1248 U.S. NATIONAL MUSEUM BULLETIN 23 7 part 2 



First found on Las Trampas Peak, Contra Costa County, Calif., 

 this subspecies is now known from Alameda and Contra Cosa counties 

 south to southern San Benito County. 



Its choice of habitat parallels that of other black-chinned sparrows, 

 being, according to Grinnell and Miller (1944) "Arid chaparral, in 

 which adenostoma, ceanothus and scrub oak predominate. In one 

 instance has nested in a tract of Baccharis pilularis. Bushes are 

 fairly dense and 3 to 6 feet high, and occasional trees may be inter- 

 mLxed." 



A. H. Miller (1929) in his original diagnosis describes this race as 

 follows : 



A subspecies of Spizella atrogularis characterized in comparison with the other 

 races by dark and less brown coloration. Neck, lower throat, and breast between 

 no. 6 gray and a light neutral gray * * *; whitish area of belly narrowly restricted, 

 and tinged with gray; flanks and under tail coverts pale neutral gray. Pileum 

 and hind neck near deep neutral gray, usually lacking shades of brown; black, 

 cinnamon, and cinnamon brown tones of back deep; rump and upper tail coverts 

 neutral gray. Wing and tail long as in S. a. atrogularis [the Mexican race]. 

 Breast and flanks of juvenile with pronounced streaks of dark neutral gray. 



Miller, in the same paper, compares caurina with the race cana: 



Caurina differs from cana * * * in a decided general lack of brown and buff 

 colors on the body plumage and in the smaller area of white on the belly ; the gray 

 of the head is distinctly darker. The cinnamon of the back of cana usually 

 becomes more nearly cinnamon-rufous in caurina. 



* * * The immature plumage of caurina stands in sharp contrast with the same 

 plumage of cana in that the underparts are neutral gray with almost a total lack 

 of the buff tippings so extensively seen in the fresh fall plumage of the southern 

 California birds. The pileum is decidedly darker in the new race, the new feathers 

 being only slightly tipped with brown. 



The few available dates suggest that caurina departs early from its 

 breeding grounds. In Alameda County, the latest date is August 13, 

 and in Los Angeles County, September 10 (Grinnell and Miller, 1944). 



Distribution 



Range. — The San Francisco black-chinned sparrow breeds in coast 

 ranges of central western California (Oakland south to San Benito 

 Mountain) ; the only winter record is from Santa Cruz Island, Cali- 

 fornia. 



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