BUTEO SWAINSONI. 585 



the theory advanced by Dr. Bi-yant/ that the several supposed species 

 described by Mr. Cassin under the names of B. hairdl, Hoy, B. insignatiis, 

 Cassin, and B. swainsonl, Bonap., were merely different plumages of one 

 species, the very first specimens obtained by us being- a family of four 

 }'Oung, Avith their parents, the former being- B. hairdi, whih' of tlie latter 

 tlie male was a very light-colored, or extremely tyi)ical, B. swaii/so)//, and 

 tlie female a vei-y extreme example of B. uishjiKitm;! Similar cases were 

 often observed afterward, the plumag'e of the adults being- sometimes re- 

 versed — that is, a male in the plumage of the so-called utvignatus being- 

 sometimes paired with a very light-colored female. 



The family mentioned above was lirst oliserved on the 2Gth of Julv, 

 Avhile we were hunting among the cotton-woods of the lower Truckee Valley. 

 Our attention was attracted by a peculiar squealing cry, not before heard • 

 by us, and upon emerging from the Avillows and looking across the open 

 meadow we observed among the trees on the opposite side several large 

 Hawks, one of which was feeding a young one in a nest in the top of a tall 

 cotton-wood. We then approached this tree under cover of the willows, 

 but upon arriving there found that the old Hawk had gone after more food 

 for its young, three of which were in the trees on the opposite side of a 

 deep and wide slough which we were imable to cross. We then shot tlio 

 one in the nest, as it looked over the edge at us; but, as it did not fall, 

 found it necessary to ascend the tree, which was easily done. The nest 

 was very similar to that of other Buteones, being composed almost entirely 

 of sticks, but appeared rather small for the size of the bird, measimng but 

 about two feet in diameter by one foot in thickness. We found it so filled 

 with the accumulated remains of animals carried to the young that scarcely 

 •M\y depression was noticeable on the top, the decomposing rubbish con- 

 sisting of bones and other remnants of small hares CLepiis artemisia), 

 ground squirrels {Sinrmoplnlus lateralis; S. harr'm, and Tamias quadrivittatm), 

 and, strange to say, a full-grown young Sparrow Hawk (Faico sparver'ms). 

 We had scarcely reached the nest before the male arrived, and flying 

 about us uttered plaintive cries, of a meAving character, somewhat like the 



'"Remarks on the Variations of. Plumage of Butco borcalis, Auct., niid Bntco 

 harlani, AuD." Proc. Bost. See. Nat. Hist., VIII, 1861, pp. 107-119. 



