"iVos ] Cameron, Changes of Plumage in Biiteo swainsoni. 469 



only shot two specimens of this t^-jDe, certainly not that I had only 

 seen two, as Mr. Peabody phrases it, and in the line immediately 

 above I distinctly state that I did see a very few individuals of a 

 uniform lavender on the particular occasion referred to. At the 

 same time I admit that the expression "have never obtained" is 

 open to misconstruction, and am glad to have this opportunity of 

 explaining it. During my nineteen years' residence here, I have 

 seen (as Mr. Peabody says), many hundreds of these hawks,^ and 

 amongst them not two but a considerable number of bluish ash or 

 lavender examples. I have no doubt that I could easily have ob- 

 tained a dozen skins of the latter, and also the complete series 

 necessary to show the progress to maturity from the brown and 

 chestnut fledgling to the adult lavender colored male. 



This color phase has no more connection with albinism than has 

 the cinereous shade of the adult Marsh Hawk, and is accomplished 

 by a normal succession of moults. In my opinion B. swainsoni 

 requires four or five years to assume the full adult dress, as is the 

 case with the Golden Eagle (Aquila chrysaetos) and others of the 

 family. I have never myself seen an albino example of Swainson's 

 Hawk. 



Some of these hawks breed regularly in my vicinity every year. 

 Two pairs nested here this summer. In June, 1893, a pair made 

 their nest in a white ash tree, in the fenced pasture adjoining my 

 ranch. Both of these were shot. The male was of the light 

 cinereous form with white throat spot, identical with the one ob- 

 tained in April, 1890, and now in the British Museum. In 1899, 

 I had three nests under constant observation and made volumi- 

 nous notes. The three cock birds were all quite different, but more 

 or less of a brown coloration, and owing to my intervention none 

 of the hawks were molested. One of these males was as described 

 by Coues, — with the primaries and tail feathers "strongly slate- 

 colored," the whole of the underparts white, streaked with chest- 

 nut, and the white throat "immaculate." I have supposed this 

 plumage to be intermediate between the extreme dark brown and 

 bluish gray forms. Dr. Coues, who examined forty s])ecimens, 

 had obviously never come across the light, slate-colored birds. He 



1 On a rough estimate I must have seen about 2500 of this species at the migra- 

 tion periods. 



