GRAY GYRFALCON. 
354. Falco rusticolus. 23 inches. 
These are birds of the Arctic regions and are rarely taken 
in the United States even in winter. 
Nest. —They build upon the ledges of high cliffs, laying three 
or four eggs of a buffy color, marked with fine spots and 
blotches of shades of brown. 
PRAIRIE FALCON. 
355. Falco mexicanus. 18 inches. 
This is quite an abundant species in some localities, and like 
the Duck Hawk in many ways is one of the most graceful, 
fearless and swiftest of the Falcons. A blackish patch on the 
sides of the throat; upper parts brownish with darker mark¬ 
ings; under parts white, streaked with brown, much heavier 
on the flanks. Throat, clear white. 
Nest. —Is generally placed on rocky ledges and cliffs, and some¬ 
times in trees. Their nests are made of sticks lined with weeds 
and grass; three or four eggs of a reddish buff color, thickly 
blotched and sprinkled all over with reddish brown (2.05x1.60). 
Range. —West of the Mississippi and from Dakota and 
Washington south to Mexico. Their food is mostly rodents 
secured on the prairies. 
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