122 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



Another nest before me, from the Huachucas, has a foundation of 

 moss and lichens, dry leaves, and strips of cedar mark, over which are 

 finer strips of the bark and shreds of dry weed stalks and grasses, with 

 a lining of still finer fibers; it is a shallow nest, its diameter being 

 3 by 3I/2 inches outside and 2 inches inside. 



Eggs. — While 4 eggs seem to constitute the usual set for Virginia's 

 warbler, as few as 3 and as many as 5 have been reported. These are 

 ovate to short ovate and only slightly lustrous. They are white, finely 

 speclded or spotted with shades of reddish brown, such as "chestnut" 

 and "auburn," intermingled with faint specks of "pale vinaceous- 

 drab." Some eggs are profusely spotted over the entire surface, while 

 others have the markings concentrated at the large end. The measure- 

 ments of 40 eggs average 15.9 by 12.4 millimeters; the eggs showing 

 the four extremes measure 17.0 by 12.4, 16.0 by 13.0, 14.2 by 12.2, and 

 16.3 by 11.2 millimeters (Harris) . 



Young. — On the period of incubation and on the development and 

 care of the young we have no information except the following obser- 

 vations of Bailey and Niedrach (1938) : "The hatching time of many 

 species of Colorado birds seems to coincide with an abundance of larvae 

 feeding upon plants among which the birds are nesting. We have 

 noticed time and again, that pests are numerous upon the vegetation 

 when the fledglings are in the nest, but a few weeks later, after the 

 little fellows have taken wing and are able to move to other parts, 

 the caterpillars have gone into the pupa stage." At a nest they were 

 watching, they observed that both parents shared the work of feeding 

 the young, averaging a trip every 6 minutes. 



A. J. van Rossem (1936) took young birds that were not fully grown 

 on July 10, and others on July 13 that had nearly completed the post- 

 juvenal molt, from which he inferred that two broods might be raised 

 in a season. H. S. Swarth (1904) noted that the young birds began 

 to appear in the Huachuca Mountains about the middle of July, after 

 which both old and young birds moved down into the foothills. 



Plwniages. — The young Virginia's warbler in juvenal plumage is 

 plain grayish brown above; the throat, chest, and sides are paler 

 brownish gray ; the abdomen and center of the breast white ; the upper 

 and under tail coverts are dull greenish yellow ; there is no chestnut 

 crown patch ; and the greater and median wing coverts are tipped with 

 dull buffy. The sexes are alike. 



The postjuvenal molt begins early in July and is often complete 

 before the end of that month. The first winter plumage is similar 

 to that of the adult female at that season. In this plumage the sexes 

 are not very different, and the crown patch is not much in evidence or 

 is altogether lacking in the young female ; both sexes are browner and 

 with less yellow than in the adult plumage, and the female is duller 

 than the male. 



