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 of 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 Eed-tailed Hawk is exceedingly shy 

 and wary, and is taken with difficulty, unless approached on horse back 

 or in a sleigh or wagon. Bed-tailed Hawks in their fall migrations are 

 gregarious. One clear, cold autumn afternoon in 1876, 1 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 aerial antics, continued their southern flight. Combats 

 in midair are quite common among Eed-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, 



