188 Birds of Colorado 
But few details have been noted about its nesting-habits 
in Colorado, except that it makes use of crevices and ledges 
in high cliffs and cafion walls. Some notes by Gale, 
quoted by Bendire and Cooke for this species, refer, 
according to Gale’s notebook, to the Mexican Falcon, 
and not to this species. The eggs are deposited about 
the middle or end of April on a bare ledge, with little 
or no nest. They are three or four in number, and are 
generally short, rounded and ovate. They vary consider- 
ably in colour and markings, the ground-colour, when 
visible, being creamy-white, sometimes blotched and 
streaked, sometimes entirely overlaid, with reddish and 
sepia browns. In size they average 2°1 x 16. 
Pigeon-Hawk. Falco columbarius. 
A.O.U. Checklist no. 357—Colorado Records—Ridgway 73, p. 186; 
Drew, 85, p. 17; Morrison 88, p. 115; 89, p. 65; Kellogg 90, p. 87; 
Fisher 93, p. 109; Lowe 94, p. 267; McGregor 97, p. 38 ; Cooke 97, 
p. 76; Rockwell 08, p. 163. 
Description.—Adult Male—Above bluish-slate, most of the feathers 
with a black shaft-line; quills dusky, with white spots along the inner 
webs only ; tail like the back, with four transverse black bands more 
or less completely developed, the terminal one much broader than the 
others and tipped with white; below white, washed with tawny 
posteriorly, the throat plain, the rest longitudinally streaked with 
sepia-brown ; sides of the face bluish and streaked ; iris brown, bill 
bluish-black, base and cere yellowish, legs yellow. Length 11-5; 
wing 7-7; tail 4-5; culmen -55; tarsus 1-4. 
The female is dusky brown above, and the tail is like the back, but 
crossed by four narrow, sometimes nearly obsolete, whitish bands 
the uppermost often concealed by the coverts; below as in the male, 
but often more fulvous and the streaking heavier ; wing 8-5. Young 
birds resemble the female, and this is the plumage most generally 
met with, as adult males are not often seen. 
Distribution.—The whole of North America, breeding chiefly north 
of the United States, but south of the boundary along the higher 
elevations of the Cascades, Rockies and Alleghanies ; south in winter 
to the West Indies and northern South America. 
In Colorado the Pigeon-Hawk is by no means a common, bird, and is 
chiefly met with on migration, though a few birds remain to breed in the 
