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FALCONS, CARACARAS, ETC 
354. Falco rustieolus rustieolus {Linn.). Gray Gyrfalcon. Ads . — 
Head streaked with buffy or whitish and fuscous, in about equal amounts; 
upperparts grayish, slaty or brownish gray barred with white or whitish; 
tail barred with brownish gray and white in about equal amounts; below 
white with elongate spots from chin to vent; flank plumes barred , under 
tail-coverts barred or with shaft-streaks. Im . — -Head more narrowly streaked 
with fuscous; upperparts browner margined with whitish and with more or 
less concealed spots or broken bars of whitish or buffy; underparts more 
heavily streaked. L., 20*00; W., 15*50; T., 9*50; B. from N., *90. 
Remarks. — -In any plumage the various races of rustieolus are to be 
distinguished from islandus by their barred, streaked, or shaft-streaked 
under tail-coverts. The distinctive characters of our three races of rustieolus 
are the broadly-streaked head of F. r. rustieolus , the barred or margined 
back and solid or comparatively unstreaked head of gyrfalco, and the black 
back and almost black underparts of obsoletus. 
Range. — Arctic regions. Breeds in Arctic Am. from Alaska, e. to s. 
Greenland; in winter casual s. to B. C., Kans., Wise., Ont., and Maine. 
Nest, on cliffs or in trees. Eggs, 3-4, not distinguishable from those 
of the preceding, 2*37 x 1*72. Date, Iceland, Apl. 15 (Thayer Coll.). 
354a. F. r. gyrfalco {Linn.). Gyrfalcon. Similar to F . r. rustieolus 
but darker; ad. less distinctly barred above and with the head fuscous, 
unstreaked. Im. — Head grayish brown, little if at all streaked or margined 
with buffy; back grayish brown, almost uniform, or but slightly margined 
or spotted with buffy. 
Range. — Arctic regions. Breeds in Ellesmere Land, n. Greenland, and 
e. to Franz Josef Land; in winter casual s. to Minn., N. Y., R. I., Mass., 
and Maine. 
Nesting date, Ft. Anderson, Mack., May 9. 
354b. F. r. obsoletus {Gmel.). Black Gyrfalcon. Head fuscous, 
narrowly margined with buffy, rest of upperparts uniform slaty fuscous, 
without bars; tail the same, without or with only broken bars; underparts 
of the same color as the back; the feathers with partly concealed buffy spots 
or margined with buffy. 
Range.. — Breeds in Ungava; s. in winter to N. S., Que., Ont., and Maine, 
and casually to N. Y., N. H., Mass., and R. I. 
Nesting date, Ft. Chimo, Lab., May 22. 
355. Falco mexicanus Schleg. Prairie Falcon. Ads. — Above, 
grayish brown; primaries and inner webs of all but the middle tail-feathers 
with numerous buffy bars or spots; below, white, streaked and spotted with 
dark grayish brown. Im. — Similar, but with the upperparts margined with 
ochraceous-buff or buffy. cT L., 17*00; W., 12*20; T., 7*00. 
Range. — Transition and Sonoran zones from e. border of the Great 
Plains and from s. B. C. and se. Sask. to s. L. Calif., and s. Mex.; casual e. 
to Minn, and Ills. 
Nest, on cliffs, sometimes in hollow trees. Eggs, 2-5, “creamy white, vin- 
aceous-white, or pale vinaceous-buffy, sprinkled, speckled, or irregularly 
spotted with madder-brown, 2*06 x 1*60” (Ridgw.). Date, Gilmer, Wyo., 
Mch. 25. 
“The Prairie Falcon, as the names implies, is a typical plains bird, 
and inhabits the dry interior. . . . 
“The flight of this Hawk is swift and graceful, though in most 
cases it is carried on at no great distance from the ground. It is not 
a shy bird, except in sections where it has been persecuted and has 
learned that man is its worst enemy” (Fisher). 
