368 U.S. NATIONAL MUSEUM BULLETIN 23 7 part i 



of brooding and feeding the young falls to the female. After the 

 first week the male helps feed his offspring and both parents then 

 continue this function until the young are independent. 



On the 4th day of nest life the eyes of the young birds are opening 

 and the nestlings begin chirping, especially at feeding time. On the 

 7th day the feathers begin breaking from their sheaths and, by the 

 11th day, the nesting bird appears completely covered by feathers. 

 The young leave the nest at approximately 20 days of age. After 

 this they remain among the rocks where their gray color makes them 

 very difficult to locate, even when they call frequently. The young 

 birds are probably fed by the parents for as long as 2 weeks after 

 leaving the nest. During this time the young beg energetically from 

 the parent whenever it is near and follow it as it retreats. The adults 

 use this trait to lead their young in flight to a safe place among the 

 tumbled rocks, where they leave them by flying off too rapidly for 

 the young to follow. In such places several families become con- 

 solidated in a single flock. After they are thus assembled parental 

 care of the young wanes and ceases. 



Plumages. — The general coloration of a bird in juvenal plumage 

 is lilac-gray, darker dorsally. The con torn* feathers have somewhat 

 brownish edges, providing a faint buffy color, especially ventrally. 

 The flight feathers are darker. The secondaries show broad buffy 

 margins and the central rectrices a narrow margin of the same color. 

 The remaining rectrices and especially the primaries show distinct 

 but very narrow whitish margins. The primaries and their coverts 

 have narrow margins of pink, wider proximally on the remiges. The 

 nasal tufts are whitish, as in the adults. 



In late August or September the first winter plumage is acquired 

 by a partial postjuvenal molt. The rectrices, remiges, wing coverts 

 and perhaps some of the tail coverts remain unchanged. With the 

 exception of slight differences in these feathers, the first winter 

 plumage is similar to the adult winter plumage. 



There is no prenuptial molt, the adult breeding dress being 

 acquired by wearing off of the dusky, grayish, brownish, or pinkish 

 edgings of the feathers. Unlike the other members of the genus 

 Leucosticte in North America, the black rosy finch shows rather 

 strong sexual dimorphism. The body and head of the male are sooty 

 black, with a light gray crescent extending from eye to eye over the 

 back of the crown, and a pink wash on the belly, flanks, and tail 

 coverts. The flight feathers are nearly as dark centrally as the con- 

 tour feathers but are lighter below, the ventral aspect of the extended 

 wing appearing almost pearl-gray. The primaries of a fully adult 

 bird have even more extensive white and pinkish edgings than those 

 of the juvenile. The pink color is most pronounced along the bend 



