Vol. XXXIIl 

 1915 



Tovxsexd, Notes on the Rock Dove. 307 



for example, to realize the immense plasticity of the species and the 

 changes wrought by artificial selection through the ages. Darwin 

 showed that all these races, although breeding true, were fertile 

 among themselves, and that the hybrids were fertile; that the young 

 of the different races could hardly be distinguished apart within 

 twelve hours of hatching; and lastly that diverse races and their 

 hybrid offspring when bred together result in Rock Doves, typical 

 in form and plumage. 



This same interbreeding has occurred in the flocks of Pigeons 

 seen in our cities. Here the majority of the birds have the general 

 grayish-blue color with iridescent necks and breasts, white rumps, 

 white axillaries and lower wing coverts, two black wing-bars and 

 black terminal or sub-terminal tail bands, typical of the Rock Dove. 

 Albinism is not uncommon in these flocks but irregular plumage is 

 rare, and unusual form is practically never seen. In a flock of 83 

 Pigeons seen on Boston Common, one bird was a full albino, four 

 partial albinos, three were chocolate-colored and the rest nearly all 

 in the regular plumage. A few of these were darker blue than usual 

 with little or no white on the rumps, and a number more showed 

 slight albinism in the wing feathers, seen only in flight. In a group 

 of 150 birds counted at another time, one was chocolate-colored, 

 12 more or less albinistic and the rest nearly typical of the Rock 

 Dove. 



I am inclined to think that the prevalence of albinism in these 

 Pigeons may be partly accounted for by the fact that there are, 

 with rare exceptions, no hawks in cities to pick off prominently 

 marked birds, for it is reasonable to suppose that a bird, conspicu- 

 ous through albinism, would afford a more shining mark to a hawk, 

 and would therefore be more subject to capture. This supposition 

 is borne out by an observation related to me by Mr. William Brews- 

 ter. He brought to his place at Concord a flock of Pigeons, the 

 majority of which were more or less albinistic or else were light 

 chocolate in color, but about one fourth of the flock were in the 

 ordinary plumage of the Rock Dove. The flock was from time to 

 time harried by hawks who killed a number of the birds, and the 

 interesting part is that at the end of some three years the albinistic 

 and chocolate-colored birds were practically all weeded out and 

 the typical blue birds alone remained. 



