Western Yellow-throat 465 
Other dates are Estes Park, June 15th (Chapman), 
and Decker’s Ranch, near Crested Butte, 9,000 feet, 
July (Warren). 
Genus GEOTHLYPIS. 
Bill short ; rictal bristles obsolete ; wing short and rounded, about 
22 the length of the tarsus ; the outer primary (ninth) shorter than the 
sixth ; tail nearly as long as the wing, distinctly rounded ; plumage 
olive and yellow, with a black mask in the male. 
An extensive genus of about twelve species, ranging south to the 
Argentine. Only one species in the United States. 
Western Yellow-throat. Geothlypis trichas occidentalis. 
A.O.U. Checklist no 68la—Colorado Records—Aiken 72, p. 197; 
Henshaw 75, p. 204; Allen & Brewster 83, p. 158; Drew 85, p. 15; 
Beckham 85, p. 141; Cooke 97, pp. 19, 117, 219, 220; 04, p. 119; 
Aiken 00, p. 298; Henderson 03, p. 108; 09, p. 240; Markman 07, 
p. 158; Chapman 07, p. 259; Rockwell 08, p. 177; Cary 09, p. 183; 
Hersey & Rockwell 09, p. 121. 
Description.— Adult male in spring—A black mask over the front 
of the crown and extending back through the eye to the ear-coverts, 
bordered posteriorly with white ; above olive-green, rather more dusky 
on the wings and tail; under-parts bright orange-yellow, fading into 
buffy-brown on the centre of the abdomen and the flanks ; iris brown, 
bill blackish, legs light brown. Length 4-5; wing 2-25; tail 2-10; 
culmen -45 ; tarsus -75. 
The female has no black mask, but the front of the crown is slightly 
tinged with cinnamon. The under-parts are always much paler and 
less brilliant than in the male; sometimes the yellow is confined to 
the under tail-coverts. The autumn plumage is very similar to the 
spring, but the bill is always paler and less dusky. Young birds have 
no black mask, and closely resemble the females. 
This subspecies is distinguished from the eastern form (G. ¢. trichas) 
by its brighter yellow under-parts, whiter and less greyish frontal 
band, and its longer tail. The Yellow-throat taken near Colorado 
Springs May 3lst, 1898, by Aiken, and referred by Cooke (p. 219) to 
the eastern form, appears to me on the whole nearer the western variety, 
and I think it best to include all Colorado birds under the western name. 
Distribution.—Breeding in western North America from the Canadian 
border to northern Mexico, and from Kansas to California, wintering 
in southern California and western Mexico to Tepec. 
In Colorado the Western Yellow-throat is a fairly common summer 
bird in the plains and along the foothills of the eastern half of the State, 
GG 
