1376 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 3 



ber, when it amounts to 24 percent of the food of the month. A little amaranth 

 and lamb's quarters are eaten; and gromwell, chickweed, wood sorrel, sedge, 

 violet and sheep sorrel are all represented in the diet. But the principal weed 

 seeds found in the stomachs are those of ragweed and different polygonums. * * * 

 The two weeds form 25 percent of the food for the year, of which ragweed fur- 

 nishes 9 percent, and the polygonums 16 percent. During October, ragweed 

 alone constitutes 45 percent of the month's food. * * * 



The insect food resembles that of many other species in general character, 

 but some interesting differences appear when it is reviewed in detail. Hymenop- 

 tera constitute 6 percent of the year's food; Coleoptera, 5 percent; Heteroptera 

 and Diptera, taken together, 3 percent; and Lepidoptera, 3 percent, the cus- 

 tomary quota of spiders, millipedes, and snails supply the remaining 2 percent 

 of the animal food. 



The following items may be added to Judd's list: fruits of dogwood, 

 sumach, wild grapes, persimmon, smilax, cedar, and privet (Skinner, 

 1928) ; elder, mountain ash, blueberry, blackberry, wild cherry and 

 high bush cranberry fruits (Roberts, 1932) ; and greenbriar, spice 

 bush, wild sarsaparilla, and strawberry fruits (Howell, 1932). Low- 

 ther noted that raspberries and bunchberries were important food 

 sources during August in Algonquin Park. White-throats in cap- 

 tivity feed readily on various cereal grains, oranges, tangarines, 

 lettuce, cabbage, and leaves of geraniums. 



The foods consumed appear to change with the season. During 

 the winter the birds feed mainly upon weed seeds, small fruits, and 

 occasionally insects which are picked up from the ground. Arthur 

 T. Wayne (1910) reports that "with the approach of spring * * * 

 [the white-throat] resorts to the tops of the tallest oaks and maples 

 to feed upon their buds." Benjamin Warren (1890) records that 

 in April and May the buds and blossoms of apple, maple, and beech 

 trees are eaten. Milton B. Trautman (1940) reports that "during 

 late April and May, the species ate great quantities of newly formed 

 seeds of such trees as white elm, slippery elm, silver maple and red 

 maple" which the birds obtained directly from the trees. 



During the spring and early summer the white-throat becomes 

 more carnivorous, and larval and adult forms of many insects con- 

 stitute the bulk of the food. In Algonquin Park white-throats were 

 observed feeding on Hymenoptera and Lepidoptera larvae which 

 they gathered from the leaves and branches of trees and shrubs. 

 The young apparently are fed entirely on animal matter. That this 

 change to a carnivorous diet is not totally governed by the abun- 

 dance of insects and lack of seeds and fruits is evidenced by the 

 failure of white-throats to feed on bread crumbs and grain seeds 

 put out at feeding stations during the summer. Lowther has ob- 

 served white-throats bypass grain in favor of insect larvae in late 

 May, June, and early July. 



