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 

 2| 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 ^ecies, ranging south to the 

 Argentine. Only one species in the United States. 



Western Yellow-throat. Geothlypis trichas occidentalis. 



A.O.U. Checklist no 681a— 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 tlie 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 ; tarsias -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 iinder tail-coverts. The autumn plmnage 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 (0. t. tricJias) 

 by its brighter yellow under-parts, whiter and less greyish frontal 

 band, and its longer tail. The Yellow-throat taken near Colorado 

 Springs May 31st, 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 Tepee. 



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 



