318 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



easily distinguish the white- throated from the other two western 

 swifts. 



Winter. — At least a few white-throated swifts attempt to spend 

 the winter as far north as west-central California, although some of 

 them evidently perish in the attempt, for lack of food or from the 

 effects of the cold. Dr. Gayle Pickwell's (1937) observers reported 

 that during January 1937 only about a dozen swifts were seen entering 

 the roosting place in the rock in Santa Clara County, referred to 

 above, and that two or three dead birds were found on the ground 

 below the rock. 



Mr. Hanna (1917) reports that "during the extremely cold wave of 

 early January, 1913, eight, to me perfectly healthy, swifts were taken 

 out of a crevice where they, with many others, seemed to be roosting 

 in a dazed or numb state. They were kept in a room for about six 

 hours and then turned loose, one at a time, a few hundred feet from 

 the point where they were captured. All flew^ away in a dazed fashion 

 and nearer the ground than usual and none were observed to return to 

 the place where they were captured. * * * The facts are that 

 these birds are not observed for many days in the coldest weather, 

 yet are found to be plentiful within the rocks, in a dormant state." 



DISTRIBUTION 



Range. — ^Western North America north to southern British Colum- 

 bia. 



Breeding range. — The breeding range of the white-throated swift 

 extends north to southern British Columbia (Vaseu.x Lake) ; Mon- 

 tana (Libby, Columbia Falls, Yogo Creek, and Billings) ; and north- 

 western South Dakota (Slim Buttes). East to western South Dakota 

 (Slim Buttes, Elk Mountains, and Hot Springs) ; northwestern Ne- 

 braska (West Monroe Canyon) ; southeastern Wyoming (Goshen Hole 

 Rim) ; eastern Colorado (Chimney Canyon, Golden, and Garden of 

 the Gods) ; New Mexico (Lake Burford, Caiion el Diablo, Anton 

 Chico, and Capitan Mountains) ; western Texas (Davis Mountains 

 and Chisos Mountains) ; Tamaulipas (Jaumave) ; Hidalgo (Chico) ; 

 and El Salvador (Los Esesmiles). South to El Salvador (Los 

 Esesmiles) ; western Guatemala (Duenas) ; southwestern Chihuahua 

 (Jesus Maria); and Baja California (Guadalupe Island). West to 

 Baja California (Guadalupe Island, San Fernando, San Ysidro, and 

 Los Coronados Islands) ; western California (Escondido, San Juan 

 Capistrano, Santa Cruz Island, Santa Barbara, San Luis Obispo, 

 Pine Canyon, and probably Mount Lassen) ; central Washington 

 (Lake Chelan) ; and British Columbia (Fair View and Vaseux 

 Lake). 



