BUTEO. 63 



therefore of opinion that the true B. horealis does not winter in any part of Central 

 America, but possibly journeys to South America by way of the West Indian Islands". 

 A single specimen was obtained at Santa Cruz in Patagonia by Darwin, and further 

 investigations may show that B. horealis migrates with B. swainsoni into the southern 

 portion of the South American continent. On this point, however, we are without 

 exact information, and its winter home has yet to be correctly ascertained. 



In Western North America there is a large form which has been variously called by 

 writers B. montanus and B. calurus. This bird has not apparently received a specific 

 designation and we propose calling it Buteo rufescentior. It is slightly larger than the 

 true B. horealis, with much more rufous thighs, but has the blackish throat of that 

 species, differing from it in having a reddish patch across the- lower breast and 

 abdomen, on which the black spots are conspicuous. This form extends from Sitka 

 and British Columbia to California, and in the Henshaw Collection there are examples 

 from Utah, Colorado, and New Mexico. Our collection also contains specimens from 

 Zacatecas, San Luis Potosi, Colima, Jalisco, Sonora, the Valley of Mexico, Vera Cruz, 

 Guatemala, and Nicaragua. 



Buteo krideri is a pale form from the Middle States of America, having the upper 

 plumage mottled with white, instead of rufous, especially on the scapulars and inner 

 secondaries ; the under surface is almost white, with a few longitudinal streaks 

 on the abdomen ; the thighs are even paler than in typical B. horealis. The 

 tail is of a much lighter rufous colour than in the latter species, being of a light 

 cinnamon ; the black subterminal bar is either narrow or broken up, or entirely 

 absent. A similar variation in this respect is often observed in true B. horealis, 

 and a specimen from Illinois in the Henshaw Collection, at first sight referable to 

 B. krideri, appears to us to be an unbarred example of B. horealis, having the dark 

 chestnut tail of the latter. We can trace this light-coloured race to Zacatecas, and we 

 have a specimen from Ciudad in Durango, while another from the Southern Pine 

 ' Kidge in British Honduras may perhaps be referred to B. krideri. 



The true B. calurus of Cassin is very large and dark in colour. The throat and 

 abdomen are smoky brown and the chest-patch rufous, while the rufous thighs and 

 under tail-coverts are also conspicuous features. The young bird has a remarkable 

 appearance, being very dusky underneath and having broad bands across the thighs. 

 In this immature stage the species has often been mistaken for B. harlani, and we refer 

 the so-called B. harlani from Guatemala to B. calurus. The British Museum contains 

 specimens of the last-named form from California and Mexico, and we possess examples 

 from Zacatecas, the Sierra Madre de Nayarit, Orizaba, and Jalapa. 



Buteo lucasanus from Cape San Lucas we have not seen. It is described as a dark 

 form of B. horealis, with no subterminal black band on the .tail. Mr. Brewster, 

 writing to the late Capt. Bendire (Life Hist. N. Amer. Birds, p. 216), emphatically 

 refuses to believe in the distinctness of the Cape San Lucas bird, having compared 



