TREE SPARROW 1155 



were strikingly scant in the summer diet, being found in only one 

 individual in late August. Besides seeds, plant matter was found in 

 the form of soft bits of wood or chips, fibers, leaf fragments, galls, 

 and unidentified debris. 



The insects represent a large number of families and genera, among 

 which the following groups are most conspicuous: Arachnida, Cole- 

 optera (especially Donacia), Ichneumonidae, Lepidoptera, Nematinae, 

 and Trichoptera. The adult stage predominated, but eggs, larvae, 

 and pupae were also taken. A complete list of food species of the 

 tree sparrow is included in Baumgartner (1937c). 



In observations at the nest, the adult birds came repeatedly with 

 bill overflowing with small green and brown caterpillars, as well 

 as flies, mosquitoes, and other adult insects. At first the material 

 is partially masticated, and the pidpy mass is jammed far down the 

 young bird's throat. Several birds may be fed at a single visit. 

 Later great billfulls of more or less entire insects are brought to the 

 nest. But however great the quantity, it seems scarcely enough 

 to satisfy one or two gaping mouths. The iinmensily of the old 

 birds' task was shown by a male collected in the field holding in its 

 bill 41 adult insects, 4 larvae, and fragments of others, all captured 

 presumably witliin 3 or 4 minutes. 



Although during June and July in the North almost full daylight 

 extends from 2:00 a.m. until 10:00 p.m., tree sparrows do not begin 

 feeding until 3:15, and cease shortly before 9:00, a "working day" 

 of 17.75 hours. From this it may be computed that, at an average 

 of 16 feedings per hour, some 275 feedings are made daily, divided 

 among the four or five young. It is interesting to compare with 

 this the parental care given by that closely related species of more 

 temperate latitudes, the cliipping sparrow (Weed, 1898). Averaging 

 12 visits per hour, divided among only 3 nestlings, each individual 

 young of this species seems to be fed as many times per hour as do 

 individual j'oung of the tree sparrow. But here the working day 

 begins at 5:00 a.m. and closes at 7:30 p.m. with only 14.5 hours in 

 which to work. It is strongly suggested that these 3 extra hours a 

 day make it possible for young tree sparrows to leave the nest at 

 9K da3's, two days earlier than chipping sparrows at 11/^ days. 

 Thus the longer hours of daylight compensate in a measure for the 

 briefness of the nesting season. 



Economic importance. — Because of the vast quantities of obnoxious 

 weed seeds the tree sparrows consume during their winter sojourn 

 in the States, much has been made of the economic value of this 

 species. The Department of Agriculture estimates that the sparrow 

 tribe — of which the tree sparrow is one of the most abundant species — 

 saves the farmer $00 million a year. Judd (1901) describes the 



