^"I'gf^^l Chadbourne, Spritig Plumage of the Bobolink. 1^^^ 



The possibility of a spring ' moult ' being entirely overlooked is 

 worth considering at this point. If we assume for the moment 

 that none of the old feathers change to the color of the breeding 

 dress, and that all which are unlike those of the preceding 

 plumage, have replaced old feathers already ' moulted,' can we 

 then form any idea of the loss during the development of the 

 spring dress of the male Bobolink ? In other words, how many 

 feathers would a Bobolink lose during a complete ' moult ' ? I 

 have tried to estimate this approximately in a male Bobolink, 

 killed May 30, by carefully pulling out, one by one, all the contour 

 feathers from the two ventral feather-tracts, including the ' inner 

 lateral,' but neither the 'humeral' nor the ' gular tracts' of 

 Nitzsch ; ' and then gluing each separately on sheets of paper. 

 Both my patience and mucilage gave out by the time I had 

 finished the sheets in question, — about one third of the under 

 parts of the bird." The contour feathers on the sheets amounted 

 to 439 in all, none of which, judging from their color alone, could 

 have formed a part of the winter dress. The feathers on the 

 upper breast, neck, and throat are smaller, and must be relatively 

 more numerous ; and it is certainly safe to estimate the total loss 

 from the abdomen, breast, and throat, at three times actually 

 counted, making the total 1317. The back and upper parts must 

 increase this number by at least one half ; and the hypothesis of a 

 ' moult without color-change ' 7i.iould therefoj-e imply a loss of 26J4 

 feathers for the development of the full spring plumage of the male 

 Bobolink. 



If the process lasted from three to six weeks — (it was three 

 weeks from the time the first black spot appeared, until the 

 full plumage of my Bobolink has been attained by color-change 



' Pterylographia. (English translation by Sclater.) Publications of the Ray 

 Society, London, 1867, p. 26, seq. 



'•* It will be noticed that in this estimate the plumage of the head, wings, 

 legs, and tail has not been included. The flight feathers, because they are 

 often broken accidentally, and cast off by cage-birds when not 'moulting'; 

 those of the head and legs, because they are so small as to be easily over- 

 looked ; while by omitting the remainder of the wings and tail, and counting 

 the total loss from the upper parts as only one half that from the gastrseum, 

 my result must be an underestimate. 



