Condor 83:65-77 0 The Cooper Ornithological Society 1981 MIGRANTBIRDS’ AT SHEMYA ISLAND, ALEUTIAN ISLANDS, ALASKA DANIEL D. GIBSON ABSTRACT.-A five-season study of bird migration in the Near Islands, west- ern Aleutian Islands, Alaska, resulted in data that suggest that some 30 Pale- arctic and Aleutican taxa that are of irregular occurrence or are virtually un- known in Alaska east of 180” occur regularly on passage in this area in small numbers, some of them both spring and autumn. Most of these forms are apparently en route in spring to the Koryak Highlands or the Anadyr River basin, both of which areas lie directly north of the Near Islands, in the U.S.S.R. An annotated list of 147 taxa discusses all forms recorded. The Near Islands, named by Russian ex- garbage dumps, World War II wreckage). plorers for their proximity to Asia, are five Their relative importance to migrants on the islands-Attu, Agattu, Alaid, Nizki, and island was not determined systematically, Shemya-that make up the westernmost partly because most migrants were water- group of the Aleutian Islands, Alaska. fowl or shorebirds, whose habitat uses were Shemya is the easternmost of the group straightforward, and partly because the (52”43N,’ 174”07E).’ It is situated 1,500 km availability of any cover and food on this west and south of the Alaska mainland, 630 small island were often the only criteria that km south and east of Cape Olyutorsk, Ko- seemed important (i.e., the substrate many ryak Highlands, and 600 km east of Kam- migrants used depended on the topography chatka (Fig. 1). It is 320 km southeast of the and its function in protecting them from the Commander Islands. weather). The island is part of the Aleutian Shemya is a small, low-lying island, a Islands National Wildlife Refuge, and since “raised, wave-cut platform” (Gates et al. 1943 the U.S. Air Force has maintained it 1971) of 14.2 km2 with a coastline of 21.5 as a military installation. km. It is treeless, as are all of the Aleutians, During the periods 9-23 May 1975, 30 but it differs from many of the others in April-31 May 1976, 29 April-7 June 1977, being quite flat-a gently rolling, meadow- 31 August-3 October 1977, and 15 August- covered plateau that drops from elevations 13 October 1978 I conducted fieldwork on of 70-80+ m above North Beach to lo-15 the island, under cooperative agreements m above South Beach. Fifteen permanent between the University of Alaska Museum lakes regularly support transient waterfowl and the U.S. Fish and Wildlife Service, and populations, but three of the largest (Upper, with the cooperation of the U.S. Air Force, Lower, and Laundry lakes) support a diver- in an effort to inventory the migrant bird sity of birds not seen at the others. The forms that occur in this poorly-known and steep bluffs along the irregularly sculpted westernmost part of Alaska and of the Ref- north shore (Fig. 2), with its protected am- uge. I was accompanied in the field in dif- phitheaters and bays and dense tall forb ferent seasons by George E. Hall, Theodore vegetation, are most important to transient G. Tobish, and Raymond S. Hadley, all ex- passerines. perienced Alaskan field ornithologists. Shemya has a maritime climate. Fog and Fieldwork was conducted on foot, except rain are characteristic, and violent storms, in spring 1977, when a truck was available. often with sustained winds over 50 kph, oc- We wanted to inventory all migrants on the cur frequently, usually arriving from the island, so we surveyed it in an opportunistic southwest or west in spring, from the north- fashion, monitoring habitats and topography west or west in fall. Eleven of the 29 avian in daily response to weather conditions and habitats described for Alaska by Kessel to the stage of migration. The small size of (1979) were identified at Shemya: Lacus- the island enabled us to survey carefully the trine Waters and Shorelines, Fluviatile entire perimeter on days when we deemed Waters and Shorelines, Inshore Waters, it profitable to do so. Experience elsewhere Rocky Shores and Reefs, Beaches, Cliffs in the Aleutians had taught that most (coastal), Wet Meadows, Dwarf Shrub through-migrants make landfall and remain Meadows, Grass Meadows, Tall Forb at the perimeter of an island, so that, except Meadows, and Artificial (e.g., buildings, to check prominent features elsewhere on [651 66 DANIEL D. GIBSON FIGURE 1. The Near Islands in perspective. (Arrows indicate routes of eastern Asia flyway [see McClure 19741 that involve Alaska migrants.) the island (e.g., deep-water lakes for water- currence farther east. This paper discusses fowl), time was best spent surveying perim- the timing, abundance, and zoogeographic eter habitats. The data presented in the an- affinities of these forms. notated list are the result of 341 man/days (174 calendar days) afield on the island. On ANNOTATED LIST only seven additional days, all in autumn One hundred forty-five species (147 forms) 1978, were storms so severe that we sus- of 27 families of birds were recorded during pended field work. the survey, 38% of the 383 species known Murie (1959) discussed the historic to have occurred in Alaska through 1978 origins of birds in the Aleutian Islands, and (Kessel and Gibson 1978, plus two addition- Emison et al. (1971) and Byrd et al. (1974) al species in this paper). Phylogenetic se- outlined the zoogeographic affinities of quence and nomenclature of species gen- birds at Amchitka and Adak islands, located erally follow Morony et al. (1975). 250 and 460 km east of Shemya, respective- Subspecies nomenclature and limits follow ly, but the large proportion of the Palearctic Vaurie (1959, 1965) or the A.O.U. (1957). and Aleutican components in the annual Status terminology follows Kessel and Gib- passage of birds through the westernmost son (1978). Aleutian Islands has not been recognized Subspecies listed without parentheses heretofore. It is clear from a comparison of are represented by specimens collected Shemya data with those available from the during the survey. They are on deposit at Kurile Islands, Kamchatka, Commander Is- the University of Alaska Museum (UAM), lands, Koryak Highlands, Chukotsk Penin- and I have identified them unless it is stated sula, St. Lawrence Island, Pribilof Islands, otherwise. Subspecies within parentheses and from elsewhere in the Aleutians, that are not specimen-based identifications; the Near Islands provide an annual eastern they include some forms that are recogniz- dispersal limit for a number of species and able in life (e.g., Somateria mollissima w.- subspecies of only casual or accidental oc- nigrum, Melanitta nigra americana, Nu- ALEUTIAN ISLANDS MIGRANTS 67 FIGURE 2. North Beach bluffs, Shemya Island, looking east, 2 October 1977. menius phaeopus variegatus, Leucosticte thiu), at least three monotypic genera arctoa griseonucha) and others that are pre- (Aphrixa, Eurynorhynchus, Cyclorrhyn- sumptive assignments based on range. Most &us), at least one polytypic species (Rock are, as well, inferences based on specimens Sandpiper), several monotypic species (e.g., of these forms taken elsewhere in the Aleu- Red-faced Cormorant, Emperor Goose, tian Islands. Only one of the presumptive Wandering Tattler), and a number of sub- subspecies allocations implies occurrence species (e.g., Somuteria mollissima v.-ni- of a form not substantiated by specimen in grum, Leucosticte arctoa griseonucha). Alaska-the occurrence of Podiceps a. au- Gavia stellutcl (stelluto). Red-throated Loon. Essen- ritus is inferred from timing of, and western tially Holarctic. Casual in spring. One altemate-plum- Bering Sea origin .of weather systems pre- aged bird was seen 26 May 1976. Snecies breeds else- ceding, the birds ’ arrivals. where in the Near Islands-(Murie i959). Among those not substantiated by speci- Guvia immer. Common Loon. Nenrctic (and W Pale- men at Shemya are four polytypic Holarctic arctic). Annual in spring and fall, rare. Species breeds elsewhere in the Aleutians (Murie 1959), as close as species for which I do not believe the sub- Alaidand Nizki (J. L. Trapp, U.S.F.W.S., pers. comm.). species can be inferred from either sight- Gnuiu udnmsii. Yellow-hilled Loon. Aleutican. Cas- ings or known range. The affinity of these ual in spring. One basic-plumaged bird was seen 3 May species-Common Goldeneye, Marsh 1976. Species probably winters sparingly throughout the Aleutians (pers. ohserv.). Hawk, Rough-legged Hawk, and Glaucous Podicepsgrisegena (holhollii). Red-necked Grehe. E Gull-is listed simply as Holarctic. Palearctic and W Nearctic. Annual; uncommon in Zoogeographic affinity listed after each spring and rare in fall. Maximum was 39 birds on 2 form is the fauna1 region in which the May .I977. Species prohahly winters throughout the Aleutians (pers. ohserv.). breeding range, or the greatest proportion Podiceps uuritus (au&us). Horned Grehe. Palearc- of the breeding range, of a subspecies-or tic. Casual in fall. Up to four birds were present 30 species, if monotypic-lies. Of the fauna1 September3 October 1977. There are few western regions recognized here, the Aleutican re- Aleutian records of the species (Murie 1959); this form quires explanation. This region encompas- has been recorded in the Commander Islands (Johan- sen 1961). ses the Aleutian and Commander islands, Diomedeu immutubilis. Laysan Albatross. North Pa- Bering Sea islands, northeastern Asia from cific Ocean. Annual in spring, uncommon. Species oc- the base of Kamchatka and Chaun Bay east, curred regularly off East End, where seen within one and most of Alaska (see Fay and Cade 1959). km of shore. Maximum was IO+ on 9 May 1977. Puffinus tenuirostris. Short-tailed Shearwater. South It is considered to be the differentiation Pacific Ocean.