Original description: Passerculus guttatus Lawrence 1867
AOU 1 (1886): Belding’s Marsh Sparrow, Ammodramus beldingi; St. Lucas Sparrow, Ammodramus rostratus guttatus
AOU 2 (1895): Belding’s Marsh Sparrow, Ammodramus beldingi; St. Lucas Sparrow, Ammodramus rostratus guttatus
AOU 3 (1910): Belding’s Sparrow, Ammodramus beldingi; San Lucas Sparrow, Ammodramus rostratus guttatus
AOU 4 (1931): Bryant’s Sparrow, Passerculus sandwichensis bryanti; Belding’s Sparrow, Passerculus beldingi; San Lucas Sparrow, Passerculus rostratus guttatus
AOU 5 (1957): Savannah Sparrow, Passerculus sandwichensis beldingi, Passerculus sandwichensis anulus, Passerculus sandwichensis guttatus, Passerculus sandwichensis magdalenae
AOU 6 (1983): Savannah Sparrow, Passerculus sandwichensis [beldingi group]
AOU 7 (1998): Savannah Sparrow, Passerculus sandwichensis [beldingi group]
IUCN Conservation Status: Of least concern
Behavior: Belding Sparrows feeding on the ground are often fairly approachable, especially in localities regularly used by birders, walkers, and other human recreationists; they are more wary at sites where such intrusion is irregular and infrequent, giving the birds less opportunity to learn that human disruption is usually transitory. Feedings birds walk, hop, and scratch in the shade of marsh vegetation, often coming out to forage on more open patches of sand or mud.
Approached too closely or otherwise disturbed, Belding Sparrows fly off in fast, low, swooping flight, often calling on flushing and then disappearing into cover.
In the coastal marshes where they breed, patience and the rising tide generally result in good views. Belding Sparrows readily perch on the tops of short plants, especially in early spring when pairs are establishing territories.
Voice: The call notes are high, thin, and very short, like those of the other Passerculus sparrows. Males sing from a low but conspicuous perch. The song is thin, short, and markedly insect-like; a short series of fine cricket-like notes is followed by one or two dry buzzes and a downslurred cadence: ee-ee-t’DZEE-dlit.
Detailed description and measurements drawn from standard reference works
The description is of the nominate race.
Adult: Tail feathers dark gray-brown with neat white edges. Rump and upper tail coverts olive-tinged gray-brown, with large central black streaks. Mantle and scapular feathers olive-tinged gray-brown with very broad black shaft streaks and, in fresh plumage, grayish edgings, creating a strong pattern of heavy black streaks. Primaries dull brown-gray with paler edges, secondaries rustier, tertials black with broad rusty (longest two) or white (shortest) edges. Greater coverts rusty with large black teardrops; in fresh plumage, small white tips produce inconspicuous lower wing bar. Median coverts largely black with white tips producing upper wing bar. Nape olive gray-brown with fine black streaks. Ground color of under parts white, with olive-brown on flanks and sides of breast; breast, breast sides, and flanks conspicuously streaked with blackish brown. Belly, vent, and under tail coverts white with sparse or no streaking. Crown olive-gray with fine dark streaks; white median stripe short or absent. Long, broad supercilium olive with fine black streaks, deep yellow above lore; sometimes most of supercilium yellow. Lore dull olive-gray. Greenish brown ear coverts bordered above by blackish line behind eye, below by black whisker. Jaw stripe yellowish gray, separated by black lateral throat stripe from white, faintly streaked or spotted throat. Long bill shallow at base, pointed at tip; dull pink, with extensively dark gray culmen. Strong tarsi and toes dull pink.
Juvenile: Similar to adult, but less starkly marked black above and below.
Length 119-123 mm (4.7-4.8 inches)
Wing chord 65-69 mm (2.6-2.7 inches)
Tail 48-50 mm (1.9-2.0 inches)
Mass 15.5-22.5 g