Original description: Emberiza Belli Cassin 1850
Taxonomic history in AOU/AOS Check-list
AOU 1 (1886): Bell’s Sparrow, Amphispiza belli
AOU 2 (1895): Bell’s Sparrow, Amphispiza belli; Gray Sage Sparrow, Amphispiza belli cinerea
AOU 3 (1910): Bell’s Sparrow, Amphispiza belli; Gray Sage Sparrow, Amphispiza nevadensis cinerea; California Sage Sparrow, Amphispiza nevadensis canescens
AOU 4 (1931): Bell’s Sparrow, Amphispiza belli belli; Gray Sage Sparrow, Amphispiza belli cinerea; California Sage Sparrow, Amphispiza nevadensis canescens
AOU 5 (1957): Sage Sparrow, Amphispiza belli canescens, Amphispiza belli belli, Amphispiza belli clementeae, Amphispiza belli cinerea
AOU 6 (1983): Sage Sparrow, Amphispiza belli
AOU 7 (1998): Sage Sparrow, Amphispiza belli [belli group]
IUCN Conservation Status: Of least concern
The San Clemente Bell Sparrow, Amphispiza belli clementeae, is listed by the US Fish and Wildlife Service as threatened and is a species of special concern in California. In the mid-1980s, the population of this subspecies was thought to have shrunk to fewer than 40 individuals; after rising to more than 1,500 adults in 2002, the population once again retracted until an estimated 539 adults inhabited approximately 6,000 acres of San Clemente Island seven years later. The principle threats to this population include habitat loss and succession. Nearly a century of intensive grazing by livestock and feral goats destroyed much of the sparrows’ original desert scrub habitat; though some sites have recovered since the removal of goats, the suitable habitat remains fragmented.
San Clemente Island is owned by the United States Navy, which has a small permanent presence on the island and conducts exercises and maneuvers there; there is at present no indication that those activities have a substantial negative effect on the Bell Sparrows, though the risk of habitat destruction by fire remains a concern. The Navy has worked to decrease the numbers of introduced rats and feral cats on the island, both of which have severely limited the recovery of both this species and the island’s endangered Loggerhead Shrikes.
The San Clemente Bell Sparrow appears to be extremely sensitive to drought, with far fewer fledglings surviving to breed in dry periods; global warming and natural climate fluctuations may pose the greatest threat to this subspecies’ survival.
Elsewhere in the species’ range, Bell Sparrows are subject to local extirpation as a result of vegetative succession and urbanization or agricultural conversion of chaparral and coastal scrub. H
Behavior: The Bell Sparrow is a shy bird, keeping close to cover and low to the ground, fleeing in low, fluttering flight or rapidly running away if it finds itself observed. Feeding birds in search of small seeds or, in the breeding season, insects stay beneath the vegetation, scampering across open areas of dry ground with the tail held high. When Bell Sparrows take a low perch atop a bush or tumbleweed, they continually flick the tail abruptly up, twitching like the second hand on a schoolhouse clock; that behavior is shared by the Sagebrush Sparrow and, to a lesser extent, the Black-throated Sparrow. Males sing from a low perch, sometimes below the sparse canopy of shrubs or chaparral.
The migrant subspecies canescens forms small loose flocks, possibly family groups, in the winter, often associating with Black-throated and Brewer Sparrows on saltbush flats. Feeding individuals in these flocks usually maintain a distance of several feet from one another.
Voice: The songs of the Bell Sparrow and the Sagebrush Sparrow are quite different. While Sagebrush Sparrows give buzzy, low-pitched, strongly cadenced songs, Bell Sparrows of the subspecies belli and clementeae (and presumably of the southern race cinerea) sing a bright, light, chirping and chipping warble. The thin tone and slightly stuttering rhythm may recall the song of a Horned Lark, while in its length and jumbled cheerfulness the song resembles that of a Painted Bunting.
The California Sparrow canescens appears to be capable of songs resembling both belli and the Sagebrush Sparrow; the song repertoire of this “confusing intermediate group” may in fact “grade clinally from nevadensis-like songs in the northeastern part of its range to belli-like songs in the south and west,” a circumstance that further complicates the field identification of this bird.
The flight calls of the Bell Sparrow are high and metallic, with the hint of a penetrating buzz; they are very short, with a harsh attack and virtually no audible decay. In flight, the calls may be even shorter and uttered in a quick series of up to ten notes, verging on a tremolo.
Detailed description and measurements drawn from standard reference works
Adult Artemisiospiza belli belli: Tail feathers dull blackish, with narrow light buffy edges. Upper tail coverts and rump brownish slate. Ground color of back and scapulars slaty brown, sometimes with obscure fine darker shaft streaks, especially on scapulars; center of back virtually unstreaked. Primaries and secondaries dull blackish with slightly paler gray edges; tertials darker, with broader gray-brown edges, fading to brownish white at tips. Greater coverts brownish black with narrow creamy brown edges and tips, in fresh plumage forming poorly defined, low-contrast wing bar. Median coverts blacker, with creamy brown tips, in fresh plumage forming inconspicuous wing bar. Marginal coverts of underwing very pale yellowish. Nape brownish slate.
Undertail coverts dull buffy white, brightening gradually into bright white of vent, belly, and breast. Sides of breast and flanks tinged darker buff, with coarse, irregular dark brown shaft streaks. Central breast spot dark grayish brown. Throat bright white, separated by well-defined blackish lateral throat stripe from broad white jaw stripe; jaw stripe curls onto front of nape to set off brownish slate ear coverts. Crown brownish slate, with a few or no narrow, inconspicuous blackish shaft streaks. Short whitish supercilium begins above or ahead of rear of narrow whitish eye ring and extends to base of bill above lore; sometimes reduced to slightly elongated spot above lore. Tarsus and toes dark pinkish brown. Bill blackish above, dull silvery blue below.
Juvenile Artemisiospiza belli belli: Tail feathers dull blackish, with narrow brown edges. Upper tail coverts, rump, back, and scapulars brown with broad black shaft streaks. Primaries and secondaries dull blackish with slightly paler gray edges; tertials darker, with broader gray-brown edges, fading to brownish white at tips. Greater coverts brownish black with conspicuous buffy edges and tips. Median coverts blacker, with buffy tips. Nape dull brownish slate.
Undertail coverts buffy white, brightening gradually into dull brown-washed white of vent, belly, and breast. Breast and sides of breast with coarse, irregular blackish streaks. Sides of breast and flanks pale yellowish buff, with fairly narrow, irregular blackish shaft streaks. Throat dull white, bordered by faint or no pale brown lateral throat stripe; jaw stripe dull yellowish white. Crown dull gray with blackish shaft streaks. Short, narrow, poorly defined whitish supercilium begins at rear of narrow buffy eye ring and extends to base of bill above lore. Tarsus and toes pinkish brown. Bill blackish above, dull silvery blue below.
Length 135-137 mm (5.2-5.3 inches)
Wing chord 64-67 mm (2.5-2.6 inches)
Tail 63-66 mm (2.5-2.6 inches)
Mass 15 g