Vol. xxxvn 



1919 



Taverner, Birds of Red Deer River, Alta. 17 



this forms the subject of a separate publication, 1 and calls for no further 

 treatment here. 



63.* Buteo swainsoni. Swainson's Hawk. — Much that has been 

 said of the previous species especially as to food, can be applied to this. 

 Through the upper part of our course down as far as Camp 4, near Nevis, 

 it seemed less numerous than the Red-tails; below that point it was about 

 equal to them, disappearing with them at the entrance to the desert-like 

 lower bad lands. Owing to the great variety of plumage of these two large 

 Hawks it was in most cases practically impossible to distinguish between 

 them except when in most characteristic plumage. Usually a dark breast 

 band indicates Swainson's Hawk but we saw many variations that made 

 us doubt the absolute reliability of even this character. On the whole, 

 I suspect that the dark phase was slightly more common in swainsoni than 

 in borealis. The commonest type of coloration had such a breast band but 

 they ran through a redder type with less conspicuous breast band to a 

 nearly black bird on one hand and to light plumages similar to normal 

 juvenile eastern Red-tails. We took twelve specimens in all including 

 downy young. In nesting there was little difference that we observed, 

 between these and Red-tails, though they were perhaps more prone to 

 choose smaller isolated trees standing in the open, a location we did not 

 see used by borealis at all. 



64. Archibuteo lagopus. American Roughlegged Hawk. — 

 Horsbrough reports a few specimens on fall migration dates. Older 

 literature includes nesting records for this and adjoining sections, but 

 if is problematical whether they do not refer to the next species. 



65.* Archibuteo ferrugineus. Ferruginous Rough-leg.— Though 

 we recognized no Rough-legs as such on the upper river or before we passed 

 Camp 4, near Nevis, the residents about Camp 1 spoke of " Chap Hawks " 

 so called from the feathering of the legs. Just above Camp 4 in the top of 

 a cottonwood we saw a very large old nest that aroused our curiosity and 

 which we later attributed to this species. Below Nevis we had our first 

 > ew of the species and from thence on it was very common, nesting on the 

 tops of pinnacles and shelves of the bare eroded exposures and occasionally 

 in trees. The nests were immense masses of coarse sticks and seemed to 

 be added to and used year after year. Some nests seen about Camp 11 

 on the Little Sandhill Creek seemed to have been occupied for many years. 

 One built upon a salient buttress of a cliff had increased with annual 

 additions until it formed a mass of material twelve or fifteen feet high. 

 The lower masses of the nest were rotten and merged into the original clay 

 foundation whilst it grew fresher towards the top until the final layer was 

 of this year's construction, — mostly sage-brush roots. In a little hollow 

 adjacent to such a nest we found an accumulation of over a bushel of dried 



1 The Hawks of the Canadian Prairie Provinces, in their Relation to Agriculture, by 

 P. A. Taverner. Museum Bull. No. 28, Biol. Series No. 7, Geological Survey, Dept. of 

 Mines, Ottawa, Aug. 1918. 



