190 TJ- S. NATIONAL MUSEUM BULLETIN 217 



The flocks in winter occasionally flew out of sight several miles 

 away. In summer male birds signaling or nesting were not seen 

 closer together than about a mile. In the barren Old Crow Moun- 

 tains that much range might be required for a brood of chicks, and 

 the winter flock of 50 would accordingly need some 25 square miles 

 of mountain for nesting. The first Old Crow Mountain scarcely con- 

 tains 10 square miles of nesting territory. The others of that iso- 

 lated mountain group may provide 100 square miles for nesting. 

 These rough estimates suggest that winter flocks convene from a nest- 

 ing area with peripheral points 30 miles separated. Within this area 

 some may be resident through a year. Tracks showed that early in 

 April rock ptarmigan had been among the dwarf birch, willow, and 

 alder along the margin of the spruce forest, at about 1,500 feet eleva- 

 tion. We saw them in April, May, and June above 2,000 feet on the 

 bare rocky slopes and mountain tops. Winter and summer move- 

 ments of rock ptarmigan over Old Crow did not show regularity worth 

 the designation of migrations, and we have not had certain evidence 

 for any regular migration of rock ptarmigan in Alaska. As they are 

 one of the swiftest among birds and have large hearts for their weight, 

 rock ptarmigan are physically equipped for long flights. 



The race L. m. nelsoni, which is easily distinguishable by the pat- 

 tern of even a few feathers of summer plumage in both sexes, occupies 

 all Alaska except the southeastern part. In arctic Yukon this race 

 extends eastward at least to Old Crow without deviation in character- 

 istics. Somewhere between there and northern Mackenzie occurs the 

 border between nelsoni and rupestris. Porsild (1943) reports rwpes- 

 tris a rare visitor to the Mackenzie Delta where the forested lowland 

 may separate the races of these mountain and tundra birds. In south- 

 ern Yukon, however. Rand (1946) assigns 15 specimens to rupestris. 

 As is the case among several species of migratory birds, the race found 

 in Alaska extends eastward only across northern Yukon. 



The Indian name for the rock ptarmigan is Toko. 



FamOy GRUIDAE: Cranes 

 Grus canadensis canadensis (Linnaeus) 



The first crane that we saw on May 14 was alone circling and call- 

 ing high in the air. Again we heard one on May 18 and saw two on 

 May 22. Cranes are well known to the Indians, who said that they 

 nest on Crow Flats, but evidently not many come to Porcupine Valley. 

 Their Indian name is Chya. 



Rand (1946) quoted reports of great migrating flocks passing over 

 points marking courses from the Liard River to the upper tributaries 



