1148 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



At nest VII after one young had hatched, the parent alternated these 

 positions at frequent intervals. 



During incubation the male continues to show a direct interest in 

 home and mate, visiting the nest frequently. At nest III he appeared 

 three times during 2 hours, and the pair flitted away together to feed. 

 During the gray dusk which is the northern night, males of four nests 

 were flushed from 20 to 60 feet from their nests. From the ground 

 or the base of the bushes, they scudded low a few feet ahead of me, 

 silently or with a low tsip. One sang a few bars of song and trailed 

 off to silence in the middle of a note. 



Young. — Development of the young has been described in detail 

 (Baumgartner, 1937). Summarizing the major points, hatching may 

 occur at any time of the day, the sequence not dependent upon the 

 order of laying, and the down dries in about 3 hours. The female 

 subsequently swallows the egg shells. 



Upon hatching the skin is yellowish with a pinkish undertone and 

 is sparsely clad in tufts of fuscous down; bill and feet pinkish horn, 

 lining of mouth orangish pink. The average length is 33.5 milli- 

 meters, weight 1.62 grams. Pin feathers begin to protrude at the 

 age of 4 days on dorsal, ventral, and alar tracts, at 5 days on the 

 caudal. At 6 days free feathers emerge beyond the sheaths of aU 

 tracts. At 8 days nestings are almost covered dorsally, the lower 

 belly is bare, and the tail a stubby pincushion with feather tips barely 

 showing. 



At 9K days, the age at which undisturbed young leave the nest, 

 the back is fully covered, lower beUy still shghtly bare, wings two- 

 thirds grown, and tail still a stub; weight is 16.70 grams, a 930 percent 

 gain over the bird's weight on hatching, and equal to that of the aver- 

 age July adult. 



Development of fledgling birds was traced in a brood confined to 

 its nest area by a wire mesh cage, and through the recapture of 

 banded young of known age. In both cases a loss of 1.5 grams was 

 noted the first day out of the nest, then a gradual increase to 2 1 days 

 with a total gain of 3 grams. Wings were then still slightly short and 

 tails about two-thirds grown. 



During August all birds were in heavy molt. In a series collected 

 on August 19, measurements of the young were comparable to those 

 of adults, and many were in almost complete adult plumage. Weights 

 averaged slightly less than adults of the same sex. 



