FOX SPABBOWS 477 



During the nesting season the birds are noisy and the males are 

 belligerent, each jealously guarding his home precinct, A male watched 

 at Mono Meadow, June 20, drove away in quick succession a Western 

 Tanager and a Wright Flycatcher. On August 17, 1915, an adult and one 

 juvenile fox sparrow were seen under some golden oak brush near Glacier 

 Point. The adult seemed unusually forward in its actions as if it were 

 attempting to distract attention from the young bird. 



Up till late in the fall, as in summer, the thickets of the Canadian Zone, 

 so long as they are free from snow, are inhabited by fox sparrows. The 

 mannerisms of the birds then in evidence are the same as in summer and 

 the same places are frequented — but the grayish bro^\Ti birds of summer 

 have been replaced by birds with reddish brown backs. The former, the 

 Mariposa and Mono fox sparrows, have emigrated elsewhere, and from the 

 north, from various places in Canada and Alaska (see footnote 31) have 

 come several races of brown-backed birds. The replacement is complete 

 and yet so gradual that the casual observer would not detect the exchange. 

 These winter visitants from the north also take possession of the lower 

 zones, the Lower Sonoran as at Snelling, Upper Sonoran as at El Portal, 

 and Transition as in the western part of Yosemite Valley. We believe 

 that in summer the temperature conditions in these lower zones are 

 unsuited to the requirements of the fox sparrows, or else that the niche 

 which they occupy there in the winter is in summer filled by other species. 

 Then, too, fox sparrows, being ground-feeding birds, must live below the 

 altitude at which snow lies on the ground for any length of time. Thus 

 the brown-backed birds which migrate into the Canadian Zone in the fall 

 drop to lower elevations when the heavy snows of winter come. 



Spurred Towhees. Pipilo maculatus Swainson^^ 



Field characters. — Size large for a sparrow, bulk between that of Jimco and Eobiu ; 

 tail about as long as body, and usually carried up at an angle with back. ^Vhole upper 

 surface and forepart of body, black; small spots ('tear drops') in rows on wings, larger 



32 Two subspecies of the Spurred Towhee inhabit the Yosemite region, occupying 

 separate territory, on the western and eastern flanks of the Sierra Nevada respectively. 



Sacramento Spurred Towhee, Pipilo Dwc-ulatus falcineUus Swarth. This is the race 

 of the western slope of the Sierras, ranging in the breeding season from the vicinity of 

 Snelling up as high as the floor of Yosemite Valley. In autumn, wanders still higher, 

 as to Aspen Valley at 7000 feet and on lililouette Creek at 6200 feet. 



Nevada Spurred Towhee, Pipilo maculatus curtatus Grinnell, the race of the Great 

 Basin area, enters the Yosemite region from the east and breeds in the vicinity of 

 Mono Lake, where found by us at Mono Lake Post Office, near the mouth of Leevining 

 Creek, and about the base of Williams Butte. One individual was obtained in Glen 

 Aulin, 7700 feet altitude, October 4, 1915, which would seem to indicate a westward 

 movement of this interior race in autumn over the Sierran crest. 



The differences between the two races, falcineUus and curtatus, are so slight that only 

 specimens in hand can be distinguished. Curtatus, as compared with falcineUus, shows 

 a shorter hind claw, a smaller bill, a shorter tail, a greater amount of white on shoulders, 

 wing coverts, and tail, and paler tone of coloration on sides and lower tail coverts. 



