468 Birds of Colorado 
medley of calls and whistles, and are very often heard 
at night, especially if it is moonlight. 
The nest is placed among small saplings or briers at 
from two to three feet above the ground; it is constructed 
of leaves and grasses, and has as a rule no special lining. 
The eggs, usually four, are clear white with spots and 
specks, or sometimes large blotches of various shades 
of brown, and measure about °86 x ‘66. Fresh eggs 
should be met with about the second week in June near 
Denver, according to Dille. 
Genus WILSONIA. 
Small fly-catching Warblers with a very short, broad and flattened 
bill, distinctly wider than deep at the nostrils; rictal bristles con- 
spicuous ; wing with the ninth (outer) primary longer than the fifth, 
the sixth to eighth the longest ; tail shorter than the wing and somewhat 
rounded ; plumage chiefly yellow and green, no red. 
Three species, all breeding in the United States. 
For key, see p. 439. 
Pileolated Warbler. Wilsonia pusilla pileolata. 
A.O.U. Checklist no 685a—Colorado Records—Allen 72, pp. 156, 
162 ; Aiken 72, p. 197; Trippe 74, p. 232 ; Henshaw 75, p. 207 ; Minot 
80, p. 228; Tresz 81, p. 286; Allen & Brewster 83, p. 159; Stone 84, 
p. 20; Drew 85, p. 15 ; Beckham 87, p. 123 ; Morrison 88, p. 72 ; Lowe 
94, p. 269 ; McGregor 97, p. 39 ; Cooke 97, pp. 19, 117, 228 ; 04, p. 128; 
Keyser 02, pp. 68, 238; Henderson 03, p. 108; 09, p. 240; Warren 
06, p. 24 ; Gilman 07, p. 194 ; Chapman 07, p. 278 ; Rockwell 08, p. 177. 
Description.—Male—Crown glossy black, forehead, eyebrow and 
cheeks very bright yellow ; above olive-green, dusky on the wings 
and tail; below bright yellow throughout ; iris brown, bill dusky- 
brown, paler on the lower mandible, feet light brown. Length 45; 
wing 2-25; tail 2-0; culmen -30; tarsus -75. 
The female resembles the male, but is usually duller in colour, and 
the black crown-patch is less glossy and smaller. The male in the 
autumn is very similar, and the young bird has even less trace of the 
black cap. 
Distribution.—The species is found breeding throughout western 
North America from Alaska to western Texas, but only at considerable 
elevations towards the south. It winters throughout the greater 
part of Mexico, and as far south as Panama. 
