RUSSET-BACKED THRUSH 167 



Stanley G. Jewett (1928) tells an interesting story of a russet- 

 backed thrush that assisted in feeding a brood of young robins in their 

 nest. He and his sister watched the robin's nest for a period of four 

 hours one afternoon, during which time the thrush made at least 12 

 visits to the nest and fed the young robins. "There were two robins 

 and two thrushes near the nest during the entire afternoon. Al- 

 though a systematic hunt was made for the thrushes' nest, it was not 

 found." 



Voice. — One who is familiar with the song of the olive-backed thrush 

 in the East should easily recognize the the song of the russetback ; the 

 songs are very similar with the same rising pitch. Grinnell and Storer 

 (1924) write: 



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 changing from song to song as does 

 the Hermit. The first syllables of any individual's song are always on the same 

 pitch, and full, clear, and deep; the remainder are more wiry, ascending, and some- 

 times the last one goes up so high in pitch as to become almost a squeal: wheer, 

 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, what or whoit, 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. 



According to Mr. Rathbun, this thrush does not sing its full song 

 immediately on its arrival in western Washington, for in his notes for 

 June 5 he wrote: "Although in a good locality, where this bird was 

 common, its song was seldom heard, and even then was not sung in 

 full. The song of the russet-backed thrush is a succession of round, 

 smooth notes, flowing easily in an ascending scale, the latter part 

 having a reedy sound. It spirals upward, as it were, and will be heard 

 at its best in the early morning and in the dusk of evening on a quiet 

 day. Its song practically ceases by the end of July, except on rare 

 occasions; then a period of silence seems to ensue; and about the first 

 of September, one will again hear the call notes, and shortly thereafter 

 the migration southward begins." 



Enemies. — Dr. Friedmann (1929) records only one case in which this 

 thrush has been imposed upon by the dwarf cowbird; there were two 

 eggs of the thrush and one of the cowbird in the nest. 



Field marks. — The russet-backed thrush is not likely to be confused 

 with any other bird on the Pacific slope except with one of the hermit 

 thrushes, but the uniform russet-brown of its back is easily distin- 

 guished from the contrasted brown back and rufous tail of the hermits; 



