BIRDS OF PENNSYLVANIA. 
127 
tipped with white. Breast of adult mostly spotted or marked with reddish-brown; 
in the young, breast is pure white enclosed by numerous dark markings. Length 
of male, 19 to 22 inches ; extent ot wings, 41 to 47 inches. Female — length, 22 to 24 
inches ; extent, 51 to 55 inches. From a careful examination of over one hundred of 
these hawks, I have found that they, like other of the raptores, not only vary greatly 
in the markings of their plumage, but also show marked differences in the color of 
the irides. The iris of the adult, though usually brown, is sometimes both brown 
and yellowish. In immature birds the iris is commonly straw color, but sometimes 
it is nearly white, and occasionally, though rarely, is brown ; in other specimens T 
have seen one-half of the iris brown while the remainder would be white or yel- 
lowish. In immature birds, light-colored irides with specks of brown are frequent. 
Habitat. — Eastern North America, west to the great plains. 
This hawk — the most abundant of our raptorial birds — is the detested 
“ Hen Hawk ” of the farmer. The Red-tailed Hawk is exceedingly shy 
and wary, and is taken with difficulty, unless approached on horse back 
or in a sleigh or wagon. Red-tailed Hawks in their fall migrations are 
gregarious. One clear, cold autumn afternoon in 1876, I saw, near West 
Chester, a flock of these hawks. The sky was destitute of clouds, ex- 
cept a cumulus stratum directly beneath, and apparently about half way 
between the hawks and the earth. In the center of this vapor was an 
opening of sufficient size to enable me to watch the gyrations of the 
birds ; two of them suddenly separated from the main body, approached 
each other screaming, and apparently in great rage. They descended 
screaming, and, to all appearances, clinched, to within about one hundred 
yards of the earth, when they parted. Evidently neither bird had re- 
ceived much injury, as they both, after taking short flights across the 
meadow, ascended in company with two or three of their companions 
that had accompanied them part way down, to the main body. Another 
individual closed his wings until the body presented a triangular outline, 
descended with almost lightening-like rapidity to the top of a sycamore, 
where it alighted, and remained for some seconds pluming itself. This 
party of hawks, after performing for nearly twenty minutes, these, and 
numerous other serial antics, continued their southern flight. Combats 
in midair are quite common among Red-tailed Hawks. I have repeat- 
edly witnessed such battles, and am fully convinced that in the great 
majority of cases food is the incentive to such action. Illustrative of the 
superior vision of this hawk — and the same applies to other of the Ra- 
pacia — the following is given, as observed by the writer : A clear morn- 
ing early in March, I saw a Red-tail circling over the meadows ; every 
circle took him higher and higher in the air, until at an altitude where 
he appeared no larger than a blackbird, he stopped, and with nearly 
closed wings, descended like an arrow to a tree near by me ; from this 
perch, almost the same instant he had alighted, he flew to the ground 
and snatched from its grassy covert a mouse. The momentum with 
which this bird passed through the atmosphere produced a sound not 
very unlike that of the rush of distant water. This species when wounded, 
