480 



BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Adults in winter. — Head and neck white, the hindneck tinged 

 with pale gray, the auricular region and a crescentic space immedi- 

 ately in front of eye dusky grayish ; otherwise as in summer. 



Young. — Upper parts pale gray, the feathers more or less tipped 

 with pale clay color or dull buff, this sometimes nearly uniform on 

 back and scapulars, where the gray is mostly concealed, the pileum 

 and hindneck, as well as back and scapulars, sometimes streaked with 

 dusky, but oftener immaculate; a blackish crescentic spot immediately 

 in front of eye, and a dusky grayish suffusion on upper portion of 

 auricular region, forming a more or less distinct postocular stripe; 

 rump, upper tail-coverts, tail, and wings nearly uniform pale gray; 

 remiges deeper, more silvery, gray, the secondaries and proximal 

 primaries tipped or terminally margined with white; rectrices darker 

 gray subterminally and tipped with white or buffy; under parts 

 immaculate white; bill dusky brownish, the mandible dull brownish 

 orange, dusky terminally; legs and feet varying from dull reddish 

 brown to dusky brown (in life), the soles more reddish. 



Downy young. — Upper parts light gi'ayish buff with several large 

 and tolerably well-defined dusky irregular spots on posterior half of 

 head, a distinct dusky stripe down each side of hindneck and upper 

 back, the wings, rump, and flanks with rather distinct large spots of 

 dusky; under parts white, tinged with grayish on sides of throat; 

 bill brownish inclining to orange (in life) on mandible; legs and 

 feet brownish orange (in life). 



Adult male.~Wmg, 288-338 (301); tail, 104.5-135.5 (114.8); 

 exposed culmen, 37-42 (38.7); tarsus, 27-36 (29.5); middle toe, 

 20-25.5 (21.4).« 



Adult female.— Wmg, 275-313 (292.3); tail, 103-127 (112.2); ex- 

 posed cuimen, 35-38 (36.5) ; tarsus, 27.5-32 (29.1) ; middle toe, 20-22.5 

 (20.8).« 



