294 BULLETIN 197, tJNITljjD STATES NATIONAL MUSEUM 



The second might be considered an average nest, built in July and 

 very insecurely attached to a forked twig of a swamp white oak ; it is 

 prettily made of strips of inner bark of various kinds, bits of lichens, 

 and mosses and decorated externally with many pieces of paper from 

 the nests of wasps or hornets and a few spider nests ; it is profusely 

 lined with fine needles of the white pine. It measures about 31/2 

 by 3 inches in external diameter and about 214 inches in external depth ; 

 the inner cavity is about IV2 inches in depth and about 2 by 21/4 inches 

 across the top, with very little overhang. 



The third came to me from Lancaster, N. H., taken by Fred B. 

 Spaulding. It is the largest, most compactly built, and handsomest 

 nest that I have seen of this species, perhaps more typical of northern 

 nests than of those with which I am familiar. It is securely attached 

 to two diverging twigs close to the upright stem of a sapling with a 

 quantity of usnea and fine strips of outer bark of the yellow birch. 

 The bulk of the nest is made up largely of various lichens and mosses, 

 mixed with bits of small dry leaves, bits of fine string, and spider nests, 

 all apparently firmly interwoven with narrow strips of the outer bark 

 of the yellow birch, with which tlie exterior of the nest is profusely 

 decorated. It is smoothly lined with very fine grass tops and a few 

 hairlike rootlets. Externally it measures about 3 by 3i/4 inches in 

 diameter and 314 inches in depth ; internally it measures about 2 by 

 1% in diameter and about ly^ inches in depth, the walls being very 

 firm and thick. The above measurements do not include the extent 

 to which some of the loose streamers of the birch bark hang below and 

 around the nest. 



I have twice watched blue-headed vireos building their nests. Both 

 of the pair help in this work, though the female seems to do most of it 

 and to be the dominant influence, the male's part consisting mainly of 

 bringing material. At the beginning of the nest a few hanging loops 

 of soft fibers are attached at both ends to the supporting twigs; as 

 these increase and the bag is formed, the ends are securely bound to 

 the twigs by strips of usnea or fine shreds of inner grapevine bark, 

 forming the rim of the nest; some spider web may be used for tliis 

 purpose, but it does not seem to be much in evidence in the nests that 

 I have seen ; apparently the bluehead does not use so much of it as do 

 other vireos. The rest of the material is worked in between the hang- 

 ing loops, and finally the lining is added and the interior is shaped 

 by the turning of the bird's body in it. The birds are very apt to 

 desert an unfinished nest, if watched, as happened in the two cases that 

 I observed. 



Eggs. — The blue-headed vireo lays three to five eggs in a set, usually 

 four. These are usually ovate in shape, but some are quite pointed. 

 The ground color varies from pure white to creamy white. They are 

 rather sparingly spotted or dotted, mostly near the large end, with 



