734 U.S. NATIONAL MUSEUM BULLETIN 237 part 2 



The post-ju venal molt, according to Sutton (1936), takes place in 

 late June or early July with the young of the first brood. Second and 

 third brood young may be wearing part of the juvenal plumage as 

 late or even later than mid-September. The body feathers of the 

 juvenal plumage are lost first, while the flight feathers and tertials 

 may be held for a longer period. At 20 days russet-tipped feathers 

 appear on the back; the superciliary line still is sharply streaked; the 

 rectrices are sheathed at the base. At 4 weeks the juvenal feathers 

 are lost on the crown and the superciliary line, together with all 

 remaining body feathers lacking russet tips. At 36 days the buff- 

 margined juvenal feathers are practically gone, replaced by buffy 

 feathers on the chest, sides, flanks, and lower throat. The back is 

 thickly set with incoming fully-sheathed feathers, and new lesser 

 wing coverts with a strongly yellowish cast appear. At about 6 weeks 

 the juvenal rectrices are lost almost simultaneously. The molt of the 

 juvenal primaries starts from the innermost outward. 



A dull yellow superciliary is present in some juvenal males, but 

 apparently is absent in juvenal females. The yellow superciliary 

 spot is acquired by both male and female birds with the post-juvenal 

 molt in the latter part of summer and fall, and not in April with a 

 partial prenuptial molt as described by D wight (1900). 



The first winter pumage contains no streaked feathers on the chest. 

 The back feathers are black with apical chestnut spots edged with 

 pearl gray. The median crown stripe, edging of tertiaries and wing 

 coverts, sides of the head, superciliary fine, and underparts are rich 

 buff. New feathers above and in front of the eye are deep yellow. 

 The neck feathers are red-brown medially. Middle of the abdomen 

 is pure white. 



There is no evidence of a prenuptial molt except for replacement of 

 feathers lost accidentally. Sutton (1936) states that "the large 

 majority of spring birds are exactly like fall adults except that the 

 plumage is a little more worn. Fall birds are beautifully fresh, 

 breeding birds are noticeably worn, late summer birds are very de- 

 cidedly worn, and spring birds are in an exactly intermediate position 

 between fall and summer." 



The second winter plumage is acquired by a complete postnuptial 

 molt. According to Dwight (1900) it differs little "from the first 

 winter dress, the buff less obvious and the colors deeper." 



The adult western grasshopper sparrow, A. s. perpallidus, is paler 

 and grayer than the eastern race, with more chestnut and rusty 

 brown and less black above. 



Oberholster (1942) describes the Arizona race as similar to A. s. 

 perpallidus. The upper parts are decidedly paler, with more chestnut 



