296 BULLETIN 2 03, UNITED STATES NATIONAL MUSEUM 



the nest was chiefly shaped. I never saw a more substantial looking little nest. 

 It was also one of the most beautiful I have ever found, a perfect harmony in 

 grays. 



A very pretty nest in my collection is largely made, externally, of 

 usnea and is profusely decorated with masses of the curly outer bark 

 of the yellow birch. The larger of two nests before me measures about 

 4 by 31^ inches in outer diameter, the smaller about 3 inches ; both are 

 about 2 inches high, nearly 2 inches wide and II/2 deep inside. 



Eggs. — The black-throated green warbler usually lays 4 eggs to a 

 set, but quite often 5. These are ovate to short ovate and slightly 

 glossy. The ground color is grayish white or creamy white. The 

 markings consist of specks, spots, blotches, or small scrawls of reddish 

 browns, such as "auburn," "chestnut," "bay," "Mars brown," or "rus- 

 set," with underlying spots of "light brownish drab," "deep brownish 

 drab," or "light purplish drab." Generally the markings are concen- 

 trated at the larger end, where they usually form a wreath, but occa- 

 sionally the spots are well scattered over the entire egg. There is con- 

 siderable variation. Some eggs have a faint wreath of the pale drab 

 coloring which is relieved with a few bold spots or scrawls of dark 

 "bay" or "Mars brown." Others are richly spotted and blotched 

 equally with browns and drabs, or they may have a solid ring of 

 "russet" blotches which completely covers and conceals the drab under- 

 tones. The measurements of 50 eggs average 17.0 by 12.7 millimeters ; 

 the eggs showing the four extremes measure 18.8 by 12.8, 17.2, by 13.4, 

 15.5 by 12.2, and 18.0 by 12.0 millimeters (Harris) . 



Young. — It is generally conceded that the period of incubation is 

 about 12 days and that the young remain in the nest from 8 to 10 days^ 

 depending on the amount of disturbance. Probably the female does 

 most, or all, of the incubating and brooding, but both sexes assist in 

 feeding the young and in swallowing or removing the fecal sacs. Miss 

 Stanwood (1910b) refers to the development of the young as follows: 

 "On the third day the young birds grow rapidly, burnt-orange in color, 

 covered with an abundant supply of burnt-umber down. The quills 

 and pin feathers showed blue-gray through the skin, and the eyes were 

 just beginning to open." At another nest, "on the eighth day, the nest 

 was simply stuffed full of little green-gray birds, strikingly like the 

 color of the nest. 



* * * On the eleventh day, quite early in the morning, as I 

 neared the nesting place, I heard the fledglings calling from the tree- 

 tops. Soon I caught a glimpse of the Black- throated Green Warblers 

 marshalling their little band away." 



Margaret M. and L. B. Nice (1932) made detailed studies of two 

 nests of this warbler, to which the reader is referred. I quote from 

 their summary : 



