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U. S. NATIONAL MUSEUM BULLETIN 217 



Table 9. — Land birds migrating to nest mainly in Alaska, Yukon, and western 



Mackenzie 



[ Explanation— (P) present, (M) migrant. Miration routes: (W Am) western Ajnerica, (E Am) eastern 

 America, (Pac) Pacific, (Asia) Asia, (Al) Alaska.] 



Birds 



Migration 



Anak- 



Kobuk 



Old Crow 



Range of 





route 



tuvuk 







tbe species 



Branta canadensis tavemeri 



WAm 



M 



P 



P 



Am 



Arenaria interpres interpres 



Pac 



M 



M 





Eu As Am 



Aphriza virgata 



WAm 





P 





Am 



Tringa solitaria cinnamomea 



WAm 



P 



P 



P 



Am 



Heteroscelus incanum 



Pac 



P 



P 





Am 



Limnodromus scolopaceus 



WAm 



P 



P 





Am 



Limosa lapponica baueri 



Asia 



P 



P 





Eu As Am 



Sayomis saya yukonensis 



WAm 



P 





P 



Am 



Eremophila alpestris articola 



WAm 



P 



P 



P 



Eu As Am 



PhyUoseopus borealis kennicotti 



Asia 



P 



P 





Eu As Am 



Motacilla flava tschutschensis 



Asia 



P 



P 





Eu As Am 



Ixoreus naevius meruloides 



WAm 





P 



P 



Am 



Hylocichla ustulata uieana 



E Am 







P 



Am 



Luscinia sveeica svecica 



Asia 



P 







Eu As Am 



Oenanthe oenanthe oenanthe 



Asia 



P 



P 



P 



Eu As Am 



Dendroica coronata hooveri 



WAm 





P 



P 



Am 



Leucostiete tephrocotis irvingi 



WAm 



P 



P 





Eu As Am 



Calcarius lapponicus alascensis 



WAm 



P 



P 



M 



Eu As Am 



Plectrophenax nivalis nivalis 



Al 



M 



M 



M 



Eu As Am 



Total (19) 













The migratory routes of these populations are diverse: 10 pass 

 through western America, 1 through eastern America, 2 over the 

 Pacific Ocean, 5 through Asia, and 1 lies within Alaska; while 9 

 of the species listed nest only in America, and 10 have a widespread 

 distribution in the three northern continents. It is unlikely that 

 any of these species migrated to Alaska and Yukon during the maxi- 

 mum of Wisconsin glaciation and their present migrations have 

 developed since the American ice cap melted. Their differentiation 

 in form has accordingly been brought about by special migratory 

 habits which have isolated these populations within Kecent geological 

 time. 



Of the 35 species, shown in table 10, that nest in Alaska and Yukon 

 and winter or migrate as maritime birds along Pacific American 

 coasts, 11 also nest over variously wide extents of North America and 

 the remainder are holarctic in distribution. A number of these species 

 also migrate along Atlantic coasts, but we have observed birds of 

 several of these species migrating to Old Crow from the west, and 

 there is evidently some segregation of the Pacific populations. Only 

 3 of these species (in the genera Numeniiis, Erolia, and Larus) are 

 differentiated as western American races, but these also nest east of 

 Mackenzie. Although neither restricted in range nor differentiated 

 as local races the use by these winter maritime species of long over- 

 land flight routes through complex terrain shows that special migra- 



