216 U.S. NATIONAL MUSEUM BULLETIN 237 part i 



were analyzed by J, M. McGugan, Micro-Analyst of the Dominion 

 Department of Agriculture in Toronto, and Ronald N. Root, of the 

 U. S. Fish and Wildlife Service. Their analyses showed the most 

 important vegetable food in the juvenal diet to be the pit of the 

 pin- or bird-cherry (Prunus pensylvanica) . Seeds of other native 

 fruits such as the hawthorn (Crataegus sp.), blackberry (Rubus sp.), 

 and blueberry (Vaccinium sp.) were taken to a lesser extent; also birch 

 {Betula sp.) seeds. Weed seeds in the diet included those of sedge 

 {Carex sp.), dock {Rumex sp.), bindweed {Polygonum sp.), goosefoot 

 (Chenopodium sp.), crowfoot (Ranunculus sp.), wild geranium 

 (Geranium sp.), and violet (Viola sp.). 



Mr. Bent writes: "Mr. Lawrence has sent me some clippings from 

 his articles in the Winnipeg Free Press, in which he describes how the 

 grosbeaks fed their young in the box elder tree in Selkirk. Both 

 adults helped in feeding the young by regurgitation of semidigested 

 food whUe the nestlings were too young to take solid food. It was 

 difficult for the old birds to insert their heavy bills into the mouths 

 of the nestlings, but his sketches, based on photographs, show that 

 the adults accomplished this by twisting their heads to one side. 

 After the young were a week old they were fed caterpillars and small, 

 soft green seeds. The young were fed at irregular intervals, and, 

 when very young, were brooded by the female between feedings." 



Foraging parents usually, but not invariably, leave and return 

 to the nest together. WTien they arrive simultaneously both perch 

 on the rim of the nest and the female feeds one nestling. Then 

 she often takes food from the male's bill and feeds another. Finally 

 the male may give any remaining food directly to the young. 



I watched one nest with young 5 or 6 days old in Lauder Township, 

 Ontario, on June 23, 1945, from 4:45 a.m. until 8:01 p.m. when it was 

 getting too dark to see, except for a half -hour absence from 6:30 to 

 7:00 a.m. During this time the young were fed 34 times. Starting 

 at 4:50 a.m. when both parents arrived with food, there were 14 feeding 

 periods between dawn and noon. For 10 feedings the adults came 

 together or nearly so. Once the mother came alone and remained to 

 repair the nest lining and brood the young. Twice the father brought 

 food when the mother was on the nest, and once unattended by his 

 mate. Intervals between feedings in the morning varied from 7 to 

 54 minutes, averaging one feeding period every 21.5 minutes. Intervals 

 between the 20 feeding periods from noon to the last one at 7:50 p.m. 

 ranged from 1 to 97 minutes and averaged one every 24 minutes. 



The father seemed to attend to the nest sanitation more assiduously 

 than did the mother; he removed fecal sacs eight times, the mother 

 only twice. In each case nest sanitation followed a feeding. The 



