Figure 428. In California, Cassin’s Sparrows have occured as spring and summer visitors to the Mojave Desert and southern coast—where many records involve territorial males—and as fall stragglers to the coast, especially Southeast Farallon Island, where these two first-fall birds were banded and photographed on 29 September 1985 (1985-180, 1985-181; Peter Pyle). See also Appendix H.

 

Figure 429. Distribution of 46 Cassin’s Sparrows accepted through 2003, showing major concentrations at Southeast Farallon Island and San Bernardino County’s Lanfair Valley and a minor one at El Cajon, San Diego County.

 

Figure 430. Annual occurrence of Cassin’s Sparrows accepted through 2003. The influx of 18 birds in May/June 1978—including 15 territorial males in the Lanfair Valley, San Bernardino County—clearly stands out as a major event for this species in the state. More thorough spring/summer coverage of potentially suitable grasslands in southeastern California during wet periods could turn up additional Cassin’s Sparrow concentrations, and possibly evidence of breeding.

 

 

 

 

 

 

CASSIN’S SPARROW Aimophila cassinii (Woodhouse, 1852)

Accepted: 46 (96%)	Treated in Appendix H: yes
Not accepted: 2	CBRC review: all records
Not submitted/reviewed: 1	Color image: H-35

This sparrow breeds in northern Mexico and the southwestern and south-central United States. The breeding range extends north to southeastern Wyoming (irregular), east to central Texas, west to central Arizona and northern Sonora, and south to Tamaulipas and Zacatecas. Northern breeders withdraw south in winter to near the international border, and the winter range extends south to Nayarit and Guanajuato. In addition to California’s records and a late June record from western Baja California, vagrants have strayed many times to points north and east of the breeding range, exceptionally to southwestern Idaho, southeastern Alberta, northern Ontario, New Jersey, New York, Maine, and Nova Scotia.

California’s first Cassin’s Sparrow was present 11–12 July 1969 on Southeast Farallon Island (DeSante and Ainley 1980), a location that has become a fairly frequent destination for this species in the state (see Figure 429). Spring and early summer records, with bracketing dates of 2 May and 12 July and a peak from mid May to mid June, account for more than three-quarters of the state’s Cassin’s Sparrows (36 of 46). A 29 May 1984 record from the mouth of the Little River, Humboldt County, is the northernmost for the Pacific coast. Nearly half of the spring/early summer total came during the interval of 21 May–7 June 1978, when 15 skylarking male Cassin’s Sparrows were found in grasslands and desert scrub of the Lanfair Valley, located in the eastern Mojave Desert of San Bernardino County. Many years later, between 8 and 30 May 1993, three skylarking males were found in the same area. Although these males remained on territories for as long as three weeks, and lone spring and summer males elsewhere in the state have behaved similarly, any evidence of nesting in California has remained hidden. As reviewed by Dunning et al. (1999), Cassin’s Sparrow exhibits a “confusing pattern of residency and migration” in the Southwest, in part because the summer range tends to expand considerably during wet periods. Both incursions to the Lanfair Valley came on the heels of wet winters that created atypically lush conditions in California’s deserts. A first-year bird present from 14 to 16 August 1993 at Death Valley Junction, Inyo County, may have been a fall migrant, but its appearance so early in the fall season, following a wet spring when territorial males were present in California, led some members to suggest that it may have been a local dispersant that originated well west of the normal range.

The remaining nine California records involve fall migrants (13 September–2 November), all but one of them from Southeast Farallon Island; see also Appendix H. The late date was furnished in 2001 by an individual photographed on San Clemente Island, Los Angeles County. Southeast Farallon Island’s 2:1 ratio of fall to spring records, and the general scarcity of fall records from the mainland, undoubtedly reflect this sparrow’s skulking habits outside of the breeding season, and perhaps also its choice of habitats during migration.