1896.] 



NATURAL SCIENCES OF PHILADELPHIA- 



US 



in the three. So far as I can judge from the material that I have, 

 the first two or three primaries are generally shed before the feathers 

 of the abdominal tracts are expanded and the outermost primary 

 is lost at about the time that the body-plumage is completely renewed, 

 while the tail in the majority of species is shed just previous to 

 this — i. e. when one or two of the old primaries still remain. 



A knowledge of these relations is very valuable in determining 

 whether early fall specimens are adults or birds of the year. In the 

 former the outer primary will be found not quite completely grown, 

 or at least with remains of the embryonic sheath at its base, while in 

 the birds of the year no trace of recent growth or immaturity will 

 be found in the wing or tail feathers, except in a few species which 

 molt the remiges and rectrices of the first plumage in the fall.* 



As regards species in which the molt of the tail occurs gradually the 

 first tail feathers are shed about the same time as the sixth primary, 

 while the last are shed simultaneously with the last or next to last 

 primary. 



In the Tyrannid?e, the body feathers begin to molt sometimes 

 before the first flight feather is shed, and in young Sphyrapicus 

 much of the first plumage is retained till long after the flight feath- 

 ers have been renewed. 



The following tables show the relative molting of the feathers in 

 some of the specimens examined, and referred to above : — 



I. RELATIVE MOLT OF BODY PLUMAGE. 



""ZT^'^^r Interscapul 



Piranga erythromelas, 



1,904, W. S just appearing. 



Sturnella magna, 1,191, 



W. S nearly complete. 



Colaptes auratus, 1,532, 



W. S nearly complete 



Quiscalus quiscula, 154,1 



W. S ! nearly complete 



Plectrophenax nivalis, 



26,987, A.N. S complete. 



Dolichouyx oryzivorus,! 



32,783, A. M. N. H j complete. 



just appearing. 



complete. 



sprouting. 



just appearing. 



half renewed. 



complete. 



Top of Head. 



half renewed. 



half renewed. 



just appearing. 



no molt. 



just appearing. 



complete. 



Throat. 



just sprouting. 



no molt, 

 just appearing. 



no molt. 



just appearing. 



center of abdo- 

 men not molted. 



NUMBER AND TIME OF MOLTS. 



When the young bird emerges from the egg, it is enveloped in a 

 more or less complete covering of down ; in ptilopsedic birds the cover- 



* In any case, a specimen showing molt or evidence of recent molt in the 

 bodj'-feathers, while the rectrices and remiges present no signs of molt, may 

 be regarded with certainty as a bird of the year. 



