182 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



Bonasa umbellus incanus Aldrich and Friedmann, Condor, xlv, 1943, 99 (Barclay, 

 15 miles e. of Salt Lake City, Utah; distr. ; descr. ; tax.).— Behle, Condor, 

 xlvi, 1944, 72 (Utah). 



BONASA UMBELLUS YUKONENSIS Grinnell 



Yukon Ruffed Grouse 



Adult (gfay phase). — Similar to that of Bonasa umbellus umbellus but 

 much paler, the palest of all the races of the species, the whitish areas 

 above more extensive and purer white, less washed with bufify ; nearest 

 to the gray phase of incana but paler, with more white, and with the 

 most extensive tarsal feathering of all the subspecies ; the gray areas 

 of the upperparts of head, body, wings, and tail pale neutral gray to 

 smoke gray, the brown, restricted to the top of the head, the inter- 

 scapulars, wings, and middle of the back, is pale tawny-olive to pale 

 Saccardo's umber; below as in umbellus but more abundantly barred 

 with buflfy drab. 



Adult (brown phase). — Similar to the gray phase but with the tail 

 between sayal brown and Saccardo's umber distally vermiculated and 

 washed with smoke gra}'-, with the feathers of the interscapulars, back, 

 and rump with very broad transverse subterminal bands of mummy brown 

 (these bands present but concealed in the gray phase), and with the 

 ventral barrings darker— Dresden brown to mummy brown. 



Juvenal (female only seen). — Above much grayer than any seen of 

 B. u. umbellus, nearest to that of B. u. phaia, the general coloration of 

 the upper side of the head, body, and wings being drab to hair brown, 

 the interscapulars, scapulars, crown, and upper back being broadly trans- 

 versely blotched with fuscous to black, and with pale tilleul-buflf shaft 

 streaks and narrow cross bars of slightly darker tilleul bufT; rectrices as 

 in phaios but slightly more washed with drab. 



Downy young. — None seen. 



Adult' male.— Wmg 174-190 (182); tail 129-168 (148.5); culmen 

 from base 24.9-29.1 (26.8) ; tarsus 38.3-45.0 (42.4) ; middle toe without 

 claw 34-38.5 (36.7) ; unfeathered part of tarsus 8.8-15.7 (11.2 mm.).^^ 



Adult female.— Wing 170-182 (177.6) ; tail 127-137 (130.8) ; culmen 

 from base 24-27.9 (26.6) ; tarsus 38.8-43.5 (41.2) ; middle toe withotit 

 claw 33-37 (34.9) ; unfeathered part of tarsus 7.3-14.9 (11.0 mm.).«8 



Range. — Subclimax deciduous woodlands (aspen, poplar, and willow 

 communities) chiefly in the white-spruce, pine, and larch association, in 

 the ecotone, between the northern coniferous and tundra biomes (Hudson- 

 ian Life Zone) ; from western Alaska (Akiak and Nulato) eastward 

 across Alaska, chiefly in the valleys of the Yukon and Kuskokwim Rivers, 



Thirty-four specimens from Alaska, Mackenzie, and northern Alberta. 

 ' Ten specimens Alaska, Mackenzie, and northern Alberta. 



