BIEDS FALCONIDAE — PALCO ANATUM. 
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Family FALCONIDAE- The Falcons. 
Sub-family FALCONINAE. 
FALCO, Linnaeus. 
Falco, Linnaeus, Syst. Nat. I, 124, (1766.) 
General form robust and compact. Bill short, curved strongly from the base to the point, which is very sharp, and near 
which is a distinct and generally prominent tooth ; nostrils circular, with a central tubercle. Wings long, pointed, formed for 
vigorous, rapid, and long-continued flight ; tail rather long and wide ; tarsi short, robust, covered with circular or hexagonal 
scales ; middle toe long ; claws large, strong, curved, and very sharp. 
This genus, as restricted, contains species found in all parts of the world, and easily distin- 
guished from all other hirds of this group by the prominent tooth in the upper mandible. 
They are justly regarded by naturalists as the typical or most highly or completely organized 
of rapacious birds. They are remarkable for exceedingly rapid flight, and great boldness in 
the attack and capture of small quadrupeds and birds, on which they subsist. 
Sub-genus Falco. 
FALCO ANATUM, Bonaparte. 
The Duck Hawk. 
Falco analum, Bonap. Comp. List, p. 4. (1838.) 
" Falco peregrinus," Wilson, Audubon and other authors. 
Figures.— Wils. Am. Orn. IX, pi. 76 ; Aud. B. of Am. pi. 16 : Oct. ed. I, pi. 20 ; Lembeye B. of Cuba, pi. 1, fig. 2; 
De Kay, Nat. Hist. New York, Birds, pi. 3, fig. 8. 
Mult. — Frontal band white. Entire upper parts bluish cinereous, with transverse bands of brownish black, lighter on the 
rump. Under parts yellowish white, with cordate and circular spots of black on the breast and abdomen, and transverse bands 
of black on the sides, under tail coverts and tibiae ; quills and tail brownish black, the latter witli transverse bars of pale 
cinereous. Cheeks with a patch of black ; bill light blue; legs and toes yellow. Sexes alike. 
Younger. — Entire upper parts brownish black, frontal spot obscure, large space on the cheeks black. Under parts dull 
yellowish white, darker than in adult, and with longitudinal stripes of brownish black ; tarsi and toes bluish lead color. 
Total length 18 to 20 inches, wing 14 to 15, tail 7 to 8 inches. 
Hab. North America, west of the Rocky mountains. Specimens in National Musuem, Washington, and Museum Academy, 
Philadelphia. 
One specimen of this kind only is in the collections made by the expeditions, the results of 
which are embraced in the present report. 
This species is apparently restricted to that portion of North America east of the Rocky 
mountains, being replaced in the western countries of our continent by the smaller Falco 
nigriceps. We have never seen the present bird from any locality on the western coast of the 
United States, though on the eastern it ranges throughout the extent of the coast from Green- 
land to Cuba. 
The specimen now before us is of especial interest, having been obtained at the most western 
locality yet ascertained for this species, and demonstrating a vast range of longitude, in local- 
ities which it never before was known to inhabit. It was obtained on the Vermilion river, in 
.Nebraska T rritory, by Lieutenant Warren's expedition. 
