228 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



of his nests, evidently built in an upright fork, measured "diameter, 

 outside, 31/2 inches, inside, 2^4 inches ; height, outside, 5 inches ; depth, 

 inside, 1^^ inches." 



T. E. McMullen has sent me the data for 22 nests, found in the 

 Pocono Mountains, Pa. All of these were built in rhododendrons in 

 woods, two on hillsides, one on the edge of a road, one on the edge of the 

 woods, one near a creek, and three along a creek bank. Most of Mr. 

 Brewster's (1938) Lake Umbagog nests were placed low down in yews 

 (Taxus canadensis). Apparently, the favorite nesting sites of the 

 black-throated blue warbler are in the broadleaf evergreens, mountain- 

 laurels and rhododendrons, where these are available; next in popu- 

 larity come the other evergreens (spruces, firs, and hemlocks) of small 

 size ; but nests have been found in many places in deciduous seedlings, 

 saplings and sprouts, mainly maple and beech, or in various other 

 bushes or tangles. 



Mrs. Harding gave me an account of the building of a nest, which 

 she watched during a period of four days. Most of the work was done 

 by the female, but the male helped shape the nest occasionally. The 

 beginning of the nest and much of the main part of it was made of thin 

 strips of the paperlike bark of the white, or canoe, birch firmly bound 

 in place with great quantities of cobwebs ; during the early stages of 

 building the rim was anchored with several strands of cobweb to the 

 surrounding leaves and twigs to secure it while the nest was being 

 shaped ; this the bird did by sitting in the nest and turning around in 

 all directions, molding it inside with her feet and breast and pressing 

 her tail down over the edge to smooth the exterior. The male sang in 

 the vicinity and brought some of the material, and once he drove away 

 another male. The nest was finished on the fourth day. This process 

 is described in more detail in Mrs. Harding's (1931) paper, where she 

 notes "there is usually an interim of at least twenty-four hours before 

 the first egg is laid. The female lays the eggs at intervals of twenty- 

 four hours — frequently early in the morning. * * * On the morn- 

 ing of the fourth day when the clutch is complete the female com- 

 mences incubating." 



Eggs. — The black-throated blue warbler lays normally four eggs, 

 three are not a rare complement, but five are seldom found. Richard 

 C. Harlow tells me that in over 200 nests that he has examined he has 

 found only 4 sets of five. 



The eggs vary in shape from ovate to short ovate, rarely tending 

 to elongate ovate, and are only slightly lustrous. They are white or 

 creamy white, speckled, blotched, or clouded with tones of "pecan 

 brown," "russet," "Mars brown," "cinnamon-brown," "chestnut- 

 brown," "bay," or "auburn," with undertones of "benzo brown," "light 

 brownish drab," "light violet-gray," or "pale Quaker drab." There 



