370 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



ear, before they have yet attained their brilliant gorgets, with results 

 that sometimes rather resemble the song of the Anna's Hummingbird, 

 though much fainter and less sustained." 



Field marks. — ^With the exception of the calliope, Costa's hum- 

 mingbird is the smallest of the common North American species. The 

 adult male should be easily recognized by its full helmet, crown, 

 gorget, and elongated sides of the gorget, of brilliant amethyst, 

 purple-violet, though these colors appear black in certain lights. The 

 young male is like the female but usually shows some violet feathers 

 about the head. The adult female is almost impossible to distingviish 

 from the female black-chinned in the field; for the characters that 

 distinguish these two females the reader is referred to the field marks 

 of the black-chinned hummingbird. 



DISTRIBUTION 



Range. — Southwestern United States and Mexico; only slightly 

 migratory. 



Breeding range. — Costa's hummingbird breeds north to southern 

 California (Fresno and Owens Valley) ; southern Nevada (Cave 

 Spring and Bitter Springs) ; and probably southwestern Utah (Bea- 

 verdam Mountains). East to probably southwestern Utah (Beaver- 

 dam Mountains) ; east-central Arizona (Salt River Reservation) ; and 

 rarely southwestern New Mexico (Cliff). South to rarely southwest- 

 ern New Mexico (Cliil) ; southeastern Arizona (Tombstone and Hua- 

 chuca Mountains), and southern Baja California (La Paz and Santa 

 Margarita Island). West to Baja California (Margarita Island, 

 Magdalena Bay, Cerros Island, San Benito Island, Todos Santos 

 Island, and Los Coronados Islands) ; and California (El Cajon, 

 Escondido, Santa Barbara Island, Glendale, and Fresno). 



Winter range. — In the winter season this species is found north to 

 southern California (Azusa, Riverside, Palm Springs, and rarely 

 Amboy) ; and southwestern Arizona (Camp 117, Phoenix, and Tina- 

 ches) . East to southern Arizona (Tinaches and Tucson) ; Sonora 

 (Tiburon Island and Tesia) ; and southeastern Baja California (La 

 Paz). South to southern Baja California (La Paz and Santa Mar- 

 garita Island). West to Baja California (Santa Margarita Island, 

 Magdalena Bay, Cerros Island, and Rosarito) ; and southwestern 

 California (San Diego and Azusa). 



Migration. — The only data available are applicable to the spring 

 migration. The following are early dates of arrival: Arizona — 

 Tombstone, March 5. California — Los Angeles, March 21. 



Casual records. — A specimen was taken at Oakland, Calif., on May 

 8, 1890, well north of the normal range. 



