ROUGH-LEGGED BUZZARD. 199 



food, to enable them to fly off. The species is more nocturnal 

 in its habits than any other hawk found in the United States." 

 Although it has not been met with between the Alleghanies 

 and the Rocky Mountains, Dr Townsend found it breeding on 

 the banks of Bear River, westward of the latter. " Its nest was 

 placed in a willow, ten feet from the ground, and formed of 

 large sticks. It contained two young almost fledged." 



Remarks. — A hawk precisely similar in every respect, except- 

 ing colour, to the Rough-legged Falcon, was described by Pen- 

 nant and Wilson under the names of Falco Sancti- Johannis and 

 Falco niger. This bird Mr Audubon, by an extensive compari- 

 son of specimens, found to be identical with that species, and it 

 has been referred to by Nillson as the young of the Buteo lagopus. 

 Mr Audubon, however, is positive as to its being the old bird, 

 and gives analogical and other reasons in support of his opinion, 

 young birds taken from the nest not having been seen by him. 

 These reasons will be found in the second and fifth volumes of 

 his Ornithological Biography. The state of plumage alluded 

 to is chocolate or blackish-brown, but with some of the charac- 

 teristic markings of the species, such in particular as the white 

 bases of the quills, remaining. 



No person, however, has seen these black individuals breed- 

 ing ; but on the contrary, Dr Richardson, as mentioned above, 

 observed a pair of the usual colour having a nest; and Dr Towns- 

 end, in stating the fact mentioned above, concludes with saying 

 " the birds were in the same plumage as that figured by you" — 

 that individual then figured being an ordinary Buteo lagopus. It 

 is thus clear that the light-coloured birds breed, and therefore 

 must be considered adult, unless the black be also found breed- 

 ing, in which case some additional circumstance would be re- 

 quired to settle the question. If the old birds are black, how is it 

 that none have ever been seen in Britain, or in Holland, although 

 these countries are not by any means on the limits of their 

 migration, the species occurring as far south as the ISIediterra- 

 nean I On the other hand, if the young birds are black, how 

 do they not appear iji these countries, since in the southward 

 migration of an arctic bird the young generally proceed far- 

 thest I There are two ways of solving the difficulty. The dark- 



