RUSSET-BACKED THRUSH 165 



on which it was placed, a neutral reddish-brown hue; whereas the 

 color of the moss placed exteriorly blended with that of the leaves of 

 the huckleberry. To carry out the illusion further there were inter- 

 woven in the green moss across the more exposed side of the nest, 

 three of the brown bracken stalks, these giving the effect of being 

 huckleberry branches and, also, affording additional support." 



W. L. Dawson (1909) says of Washington nests: "In distance from 

 the ground, nests varied from six inches to forty feet, altho a four 

 or five foot elevation was about the average." Again he says "some- 

 times 30-60 feet high in trees." 



Eggs. — The russet-backed thrush lays three to five eggs to a set, the 

 commonest number being three or four; some say that three is the 

 commonest number and some say four. The eggs are practically 

 indistinguishable from those of the olive-backed thrush, which the 

 reader will find described under that subspecies. The measurements 

 of 50 eggs in the United States National Museum average 23.2 by 17.2 

 millimeters; the eggs showing the four extremes measure 25.4 by 17.8, 

 24.4 by 18.0, 20.8 by 16.8, and 21.3 by 15.2 millimeters. 



Young. — The period of incubation is said to be 14 days, and the 

 young birds are said to remain in the nest for about the same length of 

 time, if not disturbed. I have no information as to whether both sexes 

 incubate or not, and nothing seems to have been published on the 

 care and development of the young except in Professor Beal's (1907 

 and 1915b) papers on food. "Two nests were carefully and regularly 

 watched, and from these it was determined that the parent birds 

 fed each nestling 48 times in 14 hours of daylight. This means 144 

 feedings as a day's work for the parents for a brood of three nestlings, 

 and that each stomach was filled to its full capacity several times 

 daily, an illustration that the digestion and assimilation of birds, 

 especially the young, are constant and very rapid." 



He examined the stomach contents of 25 nestlings, eight broods of 

 young birds sacrificed in the cause of science, and found that their 

 food was 92.60 percent animal and only 6.8 percent vegetable matter, 

 a considerably higher percentage of insects than was found in the 

 stomachs of adults. Caterpillars formed the largest item, nearly 

 27 percent; beetles amounted to 22 percent, including 7.7 percent of 

 hard-shelled Carabidae; Hemiptera, including stink bugs, leafhoppers, 

 treehoppers, shield bugs, and cicadas, made up 13.8 percent of the 

 food; ants and a few other Hymenoptera amounted to 12 percent; 

 only three stomachs contained remains of grasshoppers. "The vege- 

 table food consisted of fruit (6.8 percent), mainly blackberries or 

 raspberries, found in 11 stomachs, and twinberries in 1, and two or 

 three other items, including a seed of filaree and some rubbish." 



Plumages. — Mrs. Irene G. Wheelock (1904) says of a brood of three 



