6 
BULLETIN 1355, U. S. DEPARTMENT OF AGRICULTURE 
When the mating season arrives, from the middle of May to the 
last of June, the nest is started in a convenient fork of a branch, often 
near the ground; and, when finished, this is suspended by the rim 
rather than supported from below. The nest is a trim affair, about 
the size of a small teacup, woven of fibrous matter, among which 
may be instanced such substances as bits of birch bark, grapevine 
bark, or flax. Diligent search is required to disclose a nest when the 
leaves are green, but the number visible in fall is surprising. The first 
egg may be laid even before the nest is finished, and when this is the 
case the female remains at the nest while her mate searches for 
additional building materials. During the season of rearing the 
young, the patience of the red-eye is taxed to the utmost by the cow- 
oird. Brewer has reported a case of this form of parasitism where 
the vireos reared three young cowbirds without laying eggs of their 
own, and other records show that one or two cowbirds' eggs are not 
uncommonly found in a vireo nest. 
S?^y€>.\Af^? 
38 
Fjg. 2.— Monthly proportions of the various items in the food of the red-eyed vireo ( Vtreosylva olivacea) 
based on the analysis of the contents of 589 stomachs, with the average of each item for the year 
The annual food of the red-eyed vireo is composed of 85.28 per 
cent animal matter and 14.72 per cent vegetable. (See fig. 2.) The 
vegetable matter is taken more often late in summer and in fall and 
consists of the berries and fruits of such plants as wild cherry, sassa- 
fras, cornel (or dogwood), wild grapes, and woodbine. Of a total of 
653 stomachs available, 569 contained sufficient food for the correct 
estimation of percentages, and it is on the examination of the latter 
that the present report is based. This material was collected during 
the months April to October, inclusive, over the greater part of the 
range of the species in North America. 
