CO BULLETIN FERGUS COUNTY HIGH SCHOOL 



inches deep. On the same day I found another nest of Swainson's hawk, 

 in a cottonwood along Big Spring Creek. This nest was thirty feet from 

 the ground, near the top of the tree, being an old crow's nest repaired with 

 fresh sticks. The cavity was eight inches across and one and one-half 

 inches deep. A partially eaten gopher was lying on the edge of the nest. 

 There were two fresh eggs, which were left until June 5, when no additions 

 had been made to the complement and the nest appeared to be deserted. 



A pair of these hawks sometimes manifests unusual zeal in establish- 

 ing their nest for the season. On May 2, 1903, I found a pair in possession 

 of a nest in a coulee opening into Big Casino Creek, near Lewistown. 

 Thinking that they were only looking forward to occupying the nest later, 

 I did not disturb them; but on May 9 I climbed to the nest, which was in 

 the top of a pine fifty-five feet from the ground. It was an old nest, re- 

 furnished with small pieces of fir branches. The structure was about three 

 feet across, the cavity being ten inches in diameter and two and one-half 

 inches deep. There were three eggs, far advanced in incubation. The 

 female always left the nest when I entered the coulee, and soared about 

 over the neighborhood, screaming angrily, in which she was generally 

 joined by her mate. 



Distinguishing features: Upper parts grayish brown; chin and throat 

 white; upper part of breast dark reddish-brown; lower parts dull yellowish 

 white, often barred or spotted with darker; length 19-22 inches. This is the" 

 common so-called "henhawk" or "cliicken hawk" of this region. 



348. FERRUGINOUS ROUGH-LEG. Archibuteo ferrugineus. 



A very common resident of this region. Like most of the other large 

 hawks, its activity is more noticeable after the gophers make their appear- 

 ance, which follows the middle of March in ordinary seasons. This hawk 

 begins to nest about the latter third of April, generally selecting an old nest 

 made by a crow or a more industrious hawk in a preceding year. On April 

 21, 1900, I disturbed a ferruginous rough-leg from a nest in a large pine 

 tree, in a rugged coulee along Big Casino Creek. The male was hovering 

 low on the opposite side of the coulee. Both birds balanced in air while 

 I remained near the nest. The female uttered several cries like the sylla- 

 bles "cay eye" as she hovered overhead. I did not disturb the nest, fear- 

 ing that the full complement of eggs had not been deposited. On April 23 

 I again visited the nest, and as before found the female upon the nest. 

 There was a drizzling rain, and she remained on the nest in spite of my 

 pounding on the trunk of the tree, not leaving until I startled her by 

 throwing a rock among the adjacent branches. I did not visit the nest 

 again until April 25, when the nest was examined and found to contain 

 two fresh eggs, evidently an incomplete set, though the female had occupied 

 the nest steadily since April 21. The two eggs measured about 2.38 

 by 1.80 inches, and 2.42 by 1.78 inches. One of the eggs was somewhat 

 rain-washed. The other egg was grayish or dingy white in color, marked 

 with reddish brown in blotches, and small irregular spots of similar vary- 

 ing colors. The nest was fifty-two and one-half feet from the ground, and 



