936 U.S. NATIONAL MUSEUM BULLETLN 23 7 paet 2 



Most young leave the nest before they are completely covered by a 

 coat of feathers, with the wings and tail only partly grown. 



The Juvenal plumage of this species, according to Robert Ridgway 

 (1901), is "Much like [thel adults, but pileum dull brown, obsoletely 

 streaked with darker; back more narrowly streaked with darker brown; 

 chest narrowly streaked with dusky brown, and submalar streak 

 indistinct or obsolete." The greater secondary coverts are margined 

 with buffy in the juvenile and with grayish in the adult. Often the 

 tail feathers are more acute than in the adult birds, but this character 

 is variable and not a completely reliable one for aging individuals. 



Probably some young begin the postjuvenal molt within 6 to 8 

 weeks after leaving the nest. The earliest records of individuals in 

 the initial stages of the postjuvenal molt are in mid-June. Young 

 hatched later may not begin the molt until late August or early 

 September. The many young birds found later in the year in the 

 early stages of the molt that have not completed growth of the tail 

 feathers suggests that late-hatched young begin the postjuvenal molt 

 at a younger age than those hatched earlier. 



The postjuvenal molt usually begins on the mid-back and scapular 

 regions. From there it spreads both anteriorly and posteriorly along 

 the back at the same time as the breast and sides are beginning to 

 molt. Some individuals may begin the breast and side molt simul- 

 taneously with or even before the back molt. Usually the forehead 

 begins to show new feathers as the breast feathers are replaced. The 

 last areas to molt are the lower parts of the back and abdomen, the 

 under tail coverts, and the sides of the head and neck. 



Molt of the flight feathers occurs as the body molt is nearing 

 completion. While the body molt is invariably complete, the wing 

 feathers are replaced to different degrees in different individuals. 

 Most individuals replace one or more of the primaries and secondaries. 

 If only a few are changed, they are the outer feathers on the primary 

 tract and the secondaries closest to the body. Presumably this partial 

 replacement includes those feathers that are most subject to wear in 

 this sparrow's rather harsh environment. Usually all the tail feathers 

 are molted; occasional birds may retain all the juvenal tail feathers 

 until after the first breeding season. 



The only regular normal molt after the postjuvenal molt is the 

 postnuptial, which takes place annually after the breeding effort. 

 This molt renews the complete feather coat. The new feathers are 

 identical in color to those being replaced in all birds 2 years of age and 

 older. The species has no prenuptial molt, and in the breeding season 

 the birds are attired in their most worn plumage. 



The adult plimiage of ruficeps has the forehead and crown rusty 

 \vith grayish margins on the feathers in fresh plumage. The lores 



