166 BULLETIN 196, UNITED STATES NATIONAL MUSEUM 



young russet-backed thrushes that were evidently about a week old: 

 "They were sparsely covered with brownish gray down, and pin- 

 feathers were just showing along the feather tracts." 



Subsequent molts and plumages are apparently similar to those of 

 the olive-backed thrush, which are more fully described under that 

 subspecies. 



Food. — Professor Beal (1907) examined 157 stomachs of the russet- 

 backed thrush, taken mainly in the San Francisco region from April 

 to November. The examination showed 52 percent of animal and 48 

 percent of vegetable food. Ants formed the largest item in the insect 

 food, amounting to 16 percent; "Hymenoptera, other than ants 

 (mostly wasps), bugs, flies, and grasshoppers, with some spiders, 

 amount altogether to 12 percent of the year's food," but grasshoppers 

 were found in only four stomachs. Beetles, only 3 percent of which 

 were useful species, constituted 11 percent of the year's food; and 

 caterpillars amounted to somewhat more than 8 percent. 



The vegetable food consists mainly of fruit and only a trace of weed 

 seeds. "It is probable that the greatest harm done by this bird is to 

 the cherry crop, though undoubtedly it eats the later fruits to some 

 extent. In May and June the fruit eaten reaches 41 and 38 percent, 

 respectively, and this probably represents the greatest injury which 

 the bird does, as most of the fruit was the pulp and skins of cherries." 

 Other vegetable food included seeds of blackberries, raspberries, both 

 wild and cultivated, and seeds of the twinberry, elderberry, coffee- 

 berry, peppertree, and poison-oak. Fruit eaten in September 

 amounted to 80 percent, the largest amount for any month. 



Ian McT. Cowan (1942) records the russet-backed thrush among 

 the species that he has seen feeding on the^termite Zootermopsis 

 angusticollis in southwestern British Columbia, where "the extensive 

 areas of deforested land, strewn with decaying logs and stumps, pro- 

 vides ideal habitat for termites." 



Behavior. — The russet-backed thrush is a close sitter when incu- 

 bating and will allow a close approach to the nest; it then slips quietly 

 off the nest and disappears in the shrubbery, keeping out of sight and 

 uttering its peculiar notes of protest but offering no attempt at active 

 defense. At other times it is a shy retiring bird, much oftener heard 

 than seen; one hears its beautiful song or its characteristic alarm notes 

 and attempts to follow it, but it fades away under the cover of the 

 thick foliage, and one hears its notes again from some more distant 

 point. It feeds mainly on the ground, as the other thrushes do, 

 running over the ground and drawing itself up to its full height when 

 it halts, as the robin does on the lawn. It seems less nervous than 

 the hermit thrush, and is seldom seen to raise and lower its tail when 

 excited. 



