AVES FALCONID^. 



637 



In considering a large series of skins of Buteo erythronotus, it is apparent 

 that they may be divided into five distinct plumages which may be dis- 

 criminated as adult and, if by this we mean breeding birds, there are 



Fig. 322. 



Btiteo erythronotus. Adult male. P. U. O. C. 8307. One-fourth natural size. 



three plumages in which the birds breed ; a fourth plumage is the normal 

 immature and young birds of the year, while a bird collected by Mr. 

 Hatcher, which can only be described as black, must be a dimorphic, or 

 dichromatic phase ; this seems unusual and has not been heretofore dealt 

 with ; as to age it appears to be an adult. 



