24 BULLETIN 20 3, UNITED STATES NATIONAL MUSEUM 



the alar tracts penetrated the skin the first day after hatching. On 

 the second day after hatching the eye-slits began to open. Feather 

 sheaths of the humeral, femoral, and crural tracts emerged on the 

 third day; those on the dorsal and ventral tracts emerged on the 

 fourth day, and those of the capital and caudal tracts on the fifth day. 

 On the fifth day the sheaths began breaking." During the next five 

 days the young developed rapidly and became more and more active, 

 and on the tenth day began to leave the nest. 



Young observed by Dr. Walkinshaw (1914) at Reelfoot Lake "aver- 

 aged 11 days of age when leaving the nest in 1939, while 21 young in 

 Michigan during 1939 and 1940 remained in the nest for a period of 

 10% days." Of the comparative nesting success in the two localities, 

 he says : 



In Michigan from 1930 through 1940, 121 nests of the Prothonotary Warbler 

 were observed. Only 28, or 23.14 per cent, were successful. Out of 413 eggs, 159 

 (38.47 per cent) hatched and 100 young were fledged (.87 per total nest; 3.78 per 

 successful nest). The fledgling success was 25.66 per cent of eggs laid. More 

 failures in Michigan resulted in more nestings by individual birds. 



In Tennessee during 1939, 30 nests were observed until terminated or success- 

 ful ; 19 were successful (63.33 per cent) while out of 139 eggs, 78 hatched and all 

 the young lived to leave the nest or 56.11 per cent fledging success of eggs laid ; 

 2.6 young were fledged per total nest ; 4.1 per successful nest. 



He also notes that in Michigan the species is typically single-brooded if 

 the first nesting is successful, but that in Tennessee it is typically 

 double-brooded. 



Plwnages. — According to Dr. Dwight (1900) the natal down, lo- 

 cated as indicated above, is brownish mouse-gray. Ridgway (1902) 

 gives rather the best description of the juvenal plumage as follows: 

 "Pileum, hindneck, back, and scapulars dull olive-greenish; wing- 

 coverts, tertials, rump, and upper tail-coverts slate-gray, tinged with 

 olive, the middle and greater wing-coverts narrowly tipped with light 

 olive-greenish, producing two very indistinct bands ; secondaries, pri- 

 maries, and rectrices as in adults ; sides of head pale yellow^ish olive ; 

 chin, throat, and chest dull light grayish olive, darkest on chest rest of 

 under parts dull white, passing on sides and flanks into olive-grayish." 



In very young birds, according to Dr. Dwight, there is a variable 

 amount of brownish wash on the back, which fades out to gray. And 

 Dr. Chapman (1907) says that the white on the inner webs of the tail 

 feathers is more restricted than in adults and more or less mottled 

 with blackish. This first plumage is followed in June and July by a 

 partial postjuvenal molt involving all the contour plumage and the 

 wing coverts but not the rest of the wings or the tail. The young bird 

 now becomes a golden swamp warbler, the young being nearly like the 

 adults, the females being considerably duller in color than the males 

 and having less white in the tail. 



