HAWKS 291 



of a hit or miss process, as was evinced by the loss of these twigs and 

 by the simple manner in which the nest twigs rested one upon another. 

 The irregular form of the twigs doubtless serves a good office in helping 

 to hold the structure together. A few down feathers from the adult birds 

 clung to the leaves in the nest. 



When visited on May 7 the nest contained one egg; the next morning 

 there were two, the usual complement for this species. As the nest was 

 approached on the second morning, one of the hawks flushed at long range 

 from its perch in the adjacent dead tree and circled for some minutes 

 high overhead, giving at intervals a loud prolonged cry that was clearer 

 and more sustained than that of a Red-tailed Hawk. This bird, presum- 

 ably the male, was evidently acting as 'observer'; for the mate remained 

 on the nest until we approached within 50 feet, when it, too, took to flight. 

 Both birds soon disappeared, and were not again seen. The area beneath 

 the nearby dead tree was splashed with 'whitewash' (excrement), showing 

 that it had been occupied frequently as a roost. It was doubtless the 

 accustomed perch and lookout post for the mate of the sitting bird, and 

 its proximity may have determined the selection of the nest tree itself. 



Incidentally, it may be remarked that this perching tree of the hawks 

 was tenanted by a pair of Plain Titmouses, with their brood of young, 

 and a pair of Western Bluebirds with a completed set of eggs; while a 

 likely looking hole higher up w^as being prospected by a pair of Violet- 

 green Swallows. The close proximity of this pair of birds of prey, repre- 

 sentatives of a species which rarely if ever eats small birds, was evidently 

 of no more concern to the titmouses and bluebirds than would have been 

 the presence of a pair of California Woodpeckers within similarly close 

 range. 



A Swainson Hawk observed in flight showed a light throat (pi. 44/i), 

 dark chest, rather narrow but bluntly ended wings, and a light patch at 

 the side of the rump. AU of these points aided in differentiating the bird 

 from the Red-tailed Hawk. Of course, there is no red on the tail of the 

 Swainson at any age. In motion this bird's wing-beats are quicker and 

 more frequent than those of the Red-tail. 



Ferruginous Rough-legged Hawk. Archibuteo ferrugineus (Lichtenstein) 



Field characters. — Size large, slightly greater than that of Eed-tailed Hawk; wings 

 broad; tail short. Upper surface of body dark brown appearing; under surface white, 

 with small scattered streaks or bars of dark brown; base of tail in flight appearing 

 white; legs down to bases of toes covered with feathers of a rusty or duller brown tone. 



Occurrence. — Sparse winter visitant on west side of Sierra Nevada. Kecorded 

 definitely at Smith Creek, 6 miles east of Coulterville, October 17, 1919 (one specimen). 

 Inhabits open ground. 



