420 University of California Publications in Zoology. [Vol. 7 



Water from a recent dip in the stream was still clinging to its 

 feathers. Another individual was heard several hundred yards 

 up the creek. Two birds, evidently a pair, were seen May 18 

 at Quinn River Crossing in the sagebrush near the ranch. This 

 species was evidently migrating, being found by us only in Upper 

 Sonoran zone. Two female specimens (nos. 8662, 8663) were 

 taken. 



; Hylocichla ustulata swainsoni (Tschudi) 



Olive-backed Thrush 



Distribution. — ^Noted along Big and Alder creeks between the 

 altitudes of 5700 and 8500 feet. Its habitat falls within that 

 part of Transition which has a Boreal infusion. 



Habits. — The song of this bird, which was perhaps the most 

 attractive esthetically of all the bird-music we heard, was first 

 noted at the head of Big Creek. Regularly while we were en- 

 camped in the mountains it was noted early in the morning and 

 in the evening until eight o'clock. The limber pines, quak- 

 ing aspens, and various thickets along streams seemed to be 

 favorite places of habitation. One locality in particular, situated 

 at a height of 7000 feet on Big Creek, was preferred to other 

 places. A thick growth of moisture-loving plants, such as 

 nettles, and the dense shelter afforded by the extensive quak- 

 ing-aspen groves, together with the presence of streams flowing 

 from small springs on the nearby slopes, made ideal surround- 

 ings for this thrush. 



Three young thrushes in newly acquired juvenal plumage 

 were recorded on Alder Creek (7000 feet) on July 13. 



Planesticus migratorius propinquus (Ridgway) 



Western Robin 



Distribution. — Secured generally throughout the region. One 

 of the most numerous birds observed. In scarcely diminishing 

 numbers it invaded the mountains to an altitude of 9000 feet. 

 Below this it was very common. It inhabited every suitable 

 stream and willow clump on the desert. Its zonal distribution 

 was Upper Sonoran and Transition. 



