123 
30, insects; 2, earthworms; 4, crawfish. Without further analysis this 
evidence is sufficient to free this species from any stigma of being harmful. 
347a. Rough-legged Hawk. FR.—LA BUSE PATTUE D’AMERIQUE. Archibuteo lago- 
pus sancti-johannis. L, 22. The largest of our true Hawks. It occurs in two phases: 
one all dark, almost black; and the other light, of almost infinite variety of colour tone 
and pattern. All intermediate stages occur. The most common form is brown above 
more or less mixed with ochre, especially about head, and ochre below with dark abdominal 
band and stripes on breast and throat. The tarsus, being feathered to the toes, is the 
basis of the common name and is characteristic of the genus. 
Distinctions. Large size and the feathering of the tarsus to the base of the toes is 
diagnostic. 
Field Marks. Large size, broad masses of black below, tail white at base (not a white 
rump), and prominent black wrist marks on the under surface of the wing are all good 
field marks. 
Nesting. In the far north on ground, on rocky ledges, or in trees. 
Distribution. As a species, inhabiting the northern portions of the northern hemi- 
sphere. The American form is found from Mexico to the Arctic. Breeds on or near the 
barren grounds. 
SUBSPECIES. The Rough-legged Hawk is represented in the New and Old Worlds 
by two subspecies. The one peculiar to America is the American Rough-legged A. I. 
sancti-johannis, and is only distinguished from the European and Asiatic bird by its 
slightly lighter colour and the greater rarity of the black phase. 
This large Hawk is only a migrant in settled Canada to or from the 
barren grounds of the north. It is a bird of large marsh expanses and can 
be seen beating over the grass until late in the evening something after the 
style of the Marsh Hawk. Usually, however, it is observed high in the 
air working its way gradually, with many pauses and circlings, to or from 
its breeding grounds. Owing to the dichromatism of the species an almost 
infinite variety of plumages may be found. 
Economic Status. Though our largest Hawk, it is the least harmful 
one. Of 45 stomachs examined, 40 contained mice; 5, other mammals; 
1, lizard; 1, empty. A record like this is enough to condemn the indis- 
criminate killing of Hawks. The feet of the Rough-leg are weak and 
incapable of holding large prey; it is, therefore, a mouse-hawk par excel- 
lence. It also feeds on grasshoppers and has been known at times to do 
most excellent work controlling plagues of these destructive insects. 
GENERA—AQUILA AND HaLiaetus. EAGLES. 
The Eagles are our largest Birds of Prey. Size alone will differentiate 
them from the Hawks. Any Bird of Prey over 30 inches long or 6 feet in 
extent is an Eagle. Contrary to usual conception, the Eagle is not the 
noble bird of prey usually pictured. It is typically an overgrown Buzzard. 
Much of its quarry is of large size, but it is rarely dangerous to human 
interests. In some sections young lambs are occasionally threatened, 
but in eastern Canada Eagles can be looked upon more as scavengers 
than anything else, taking little of economic value and subsisting mostly 
on offal. 
349. Golden Eagle. Frr.—t.’aIGLE pore. Aquila chrysaetos. L, 30. A large, dark- 
brown Eagle, the head suffused with faint ochraceous suggesting the name golden and the 
basal half of tail with broken greyish bars against dull white. Tarsus feathered to the 
toes. 
57172—9 
