PATTERN DEVELOPMENT IN MAMMALS AND 

 BIRDS. Ill 



GLOVER M. ALLEN 

 Boston Museum of Natural History 



Partial Albinism in Wild Bikds 



In birds under natural conditions of wild life partial 

 albinism is fairly common. Lists of species of which 

 albinistic specimens are known were published by Ruth- 

 ven Deane (1876, 1880) some years ago, and by others. 

 Scattered instances are in all the bird journals or maga- 

 zines of general natural history. In most cases in which 

 the white markings are clearly defined against the pig- 

 mented parts of the plumage, these may be referred to 

 their particular primary breaks between the several 

 areas of pigment formation. In other cases the pigment 

 reduction is of the diffuse type, tending to form spots. 



A few instances follow in which the several primary 

 patches have been observed in wild birds, either as acci- 

 dental marks or as permanent parts of the pattern. 



The Crotvn Patch. — In 1908, a pair of robins nested 

 near Lowell Park, Cambridge, one of which showed a 

 partial separation of the crown patch, through the pres- 

 ence of a white band, as broad as the eye's diameter, 

 passing from one eye around the back of the head to the 

 other eye. In the Wilson Bulletin (Vol. 2, p. 45, 1908) 

 W. E. Saunders records the capture of two robins each 

 with a white collar about the neck, probably marking the 

 separation of the neck patches from the shoulder patches. 

 Coues (1878) records a brood of black robins at St. 

 John's, N. B., one of which was kept in captivity by the 

 late G. A. Boanlman. In September, after moulting, it 

 was still pure black, except for white wings and tail, 

 which seems to indicate an areal restriction of the 

 shoulder and rump patches, though the pigment, where 



