24 THE PRAIRIE FALCON, 
sm" 
white, immaculate on throat, elsewhere marked with brownish gray of same shade 
as back, narrowly and distinctly on breast, broadly on sides and flanks, where 
falling into bars, sparsely on crissum, coalescing in maxillary region into broad 
mustache. Bill dark bluish changing to yellow at base and on much of lower 
mandible; feet yellow; iris brown. Young birds are darker above with feathers 
distinctly margined with light rusty, and their underparts are tinged with pale 
buffy and more broadly streaked ;—the younger the bird the richer the coloration. 
Downy young, pure white. Length of adult male: 17.00-18.00 (431.8-457.2) ; 
wing I1.50-12.50 (292.1-317.5); tail 6.50-7.50 (165.1-190.5) ; culmen .75 (19.1); 
tarsus 2.00 (50.8). Adult female, length: 18.50-20.00 (469.9-508) ; wing 13.25- 
14.25 (336.6-362) ; tail 8.00-9.00 (203.2-228,6); culmen .87 (22.1); tarsus 2.25 
(57.2). 
Recognition Marks.—Crow size; powerful, easy flight; light brownish gray 
coloration with size distinguishes it from any related local species, especially the 
darker Peregrine; varied screaming cries. 
Nesting.—Nest: a ledge or cranny of cliff; usually unmarked, occasionally 
bounded by a few sticks. Eggs: 4 or 5, creamy buff or pale vinaceous, heavily 
sprinkled or, rarely, stained and blotched with cinnamon, Avy. size, 2.18 x 1.60 
(55.4 40.6). Season: May 1-15; one brood, 
General Range.—\Western United States east to eastern border of Great 
Plains passing northern border into southern British Columbia, Alberta, and 
Assiniboia; south into Mexico. 
Range in Washington.—Common summer resident in Upper Sonoran and 
Transition life-zones of eastern Washington; rare or casual west of the Cascades. 
Authorities—/alco polyagrus, Cassin, “Illustrations” (1856), p. 88 
(“Puget’s Sound”). 
Specimens.—!"'. Proy. C. 
IN SPITE of the fact that the Prairie 
Falcon is really one of the commonest rap- 
tors in the West, its discovery within the 
United States was not reported till 1853", 
and it long remained a rare and little-known 
bird. Coues in 1874° confessed to having 
seen but one of them; and a set of eggs 
taken in 1860 by Dr. Hayden in the Wind 
River Mountains of Wyoming was for some 
years unique. In this respect the history 
of the Prairie Falcon shows analogy to that 
of certain sea fowl. Birds that have been 
known vaguely for years as inhabitants of 
Photo by the Author. the open ocean, may not be fully known 
A-WING until their breeding haunts are discovered,— 
a "Cassin, B. of Cal. and Texas, L, p. 88, Pl. 16, 
b. Birds of the Northwest (1874), p. 346 
