BELL'S VIREO 255 



"Forbush, in the 'Birds of Massachusetts' [vol. 3] states that the nest 

 is 'lined with soft substances, such as down or hair,' and others have 

 mentioned down and hair. Linings of the nests observed by me could 

 not be even remotely regarded as of soft substances. While occasion- 

 ally a horsehair may have been worked into the lining, neither plant 

 down, poplar, nor willow 'cotton', nor similar materials, though often 

 easily available, have been included. 



"Typical nests of this locality may be described as composed exte- 

 riorly of soft, grayish plant strips and shreds, fibers, leaf fragments, 

 and small pieces of bark, neatly lined almost invariably with fine, 

 brownish grass stems. The exterior, especially at the rim, as well as 

 the lining, may be supplemented by spider web and cocoons. 



"Two nests before me provide fair examples of measurements: (1) 

 exterior diameter, 2% by 3 inches ; interior diameter, li/o by 1% inches; 

 exterior depth, 3% inches; interior depth, 11/2 inches. (2) exterior di- 

 ameter, 3 inches ; interior diameter, 1% by 1% inches ; exterior depth, 3 

 inches; interior depth, li/4 to 1% inches." 



Many years ago, A. Dawes Du Bois sent me some notes on Bell's 

 vireo. On June 5, 1913, he watched a pair of these vireos near Lincoln, 

 111., "in a raspberry patch adjoining an orchard and thus located their 

 nest, which was fastened to a raspberry stalk about 2 feet from the 

 ground. The little twig, which had formed one prong of the fork 

 in which the nest was originally built, had broken loose so that the 

 nest hung from one side only, and the four eggs were not very secure 

 in a wind. Beneath the nest on the ground was the empty shell of 

 a fresh cowbird's egg, about one third of it, at the large end, broken 

 away as if by the bill of a bird. I suspect that the vireos had thrown 

 it out." He took this nest and the eggs, but the birds built another 

 nest and raised a brood in the same raspberry patch; they had fully 

 grown young on July 21. 



Some years later, Mr. Du Bois (1940) published an account of this 

 and two other nests, which he found near Springfield, 111., in 1922 

 and 1923. One of these "was two and a half feet from the ground, 

 in a haw bush at the edge of a brier patch." It "was composed of 

 bark shreds, plant fibers, numerous thin, paperlike dried leaves, and 

 some bits of newspaper; lined with fine grass stems and a very few 

 coarse hairs." One of the others "was three feet from the ground, 

 exceedingly well hidden, in a bushy wild crab, in a narrow but dense 

 thicket." It was similar in construction. 



Pitelka and Koestner (1942) made a study of five nests of Bell's 

 vireo in central Illinois. "These consisted of three attempts at nest- 

 ing and a fourth successful nesting of one pair together with one 

 successful nesting of a second pair. Nest building lasted 4 to 5 

 days. * * * Cowbird interference was probably the cause of de- 

 sertion of the first two, and possibly three, nests of one pair. At each 



