IC2 Chapman, Spring Moult of the BohoJhtk. [apHI 



Dr. Chadbourne has examined this Corumbii specimen, but his 

 conclusions dififer from my own. In brief, he says that the moult 

 is not a complete one, but that certain feathers of the winter 

 plumage have changed to the color of the breeding plumage, and 

 that in the white area of the abdomen there are some white 

 feathers not fully mature. He further says : " My Bobolink 

 showed none of this white marking on the breast or abdomen, nor 

 did it have the chestnut shading, which is so prominent in the 

 Corumbt'i specimen, and Dr. Allen says nothing of any similar 

 coloring among the birds seen by him. When we call to mind 

 the fact, to be referred to later, — that the black of the Bobolink is 

 really due to brown, instead of black coloring matter, — it is at 

 once clear that the excess of chestnut and white show a lack of 

 the normal quantity of pigmented matter ; and it seems almost 

 sure that in the CorumbA bird, we have not a normal example, 

 but a partial albino! " 



In attempting to explain the reason for this difference in Dr. 

 Chadbourne's opinion and my own, let us first consider the 

 question of change in the color of an old feather (figure i of the 

 plate accompanying his paper). The plumage of the Reedbird, 

 especially of adult specimens, often contains black feathers, the 

 terminal yellow tips of which show them to be new. Dr. 

 Chadbourne figures such a feather in his plate (fig. i). What 

 becomes of these feathers .'' In an adult male taken September 

 25, in Jamaica, W. I. (Am. Mus. No. 42134) nearly all the 

 feathers of the breast and sides are so marked. The bird could 

 not well lose them without these parts becoming featherless. There 

 is no reason to doubt, therefore, that they are retained until the 

 spring moult, and in my opinion it is on one of these black 

 feathers that Dr. Chadbourne bases his statement of spring 

 color change without moult of the feather in the CorumbA 

 specimen, when in truth there is no evidence whatever to show 

 that this feather was not black when it was acquired at the 

 preceding moult. 



As to the " not fully mature feathers " which Dr. Chadbourne 

 reports finding in the white area on the lower breast and abdo- 

 men of the Corumbii bird, one of which he figures (fig. 2), I 

 must confess that after the most careful search I have failed to 



