278 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



decorated with numerous bits of spider cocoons. They are lined with 

 line brown and white hairs and small, soft feathers. 



In New Mexico, Jensen (1923) reports two nests in pinon pines; 

 one was 3 feet and the other 5 feet above ground. 



Eggs. — From 3 to 5 eggs, usually 4, constitute a full set for the 

 black-throated gray warbler. These are ovate to short ovate and are 

 only slightly glossy. The ground color is white or creamy white 

 and is speckled, spotted, and sometimes blotched with "chestnut," 

 "auburn," "bay," or "russet," occasionally with "mummy brown," 

 with underlying spots of "light brownish drab," or "light vinaceous 

 drab." The spots are usually concentrated at the large end, forming 

 a loose wreath, with the drab markings frequently in the majority. 

 Some eggs are only lightly speckled, while others are boldly marked. 

 The measurements of 50 eggs average 16.5 by 12.5 millimeters; the 

 eggs showing the four extremes measure 18.2 by 12.3, 18.1 by 13.1, 

 14.6 by 12.9, and 16.2 by 11.6 millimeters (Harris) . 



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

 recorded for this warbler. It is probably performed by the female 

 entirely, but both parents share in the feeding of the young. Infor- 

 mation on this subject is scanty. 



Plumages. — The young black-throated gray warbler in juvenal 

 plumage shows the characters of the species more than do the young 

 of other wood warblers; the black and white areas about the head 

 and throat are strongly indicated in a duller pattern and there are 

 two broad white bars tipping the median and greater wing coverts 

 (see pi. 35) ; these markings are more subdued in the female than 

 in the male, thus making a slight sexual difference. The back is 

 brownish gray and the underparts grayish white, faintly streaked 

 with blacks 



I have not been able to trace the post juvenal molt, but it is perhaps 

 less extensive than in most other warblers. In first winter plumage 

 the young male is much like the adult male at that season, but it is 

 more strongly washed with brown above and with yellowish beneath, 

 the chin is white, the black throat is mottled with white, and the 

 streaking above and below is duller and more obscured. The young 

 female differs from the adult female in about the same way. 



Apparently, the nuptial plumage is produced mainly by wear, or 

 by a limited prenuptial molt. The postnuptial molt is evidently com- 

 plete in late summer. 



The adult winter plumages of both sexes differ but little from the 

 spring plumages; in the male, the feathers of the upper parts and 

 cheeks are margined with brownish gray and the throat with white, 

 the sides are washed with brown and the black streaks are obscured ; 

 in the female, the plumage is tinged with brownish in the same way 

 and the black streaks are obscured. 



