THE OSPREY. 



AM ILLLLSTP/VrCD A\/\(J/\ZIMi: Or POPULM^ oijmhholoqy, 

 Published Monthly except in July and August. 



Volume III, 



APRIL, 1899. 



Number 8. 



Original Articles. 



APTOSOCHROMATISM IN CHRYSOTIS LEVAILLANTI.* 



By Fkancis Joseph Birtwell, Dorchester, Mass. 



Aptosochromatism is defined by the Century 

 Dittior.ary as "chang'e of color of the plumage 

 without loss or g'ain of any feathers. Coues." 

 Such color chang'e is a subject which appears 

 to \<f not only of considerable importance in 

 the study of feathers, but also of peculiar 



FRANCIS JOSEPH BIRTWELL. 



interest. Although as yet this topic has been 

 only inadequately treated, the abundance of 

 available material for this attractive field of 

 investigation will doubtless soon stimulate 

 such an active movement among oniitholo- 

 gists as will place the subject among the fore- 



most recognized branches of ornithological 

 science. 



Comparatively little has been learned in this 

 regard of the i'sittaci, though few groups of 

 birds are so well known as Parrots in cap- 

 tivity or semi-domestication. The peculiar 

 colors, and their changes and combinations 

 without moult, found among various mem- 

 bers of this order of birds, offer some feat- 

 ures of marked interest in their bearing 

 upon the study of aptosochromatism. The 

 ilexican Double Yellow-head, or Yellow- 

 he;ided .\nuizon. Chrysotis Levaillanti, for 

 example, affords an inviting case of change 

 in the coloration of individual feathers, in- 

 dependently of moult. 



Jly attention was first directed to this 

 phenomenon by continued observation of a 

 yciuiig Yellow-liead in the possession of Mrs. 

 William I*. Holies, of Boston. The bird being 

 friendly, it was often eareesed, and I soon 

 not iced traces of a process of color change 

 going on in the feathers of the crown. Re- 

 alizing the im])ortance of the matter, I 

 made freciuent examinations of the plumage, 

 and specimen feathers were collected. On 

 .July 13th I was obliged to absent myself on 

 hiisiness matters for two months. Upon my 

 return 1 found the bird to be completing the 

 regular fall moult, and was pleased to ob- 

 serve that the yellow of the crown had ad- 

 \aMced quite half an inch beyond its July 

 limit. .After that, cast-off feathers were 

 carefully preserved, and the whole number 

 of contour feathers of the head which were 

 dropped did not exceed twenty. To appre- 

 ciate the fewness of this number, in propor- 

 tion of the whole plumage of the head, one 

 lias but to count those feathers upon a skin. 

 Also, the feathers lost were chiefly old ones 

 from the forehead, and of a yellow color. 

 Thus the possibility of extensive feather 

 loss is put quite out of the question in the re- 

 marks which will follow. In addition to saving 

 the cast feathers, the bird was frequently in- 

 spected; and through the courtesy of Boston 

 dealers seven other individuals were exam- 

 ined. t These birds, with one exception, were 



♦Read before the Nuttall Oruitliologi.-.il Club, of C.ambritise. Jan. 2. 1809, with exiiibition of micro- 

 scopical preparations. , ,, . i t, i 



fThus the whole of the material examlued was eight birds, from the following sources: 1 bird 

 from Mrs. Bolles: 1 from G. S. Greenleaf & Co.; 2 from G. H. Holden; 2 from Cbas. Ludlam; and 

 2 from Ludlam Bros. 



