564 
Archibuteo, 178 
Architrochilus, 252 
Arctic Tern, 24 
Arctic Towhee, 394 
arctica, Gavia, 11 
arctica, Sialia, 529 
arcticus, Pipilo maculatus, 394 
Ardea, 82 
Ardeide, 79 
arenacea, Spizella pusilla, 373 
Arenaria, 136 
arenaria, Calidris, 118 
arenicola, Otocoris alpestris, 279 
argentatus, Larus, 16 
Arizona Goldfinch, 345 
arizone, Astragalinus psaltria, 345 
arizonz, Spizella passerina, 369 
Arkansas Goldfinch, 344 
Arkansas Kingbird, 262 
Ash-throated Flycatcher, 264 
asiatica, Melopelia, 161 
Asio, 197 
Astragalinus, 342 
Astur, 171 
Asyndesmus, 235 
ater, Molothrus, 302 
atrata, Leucosticte, 338 
atricapillus, Astur, 171 
atricilla, Larus, 18 
auduboni, Dendroica, 453 
auduboni, Hylocichla guttata, 521 
Audubon’s Warbler, 453 
auritus, Colymbus, 6 
auritus, Phalacrocorax, 27 
aurocapillus, Seiurus, 461 
australis, Leucosticte, 338 
utumnalis, Plegadis, 76 
Avocet, American, 104 
Beolophus, 503 
bairdi, Centronyx, 358 
bairdi, Dryobates scalaris, 227 
bairdi, Pisobia, 115 
bairdi, Sialia mexicana, 527 
bairdi, Thryomanes bewicki, 490 
Baird’s Sandpiper, 115 
Baird’s Sparrow, 358 
Baird’s Wren, 490 
Bald Eagle, 183 
Baldpate, 40 
Baltimore Oriole, 312 
Band-tailed Pigeon, 157 
Bank-Swallow, 422 
Barn-Owl, American, 196 
Barn-Swallow, 417 
Barred Owl, 200 
Barrow’s Golden-eye, 57 
Birds of Colorado 
Bartramia, 125 
Bartramian Sandpiper, 125 
Batchelder’s Woodpecker, 226 
belli, Vireo, 437 
‘Bell’s Vireo, 437 
Belted Kingfisher, 221 
bendirei, Toxostoma, 484 
Bendire’s Thrasher, 484 
bicolor, Iridiprocne, 418 
bimaculatus, Ammodramus 
savannarum, 359 
Bittern, American, 79 
Bittern, Least, 81 
Black and White Warbler, 441 
Black Rail, 96 
Black Rose-Finch, 338 
Black Swift, 248 
Black Tern, 25 
Black-bellied Plover, 130 
Black-billed Cuckoo, 220 
Blackbird, Brewer’s, 316 
Blackbird, Red-winged, 306 
Blackbird, Rusty, 315 
Blackbird, Yellow-headed, 304 
Black-chinned Humming-bird, 252 
Black-crowned, Night-Heron, 87 
Black-headed Grosbeak, 399 
Black-necked Stilt, 106 
Blackpoll Warbler, 455 
Black-throated Blue Warbler, 451 
Black-throated Green Warbler, 459 
Black-throated Grey Warbler, 457 
Black-throated Loon, 11 
Blue Jay, 285 
Bluebird, Chestnut-backed, 527 
Bluebird, Eastern, 527 
Bluebird, Mountain, 529 
Blue-winged Teal, 43 
Bobolink, 300 
Bob-white, 139 
Bohemian Waxwing, 425 
Bombycilla, 424 
Bombycillide, 424 
Bonaparte’s Gull, 20 
Bonasa, 147 
borealis, Cypseloides niger, 248 
borealis, Lanius, 428 
borealis, Nuttallornis, 268 
boschas, Anas, 36 
Botaurus, 79 
brachyotus, Otus, 199 
Brant, 71 
Branta, 68 
breweri, Spizella, 372 
Brewer’s Blackbird, 316 
Brewer’s Sparrow, 372 
Broad-tailed Humming-bird, 253 
