224 BULLETIN 16 7, UNITED STATES NATIONAL, MUSEUM 



outside diameter ; the inner cavity was from 8 to 9 inches in diameter 

 and was hollowed to a depth of from 2 to 5 inches. All the nests 

 found around June 1 had incomplete sets, and fresh sets were found 

 up to June 14, showing that most of the eggs were laid during the 

 first two weeks in June. The first young, just hatched, were found 

 on June 25. These hawks desert their nests on slight provocation; 

 several new freshly lined nests and nests with incomplete sets that we 

 examined early in the season were later found to have been aban- 

 doned. Hunting for nests of Swainson's and ferruginous rough- 

 legged hawks is a simple and easy matter in this open country; all 

 one has to do is to drive along near the timber belts and watch for 

 the conspicuous nests; and climbing irons are seldom needed. 

 Mr. Cameron (1913) says of Montana nests that he has seen: 



The nests of B. swainsoni are made entirely of sticks, or of sticks combined 

 with other materials, such as sage-brush, wild-rose brambles, and cottonwood 

 or cedar twigs. Tliere may be an elaborate lining of green weeds, or quantities 

 of wool — perhaps only a scanty layer of grass. Some birds line their nests 

 with fresh leaves, which are renewed at intervals, but, in my experience, this 

 does not occur until after the full clutch of eggs has been laid. The parent 

 birds roll back the eggs and replace them on the leaves, which is not a difficult 

 feat, as many nests are almost flat. As the hawk apparently mates for life, 

 the nest, which is very strongly put together, increases in size with the yearly 

 repairs. In my own experience I have known disused nests to be practically 

 intact after a period of seven or eight years. Since 1889, I have seen a great 

 many occupied nests, but only kept notes of fourteen. Of these six were in ash 

 trees, six in cottonwoods, one in a low cedar, and one in a wind-swept pine-top. 

 This last, on a dominant scaur of the pine hills, was the most picturesque of all, 

 but could not, of course, endure long without renewal, and is the only nest I 

 have seen thus exposed. 



S. F. Rathbun tells me of a nest he found in eastern Washington 

 that was placed on "a rather large pinnacle rock. It was about 8 

 feet in height, and its top was almost flat. The color of the rock and 

 that of the nest were so much alike that at a little distance the two 

 blended, but anyone who knew what he was looking for would see the 

 nest. It was about 2 feet high and nicely made. Outwardly it was 

 made of dry branches of sage, with a lining of soft strips of the sage." 

 The nest contained only one egg. When he visited the nest the next 

 day, to see if more eggs had been laid, he "found there had been 

 placed across the top of the inside of the nest a tuft of bunchgrass", 

 concealing the egg. This may have been done to protect the egg 

 against marauders. 



Mr. Skinner mentions in his notes from Yellowstone Park "a nest 

 on a tall fir at the edge of a cliff." A. Dawes DuBois describes in 

 his notes a nest "35 or 40 feet from the ground in the top of a cot- 

 tonwood" in Montana. "It was composed of sticks and coarse twigs 

 (the largest about three-eighths of an inch thick), most of them 

 freshly broken. There was a doubled piece of baling wire in the 



