2 NORTH AMERICAN FAUNA 76 



uncommon to very rare, and 20% (27) were localized. Shrub thicket, dwarf shrub 

 mat, coniferous forest, deciduous forest, mixed deciduous-coniferous forest, and 

 fluviatile water and shoreline habitats supported the greatest diversity of species 

 breeding and suspected of breeding. The highest concentrations of birds 

 occurred in the estuaries of Nanvak, Chagvan, and Goodnews bays during spring 

 and fall migrations and on the coastal and island cliffs during the breeding season. 



The information presented here provides the basis for range extensions of 

 several species. Our records further clarify the known or probable Alaska 

 breeding ranges of 11 species (fork-tailed storm-petrel, Oceanodroma furcata\ 

 double-crested cormorant, Phalacrocorax auritus; red-faced cormorant, 

 Phalacrocorax utile; brant, Branta hemicla; king eider, Somateria spectabilis; 

 white-tailed ptarmigan, Lagopus leucurus; black-bellied plover, Pluvialis 

 squatarola\ Pacific golden-plover, Pluvialis fulva; lesser yellowlegs, Tringa 

 flavipes; Say's phoebe, Sayomis saya; and Bohemian waxwing, Bombycilla 

 garrulus). We also provide further information on distributions or 

 documentation of unusual occurrences for nine taxa (frigatebird, Fregata spp.; 

 Baikal teal. Anas fonnosa; American kestrel, Falco sparverius; Terek sandpiper, 

 Xenus cinereus; bristle-thighed curlew, Numenius tahitiensis; slaty-backed gull, 

 Larus schistisagus; rufous hummingbird, Selasphorus rufus\ song sparrow, 

 Melospiza melodia; and red-winged blackbird, Agelaius phoeniceus). We 

 provide quantitative data on the coastal migration of 1 1 species along Bristol Bay 

 (red-throated loon, Gavia stellata; Pacific loon, Gavia pacifica; pelagic 

 cormorant, Phalacrocorax pelagicus; emperor goose, Chen canagica; brant; 

 Steller's eider. Polys ticta stelleri; common eider, Somateria mollissima; king 

 eider; black scoter, Melanitta nigra; white-winged scoter, Melanitta fusca; and 

 surf scoter, Melanitta perspicillatd). We document changes in nesting densities, 

 differences in numbers, or habitat variations of 32 species in response to human 

 activities (e.g., semipalmated plover, Charadrius semipalmatus; arctic tern, 

 Sterna paradisaea; tree swallow, Tachycineta bicolor, varied thrush, Ixoreus 

 naevius; yellow-rumped warbler, Dendroica coronata; and American tree 

 sparrow, Spizella arbored). We report the changes in a major colony of Aleutian 

 terns (Sterna aleutica^ at irregular intervals over 50 years. 



Keywords: Birds, western Alaska, distribution, status, migration, nesting habitat, 

 zoogeography. 



The Kilbuck and Ahklun mountains form the southeastern edge of 

 the Yukon-Kuskokwim River Delta and separate that flat, wet lowland 

 region from the mountainous and wooded Bristol Bay region, which is 

 to the south and east. The two mountain ranges are 30-130 km wide and 

 extend 300 km from the coast at Cape Newenham to the north side of 

 Mount Hamilton. The region contains a wide variety of geologic and 

 topographic features, including mountains of varied relief (600-1,500 m 

 above sea level [asl]), rivers often flowing out of or through large upland 

 lakes, wide and narrow river valleys, a small glacier, sea cliffs, large 

 estuaries, and rocky offshore islands. This ecologically complex area is a 



