224 BULLETIN 197, UNITED STATES NATIONAL MUSEUM 



ternal depth, 2.25 ; internal diameter at mouth, 1.30 x 1.68 ; internal depth, 1.40 ; 

 greatest thickness of walls, .63. 



Of the measurements of the other nest, he says: "The greatest 

 diameter is 3 niches ; inside diameter, 1.75 inch ; depth, 1.80 inch ; thick- 

 ness of walls, from .45 to .60 of an inch." 



Mr. Simmons (1925) says of the nest location in central Texas: "2 

 to 6, rarely 15, usually 4, feet from the ground, suspended from hori- 

 zontal forked twig of small scrub oak, live oak, Spanish oak, or elm 

 bush or stunted tree, usually among low shin oaks and elms and dwarf 

 plum thickets on dry hillsides near a stream, a habitat never frequented 

 by the White-eyed Vireo; in tangled thickets of dewberry; in low 

 trees on edge of thick mountain shrubbery; less commonly, in deep 

 shady ravines where the White-eyed Vireo places its nests." 



Mr. Bunker (1910) says of the nests found in Blaine County, Okla. : 



The nesting habits of the Black-cap are unlike Bell's, in that it always builds 

 in the center of a bush or rather in a clump of bushes instead of on the outer 

 edge, slips away upon the approach of an intruder, and if singing or scolding 

 in a bush, you may depend upon it, that the nest is nowhere near. * * * 



Nests were found at the bottom of canyons, and steep canyon walls, uplands, 

 and little draws leading to the canyons. They nested in jack-oak, dogwood, 

 wild plum, China berry and like shrubs. No matter where the nest was built, 

 on bottom lands, or ravines, the bush in which it was placed was always above 

 high water mark. * * * 



I was fortunate enough to watch the construction of one nest from start to 

 finish. The weaving was accomplisht after the fibers had all been attacht to 

 the forked twig, and hung down like a fringe. The female would dart down 

 from a nearby twig, catch the end of a fiber in her bill, fly up to the opposite side 

 of the fork, draw up the fiber a little at a time, turning her head from side to 

 side, as if studying her work, and then secure it. 



Eggs of the eastern, and more often those of the dwarf, cowbird are 

 sometimes found in the nests of this vireo. 



Eggs. — Three to five eggs may make up the full set for the black- 

 capped vireo, but four seems to be the commonest number. These are 

 ordinarily ovate in shape, but some are slightly pointed and others 

 are somewhat elongated. The shell is smooth, without gloss, pure 

 white in color and always (?) entirely spotless. The measurements 

 of 50 eggs averaged 17.6 by 13.1 millimeters; the eggs showing the four 

 extremes measure 19.3 by 12.7, 18.8 by 14.7, 16.0 by 12.7, and 16.7 by 

 12.2 millimeters. 



Incuhafion. — The period of incubation does not seem to have been 

 determined. Both sexes assist in the duties of incubation and usually 

 stick so closely to the nest that they can almost be touched. Nothing 

 seems to have been published on the development and care of the 

 young, but probably both parents do their shares of this work. Mr. 

 Simmons (1925) says that "usually one, rarely two, broods" are raised 

 in a season. 



Plumages.— Mr, Kidgway (1904) says that the juvenal plumage 



