468 Cameron, Changes of Plumage in Buteo swainsoni. [not 



CHANGES OF PLUMAGE IN BUTEO SWAINSONI. 



BY E. S. CAMERON. 



My attention has just been drawn to some observations of Mr. 

 P. B. Peabody on the above subject in 'The Condor' for November- 

 December, 1907. I am sorry to refer to them at such a late date, 

 but the fact is I have only recently seen this number of the maga- 

 zine through the courtesy of one of its editors. Mr. Peabody con- 

 cludes an interesting article on Prairie Falcons with the following 

 remarks: "As for albinism, however, the writer is inclined to 

 believe Mr. Cameron in error (see ' The Auk,' July, 1907) in believ- 

 ing that the Swainson Hawk normally blanches with age. I have 

 never seen but one such (in Kansas, May, 1907); yet I have seen 

 many melanists. Moreover, Mr. Cameron has seen hundreds of 

 normals to my one; yet he, by his own admission {Joe. cit.), has 

 never seen but two blanched Swainson Hawks ! " This is entirely 

 to misquote my statement and misinterpret my meaning. What 

 I really wrote in 'The Auk' (Vol. XXIV, p. 262) was as follows: 

 *'In color, as far as could be determined, these buzzards exhibited 

 every shade of brown, while some inclined to a more chestnut hue. 

 Others again appeared black, or almost black, showing the mel- 

 anistic form, and a very few indi^'iduals were a uniform lavender, 

 or bluish ash, like the male Marsh Hawk (Circus hudsonius). I 

 have never obtained but two birds in this rare dress, but I feel 

 satisfied it is the one ultimately assumed by the adult male, which 

 through a long succession of browns moults into a mature plumage 

 of lavender with white throat spot. Of this cinereous phase I can 

 find no reference in ornithological works, where the old males are 

 invariably, but I believe quite erroneously, described as brown. 

 The immature birds, both male and female of the same age, also 

 exliibit endless difference in coloration, and the attempt to trace 

 their progress to maturity has perplexed even so eminent an au- 

 thority as Dr. R. Bowdler Sharpe who states {in lit.): 'The changes 

 of plumage in these buzzards are terribly difficult to follow.'" 



As I am not a collector, either of skins or eggs, I scarcely ever 

 shoot a bird, least of all, in the breeding season. \Maen I wrote 

 "I have never obtained but two birds," etc., I meant that I had 



