122 BULLETIN 16 7, UNITED STATES NATIONAL MUSEUM 



off a chicken within a few yards of him. A Cooper's Hawk two years ago in 

 East Bridgewater behaved similarly. Four times this daring bird (with people 

 standing near) tried to get a chicken out of a hen-yard that adjoined the mixed 

 woods where it had its nest. The people "shooed" the hawk away three times, 

 but at the fourth attempt, despite their cries, it carried off a pullet. 



Enemies. — The Cooper's hawk has few enemies, except the farmer 

 or the sportsman with a gun, but the following account, sent to me by 

 Clyde L. Field, shows that the spunky little kingbird can make life 

 miserable for this hawk and defend its territory successfully against 

 it: 



Once while traveling along some foothills in Arizona, where bird life was 

 very scarce, I came to a small grove of sycamores. Here birds were very abun- 

 dant. Nesting had not yet started, except for a pair of Cooper's hawks. On 

 account of these hawks, I little hoped that many of these birds would live 

 through the summer, but, much to my surprise a month later, they were still 

 there and as many as before. 



The answer was soon forthcoming, for up the creek came a badly scared 

 Cooper's hawk with a flock of kingbirds in hot pursuit. The kingbirds were 

 striking at him from all angles and, at each hit scored, the hawk would let out 

 a squark. This wa.s repeated several times during the day. 



I came upon one of the hawks sitting on a limb with two kingbirds diving at 

 it. One of the kingbirds struck him, causing him to lose his balance. Taking 

 advantage of this, the other kingbird hit him again, knocking him off. Down 

 the creek they went, with more kingbirds joining in the chase. The kingbirds 

 made living possible here for the other small birds in the grove. 



Voice. — The ordinary alarm note, heard about its nest, is a loud, 

 metallic, cackling note, similar in form to the corresponding note of 

 the sharp-shinned hawk, but louder and on a lower key. I have al- 

 waj's written it kak, kak, kak, kak. Others have called it cac^ cac, 

 cac, or cuck, cuck, cuck. It is rapidly uttered with considerable 

 emphasis. As the female leaves the nest she sometimes gives a loud 

 scream of fright or anger. 



Field marks. — The Cooper's is a larger edition of the sharp- 

 shinned hawk and easily confused with it; there is no well-marked 

 color difference, though the adult Cooper's has a more clearly de- 

 fined black cap. The chief difference is that the sharpshin has a 

 square tail and Cooper's a I'ounded tail. Both have short, rounded 

 wings and long tails, much longer than the Buteos; and both have 

 the characteristic Accijnter flight, a few rapid wing strokes, alter- 

 nating with short periods of swift gliding. As seen from below, 

 both may be distinguished from the goshawk by the more conspicu- 

 ously barred tail and primaries. A small male Cooper's appears to 

 be not much larger than a large female sharpshin, but Dr. George 

 M. Sutton (1928) has shown that the average male Cooper's weighs 

 about twice as much as the average female sharpshin. 



Fall. — Cooper's and sharp-shinned hawks make up a large part of 

 the great fall flights of hawks that pass over the United States in 



