210 TJ. S. NATIONAL MUSEUM BULLETIN 217 



birds shows that even in the barren appearing mountains there is 

 enough food. 



The arctic breeding range of this race extends across Alaska and 

 Yukon and to Mackenzie (A.O.U., Check-list, 1957) although Porsild 

 mentions that E. a. hoyti occurs on the Mackenzie Delta. The winter- 

 ing range in the northwestern States indicates that these larks migrate 

 through the western mountains. 



The Indian name is Katu. 



Family HIRUNDINID AE : SwaUows 



Four species of swallows extend their nesting range beyond 

 the arctic circle in Yukon and Alaska and two nest also in arctic Mac- 

 kenzie. These western ranges are far north of their limits in the east, 

 and indicate northward migration through the mountain States and 

 Provinces. Inasmuch as the northwesterly nesting races of several 

 eastern species of birds extend farthest north, the tree swallows of 

 Alaska may come from eastern wintering situations. 



The four species have quite separate wintering areas, but view- 

 ing their entire distribution only the violet-green swallows (Tachy- 

 cinefa) are restricted to the west. The early presence of violet-green 

 and tree swallows at Fort Yukon is so far ahead of their arrival at 

 Old Crow that migration evidently does not enter the Porcupine Val- 

 ley from Alaska and probably does not pass westward from Old Crow 

 along the Porcupine Eiver. 



Tachycineta thalassina lepida Meams 



1 male May 21 weight 18.5 g. fat testes 4.5x6, 3.5x4 



mm. 



This violet-green swallow was brought to us by Joe Kay who 

 recognized it among the tree swallows then common about the village. 

 By comparison with breeding tree swallows the testes of this violet- 

 green swallow were not mature. Kay explained that violet-green 

 swallows are not often to be expected around the village, for as indi- 

 cated by its Indian name, Tta skait sove, it is a mountain swallow. 

 Francis Williamson had seen them when he arrived at Fort Yukon 

 on May 10. On June 21 a pair occupied a nest box at Old Crow. 



The nesting range of these swallows extends in Alaska northward 

 to Bettles but they are sometimes driven from their nesting places 

 by the more aggressive tree swallows, which are more numerous 

 where their common range just passes the arctic circle. Southward, 

 violet-green swallows nest in western Alberta and British Columbia 

 and migrate to southern California and Costa Rica in winter. 



