 4U ' LU < o 5 oc O 20- LU - Q. CD Spring (N = 8) cr DC z cr CO CO DC H H LU LU 1 LU D Q LU LU LU Q. CL D- Q. z z> X o o —1 O o a o Q 1 - , w LU _J $ > z < CO z < co 5 o D < a < C hO o CL G LU < z < 1 - z h- w _J u co cr _l < LU -i LU LU DC LU 1 - < CJ 03 111 —I co 2 oc 1 LU fA < * < 5 w _l o SMALL SHOREBIRDS S a o CD m DC < 2 LARGE SHOREBIRDS 162 SHOREBIRDS IN ELKHORN SLOUGH The fall influx of most shorebirds began in June or July, except for that of Dunlins, which were not recorded until October (Figures 4 and 5), Least Sandpipers exhibited a fall peak in abundance, whereas Western Sandpip- ers did not (Figure 4). All common species overwintered in the slough. Numbers of Dunlins generally increased in early winter and spring. Al- though dowitchers were not distinguished morphologically, vocalizations indicated that more than 90% of the wintering birds were Long-billed Dowitchers. No small shorebird species were sighted in the area during summer, but nonbreeding birds of most large species were present during June (Figure 5). There was considerable variation in patterns of abundance for large and small species (Figures 4 and 5). Habitat Use Salt Ponds. Small shorebirds used the salt ponds primarily as a roost during high tide, secondarily as a feeding area. Western Sandpipers, Least Sandpipers, and Dunlins roosted in dense multi-species flocks in shallow ponds at the northwest corner and along dikes. From 830 to 20,730 small shorebirds (primarily Western Sandpipers and Dunlins) were counted per survey (N =* 12) in the salt ponds. Of the small shorebird species that occurred in Elkhorn Slough, most individuals roosted in the salt ponds; no large flocks roosted elsewhere in the slough. Some small shorebirds fed intermittently near roosting flocks in the salt ponds. However, on average, 78.8% (standard error = 5.7) of Western Sandpipers and Dunlins were roosting. On falling tides, small sandpipers left salt-pond roosts and flew to exposed intertidal mudflats in the slough (N - 15 observations). Large shorebirds also roosted in salt ponds. We observed as many as 350 Black-bellied Plovers and 700 American Avocets roosting in tight flocks in shallow ponds during single surveys. Willets and Marbled Godwits occasion- ally roosted in flocks up to 500 birds per survey, with only a few individuals feeding. Long-billed Curlews were not observed in salt ponds. Several species fed in the salt ponds and were rarely or never observed in the main slough. We saw up to 400 Red-necked Phalaropes ( Phalaropus lobatus), 200 Red Phalaropes (P fulicarius), 150 Black-necked Stilts, 100 Snowy Plovers ( Charadrius alexandrinus), and 30 Wilson’s Phalaropes (P. tricolor ) on single surveys. American Avocets, Black-necked Stilts, Snowy Plovers, and Killdeers bred locally in the salt ponds. Salt Marshes . Maxima of 266 Willets, 257 Marbled Godwits, and 127 Long-billed Curlews were counted during the 3-hour surveys. These large shorebirds roosted and fed in salt marshes during high tides. Although most birds were observed flying over the marsh, an average of 24.3% (S.E. = 6.6) were roosting and 13.7% (S.E. = 4.2) were feeding. As the tide receded, most Marbled Godwits flew from the marsh to feed on intertidal mudflats. In Figure 3. Percent composition of most abundant small (<150 g) and large (>150 g) shorebird species by number and biomass from pooled data in fall (N = 5 surveys), winter (N = 8), and spring (N = 8) along the main channel of Elkhorn Slough. Species are ordered with increasing body weight from left to right. 163 SHOREBIRDS IN ELKHORN SLOUGH contrast, some Willets and Long-billed Curlews continued to feed in the marsh during low tides. Some small shorebirds roosted on barren mudpans or in sparsely vegetated areas of marsh, but these scattered individuals never gathered in the large aggregations that occurred in the salt ponds. Small shorebirds never roosted in dense marsh vegetation, 20 , 000 - 10 , 000 - 6000 - 4000 - cc UJ CD 2 =) 2 2000 - 1 20 - 80 - CD 5 2 40 ■ SANDERLING Jun JASONDJFMA May 1 000 ’ 500 - DOWITCHER SPECIES Jun J ASOND JFMA May Jun JASONDJFMA May Figure 4. Median number (vertical line is range) of most abundant small (<150 g) shorebird species surveyed along the main channel of Elkhorn Slough. Number of surveys is indicated above each bar. 164 SHOREBIRDS IN ELKHORN SLOUGH Mudflats, Intertidal mudflats were important feeding areas for all shore- bird species. Density of Western Sandpipers that fed along the main channel of the slough increased generally with distance inland {the most muddy end of the slough), and was lowest at the most sandy intertidal flat near the mouth (Table 1). Mean densities of all large shorebird species were BLACK-BELLIED PLOVER 3 Figure 5. Median number (vertical line is range) of most abundant large (>150 g) shorebird species surveyed along the main channel of Elkhorn Slough. Number of surveys is indicated above each bar. 165 SHOREBIRDS IN ELKHORN SLOUGH highest on mudflats about 3 km inland. Marbled Godwits and Sanderlings were the only species that fed in relatively high densities on the sandiest flats closest to the mouth. The relatively high mean density of Sanderlings at the most inland, muddy flat resulted from an unexpected count of 80 birds during one survey. Diet Western Sandpiper. Western Sandpipers primarily ate insects (mostly ephydrid fly larvae and pupae) and small infaunal invertebrates. Insect larvae and pupae ranked first in relative importance in fall and spring (Table 2). Prey composition of fall and winter samples differed markedly. Harpacticoid copepods, the bivalve Gemma gemma, Foraminifera, and the polychaete Capitella capitata occurred in at least 50% of stomachs from both seasons, but insects were not important in the winter diet (IRI = 11). Oligochaetes were found in 50% of the fall samples, but in none collected in Table 1 Density (Number per Hectare) of Shorebirds Feeding on Intertidal Mudflats at Increasing Distance from the Mouth of Elkhorn Slough Species Distance up slough (km) N a 1 3 5 9 Small Shorebirds Least Sandpiper 0.7 b 2.0 2.3 1.8 24 (0.3) (0.7) (0.7) (0.6) Western Sandpiper 5.5 51.6 100.6 64.4 24 (1.6) (8.5) (14.8) (13.0) Dunlin 4.4 7.1 13.2 10.5 19 (2.4) (2.3) (6.7) (4.3) Sanderling 0.7 0.1 0.1 0.2 14 (0.2) (0.1) (0.1) (0.2) Dowitcher 0.4 2.3 2.3 1.7 19 (0.1) (1.0) (0.5) (0.5) Large Shorebirds Black-bellied Plover 0.2 0.9 0.3 0.1 23 (0.0) 0.3) (0.1) (0.0) Willet 0.4 1.4 1.2 0.6 22 (0.1) (0.4) (0.3) (0.1) American Avocet 0.3 2.1 1.0 0.5 16 (0.2) (0.7) (0.3) (0.2) Marbled Godwit 2.9 3.0 1.6 0.5 21 (0.6) (0.5) (0.3) (0-2) Long-billed Curlew 0.1 0.3 0.1 0.1 21 (0.0) (0.1) (0.0) (0.0) 166 “Number of surveys. Tor each species, top row of figures is mean density, bottom row (in parentheses) is standard error. SHOREBIRDS IN ELKHORN SLOUGH winter. Amphipod crustaceans (Corophium spp. and Gammaridae) were the most important prey items in winter but nearly absent in fall. Although the relative occurrence of polychaetes ( Capitella capitata) was high in fall and winter (FO = 75% and 86%, respectively), total number, volume, and IRI values probably were underestimated because of digestion (Page and Stenzel 1975, Quammen 1984). Algae, plant debris, and Foraminifera probably were ingested incidentally with other prey. Willet. The highest- ranking prey of Wiliets in all seasons was the crab Hemigrapsus oregonensis (Table 3). In winter, another crab, Pachygrapsus crassipes, occurred in 63% of the stomachs, and ranked second in relative importance; crabs were the only prey in winter samples. In spring, Wiliets ate crabs and the opisthobranch snail Haminoea. Fall samples were more diverse, with eight prey categories. Wiliets ate many fewer species than did Western Sandpipers. Marbled Godwit. In fall, polychaete worms (including Capitella capitata , Boccardia hamata , and Spionidae) ranked high in occurrence and relative importance (Table 4). Bivalves ( Gemma gemma and Macoma spp.) also were relatively important (IRI - 942 and 412, respectively). In winter samples, these two bivalves were among the highest-ranking prey items. Polychaetes and crabs were secondarily important. No prey items occurred in more than 44% of the winter stomachs. In spring, the highest-ranked Table 2 Seasonal Variation in the Diet of Western Sandpipers Fall (12)° Winter (7) Spring (11) Prey %FO k IRF %FO IRI %FO IRI Insect larvae 68 3063 14 11 100 15510 Seeds 68 2564 0 0 36 72 Harpacticoida 58 2115 57 237 0 0 Gemma gemma 50 801 57 157 18 119 Insect debris 42 627 43 293 0 0 Foraminifera 50 618 86 983 9 2 Capitella capitata 75 337 86 183 0 0 Algae and plant debris 67 321 57 318 54 76 Oiigochaeta (Tubificidae) 50 172 0 0 0 0 Spionidae 42 119 0 0 0 0 Corophium spp. 17 7 100 5911 0 0 Gammaridae 0 0 71 3328 0 0 Ostracoda 25 23 100 1666 45 191 Crustacean fragments 25 36 43 525 0 0 Cumella vulgaris 25 23 43 317 0 0 Polychaete setae 8 1 43 179 0 0 Allorchestes angusta 0 0 43 70 9 6 °Number of stomachs examined in parentheses. b FO, frequency of occurrence. C IRI, index of relative importance (see text). 167 SHOREBIRDS IN ELKHORN SLOUGH Table 3 Seasonal Variation in the Diet of Willets 0 Prey Fall (5) Winter (8) Spring (8) %FO IRI %FO IRI %FO IRI Hemigrapsus oregonensis 40 855 88 9620 63 7201 Crab fragments 20 801 38 331 13 131 Orchestia traskiana 20 740 0 0 0 0 Hemigrapsus spp. 20 531 0 0 13 57 Eggs 20 389 0 0 0 0 Bivalvia 20 229 0 0 0 0 Algae and plant debris 20 219 0 0 13 181 Ostracoda 20 202 0 0 0 0 Pachpgrapsus crassipes 0 0 63 3547 13 310 Haminoea/Bulla 0 0 0 0 13 129 a For abbreviations see Table 2. prey categories were the crab H. oregonensis and the bivalve Macoma spp. Prey type, size, and diversity of the Marbled Godwit were intermediate between those of the Willet and the Western Sandpiper. Again, algae probably were eaten incidentally with other prey and occurred in the Marbled Godwit's diet throughout the year. Table 4 Seasonal Variation in the Diet of Marbled Godwits 0 Prey Fall (6) Winter (9) Spring (9) %FO IRI %FO IRI %FO IRI Polychaeta 83 5860 33 180 0 0 CapiteHa capitata 33 983 44 114 0 0 Gemma gemma 33 942 33 375 11 70 Spionidae 67 694 44 114 0 0 Macoma spp. 17 412 44 2248 44 1466 Bivalvia 17 211 33 776 22 301 Algae 50 115 33 599 67 1799 Boccardia hamata 17 95 6 0 0 0 Protothaca staminea 17 95 11 12 22 385 Macoma nasuta 0 0 44 1016 0 0 Hemigrapsus spp. 17 1 22 259 0 0 Hemigrapsus oregonensis 0 0 11 223 44 1926 Pachggrapsus crassipes 0 0 11 124 0 0 Crab fragments 17 16 0 0 22 675 Eggs 0 0 0 0 22 155 “For abbreviations see Table 2. 168 SHOREBIRDS IN ELKHORN SLOUGH DISCUSSION Relative to most coastal wetlands on the Pacific Flyway, Elkhorn Slough supports large numbers of wintering and migrating shorebirds, representing nearly 40 species (Point Reyes Bird Observatory [PRBO], unpubl. data). During recent surveys of 48 California wetlands that likely have more than 1000 shorebirds, Elkhorn Slough ranked third in gross number of birds, holding 1-3 % (>19,000 birds) of all shorebirds counted in spring and 5- 6% (>30,000 birds) of those counted in fall (PRBO, Pacific Flyway Project, unpubl. data from September 1988 to April 1990). Comparison with Humboldt Bay, which ranked a close second in gross number of birds but which is 20-30 times larger in surface area, shows the importance of Elkhorn Slough to shorebirds along the central coast. Numbers of birds were highest (relative abundance 73-88%) in the San Francisco Bay system, whose surface area is several orders of magnitude larger than that of any other California wetland. Shorebirds common in Elkhorn Slough occur commonly in other coastal wetlands along the California coast. As in Elkhorn Slough, either Willets or Marbled Godwits were among the most abundant large shorebirds, and Western Sandpipers, Least Sandpipers, dowitchers, and Dunlins were among the most abundant small shorebirds in San Diego Bay (Jehl and Craig 1970), San Francisco Bay (Page et al. 1990), wetlands from Point Reyes to Bodega Bay (Shuford et al. 1989), and Humboldt Bay (Gerstenberg 1979). The same large species that oversummer at Elkhorn Slough do so elsewhere along the California coast (Jurek 1974, Shuford et al. 1989). There are some differences in abundance, however, between wetlands. Whereas Western Sandpipers clearly were the dominant species in Humboldt Bay, Elkhorn Slough, and San Francisco Bay, Least Sandpipers were as abundant in the Point Reyes area; Willets, Marbled Godwits, Least Sandpipers, and Western Sandpipers were equally abundant in Morro Bay (Stenzel et al. 1989, Page et al. 1990). Differences among wetlands in occurrence and relative abundance of shorebirds can be influenced by climate, hydrography, and habitat resources (Shuford et al. 1989). Because species-specific density has not been estimated for shorebirds in most locations, comparisons among wetlands are difficult. Even though the most abundant wintering shorebird species were the same in Elkhorn Slough as from Point Reyes to Bodega Bay, densities in the slough usually were higher; e.g., mean densities of Western Sandpipers and American Avocets in the slough were about six times higher than maximum densities in the wetlands from Point Reyes to Bodega Bay (Table 5; Page et al. 1983). Seasonal patterns in abundance of each shorebird species in Elkhorn Slough, as at any location, reflect time of migration and routes of travel between breeding and wintering grounds. In general, most species of wintering shorebirds move into California from July to November; spring exodus to the breeding grounds occurs from late March to early May (Jurek 1974, Shuford et al. 1989). In coastal wetlands of central California, peaks in abundance of fall migrants usually are apparent for Short-billed Dowitch- 169 SHOREBIRDS IN ELKHORN SLOUGH Table 5 Mean Winter Density (Number per 100 ha) of Shorebirds on Tidal Flats in Elkhorn Slough and Range of Densities in Point Reyes- Bodega Bay Area Species Elkhorn Slough Point Reyes-Bodega Area 0 Least Sandpiper 213 (39) b 47-180 Western Sandpiper 6020 (490) 59-1055 Dunlin 1025 (243) 634-1299 Sanderling 23 (7) 16-129 Dowitcher (two species) 255 (63) 18-71 Black-bellied Plover 61 (14) 94-141 Willet 114 (23) 93-140 American Avocet 165 (28) 0-27 Marbled Godwit 223 (28) 113-758 Long-billed Curlew 20 (4) 0-12 “Includes Bolinas Lagoon, Limantour Estero, Drake’s Estero, and Abbott’s Lagoon. Data from Page et al. (1983). b Figures in parentheses are standard errors. ers, Least Sandpipers, Willets, Sanderlings, and sometimes Western Sand- pipers and Black-bellied Plovers (Shuford et al. 1989). Marbled Godwits, Long-billed Curlews, American Avocets, and Dunlins do not exhibit these peaks. Spring peaks in abundance are described for Western Sandpipers and dowitchers. These general patterns in seasonal abundance do not apply to all the state’s wetlands. For example, a well-defined peak was noted in fall for Western Sandpipers in Bolinas Lagoon, whereas very small or no peaks were obvious elsewhere around Point Reyes (Shuford et al. 1989). The beginning of fall migration into Elkhorn Slough in July and spring movement out of the slough in late March generally follows the established migratory periods. Timing of fall migration is dependent on age and reproductive status of individual birds; e.g., generally, adults migrate earlier than do immature birds (Page et al. 1979). This extended migration can obscure peaks from site-specific surveys such as ours. Also, because dow- itcher species were not distinguished in Elkhorn Slough, the larger popula- tion of wintering Long-billed Dowitchers could have masked the peaks of migrating Short-billed Dowitchers. A comprehensive survey of the regional wetlands of Monterey Bay, as well as a long-term intensive study of Elkhorn Slough, is necessary before seasonal patterns in abundance can be de- scribed adequately. Changes in abundance also occur because of localized movements of shorebirds (Pienkowski and Evans 1984). Local movements may be syn- chronous with time lags between low tides at various locations, thus extending foraging time (Connors et al. 1981). Additionally, abundance can vary with daily movement of some species to feed in inland fields (Townshend 1981, Ruiz et al. 1989). Daily movements of Willets, Marbled Godwits, Black-bellied Plovers, and Sanderlings between Elkhorn Slough and adjacent beaches of the outer coast and river mouths occurred fre- 170 SHOREBIRDS IN ELKHORN SLOUGH quently during winter (J. Warriner pers. comm,)- Irregular shifts in abun- dance of Least Sandpipers, Western Sandpipers, Dunlin, and dowitchers between the slough and the mouths of the Pajaro and Salinas rivers (5 and 8.8 km away, respectively) also are likely, because numbers of birds in these areas seem to fluctuate with habitat availability. Elkhorn Slough is the likely source of these birds because it is the closest large area of suitable habitat. The restoration of wetlands in Elkhorn Slough resulted in increased surface area of mudflats and up to an average of 0.8 hours phase lag of high and low water relative to Monterey predicted tides {Wong 1989); these changes can influence shorebird foraging behavior and local movements. Movements of greater distance are possible, especially to San Francisco Bay, which because of its large size may serve to attract and aggregate shorebirds on the central California coast. Near Point Reyes, for example, Marbled Godwits and American Avocets move daily from foraging grounds in Bolinas Lagoon to probable nighttime roosts in San Francisco Bay (Blick 1980, Shuford et a!. 1989). Snowy Plovers also move between Monterey and San Francisco bays (J. Warriner pers. comm.). In Elkhorn Slough, shorebirds roosted in salt marshes and salt ponds during high tide, then moved to intertidal mudflats to feed at low tide. Shorebird species were not distributed evenly over tidal flats. The increased incidence of Western Sandpipers feeding at the most muddy intertidal sites in Elkhorn Slough recalls Quammen’s (1982) findings that shallow-feeding shorebirds, such as Western Sandpipers, spent more time feeding and were more successful at prey capture on intertidal mudflats having little sand. She suggested that sand interferes with detection and capture of prey (small polychaetes and oligochaetes) because of similarity in size. Seasonal changes in the diet of the Western Sandpiper and the Marbled Godwit were considerable, and probably related to spatial and temporal variation in availability of prey, although prey populations were not sampled. In other coastal wetlands, insect larvae and pupae (Order Diptera) occur in high densities near the surface of mudflats during warm fall months and are common in the diet of some species of small shorebirds, especially Western Sandpipers (Couch 1966, Page and Stenzel 1975, Stenzel et al. 1983). Other prey species of Western Sandpipers and Marbled Godwits were among the most abundant infaunal invertebrates in the mudflats of Elkhorn Slough (Nybakken and Jong 1977). Similar prey types have been reported in the diet of Western Sandpipers (Page and Stenzel 1975, Quammen 1984) and Marbled Godwits (Recher 1966, Holmberg 1975, Page and Stenzel 1975) from other coastal areas, although the relative importance of each type varied with location. Salt marshes were used primarily by large shorebirds. Small shorebirds were not observed in areas of Elkhorn Slough where marsh vegetation was tall and dense, but they did feed and roost in sparse vegetation of the upper- slough marsh, suggesting that use of this habitat was restricted by height and density of vegetation. Willets were the only shorebirds that fed regularly in large numbers in the salt marsh. Their diet was dominated by crabs that are abundant in vertical banks of the marsh (Sliger 1982) and larger than the infaunal prey consumed by Western Sandpipers and Marbled Godwits on intertidal mudflats. Willets have similar feeding habits in other coastal 171 SHOREBIRDS IN ELKHORN SLOUGH wetlands (Reeder 1951, Recher 1966, Holmberg 1975, Stenzel et al. 1976). The salt ponds adjacent to Elkhorn Slough were the primary roosting areas for small shorebirds, American Avocets, and Black-bellied Plovers. Salt ponds in San Francisco Bay were similarly used by these species (Swarth et al. 1982). Seasonal changes in water depth reduce space available for resting or feeding in salt ponds (Swarth et al. 1982); rising water levels from winter rains restricted this space for small sandpipers in Elkhorn Slough. In general, little feeding took place in the salt ponds, but there were important exceptions. Several uncommon species of shorebirds (e.g., phalaropes) roosted and fed exclusively in salt ponds. The salt ponds were not flushed by the tide during our surveys. However, when a major dike broke in 1984 and a large salt pond was exposed to tidal action, many shorebirds began to feed on the new intertidal mudflat. The considerable variation in spatial and temporal use of habitat by a large variety of shorebirds within Elkhorn Slough and surrounding areas, and exchange of birds between these habitats, suggests that this wetland system is important to the viability of migrating shorebird populations. The intertidal mudflats can be regarded as critical and sensitive habitat for many of the shorebirds feeding in Elkhorn Slough during their annual migratory cycle. Degradation of this habitat could reduce the reproductive success and affect the survival of these populations. ACKNOWLEDGMENTS This research was sponsored partially by the National Oceanic and Atmospheric Administration (NOAA), National Sea Grant College Program, Department of Com- merce, under grant number 04-8-M0 1-189, project number R/CZ-45, through the California Sea Grant College. The U.S. government may reproduce and distribute this paper. Additional funding was provided by NOAA, Marine and Estuarine Management Division, to J. Oliver, G. Cailliet, and M, Silberstein for preparation and publication of this manuscript. We thank R. Cowen, G. Gillingham, T. Harvey, and S. Hawes for assistance with field surveys, and G. Gillingham, C. Jong, and L. Martin for identification of invertebrate prey. We appreciate critical review of this manuscript by J. Harvey, T, Manolis, D. Paulson, and G. Ruiz, Our thanks to R. Ramer for continued support and encouragement. LITERATURE CITED Baker, M. C., and Baker, A. E. M. 1973. Niche relationships among six species of shorebirds on their breeding ranges. Ecol. Monogr. 43:193-212. Blick, D. J., Jr. 1980. Advantages of flocking in some wintering shorebirds. Ph.D. thesis, Univ. of Mich., Ann Arbor. Broenkow, W. 1977. 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W., and Shuford, W. D. 1989. Results of the first comprehensive shorebird census of northern and central California coastal wetlands 8-12 September 1988. Point Reyes Bird Observatory, 4990 Shore- line Hwy., Stinson Beach, CA 94970. Swarth, C. W., Akagi, C., and Metropulos, P. 1982. The distribution patterns and ecology of waterbirds using the Coyote Hills salt ponds. San Francisco Bay Natl. Wildlife Ref., P. O. Box 524, Newark, CA 94560. Townshend, D. J. 1981. The importance of field feeding to the survival of wintering male and female Curlews Numenius arquata on the Tees Estuary, in Feeding and Survival Strategies in Estuarine Organisms (N. V. Jones and W. J. Wolff, eds.), pp, 261-274. Plenum, London. Wong, C. R. 1989. Observations of tides and tidal currents in Elkhorn Slough. M.S. thesis, Moss Landing Marine Laboratories, Moss Landing, CA. Accepted 7 March 1991 174 EXPERIMENTS WITH ALLEN S AND ANNA’S HUMMINGBIRDS AT SUGAR WATER FEEDERS IN SPRING TONNA HARRIS-HALLER, Department of Biology, Texas A&M University, Col- lege Station, Texas 77840 STANLEY W. HARRIS, Department of Wildlife, Humboldt State University, Areata, California 95521 Because most ornithophilous flowers in North America are red (Pickens, 1930, 1941, Pickens and Garrison 1931, Grant 1966, Grant and Grant 1968), a general belief has arisen that hummingbirds have coevolved an innate preference for red flowers. This view has been supported and challenged by field (Woods 1927, Wagner 1946, Stiles 1976) and experi- mental studies (Sherman 1913, Bene 1941, 1945, Lyerly et al. 1950, Collias and Collias 1968, Miller and Miller 1971, Ewald 1979, Wheeler 1980, Welker 1984). These and other workers have proposed that feeding hummingbirds may be influenced by weather, time of day, location of food source, chemical composition of nectar, concentration of nectar, proximity to perches, availability of alternate foods, and competition. We recorded 7517 minutes of observations of Allen’s (Selasphorus sasin ) and Anna’s ( Calypte anna) hummingbirds at Areata, Humboldt County, California, 20 February-3 May 1972 and 31 January-14 Febru- ary 1973, using a station where experimental solutions could be presented to wild birds in a uniform, carefully controlled manner. At Areata, Anna’s Hummingbird, an uncommon resident, breeds in late winter and early spring. Allen’s Hummingbird is a common to abundant spring migrant, summer resident, and breeder but occurs in winter only as a vagrant (Yocom and Harris 1975, Harris 1984). We recorded all Selasphorus as Allen’s Hummingbird, but a few early spring migrants possibly were Rufous Hum- mingbirds (S. rufus), an uncommon spring migrant in northwest California (Yocom and Harris 1975). METHODS The experimental apparatus consisted of a piece of plywood approxi- mately 1 m long, 75 mm wide, and 13 mm thick, nailed across the lower half of a sash window of a suburban residence. The board was held about 100 mm from the glass. The window was adjacent to a larger window on one side and a blank wall on the other side. We drilled four holes, 200 mm apart, in the board. Experimental solutions consisted of ordinary white sugar (sucrose) and water in 61 -ml feeders. Each feeder consisted of a clear glass bottle and a clear glass stem (feeder tube) held in the bottle by a small red rubber cork. In most experiments, we covered the red corks with white plastic tape. We discarded red plastic support sleeves supplied with the feeders. The stem of each feeder was inserted through a hole in the board, and the feeder was held in place with white elastic tape. We used four feeders in 1972, but in 1973 we placed feeders only in the two center holes of the board. We rotated the feeders across the positions on the board daily; Western Birds 22:175-188, 1991 175 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS thus, each experimental solution occupied each position once every four days in 1972 and every other day in 1973. Feeder position 1 was closest to the adjacent window and position 4 was adjacent to the blank wall. We refilled feeders with experimental solutions at the end of each day’s activity or more often as needed. We determined the initial positions of feeders by throwing a die. We separated some experiments with “rest” periods 3-24 days long, when we replaced experimental feeders with a large feeder hung in front of the board to maintain the interest of the birds in the station. The large feeder was filled with colorless 50 percent sugar water. We measured hummingbird use of the station in three ways: (1) The appearance of one bird hovering or perching immediately in front of a feeder was scored as a “visit” with each shift of a bird between feeders scored separately. Birds appearing at the station simultaneously were all scored separately. (2) The act of a bird inserting its bill into the stem of a feeder was scored as a “sip” regardless of the duration of each sip. A single visit might generate 0 to 30+ sips. (3) Total daily consumption at each feeder was measured with a graduated cylinder when the feeders were refilled to maximum capacity. We abandoned attempts to record the duration of visits and sips with a stopwatch because we were unable to record data fast enough when spring migrants sometimes made more than 30 visits per minute and when two to seven birds commonly made simulta- neous visits. We recorded data from inside the house through a closed window. Window shades covered the top half of the window supporting the feeder rack and all of the large window immediately adjacent to feeder position 1 . We took records sporadically throughout many days, but most data were from the two hours before and the one-half hour after sunset. We recorded the species and sex of each visitor. We conducted experiments to test (1) sugar concentration preference, (2) feeder position preference, (3) red-blue-yellow-green color preference, (4) red-blue color preference, and (5) the effect of adding a perch on use rates of feeders. Protocols for each experiment were as follows: Concentration trials — Trial 1: 20-26 February 1972, 1590 minutes of observation time. Trial 2: 27 February-5 March 1972, 1371 minutes. Experimental solutions: 0 (plain water); 33% sugar (one part sugar to two parts water by volume); 50% sugar (equal parts sugar and water by volume); 66% sugar (two parts sugar to one part water by volume). All solutions and feeders were uncolored, feeders were rotated for position daily, and stem corks were covered with white plastic tape. Position trial — 8-14 March 1972, 1919 minutes. All feeders contained colorless 50% sugar solution, were uncolored, were rotated daily, and had their stem corks covered with white plastic tape. Color trial 1 — 16-23 March 1972, 1132 minutes. All feeders contained colorless 50% solution and were rotated daily. The entire feeder, including stem, stem cork, and bottle, was wrapped with colored plastic tape to achieve clear, consistent colors that could be duplicated without introducing any taste bias that might happen with food dyes. Colors used were red, blue, yellow, and green. 176 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS Color trial 2 — 31 January- 14 February 1973, 803 minutes. Protocol as above except we used only red and blue feeders and rotated these on alternate days between the two center positions on the board. Perch trials — 17-24 April 1972 and 26 April-3 May 1972, 712 min- utes. We attached a movable wire perch in front of one feeder. This perch was rotated across the board between the positions daily. Feeders were uncolored and filled with colorless 50% sugar water; red stem corks were exposed. We measured use in the first trial by visits, sips, and total consumption, in the second trial by total consumption only. In most experiments, we tested the results with a chi square analysis using pooled data for each experiment (d.f. = 1) and the hypothesis that the expected rates of use for any single feeder equaled 25% (1:3 ratio) of total use in the four-feeder, 1972 trials, and 50% (1:1 ratio) of total use in the two-feeder, 1973 trials. RESULTS vSeasonal and Species Composition of Use Between 31 January and 14 February 1973, we recorded only Anna’s Hummingbirds during 803 minutes of observations. This species made 31.4 visits per 100 minutes of observation time, nearly 92% by males (Table 1). Between 20 February and 26 February 1972, Allen’s Humming- birds accounted for 26% of all visits, but no females of either species were seen (Table 1). By late February and early March, the proportion of Allen’s Hummingbirds had increased to about one-third of all visits, and the rate of visits per 100 minutes of observation time had increased, but no females had yet appeared. In the second week of March, female Allen’s Humming- birds appeared at the feeders as frequently as males, while use rates of Anna’s Hummingbird males remained essentially unchanged from the previous period. By late March, use rates by Allen's increased to more than 60 visits per 100 minutes for each sex, while the use by Anna’s males remained stable at about 34 visits per 100 minutes (Table 1). By mid- April, use by both sexes of Allen’s and by male Anna s had increased dramatically. A striking aspect of these data is that female Anna’s Hummingbirds rarely used the station, though they occasionally foraged in nearby flower beds. Simultaneous Visits Of 1082 total visits recorded in early trials (31 January-5 March), 99.8% involved single birds. The frequency of simultaneous visits increased with the influx of spring migrants to 16.5% of 2461 visits (8-14 March) and 35.1% of 4228 visits (16-24 March). Simultaneous visitors either shared a feeder and drank at the same feeder stem, or they made unshared visits to different feeders on the rack. All data combined, 81.1% of 7773 visits were by single birds, 13.8% were by two or more birds feeding simultaneously at different feeders, and 5.1% were of two or more birds sharing one feeder. Nearly two-thirds (64.7%) of the 1472 birds recorded feeding together occurred as pairs, another 357 (24.3%) occurred in groups of three, 124 (9.4%) occurred in groups of four, and 39 (2.5%) in groups of five or more. 177 JS) ~C0 G c < ~a c co IS) "c CD _o c o X CC -I— I CO CO c ■S 0) CD UL J-l CD -4—1 CO i- CC CO 3 CO -4—1 CO c/) -4—1 ♦ c n * r ™4 > CD CO (O c CL) (0 u L-. CD a- T3 CO CD -4 — 1 CO -4— I G cc § - u go .2 _o 3 E _0 3 £1 cn S s rd T3 E §< <£ m cO -t-j CD G cO _[5 - S’ .a! 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O D (— Cl -*_< *— » '3 O > 9 c — D <0 £ £ D E— Cl \-§ CO Q > 9 o _ D .2 -a o 'G D CL CO CM lO i— 1 00 O O O O O LO X CM 00 CM CM O O O O O t On O ON (N O 4-1 00 ffL LO H K on mo cm cm 4-c 00 CM ON CM CM CO 00 CM COCO 0- CM rH CM CO CO LO CM 00 t-h O O O v.0 o ON CO Tf LD CO I> O O O v£) 1_Q ON LO ON HOINLOOO ° \D h tv ro CM CO CO CO CM CO O LO ^ CO cd o o H^'vDOO i— i CM c c o o co co 1- i— -4- 1 -4-1 — C C ^ t-h c D D O cj u 3 t -3 — C c -53 _S u O O O o o Q> U O U cl U Cl CM L- o CO ON I-H CM CM o- <3n CM CM H Cl h- [n CD 9 >- tj- ON ON CO ON Tf X I c cO "3 ® LO L— to CO CM CM 00 ^ co ^ d" CM CM 0-~ I VD t"- X D 178 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS The largest single group we saw was seven birds at four feeders simulta- neously during the position trial and the largest number we saw sharing a single feeder was four at a red feeder during the first color trial. Concentration Trials In the first concentration trial, both species preferred the 50% solution as measured by both visits and sips. Both species generally visited the 66% solution at about the expected rate (Table 2), but Anna’s exceeded the expected rate when measured by sips. Both species generally used the clear water and 33% solutions at less than expected rates. The total consumption of sugar water by both species combined deviated from the expected 25% rate for clear water (no measurable amount taken) and the 66% solution (50% of all sugar water taken). In the second trial, both species avoided the clear water and preferred the 66% solution. Allen's Hummingbirds used the 33 and 50% solutions at about expected rates, but Anna’s Hummingbird used the 50% solution at greater than expected rates and the 33% solution at less than expected rates. Effect of Feeder Position We conducted the position trials after many female Allen’s Humming- birds had joined the feeding flock (Table 1). Both sexes of Allen’s Humming- bird generally used position 1 at less than expected rates as measured by visits (13.4% of 928 visits by males, 16.4% of 890 visits by females) and Table 2 Percentage of Use of Four Concentrations of Sugar Water by Male Allen’s and Anna’s Hummingbirds, 20 Feb-5 Mar 1972, Areata, Humboldt County, California Measure of Use Percentage e of Sugar Species n 0 33 50 66 Trial 1 (20-26 Feb 1972) Allen’s Visits 67 6.0 a 17. 9 b 55. 2 a 20. 9 b Sips 288 2.0 a 10. 8 a 61. 5 a 25. 7 b Anna’s Visits 194 6.7 a 15. 4 a 47. 9 a 29. 0 b Sips 1350 l.l a 14. l a 46. 5 a 38. 2 a Total Consumption (ml) 60 0 a 16. 7 b 33. 3 b 50. 0 a Trial 2 (27 Fet^5 Mar 1972) Allen’s Visits 177 4.5 a 22. 0 b 31.6 C 41.8 a Sips 629 1.2 a 21. 8 b 28. 0 b 49. 0 a Anna’s Visits 394 4.3 a 13. 7 a 34. 5 a 47. 4 a Sips 1727 1.3 a 7.3 a 33. 6 a 57. 8 a a P < 0.01. P based on x 2 from pooled data for all days of observation (d.f is that expected rate of use for any single concentration = 25% of total. b Not significant. C P< 0.05. 1); X 2 hypothesis 179 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS sips {15.7% of 2144 sips by males, 17.3% of 2440 sips by females; P < 0.01 for all tests). Male Allen’s used positions 3 (31.5% of visits, 32% of sips) and 4 (28.7% of visits, 29.3% of sips) at greater than expected rates, but female Allen’s exceeded expected rates (33.7% of visits, 33.1% of sips; P < 0.01 for all tests) only at position 4. Male Anna’s exceeded expected rates at position 2 (29% of 638 visits and 28% of 1903 sips, P < 0.02 for visits and < 0.01 for sips), and visited position 3 at a less-than-expected rate (21.2%; P < 0.01) as measured by sips. As measured by consumption, the amount of total solution taken at position 1 was slightly less (20.9% of 401 ml) than at the other positions, but this difference was not strongly signifi- cant (P < 0.10). To summarize, there was a bias by Allen’s Hummingbird away from the feeder nearest the adjacent window (position 1) and toward the feeder nearest the blank wall (position 4, but Anna’s Hummingbird did not show a strong bias for or away from any feeder position. Color Trials In 1972 male Allen’s and Anna’s and female Allen’s hummingbirds all used the red feeder at rates higher than expected as measured by visits, sips, and total consumption (Table 3). Though the sample for female Anna’s Hummingbirds was too small to test statistically, 55.5% of all visits and 69% of all sips recorded were at the red feeder, compared to expected rates of 25%. Male Allen’s also used the blue feeder more than expected as measured by both visits and sips, but the female Allen's used the blue feeder less than expected. Both sexes of Allen’s Hummingbird used the yellow and green feeders less than expected with the green feeder the least preferred by far. Male Anna’s Hummingbird used the green feeder far less than expected and generally used the blue and yellow feeders about as expected. Table 3 Percentage of Use of Sugar-Water Feeders of Four Colors by Allen’s and Anna's Hummingbirds, 16-23 Mar 1972, Areata, Humboldt County, California Species Sex Measure of Use n Color Red Blue Yellow Green Allen’s Male Visits 684 44. 4 a 31. l a 13. 9 a 10. 5 a Sips 1757 47. 2 a 28.2 a 14. 2 a 10. 4 a Allen’s Female Visits 744 62. 6 a 19. 2 a 13. 4 a 4.7 a Sips 2305 66. 4 a 19. 3 a 10. l a 4. l a Anna’s Male Visits 388 38. 4 a 24. 2 b 22. 7 b 14. 7 a Sips 1454 35. 7 a 23. 4 b 28. 5 a 12. 5 a Anna’s Female Visits 9 55. 5 C 0 C 33. 3 C 1 Ll c Sips 29 69. 0 C O 24. l c 6.9 C Total Consumption (ml) 367 61.6 a 17. 8 a 13. 8 a 6.9 a °P < 0.01. P based on x 2 values from pooled data for all days of observation (d.f. = 1); x 2 hypothesis is that expected rates of use for any single color = 25% of total. b Not significant. c Sample size for female Anna's Hummingbird too small to calculate x 2 values. 180 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS These birds consumed 61.6% of all sugar water taken through the red feeder, a rate much greater than expected, and they took nectar from the other three colors at rates less than expected. The least used feeder was green, accounting for only 6.9% of the total consumption during the 8-day trial. Further clear evidence of the preference for the red feeder is demon- strated by data on simultaneous visits. Birds arriving at the station when another bird was already present were confronted with four choices: (1) displace the bird already present and take over its feeder; (2) share the same feeder with the first bird; (3) use a nearby or adjacent feeder and drink there simultaneously; or (4) leave without drinking. We observed all four events frequently. All data combined, about 50% of all single visits were at the red feeder, 40.3% of birds feeding simultaneously but at separate feeders used the red feeder, and 75.7% of birds sharing the same feeder were at the red feeder. In fact, of all trials, the highest rate of shared use occurred during the color trial when 9.7% of 1825 visits were shared visits compared to only 5.9% for the perch trial (2403 visits) and only 2.7% for the position trial (2461 visits). During the color trial, most birds sharing a single feeder were at the red feeder. In some cases a bird originally using the red feeder was displaced by an arrival only to move to another color when the arrival took over the red feeder; in these cases, it was clear that the first color of choice for both birds was red. We offered red and blue in early February 1973 when only Anna’s Hummingbird was present (Table 1). Male Anna’s used the red feeder at rates much higher than expected as measured by both visits and sips (Table 4). Female Anna’s also used the red feeder more than the blue feeder, but the difference was not significant for the small sample of observations (Table 4). Nearly 71% of all sugar water taken in the trial was from the red feeder compared to an expected 50%. Table 4 Percentage of Use of Sugar-Water Feeders of Two Colors by Anna’s Hummingbirds, 31 Jan-14 Feb 1973, Areata, Humboldt County, California Sex Measure of Use n Percent Total Use Red Blue Male Visits 231 62.8 37. 2 a Sips 833 65.4 34. 6 a Female Visits 21 57.1 42. 9 b Sips 42 64.3 35. 7 b Total Consumption (ml) 236 70.8 29. 2 a a P < 0.01. P based on values from pooled data for all days of observa- tion (d.f. = 1); x 2 hypothesis is that expected rate of use of any single color = 50%. b Not significant. 181 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS Perch Trials Male Allen’s Hummingbird visited feeders with a perch on 18.5% of 573 visits, less than the expected 25% rate ( P < 0.01), but female Allen’s and male Anna’s showed no preference for or against the perch. Female Allen’s and male Anna’s sipped from feeders with a perch more than expected (33.9% of 4031 sips and 36.7% of 1492 sips, respectively, P < 0.01), but male Allen s did not. In both trials total consumption at feeders with perches exceeded expected rates (P <0.01) Daily Pattern of Use Rates of use were at generally low levels for both species most of the day, but increased dramatically beginning about 1700 hours and continued to increase until feeding activities stopped 30-45 minutes after local sunset (Figure 1). Generally any territorial claims established during the day were overwhelmed near sunset when many birds appeared and when some individuals, particularly male Anna’s, made visits consisting of 20+ sips Ui h- 3 Z s E UI a. at a. at 13 * 12 - 11 ‘ 10 - 9 - 9 - 7 • 6 ■ 5 ■ 4 - 3 - 2 - 1 - ; / \ allen's j ^ ~_ 2Q FFB-6 MAR / ^ 8-23 MAR * ‘I \ - - . • 17-24 APR 6 7 8 9 10 11 12 13 14 15 16 11 10 19 20 HOUR OF TH E DAY Figure 1. Hourly distribution of feeding activity at sugar water feeders by Allen’s and Anna’s hummingbirds, spring 1972, Areata, California. 182 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS compared to an average of 2-3 sips per visit during other daylight hours. This pattern of increased use late in the day remained constant throughout the spring. DISCUSSION The 1972 studies occurred during a spring of unusually heavy use. Observations in other years suggest that “normal'' usage rates in March and April were about one-quarter as high as in 1972. We have no explanation for the heavy use in 1972, but migrant swarms of hummingbirds sometimes are attracted to seasonal food sources (Stott 1942, Stiles and Wolf 1970). Our data showed that male Allen’s Hummingbirds migrate into California’s north coast somewhat earlier than do females. Phillips (1975) reported a similar pattern in both spring and fall. Female Anna’s Hummingbirds used the station only slightly. Possible explanations could be a low population of females in the area during the study, varying nutritional requirements for females just entering the nesting period (Pitelka 1951, Kelly 1955), or the inability of females to compete with massive numbers of migrant Allen’s and the normal territoriality of male Anna’s Hummingbirds. Most of the recorded usage by female Anna’s was in February 1973, before any Allen's arrived. Even then, males outnumbered females (Table 1). Several workers have mentioned that female hummingbirds do not feed in males’ territories and defend only small territories near the nest while breeding. Southwick and Southwick (1980) reported that female Ruby-throated Hummingbirds ( Archilochus colubris) fed solely on tree sap at sapsucker holes in Michigan in early spring, while males used both nectar and sap. Ewald (1979) found that female Anna’s were less territorial and less able than males to defend food sources. Nesting female Costa’s Hummingbirds ( Calypte costae ) seemed to visit flowers less often than did males, but foraged inside nonflowering trees and shrubs (Woods 1927). Similar patterns have been reported for tropical species (Stiles and Wolf 1970). Male White-eared Hummingbirds ( Hylocharis leucotis) excluded females and immatures from the “most suitable” flowers and forced them to feed at flowers under vegetative cover (DesGranges 1978). Our study was conducted at a time when when Anna’s Hummingbird apparently was in the process of colonizing the north coast as a nesting species (Zimmerman 1973), and it is possible that the early invaders in the range extension process were mostly males. Anna’s Hummingbird is now an established breeder in the area, yet we still rarely see females at sugar water feeders. Previous workers have emphasized the importance of the relative posi- tion of food sources and of perches as a factor determining hummingbird food use (Bene 1945, Collias and Collias 1968, Miller and Miller 1971, Wheeler 1980). In our study, Allen’s Hummingbirds used feeder position 1 at less and feeder position 4 at more than expected rates even though all feeders were essentially equidistant from perches used by the birds. Feeder 1 was adjacent to a large window that opened into the same room as the experimental window, and human activity inside the room may have 183 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS influenced the use of that feeder even though we kept the shade drawn during observation sessions. Conversely, position 4 was adjacent to about 3 meters of blank wall and was the farthest removed from any activity visible through the window. Welker (1984) reported that Anna’s Hummingbird preferred the two end positions at a station were four feeders were arranged in a linear fashion similar to ours. In our study, male Anna’s did not show any strong preference for any of the four feeder positions. It is possible that use by Allen’s Hummingbirds of certain feeders may have influenced Anna’s to use other, open feeders, but data on simultaneous use showed that, during the position trial, nearly 84% of 2054 visits were of single birds with a free choice of any feeder position. Thus, it seems unlikely that any detectable interspecific competitive exclusion occurred. Our protocols called for a regular rotation of each experimental solution through all four positions in an effort to minimize any tendency to a position bias. Most trials lasted for 8 days, and each experimental solution was thus exposed to two complete rotations of the positions. Furthermore, the results of each experiment were pooled for all 8 days before analysis, thus further minimizing any position bias. Van Riper (1958) found that Broad-tailed Hummingbirds ( Selasphorus platycercus) in Colorado preferred sucrose over five other sweeteners, and a 50% sugar solution over weaker ones. Collias and Collias (1968) failed to get Anna’s Hummingbird to use solutions with lower than 1:8 dilution ratios. In our concentration trials, both species quickly discriminated the plain-water feeder. The only visits/sips made at plain water were quick exploratory tests that, once made, did not seem to be repeated until the feeder position was changed the next day. The ability of birds to remember which of four identical feeders was unproductive and to avoid it maximizes the energetic efficiency of foraging. That the birds preferred the 50 and 66% solutions over weaker ones is clear evidence of their ability to seek rich nectar sources, with obvious survival value (Hainsworth and Wolf 1976). Even the 33% solution exceeded the apparent concentration of most natural floral nectar (Wagner 1946, Baker 1975, Stiles 1976, Hainsworth 1981, Tyrrell 1985). The main effect of adding a perch to the feeders was to reduce the number of visits made by male Allen’s and to increase the number of sips made by female Allen’s and male Anna’s over expected rates. Generally, the perch allowed an individual to defend a feeder more securely than when it had to hover. Thus, visits were longer, reducing the total number of visits possible at a feeder in a given time, but increasing the number of sips and the total consumption at feeders with perches. Additionally, male Allen’s took 2.3 sips per visit without the perch compared to 3.7 with the perch; female Allen’s took 2.5 without and 4.0 with, and male Anna’s took 3.0 without and 5.7 with the perch. Though the results are mixed and not strongly conclusive statistically, the perch apparently made the feeder generally more efficient for the birds to use. Some workers have found early morning (Stiles and Wolf 1970) or evening (DesGranges 1978) peaks in feeding rates, while others found no diurnal patterns (Wolf and Hainsworth 1977, DesGranges 1978). One might expect birds to seek reliable, known food sources actively at the 184 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS beginning of the day after a long night’s fast, but neither of our species showed this pattern. The visitation rate for either species did not change from dawn until the last 1 to 2 hours before sunset, when visitation and sip rates for both species increased greatly. The heavy use at the end of the day probably represents a need for the birds to take one last heavy energy load before the long night’s inactivity. Territorial claims disintegrated during the last 90 minutes of activity and many simultaneous visits were recorded then. Also, birds often made long, 20- or 30-sip visits at that time, compared to 1- to 3-sip visits earlier in the day. The most striking result of our studies is the clear, strong preference for the red feeder when a choice of red, blue, yellow, and green was offerred. Blue was a poor second choice, and green was by far the least preferred color of those offered. The effect was somewhat stronger for Allen’s Hummingbird than for Anna’s, but the results for both were highly signifi- cant. Welker (1984) worked with Anna’s Hummingbirds in fall and winter in northwestern California and reported results exactly opposite to ours. She found green most and red least preferred and suggested a possible seasonal explanation for the difference. Our 1973 mid-winter results also showed a clear preference for red, but we did not offer green in that experiment. Welker’s (pers. comm.) experimental apparatus and hence her results are not directly comparable to ours. She retained the plastic red sleeves supplied with the feeders as a means of hanging them. Consequently her feeders all had about one-quarter to one-third of the bottle covered with a red band that was visible to a feeding or hovering bird in spite of the fact that she placed over each feeder a hood made of construction paper of a color to match her experimental solutions. Also, she did not cover the small red corks that held the feeder stems in the bottles so that all of her feeders had red visible in two places, in addition to her colored solutions. Michael Hansen (pers. comm.) conducted a study similar to ours in the same area in a later spring and offered red, pink, white, and yellow. He found that Allen’s, Rufous, and Anna's hummingbirds all preferred red over the other colors with pink a second choice and white a poor third. Pickens (1930, 1941) and Pickens and Garrison (1931) suggested that hummingbirds prefer red or violet colors, but their conclusions were not based on extensive carefully controlled experiments. Wheeler (1980) found red preferred in a well-controlled experiment, as did Collias and Collias (1968) for one female Anna’s Hummingbird but not for others. Bene (1941), in a short-term, poorly controlled study, found that male Black-chinned Hummingbirds (. Archilochus alexandri) males preferred yellow and females preferred colorless feeders. Later, Bene (1945) failed to show any clear preference for color by Black-chinned Hummingbirds. Miller and Miller (1971) also failed to show a strong preference for color in a reasonably well-controlled experiment, as did Lyerly et al. (1950). Whether color preference is learned or innate cannot be determined from the data generated by this study, but it seems likely that hummingbirds learn to perceive color, especially red, to locate likely food sources. It is also likely that there has been a degree of coevolution between the development of red-flowered ornithophilous plants in western North America (Grant 185 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS 1966) and the use of color vision by hummingbirds while foraging. Because red flowers stand out against natural green backgrounds (Grant 1966) and red is not often detected by insects, particularly bees (Raven 1972), it would be mutually advantageous for birds to develop a red color sense and for plants with bird-pollinated flowers to develop red flowers. Red would advertise nectar locations that birds learn, from an early age, to recognize as food sources (Stiles 1976). It is likely our birds already had learned to associate artificial feeders with red before these studies began. Virtually every feeder in California either uses red solution or has red-colored plastic as part of its construction. At the time of these studies, other nearby residences had operating feeders and all presented red liquid. Such precon- ditioning probably influenced the birds to use red when they arrived at our experimental station. Indeed, it may not be possible to find spring migrant hummingbirds in California that have not already been preconditioned to red artificial feeders! Because high rates of use were obtained without bright colors in some of our trials, these birds obviously use other clues to find food. They undoubt- edly learn where food sources are by watching other birds, and they certainly investigate any brightly colored object while foraging. We once watched a male Anna’s move, in mid-winter, systematically down a line of colored Christmas lights along the eave of a house. The bird poked at each bulb regardless of color before moving to the next. The bulbs were red, blue, yellow, white, orange, and green and all were tested. During the perch trial, the red corks were left exposed and represented the only patches of bright color at the station. Apparent new arrivals invariably poked at each red cork in turn several times before learning they had to sip at the end of the feeder stem about 40 to 50 mm away. A male Calliope Hummingbird ( Stellula calliope), a rare migrant in the area, came to the station, poked at each red cork in turn and flew off without feeding. Five minutes later he repeated the process. Hummingbirds can use colors other than red as a “flag,” Wagner (1946) found that hummingbirds in a controlled experiment took colors matching those of natural flowers most frequently visited in the same season. Stiles (1976), working with recent captives, suggested the same conclusion. Collias and Collias (1968) reported that birds tended to persist using a color once it had been identified as a food source. In carefully controlled experi- ments, Stiles (1976) ranked the most important factors determining use: (1) concentration of nectar, (the sweeter, the better), (2) taste (sucrose best), (3) color. He suggested that color conditioning may operate as an orientation stimulus and that red would be the best color for advertising. Woods (1927), Miller and Miller (1971), and Wheeler (1980) all concluded that location of a source, once identified as food, was more important than color in continued use of the source. It is clear that hummingbirds can remember the locations of food sources (Bene 1945, Ewald 1979) for days or even months. We conclude that Allen’s and Anna’s hummingbirds make use of color vision and that discrimination of red is an important, though not indispens- able, tool these birds use while foraging. Once a source is found, it is likely that other factors such as memory of location, availability of perches, 186 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS competition, quality and quantity of available nectar, etc., may be equally or more important than color in continued use of the source. The use of color in the initial location of food sources is aided by an apparent insatiable curiosity of hummingbirds to investigate all bright or unusual objects in their environment. We are indebted to Dr. David Kitchen and Dr. Tim Manolis for critically reviewing the manuscript and making many useful suggestions for improve- ment. LITERATURE CITED Baker, H. G. 1975. Sugar concentrations in nectars from hummingbird flowers. Biotropica 7 : 3 7-4 1 . Bene, F. 1941. Experiments on the color preference of Black-chinned Humming- birds. Condor 43:237-242. Bene, F. 1945. The role of learning in the feeding behavior of Black-chinned Hummingbirds. Condor 47:3-21. Collias, N. E., and Collias, E. C. 1968. Anna’s Hummingbirds trained to select different colors in feeding. Condor 70:273-274. DesGranges, J. L. 1978, Organization of a tropical nectar feeding bird guild in a variable environment. Living Bird 17:199-236. Ewald, P. W. 1979. The hummingbird and the calorie. Nat. Hist. 88(7):92-98. Grant, K. A. 1966. A hypothesis concerning the red coloration in California hummingbird flowers. Am. Nat. 100:85-97. Grant, K. A., and Grant, V. 1968. Hummingbirds and Their Flowers. Columbia Univ. Press, New York. Hainsworth, F. R. 1981, Energy regulation in hummingbirds. Am. Sci. 69:420-429. Hainsworth, F. R., and Wolf, L. L. 1976. Nectar characteristics and food selection by hummingbirds. Oecologia 25:101-113. Harris, S. W. 1984. Field Checklist of Northwest California Birds. Redwood Region Audubon Soc., Eureka. Kelly, J. W. 1955. History of the nesting of an Anna’s Hummingbird. Condor 57:347-353. Lyerly, S, B., Riess, B. F., and Ross, S. 1950. Color preference in the Mexican Violet-eared Hummingbird, Colibri t. thalassirius (Swainson). Behavior 2:237- 248. Miller, R. S., and Miller, R. E. 1971. Feeding activity and color preference of Ruby- throated Hummingbirds. Condor 73:309-313. Phillips, A. R. 1975. The migrations of Allen’s and other hummingbirds. Condor 77:196-205. Pickens, A. L. 1930. Favorite colors of hummingbirds. Auk 47:346-352. Pickens, A. L. 1941 . A red figwort as the ideal Nearctic bird flower. Condor 43: 100- 102 . Pickens, A. L., and Garrison, L. P 1931. Two-year records of the Ruby-throat’s visit to a garden. Auk 48:532-537. Pitelka, F. 1951. Breeding seasons of hummingbirds near Santa Barbara, California. Condor 53:198-201. 187 EXPERIMENTS WITH ALLEN’S AND ANNA’S HUMMINGBIRDS Raven, P. H. 1972. Why are bird-visited flowers predominantly red? Evolution 26:674. Sherman, A. R. 1913. Experiments in feeding hummingbirds during seven summers. Wilson Bull. 25:153-166. Southwick, E. E., and Southwick, A. K. 1980. Energetics of feeding on tree sap by Ruby-throated Hummingbirds in Michigan. Am. Midland Nat. 104:328-334. Stiles, F. G. 1976. Taste preferences, color preferences, and flower choice in hummingbirds. Condor 78:10-26. Stiles, F. G. and Wolf, L. L. 1970. Hummingbird territoriality at a tropical flowering tree. Auk 87:467-491. Stott, K. Jr. 1942. An unusual concentration of hummingbirds. Condor 44:282. Tyrrell, E. Q. 1985. Hummingbirds: Their Life and Behavior. Crown, New York. Van Riper, W. 1958. Hummingbird feeding preferences. Auk 75:100-101. Wagner, H. O. 1946. Food and feeding habits of Mexican hummingbirds. Wilson Bull. 58:69-93. Welker, H. J. 1984. Food color preference in the Anna’s Hummingbird. W. Birds 15:23-27. Wheeler, T. G. 1980. Experiments in feeding behavior of the Anna’s Hummingbird. Wilson Bull. 92:53-62. Wolf, L. L., and Hainsworth, F. R. 1977. Temporal patterning of feeding by hummingbirds. Animal Behavior 25:976-989. Woods, R. S. 1927. The hummingbirds of California. Auk 44:297-318. Yocom, C. F., and Harris, S. W. 1975. Birds of Northwestern California. Humboldt State Univ. Bookstore, Areata, CA. Zimmerman, D. A. 1973. Range expansion of Anna’s Hummingbird. Am. Birds 27:827-835. Accepted 24 April 1991 188 NOTE FIRST MAINLAND RECORD OF THE RED-BREASTED NUTHATCH FROM BAJA CALIFORNIA, MEXICO GORGONIO RUIZ-CAMPOS and LORENZO QUINTANA-BARRIOS, Laboratorio de Vertebrados, Facultad de Ciencias, Universidad Autonoma de Baja California, Apartado Postal 1653. Ensenada. Baja California 22800. Mexico On 15 September 1990 we collected a Red-breasted Nuthatch ( Sitto canadensis ) at Rancho Casa Verde, western slope of the Sierra Juarez, east of Ensenada. Baja California. Mexico (32° 04’ N. 116° 05' W; altitude 1370 m). The specimen, an adult male of 113 mm total length (Figure 1). was taken climbing in Pinus jeffreyi, and represents the first mainland record of this species from Baja California. The fall of 1990 saw a large incursion of the Red-breasted Nuthatch in California, just north of the U.S. A. -Mexico international boundary (Rich Stallcup pers. comm.), and is probable that our collected bird in mainland Baja California was in transit rather than a breeder or resident. The Red-breasted Nuthatch was known previously in northwestern Mexico only from Guadalupe Island, off the coast of Baja California (Grinnell 1928. Miller et al. 1957, Howell and Cade 1954, Jehl and Everett 1985, Wilbur 1987). In 1970 and 1971 Jehl found a small breeding population of the species in the pine woods at the Figure 1. Adult male Red-breasted Nuthatch ( Sitta canadensis ) collected at Rancho Casa Verde, Sierra Juarez, Baja California, Mexico, 15 September 1990. Western Birds 22:189-190, 1991 189 NOTE north end of the island (Jehl and Everett 1985). However, Quintana-Barrios, during investigations of Guadalupe Island in October 1984 and 1985 and in March, August, and December 1986 did not find Sitta canadensis in that area. Unitt (1984) recorded this species in San Diego County, California, U.S.A., as an uncommon and very localized resident in coniferous trees, whether planted in parks and residential areas or native in mountain woodland, but there are no Red-breasted Nuthatch records for the Baja California peninsula (Grinnell 1928, Wilbur 1987). Given that the Red-breasted Nuthatch is a regular breeding species and irregular autumn migrant in California, sometimes in large numbers, just north of the interna- tional boundary, it is astounding that there have been no published records of this species for mainland Baja California. Once again, it is clear that ornithological investigations in the northern part of the peninsula are necessary. It is even possible that bird surveys have been so few that they have fallen between incursions of this species. Our specimen was deposited in the Bird Collection, Laboratorio de Vertebrados, Facultad de Ciencias, Universidad Autonoma de Baja California (UABC-0297). We thank Amadeo M. Rea and Philip Unitt (San Diego Natural History Museum) for information about Red-breasted Nuthatch records in California and Guadalupe Island, Mexico. In addition, we thank Rich Stallcup for his critical review and constructive comments to the manuscript. Philip Unitt supplied helpful editorial comments. LITERATURE CITED Grinnell, J. 1928. A distributional summation of the ornithology of Lower California. Univ. Calif. Publ. Zoo!. 32:1-300. Howell, T. R,, and Cade. T. J. 1954. The birds of Guadalupe Island in 1953. Condor 56:283-294. Jehl, J. R., Jr., and Everett, W. T. 1985. History and status of the avifauna of Isla Guadalupe, Mexico. Trans. San Diego Soc. Nat. Hist. 20:313-336. Miller, A. H., Friedmann, H., Griscom, L., and Moore, R. T. 1957. Distributional check-list of the birds of Mexico. Part II. Pacific Coast Avifauna 33. Unitt, P. 1984. The birds of San Diego County. San Diego Soc. Nat. Hist. Memoir 13. Wilbur, S. R. 1987. Birds of Baja California. Univ. of Calif. Press, Berkeley. Accepted 6 June 1991 190 WESTERN BIRDS, INDEX, VOLUME 22, 1991 Compiled by Mildred Comar Accipiter cooperii , 51 striatus, 50 Actitis macularia , 52 Aechmophorus clarkii, 46 occidentalism 46 sp., 43, 46 Aegolius acadicus, 59 Aeronautes saxatalis, 59 Agelaius phoeniceus, 73 tricolor, 73 Aimophila cassinii, 71, 111, 117 Albatross, Black-footed, 33, 46, 76 Laysan, 33, 46 Short-tailed, 33-34, 43, 100 Alfaro, Lucia, see Palacios, E. Alvarez Cardenas, Sergio, see Rodriguez- E„ R. Amadina fasciata, 83 Ammodramus bairdii, 72 caudacutus , 37-38, 72, 118, 124 leconteii, 72, 112, 117, 118 sanduiichensis , 72, 81 sanduiichensis beldingi, 31 sauannarum, 72 Amphispiza belli, 72 bilineata, 71 Anas acuta, 49 americana, 49 clypeata, 49 crecca, 49 cyanoptera, 49, 77, 139 discors, 49 platyrhynchos, 49 querquedula, 139-140 strepera, 49 Anhinga, 98, 101 Anhinga anhinga, 98, 101 Ani, Groove-billed, 111 Anser albifrons, 48 caerulescens, 48 canagicus, 103 rossii, 48 Anthus ceruinus, 65, 80, 113, 123 rubescens, 65, 80 spragueii , 65, 106, 113 Aphriza uirgata , 53 Aquila chrysaetos, 39, 51 Aratinga holochlora, 141 Archilochus alexandri , 60, 185 colubris , 59, 78, 183 Ardea herodias, 48, 76-77, 104 Ardeola bacchus, 120 Arenaria interpres, 53, 78, 160 melanocephala, 53, 78 Arnaud, Gustavo, see Rodriguez-E. , R. Asio flarnmeus, 59 ofus, 59 Athene cunicularia, 59, 78 Auklet, Cassin’s, 43 Rhinoceros, 43 Avocet, American, 29, 52, 160, 162, 163, 165, 166, 169-172 Aythya affinis , 49 collaris , 49 ferina, 95 fuligula, 103, 120-121 marila , 49 ualisineria, 49 Bartramia longicauda, 52, 77 Bittern, American, 47 Blackbird, Brewer’s, 74 Red-winged, 73 Rusty, 74 Tricolored, 73 Yellow-headed, 74 Bluebird, Mountain, 64 Western, 64 Bluetail, Red-flanked, 64, 95 Bobolink, 73 Bombycilla cedrorum, 65 garru/us , 65 Booby, Brown, 47 Red-footed, 47, 100-101 Botaurus lentiginosus, 47 Brachyramphus marmoratus, 58, 145-155 Brant, 48 Branta bernicla, 48 canadensis, 48 Bubo virginianus, 59, 78 Bubulcus ibis, 48 Bucephala albeola, 50 clangula , 50, 77 islandica, 50, 77 Bufflehead, 50 Bull, Evelyn, and Howard D. Cooper, Vaux’s Swift Nests in Hollow Trees, 85-91 Bunting, Indigo, 71 Lark, 72 Lazuli, 70, Painted, 71, 117 Snow, 73, 82, 119 Western Birds 22:191-200, 1991 191 Buteo albonotatus, 104, 121 jamaicensis , 51, 141, 142 lagopus , 51 Butorides striatus, 48 Calamospiza melanocorys, 72 Calcarius lapponicus, 73 ornatus, 73, 81 pictus , 95 Calidris acuminata, 53 a/ba, 53, 160, 164, 166, 170 alpina, 54, 78, 159. 160, 162-164, 166, 169-171 bairdii, 53 canutus, 53, 160 fuscico/lis, 108. 121 maun, 53, 131, 159, 160, 162-171 rnelanotos, 53 minutilia, 53, 131, 134-136, 159, 160, 162-164, 166, 169-171 ptilocnemis, 53 pusilla , 53 ruficollis, 82, 108 subminuta, 131-138 Calypte anna, 60, 175-188 costae , 60, 183 Canvasback, 49 Caprimulgus carolinensis, 111 Caracara, Crested, 95 Carduelis lawrencei, 75 pinus, 75 psaltria, 75, 82 sinica, 95 tristis, 75 Carpodacus cassinii, 75 mexicanus, 75 purpureus, 74 Carter, Harry R., see Sealy, S. Casmerodius albus. 48, 104 Catbird, Gray, 65, 112-113 Catbaracta maccormicki, 54 Cathartes aura, 50 Catharus fuscescens, 64 guttatus, 64 minimus, 64, 112 ustu/atus, 64 Catoptrophorus semipalmatus , 52, 159, 160, 162-171 Cepphus columba , 42-43 Cerorhinca monocerata, 43 Certhia americana , 63 Cery/e alcyon, 60 Chaetura pelagica, 59, 86, 90 vauxi, 59, 85-91 Charadrius alexandrinus, 29, 52, 163, 171 mongolus, 105 morinellus, 52, 107-108 pecuarius, 124 semipalmatus, 52, 77, 160 uociferus, 29, 52, 77, 160 wilsonia , 121 Chase, Charles A., Ill, see Sealy, S. Chat, Yellow-breasted, 70 Chen caerulescens , 48 canagica, 103 rossii, 48 Chloroceryle americana, 95 Chondestes grammacus, 71 Chordeiles acutipennis, 59 minor, 59 Chuck-will’s-widow, 111 Circus cyaneus, 50 Cistothorus palustris, 63 platensis , 112 Clangula hyemalis, 49, 77 Coccothraustes uespertinus, 75 Coccyzus americanus, 59 erythropihalmus, 58, 110-111 Colaptes auratus, 60-61 Columba fasciata, 58 liuia , 58 Columbina passerina, 141-143 Contopus borealis, 61 pertinax, 111 sordidulus, 61 uirens, 61 Conure, Nanday, 82 Cooper, Howard D., see Bull, E. Coot, American, 51 Cormorant, Brandt’s, 42 Double-crested, 3, 42 Pelagic, 42 Corvus corax, 63 Coturnicops noveboracensis, 104 Cowbird, Brown-headed, 13-26, 74 Creagrus furcatus, 95 Creeper, Brown, 63 Crossbill, Red, 75, 82 Crotophaga sulcirostris, 111 Cuckoo, Black-billed, 58, 110-111 Yellow-billed, 59, 110 Curlew, Long-billed, 53, 77, 160, 163-166, 170 Cygnus buccinator, 102, 120 columbianus, 48, 102 Cynanthus latirostris, 111, 122 Cypseloides niger, 59 Daniels, Brian E., see Patten, M. A. Dendrocygna autumnalis, 120 Dendroica caerulescens, 67 192 castanea, 69 cerulea, 69, 123 chrysoparia, 68 coronata, 67-68, 80 discolor , 68 dominica, 68, 80, 114-115 fusca, 68 graciae, 115 magnolia, 67 nigrescens, 57, 68 occidentals, 68, 80 palmarum, 68-69 pensyluanica, 67, 80 petechia, 67 pinus, 68, 115 striata, 69, 80-81 tigrina, 67 townsendi, 68 townseridi x occidentals , 68 uirens, 68 FYipkpi cqpI 71 Diomedea albatrus , 33-34, 43, 100 immutabilis, 33, 46 nigripes, 33, 46, 76 Dolichonyx oryzivorus, 73 Dotterel, Eurasian, 52, 107-108 Dove, Common Ground, 141-143 Mourning, 58, 141, 142 Oriental (Rufous) Turtle, 95 Ringed Turtle, 82 Rock, 58 Socorro, 141 White- winged, 58 Dowitcher, Long-billed. 54, 160, 163, 170 Short-billed, 54, 160, 169, 170 sp., 162, 164, 166, 169-171 Dryocopus pileatus, 85-91 Duck, Black-bellied Whistling, 120 Harlequin, 49 Ring-necked, 49 Ruddy, 50 Tufted, 103, 120-121 Dumetella carolinensis, 65, 112-113 Dunlin, 54, 78, 159, 160, 162-164, 166, 169-171 Eagle, Bald, 50 Golden, 39, 51 Egret, Cattle, 48 Great, 48, 104 Reddish, 102 Snowy, 48 Egretta rufescens, 102 thula , 48 tricolor, 98 Eider, King, 103 Steller’s, 103 Elanus caeruleus, 50 Empidonax alnorum, 82-83, 122 difficilis, 61 flauiuentris, 61 hammondii, 61 minimus, 61 oberholseri, 61 traillii, 13-26, 61, 79 wrightii, 61 Eremophila alpestris, 62 Euphagus carolinus, 74 cyanocephalus, 74 Falco columbariu s, 51 mexicanus, 51 peregrinus, 51, 77 sparverius, 51, 56 Falcon, Peregrine, 51, 77 Prairie, 51 Finch, Cassin’s, 75 House, 75 Purple, 74 Flicker, Northern, 60-61 Flycatcher, Alder, 82-83, 122 Ash-throated, 62 Browri-crested, 62 Dusky, 61 Gray, 61 Great Crested, 62 Hammond’s, 61 Least, 61 Olive-sided, 61 Scissor-tailed, 62, 112, 122, 125 Western, 61 Willow, 13-26, 61, 79 Yellow-bellied, 61 Fratercula cirrhata, 43 corniculata, 58 Fregata magnificens, 47, 76 Frigatebird, Magnificent, 47, 76 Fulica americana, 51 Fulmar, Northern, 47, 76 Fulmarus glacialis, 47, 76 Gadwall, 49 Gallinago gallinago, 54 Gallinula chloropus, 51 Gallinule, Common, 51 Purple, 105 Garganey, 139-140 Gavia adamsii, 100, 119, 125 immer, 46, 76 pacifica , 46, 76 stellata, 46 193 Geothlypis trichas , 69 Gnatcatcher, Blue-gray, 64 Godwit. Bar-tailed, 121 Marbled, 53, 159, 160, 162, 163, 165-171 Goldeneye, Barrow’s, 50, 77 Common, 50, 77 Golden-Plover, Lesser, 51-52, 56 Goldfinch, American, 75 Lawrence’s, 75 Lesser, 75, 82 Goose, Canada, 48 Emperor, 103 Greater White-fronted, 48 Ross’, 48 Snow, 48 Grackle, Common, 119, 124 Grebe, Clark’s, 46 Eared, 46, 76 Horned, 46 Pied-billed, 46 Red-necked, 46, 76 Western, 46 Greenfinch, Oriental, 95 Grosbeak, Black -headed, 70, 81 Blue, 70 Evening, 75 Rose-breasted, 70 Rose-breasted x Black-headed, 70, 81 Grothe, Scott, First Record of a Garganey in Idaho, 139-140 Ground-Dove, Common, 141-143 Guillemot, Pigeon, 42-43 Guiraca caerulea, 70 Gull, Band-tailed, 95 Bonaparte’s. 55 California, 1-12, 55 Franklin’s, 55 Glaucous, 55, 78 Glaucous -winged, 55, 78 Heermann’s, 55 Herring, 10, 55, 78 Iceland, 95 Laughing, 54, 57 Lesser Black-backed, 110 Little, 110 Mew, 55 Ring-billed, 7, 8, 55 Sabine’s, 55, 78 Swallow-tailed, 95 Thayer’s, 55, 78 Western, 30, 42 Haematopus bachmani, 42 Haliaeetus leucocephaius, 50 Harrier, Northern, 50 Harris, John H., Effects of Brood Parasitism by Brown-headed Cowbirds on Willow Flycatcher Nesting Success along the Kern River, California, 13-26 Harris, Stanley W., see Harris-Haller, T. Harris-Haller, Tonna, and Stanley W. Harris, Experiments with Allen’s and Anna’s Hummingbirds at Sugar Water Feeders in Spring, 175-188 Hawk, Cooper’s, 51 Red-tailed, 51, 141, 142 Rough-legged, 51 Sharp-shinned, 50 Zone-tailed, 104, 121 Helmitheros uermiuorus, 69, 109, 116 Henderson, R. Philip, see Pyle, P. Heron, Black-crowned Night, 48, 104 Chinese Pond, 120 Great Blue, 48, 76-77, 104 Green-backed, 48 Tricolored, 98 Yellow-crowned Night, 102, 141 Heteroscelus incanus, 52, 77 Himantopus mexicanus, 29, 160, 163 Hirundo futva, 95 pyrrhonota, 63 rust tea, 63 Histrionicus histriorticus, 49 Hummingbird, Allen’s, 60, 78-79, 175-188 Anna’s, 60, 175-188 Black-chinned, 60, 185 Broad-billed, 111, 122 Broad-tailed, 184 Calliope, 60, 186 Costa’s, 60, 183 Ruby-throated, 59, 78, 183 Rufous, 60, 78-79, 175, 185 White-eared, 183 Hyiocharis leucotis, 183 Hylocichla mustelina, 112 Ibis, White-faced, 43 Icteria uirens, 70 Icterus cucu/Iatus, 74, 82 galbuta, 74, 82 parisorum, 74 spurius, 74 Ictinio mississippiensis, 103-104, 121 Ixoreus naeuius, 65 Jaeger, Long-tailed, 54 Parasitic, 54 Pomarine, 54 Jehl, J. R., Jr., see Yochem, P. K. 194 Junco, Dark-eyed, 73, 81 Junco hyemaiis, 73, 81 Kestrel, American, 51, 56 Killdeer, 29, 52, 77, 160 Kingbird, Cassin’s, 62 Eastern, 62 Thick-billed, 83 Tropical, 62, 79 Western, 62 Kingfisher, Belted, 60 Green, 95 Kinglet, Golden-crowned, 64, 79 Ruby-crowned, 64 Kite, Black-shouldered, 50 Mississippi, 103-104. 121 Kittiwake, Black-legged, 55 Knot, Red, 53, 160 Lagopus leucurus, 95, 98 Langham, Jeri M., Twelfth Report of the California Bird Records Committee, 97-130 Lanius cristatus, 65, 107, 113-114 excubitor , 66 ludouicianus, 66 Lark, Horned, 62 Lams argentatus, 10, 55, 78 atricilla , 54, 57 belcher i, 95 californicus, 1-12, 55 canus , 55 delawarensis, 7, 8, 55 fuscus, 110 glaucescens, 55, 78 glaucoides, 95 heermanni, 55 hyperboreus , 55, 78 minutus, 110 Philadelphia , 55 pipixcan , 55 occidentalis, 30, 42 thayeri, 55, 78 Laterallus jarnaicensis, 43, 104 Limnodromus griseus. 54, 160, 169, 170 scolopaceus, 54, 160, 163, 170 sp., 162, 164, 166, 169-171 Limosa fedoa, 53, 159, 160, 162, 163, 165-171 lapponica , 121 Longspun Chestnut-collared, 73, 81 Lapland, 73 Smith’s, 95 Loon, Common, 46, 76 Pacific, 46, 76 Red-throated, 46 Yellow-billed, 100, 119, 125 Loxia curuirostra, 75, 82 Mallard, 49 Manolis, Tim, Atlasing California’s Breeding Birds-County by County, 92-94 Martin, Purple, 62 Meadowlark, Western, 73, 82 Eastern, 82, 95 Melanerpes formicivorus, 60 lewis, 60, 79 Melanitta fusca, 50, 77 nigra, 49 perspicillata, 50, 77 Melospiza georgiana, 72 lincolnii, 72, 81 melodia , 72, 81 Merganser, Red-breasted, 50, 77 Mergus serrator, 50, 77 Merlin, 51 Mimodes graysoni, 142, 143 Mimus polyglottos, 65, 141 Mniotilta uaria, 69 Mockingbird, Northern, 65, 141 Socorro, 142, 143 Molothrus ater, 13-26, 74 Moorhen, Common, 51 Motacilla alba/lugens , 65, 80 cinerea, 95, 98 Murre, Common. 42 Thick-billed, 58, 121 Murrelet, Ancient, 58, 78, 147, 150, 152 Craveri’s, 58 Marbled, 58, 145-155 Xantus, 58, 78 Myadestes townsendi, 64, 79 Myiarchus cinerascens, 62 crinitus , 62 tyrannulus, 62 Nandayus nenday, 82 Neel, L., see Yochem, P. K. Niemuth, Neal D., Golden Eagles Nest on Center-Pivot Irrigation System, 39 Nighthawk, Common, 59 Lesser, 59 Night-Heron, Black-crowned, 48, 104 Yellow-crowned, 102, 141 Nucifraga columbiana , 63 Numenius americanus, 53, 77, 160, 163-166, 170 phaeopus, 53, 160 Nutcracker, Clark’s, 63 195 Nuthatch, Pygmy, 63 Red-breasted, 63, 189-190 White-breasted, 63 Nyctanassa violacea , 102, 141 Nycticorax nycticorax, 48, 104 Oceonites oceanicus, 98, 100 Oceanodroma furcata. 47, 76 hornochroa, 42 leucorhoa, 42 melania, 47, 76 tristrami , 119-120 Oenanthe oenanthe, 64 Oldsquaw, 49, 77 Oporornis agilis, 69, 109, 116, 123-124 formosus, 69, 81, 116 Philadelphia, 69, 81, 109, 116-117, 124 tolmiei , 69 Oreoscoptes montanus, 65 Oriole, Hooded, 74, 82 Northern, 74, 82 Orchard, 74 Scott’s, 74 Osprey, 50 Otus flammeolus, 35-36 Overibird, 69, 81 Owl, Barn, 59 Barred, 98, 106, 111 Burrowing, 59, 78 Flammulated, 35-36 Great Horned, 59, 78 Long-eared, 59 Northern Saw-whet, 59 Short-eared, 59 Oxyura jamaicensis, 50 Oystercatcher, American Black, 42 Page, G. W., see Ramer, B. A. Palacios, Eduardo, and Lucia Alfaro, Breeding Birds of Laguna Figueroa and La Pinta Pond, Baja California, Mexico, 27-32 Pandion haliaetus, 50 Parakeet, Black-headed, 82 Green, 141 Parula, Northern, 67 Tropical, 141, 142 Parula arnericana, 67 pitiayumi , 141, 142 Passer domesticus, 75, 82 Passerculus sandwichensis, 72, 81 sandwichertsi s heldingi , 31 Passerella iliaca, 72 Passerina amoena, 70 ciris, 71, 117 cyartea, 71 Patten, Michael, A., An Update from the California Bird Records Committee, 95; and Kurt Radamaker, A Fall Record of the Sharp-tailed Sparrow for Interior California, 37-38; and Brian E. Daniels, First Record of the Long-toed Stint in California, 131- 138 Pelecarms erythrorhync'nos , 3 occidentalis, 42, 44, 47, 76 Pelican, American White, 3 Brown, 42, 44, 47, 76 Petrel, Cook’s, 82, 98 Solander’s, 95 Murphy’s, 95, 98 Pewee, Eastern Wood, 61 Greater, 111 Western Wood, 61 Phaethon rubricauda, 47 Phainopepla, 65 Phainopepla nitens , 65 Phalacrocorax auritus, 3, 42 pelagicus, 42 penicillatus, 42 Phalaenoptilus nuttallii , 59 Phalarope, Red, 54, 163 Red-necked, 54, 163 Wilson’s, 54, 163 Phalaropus fulicaria, 54, 163 lobatus , 54, 163 tricolor, 54, 163 Pheucticus ludouicianus, 70 ludouicianus x melanocephalus, 70, 81 melanocephalus , 70, 81 Phoebe, Black, 61 Eastern, 61 Say’s, 62, 79 Phylloscopus fuscatus, 64, 79 Pigeon, Band-tailed, 58 Pintail, Northern, 49 Pipilo chlorurus, 71 erythrophthalmus, 71, 81 erythrophthalmus socorroensis, 141 Pipit, American, 65, 80 Red-throated, 65, 80, 113, 123 Sprague’s, 65, 106, 113 Piranga flaua, 70 ludouiciana, 70, 81 oliuacea, 70, 117 rubra, 70 Plectrophenax nivalis, 73, 82, 119 Plegadis chihi, 43 Plover, Black-bellied, 51, 160, 162, 163, 165, 166, 170, 172 196 Kittlitz’s, 124 Lesser Golden, 51-52, 56 Mongolian, 105 Semipalmated, 52, 77, 160 Snowy, 29. 52, 163, 171 Wilson’s, 121 Pluuialis dominica , 51-52, 56 squatarola , 51, 160, 162, 163, 165, 166, 170, 172 Pochard, Common, 95 Podiceps auritus, 46 grisegena, 46, 76 nigricollis, 46, 76 Podilymbus podiceps, 46 Polioptila caeruiea, 64 Polyborus p/ancus, 95 Polysticta stelleri, 103 Pooecetes gramineus, 71 Poor-will, Common, 59 Porphyrula martinica, 105 Porzana Carolina , 51, 104 Powers, Kevin D., see Sealy, S. Progne subis, 62 Protonotaria citrea, 69, 98, 115-116 Ptarmigan, White-tailed, 95, 98 Pterodroma cookii, 82, 98 solandri, 95 ultima, 95, 98 Ptychoramphus aleuticus, 43 Puffin, Horned, 58 Tufted, 43 Puffinus auricularis, 119, 141 bulled, 47 carneipes , 47 creatopus, 47 griseus, 47, 76 opisthomelas, 47 tenuirostris, 47 Pyle, Peter, and R. Philip Henderson, The Birds of Southeast Faralion Island: Occurrence and Seasonal Distribution of Migratory Species, 41-84 Quintana-Barrios, L., see Ruiz-Campos, G. Quiscalus quiscula, 119, 124 Radamaker, Kurt, see Patten, M. A. Rail, Black, 43, 104 Clapper, 43 Virginia, 51 Yellow, 104 Rallus limicola, 51 longirostris, 43 Ramer, Bernadette A., Gary W. Page, and Mary M. Yoklavich, Seasonal Abundance, Habitat Use, and Diet of Shorebirds in Elkhorn Slough, California, 157-174 Raven, Common, 63 Recuruirostra americana, 29, 52, 160, 162, 163, 165, 166, 169-172 Redstart, American, 69 Regulus calendula, 64 satrapa, 64, 79 Riparia riparia, 63 Rissa tridactyla, 55 Robin, American, 65, 80 Rodriguez, Antonio, see Rodriguez-E. , R. Rodriguez-Estrella, Ricardo, Gustavo Arnaud, Sergio Alvarez Cardenas, and Antonio Rodriguez, Predation by Feral Cats on Birds at Isla Socorro, Mexico, 141-143 Ruiz-Campos, Gorgonio, and Lorenzo Quintana-Barrios, First Mainland Record of the Red-breasted Nuthatch from Baja California, Mexico, 189-190 Sada, Andres M., see Santaella, L. Salpinctes obsoletus, 63, 79 Sanderling, 53, 160, 164, 166, 170 Sandpiper, Baird’s, 53 Buff-breasted, 54, 108, 110 Least, 53, 131, 134-136, 159, 160, 162-164, 166, 169-171 Pectoral, 53 Rock, 53 Rufous-necked, 82, 108 Semipalmated, 53 Sharp-tailed, 53 Solitary, 52 Spotted, 52 Upland, 52, 77 Western, 53, 131, 159, 160, 162-171 White-rumped, 108, 121 Wood, 82 Sandplover, Kittlitz’s, 124 Santaella, Luis, and Andres M. Sada, A Short-tailed Albatross Observed near San Benedicto Island, Revilligigedo Islands, Mexico, 33-34 Sapsucker, Red-breasted, 60 Red-naped, 60 Sayornis nigricans, 61 phoebe, 61 saya, 62, 79 Scaup, Greater, 49 Lesser, 49 Schulz, Terry A., Two New Records of the Flammulated Owl ( Otus 197 flammeolus ) in the Sacramento Valley, California, 35-36 Scoter, Black, 49 Surf, 50, 77 White-winged, 50, 77 Sealy. Spencer G., Harry R. Carter, W. David Shuford, Kevin D. Powers, and Charles A. Chase, III, Long-Distance Vagrancy of the Asiatic Marbled Murrelet in North America, 1979-1989, 145-155 Seiurus aurocapillus, 69, 81 noveboracensis, 69 Selasphorus platycercus, 184 rufus, 60. 78-79, 175, 185 sasin, 60, 78-79, 175-188 ^ sp., 43 Setophaga ruticiUa , 69 Shearwater, Black-vented, 47 Buller’s, 47 Flesh-footed, 47 Pink-footed, 47 Short -tailed, 47 Sooty, 47, 76 Townsend’s, 119, 141 Shoveler, Northern, 49 Shrike, Brown, 65, 107, 113-114 Loggerhead, 66 Northern, 66 Sicilia currucoides , 64 mexicana, 64 Siskin, Pine, 75 Sitta canadensis, 63, 189-190 carolinensis, 63 pygmaea, 63 Skua, South Polar, 54 Snipe, Common, 54 Solitaire, Townsend’s, 64, 79 Somateria spectabilis, 103 Sora, 51, 104 Sparrow, American Tree, 71 Baird’s, 72 Belding’s Savannah, 31 Black-chinned, 71 Black-throated, 71 Brewer’s, 71 Cassin’s, 71, 111, 117 Chipping, 71 Chipping x Brewer’s, 71 Clay-colored, 71 Field, 71 Fox, 72 Golden-crowned, 72 Golden-crowned x White-crowned, 73 Grasshopper, 72 Harris’, 73 House, 75, 82 Lark, 71 LeConte’s, 72, 112, 117, 118 Lincoln’s, 72, 81 Sage, 72 Savannah, 31, 72, 81 Sharp-tailed, 37-38, 72, 118, 124 Song, 72, 81 Swamp, 72 Vesper, 71 White-crowned, 73 White-throated. 72 Sphyrapicus nuchalis, 60 ruber, 60 Spiza americana, 71 Spizella arborea, 71 atrogularis, 71 breweri, 71 pallida, 71 passerine, 71 passerina x breweri, 71 pusilla, 71 Starling, European, 66, 80 Stelgidopteryx serripennis, 63, 79 Stellula calliope, 60, 186 Stercorarius longicaudus, 54 parasiticus, 54 pomarinus, 54 Sterna antillarum. 30-31 caspia, 55 elegans, 55 jorsteri, 29-30. 58 hirundo, 55 paradisaea , 58 sanduicensis, 110 Stewart, B. S., see Yochem, P. K. Stilt, Black-necked, 29, 160, 163 Stint, Long-toed, 131-138 Rufous-necked, 82, 108 Storm-Petrel, Ashy, 42 Black, 47, 76 Fork-tailed, 47, 76 Leach’s, 42 Sooty, 119-120 Tristram’s, 119-120 Wilson’s, 98, 100 Streptopelia orientals, 95 risoria, 82 Strix varia, 98, 106, 111 Sturnella magna , 82, 95 neglecta, 73, 82 Sturnus vulgaris, 66, 80 Sula leucogaster, 47 sula, 47, 100-101 Surfbird, 53 Swallow, Bank, 63 198 Barn, 63 Cave, 95 Cliff, 63 N. Rough-winged, 63, 79 Tree, 62, 79 Violet-green, 62, 79 Swan, Trumpeter, 102-103, 120 Tundra, 48, 102 Swift, Black, 59 Chimney, 59, 86, 90 Vaux’s, 59, 85-91 White-throated, 59 Synthliboramphus antiquus , 58, 78 crauerl , 58 hypoleucus , 58, 78 Tachycineta bicolor, 62, 79 thalassina, 62, 79 Tanager, Hepatic, 70 Scarlet, 70, 117 Summer, 70 Western, 70, 81 Tarsiger cyanurus, 64, 95 Tattler, Wandering, 52, 77 Teal, Blue-winged, 49 Cinnamon, 49, 77, 139 Green -winged, 49 Tern, Arctic, 58 Caspian, 55 Common, 55 Elegant, 55 Forster’s, 29-30, 58 Least, 30-31 Sandwich, 110 Thompson, S., see Yochem, P. K. Thrasher, Bendire’s, 65 Brown, 65 Curve-billed, 122 Sage, 65 Thrush, Eyebrowed, 95 Gray-cheeked, 64, 112 Hermit, 64 Swainson’s, 64 Varied, 65 Wood, 112 Thryomanes bewickii, 63 sissonii, 141, 142 Towhee, Green-tailed, 71 Rufous-sided, 71, 81 Socorro Rufous-sided, 141 Toxostoma bendirei, 65 curvirostre, 122 ru/um, 65 Tringa flavipes , 52, 160 glareola , 82 melanoleuca , 52, 160 solitaria, 52 Troglodytes aedon , 63, 79 sissonii, 141, 142 troglodytes, 63 Tropicbird, Red-tailed, 47 Tryngites subruficollis , 54, 108, 110 Turdus migratorius, 65, 80 obscurus, 95 Turnstone, Black, 53, 78 Ruddy, 53, 78, 160 Turtle-Dove, Oriental (Rufous), 95 Ringed, 82 Tyrannus crassirostris, 83 forficatus, 62, 112, 122, 125 melancholicus, 62, 79 tyrannus, 62 uerticaiis, 62 vociferans, 62 Tyto alba, 59 Uria aalge , 42 lomvia, 58, 121 Veery, 64 Vermiuora celata, 67, 80 chrysoptera, 67, 114, 123 luciae, 67 peregrina, 67, 80 pinus, 108, 114, 123 pinus x chrysoptera, 123 ruficapilla, 67 uirginiae, 67 Vireo, Bell’s, 22 Hutton’s, 66, 80 Philadelphia, 66, 80, 114, 123 Red -eyed, 66 Solitary, 66 Warbling, 66 White-eyed, 66, 114 Yellow-green, 66, 114 Yellow- throated, 66, 114 Vireo bellii , 22 flavifrons , 66, 114 flavoviridis, 66, 114 gilvus, 66 griseus , 66, 114 huttoni , 66, 80 olivaceus, 66 philadelphicus, 66, 80, 114, 123 solitarius, 66 Vulture, Turkey, 50 Wagtail, Gray, 95, 98 White/Black-backed, 65, 80 Warbler, Bay-breasted, 69 Black-and-white, 69 199 Blackburnian, 68 Blackpoll, 69, 80-81 Black-throated Blue, 67 Black-throated Gray, 57, 68 Black-throated Green, 68 Blue-winged, 108, 114, 123 Canada, 70 Cape May, 67 Cerulean, 69, 123 Chestnut-sided, 67, 80 Connecticut, 69, 109, 116, 123-124 Dusky, 64, 79 Golden-cheeked, 68 Golden-winged, 67, 114, 123 Grace’s 115 Hermit, 68, 80 Hooded, 70 Kentucky, 69, 81, 116 Lawrence’s, 123 Lucy’s, 67 MacGillivray’s, 69 Magnolia, 67 Mourning, 69, 81, 109, 116-117, 123-124 Nashville, 67 Northern Paruia, 67 Orange-crowned, 67, 80 Palm, 68-69 Pine, 68, 115 Prairie, 68 Prothonotary, 69, 98, 115-116 Tennessee, 67, 80 Townsend s, 68 Townsend’s x Hermit, 68 Tropical Paruia, 141, 142 Virginia’s, 67 Wilson’s, 70, 81 Worm-eating, 69, 109, 116 Yellow, 67 Yellow- rumped, 67-68, 80 Yellow-throated, 68, 80, 114-115 Waterthrush, Northern, 69 Waxwing, Bohemian, 65 Cedar, 65 Weaver, Cutthroat, 83 Wheatear, Northern, 64 Whimbrel, 53, 160 Whistling-Duck, Black-bellied, 120 Wigeon, American. 49 Willet, 52, 159, 160, 162-171 Wi/sonia canadensis , 70 citrina, 70 pusilla, 70, 81 Woodpecker, Acorn, 60 Lewis’, 60, 79 Pileated, 85-91 Wood-Pewee, Eastern, 61 Western, 61 Wren, Bewick’s, 63 House, 63, 79 Marsh, 63 Rock, 63, 79 Sedge, 112 Socorro, 141, 142 Winter, 63 Xanthocephalus xanthocephalus, 74 Xema sabini, 55, 78 Yellowlegs, Greater, 52, 160 Lesser, 52, 160 Yellowthroat, Common, 69 Yochem, P. K., J. R. Jehl, Jr., B. S. Stewart, S. Thompson, and L. Neel, Distribution and History of California Gull Colonies in Nevada, 1-12 Zenaida asiatica , 58 graysoni, 141 macroura, 58, 141, 142 Zonotrichia albicoUis , 72 atricapilla, 72 atricapilla x leucophrys, 73 leucophrys, 73 querula, 73 200 Volume 22, Number 4, 1991 Long-distance Vagrancy of the Asiatic Marbled Munrelet in North America, 1979-1989 Spencer G. Sealy , Harry R. Carter, W. David Shuford, Kevin D. Powers, and Charles A. Chase III 145 Seasonal Abundance, Habitat Use, and Diet of Shorebirds in Elkhorn Slough, California Bernadette A. Ramer, Gary W. Page, and Mary M. Yokiavich 157 Experiments with Allen’s and Anna’s Hummingbirds at Sugar Water Feeders in Spring Tonna Harris-Haller and Stanley W. Harris 175 NOTE First Mainland Record of the Red-breasted Nuthatch from Baja California, Mexico Gorgonio Ruiz-Campos and Lorenzo Quintana- Barrios 189 Index Mildred Comar 191 Cover photo by © David A. Leatherman of Fort Collins, Colorado: Sharp-shinned Hawk (Accipiter striatus). Crow Valley Campground, Pawnee National Grasslands, Colorado. 7 October 1989. Western Birds solicits papers that are both useful to and understandable by amateur field ornithologists and also contribute significantly to scientific litera- ture. The journal welcomes contributions from both professionals and amateurs. Appropriate topics include distribution, migration, status, identifica- tion, geographic variation, conservation, behavior, ecology, population dynamics, habitat requirements, the effects of pollution, and techniques for censusing, sound recording, and photographing birds in the field. Papers of general interest will be considered regardless of their geographic origin, but particularly desired are reports of studies done in or bearing on the Rocky Mountain and Pacific states and provinces, including Alaska and Hawaii, western Texas, northwestern Mexico, and the northeastern Pacific Ocean. Send manuscripts to Philip Unitt, 3411 Felton Street, San Diego, CA 92104. For matter of style consult the Suggestions to Contributors to Western Birds (8 pages available at no cost from the editor) and the Council of Biology Editors Style Manual (available for $24 from the Council of Biology Editors, Inc., 9650 Rockville Pike, Bethesda, MD 20814). Reprints can be ordered at authors expense from the Editor when proof is returned or earlier. Good photographs of rare and unusual birds, unaccompanied by an article but with caption including species, date, locality and other pertinent information, are wanted for publication in Western Birds. Submit photos and captions to Photo Editor.