U. S. P. R. R. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT 
former marked with white on their inner webs, the latter while at its bjse. Tarsi and tibia! pale reddish yellow, spotted with 
brown. 
Total length, female, 22 to 24 inches; wing 17 to L7J, tail 9 inches. Male 20 to 22 inches ; wing 16 to 16£, tail 8 to 8| inches. 
Nab.— Eastern and northern North America. Spec, in Nat. Mus., Washington, and Mus. Acad., Philadelphia. 
One of the most abundant of the birds of this family in the eastern States, and in adult 
plumage very easily recognized, but very variable in colors of plumage. The dark brown or 
chocolate colored plumage is frequently to be met with, and in that stage this bird appears to 
be Falco spadiceus, Gmelin. In young plumage, as described above, and especially with the 
wide abdominal band well defined, this bird much resembles the young of Arcliibuteo lagopus, 
as described immediately preceding, from which it can be distinguished by its larger size and 
the much more numerous dark spots on the under parts in the present bird. 
ARCHIBUTEO FERRUGINEUS, Lichtenstein. 
California Squirrel Hawk. 
Buteo ferrugineus, Liciit. Trans. Acad. Berlin, 1838, p. 428. 
Arcliibuteo regalis, G. Ft. Gray, Gen. Birds, I, pi. 6, (plate only.) 
Buteo Californicus, Hutchins' California Magazine, March, 1857. 
Figures — Gray, Genera of Birds, I, pi. 6 ; Cassin, B. of Cal. and Texas, I, pi. 26. 
Mult. — Larger than either of the two preceding ; bill wide at base ; wings long ; tarsi feathered in front to the toes ; naked 
and scaled behind. Tibia; and tarsi bright ferruginous, with transverse narrow stripes of black. Entire upper parts dark brown 
and light rufous, the latter predominating on the rump and wing coverts ; quills ashy brown, with the greater part of their 
inner webs white ; tail above reddish white, mottled witli ashy brown ; beneath pale yellowish white. Under parts of the body 
white, with narrow longitudinal lines and lanceolate spots on the breast of reddish brown, and narrow irregular transverse lines 
of the same color and of black on the abdomen ; flanks and axillary feathers fine bright ferruginous. 
Young. — Entire upper parts dark umber brown, slightly mixed with fulvous ; upper tail coverts white, spotted with brown ; 
under parts pure white, with a few longitudinal lines of brown on the breast, and sagittate spots of the same color on the sides 
and abdomen, larger and more numerous on the flanks ; tibiae white ; tarsi dark brown, mixed with white ; under wing coverts 
and edges of wings white. 
Total length, female, 23 to 25 inches ; wing 17 to 17 1 .,', tail 9 inches. 
Hab. — Western North America. Spec, in Nat. Mus., Washington, and Mus. Acad., Philadelphia. 
This is one of the most handsome of the American Falconidre, and, though known in Europe 
for the last twenty years, was unknown to the naturalists of this country until brought to their 
notice by Mr. Edward M. Kern, who was attached to Colonel Fremont's expeditions. It is one 
of the largest of its group, somewhat exceeding in size both Arcliibuteo sancti-johannis and lagopus. 
As usual in this family, the adult and young of the present species are quite different, and 
in well characterized specimens might readily be regarded as different. Both are described 
and figured by us, as above. 
This bird is apparently exclusively western, but not restricted to the countries west of the 
Rocky mountains. In the present collection specimens are from Nebraska and New Mexico, 
as well as from California. 
