BUSSET-BACKED THBUSU 601 



The demeanor of this thnish is quiet and reserved. The bird inhabits 

 by preference the rank growth of stream-side vegetation, departing from 

 this only when the male happens to go up some distance in a nearby tree 

 to sing. In migration time when passing through the lowlands the Russet- 

 backs keep to the same sort of cover as is chosen by them for their summer 

 haunts. 



By early June, and sometimes sooner, the Russet-backed Thrushes in 

 Yosemite Valley are in full song and may be heard during the day as well 

 as in the morning and evening hours. The song is set in character and 

 each individual thrush begins his song on about the same key — not chang- 

 ing from song to song as does the Hermit. The first syllables of any indi- 

 vidual's song are always of the same pitch, and full, clear, and deep; the 

 remainder are more wiry, ascending, and sometimes the last one goes up 

 so high in pitch as to become almost a squeal : ivheer, wheer, wheer, whee-ia, 

 whee-ia, whee-ia, or quer, quer, quer, quee-ia, quee-ia, quee-ia. The call 

 note oftenest heard is a soft liquid whistle, ivhat or ivhoit, sounding much 

 like the drip of water into a barrel. An imitation of this note by the 

 observer will often bring a thrush into close range. Now and then a 

 thrush will give an abrupt burred cry, chee-ur-r; and again there may be 

 a single whistle, louder and higher than the usual call. The song season 

 lasts until early July, after which the birds become quiet. By the end 

 of the month not even the call note is to be heard. 



The nest is located in some bush in the vicinity of a stream. One found 

 in Yosemite Valley on June 24, 1915, may be described as typical in struc- 

 ture though it was placed a little higher than usual. This particular nest 

 was at a height of 7 feet above the ground, settled firmly in the crotch 

 of a willow where three branches about one-fourth of an inch in diameter 

 gave ample support. The structure was bulky, 6 inches in height and 

 about 4 in diameter on the outside, with the cavity about two and a half 

 inches deep and the same in diameter. The material used was chiefly 

 dry willow bark, with some grass stems and blades, a few pine needles, 

 leaf 'skeletons' and weed stems. There was no moss on the outside, nor 

 was there horsehair within, the lining being of loosely placed fine stems 

 and roots. Just without the lining of the nest cup was a layer of dried 

 sandy mud, "as firm as though cement were mixed with it," the notebook 

 states (Mrs. Joseph Grinnell, MS). On the 24th the four young were 

 nearly ready to leave and this they had done by the 26th, though they were 

 still in the vicinity on the latter date, for the anxious calls of the parent 

 birds were heard in adjacent trees. 



Two nests of the Russet-backed Thrush were found in Yosemite Valley 

 on June 28, 1915, by Miss Margaret W. Wythe (MS). One of those con- 

 tained 8 young birds about half-grown. The other nest held 2 young birds 

 just out of their shells, and 2 eggs which hatched on the 30th. 



