Melospiza melodia maxillaris

Suisun Song Sparrow

Family: Emberizidae · Class: Aves · Order: Passeriformes

Conservation status: G5T3 S2

The Suisun Song Sparrow is a medium-sized subspecies of song sparrow endemic to the San Francisco Bay Estuary. Adults measure approximately 14-16 cm (5.5-6.3 inches) in length with a rounded head, short stout bill, long rounded tail, and broad wings. The subspecies exhibits the typical song sparrow plumage pattern with brown and gray streaking above, whitish underparts with dark streaking, and a distinctive dark central breast spot. Suisun Song Sparrows are generally darker and more rufous than other song sparrow subspecies, reflecting adaptation to their marsh environment. The Suisun Song Sparrow occurs exclusively in the Suisun Marsh area of the San Francisco Bay Estuary, primarily in Solano County, California. This subspecies is one of three song sparrow subspecies endemic to the San Francisco Bay region, alongside the Alameda Song Sparrow (M. m. pusillula) and San Pablo Song Sparrow (M. m. samuelis). The subspecies' range is restricted to tidal marshes surrounding Suisun Bay and the western Sacramento-San Joaquin Delta. This subspecies inhabits brackish and freshwater tidal marshes, showing strong association with emergent vegetation including bulrushes, cattails, and pickleweed. Suisun Song Sparrows require dense marsh vegetation for nesting and foraging, utilizing both the marsh surface and adjacent upland edges. The birds occupy territories within the complex matrix of tidal channels, marsh plains, and levees that characterize the Suisun Marsh ecosystem. Suisun Song Sparrows are primarily granivorous, feeding on seeds of marsh plants, though they also consume insects, particularly during the breeding season. Breeding occurs from March through August, with females typically producing 2-3 broods per season. Nests are constructed in dense vegetation 0.3-1.5 meters above ground or water level, with females laying 3-5 eggs per clutch. Males defend territories year-round through song and aggressive displays, with territory boundaries often following natural marsh features like tidal channels. The subspecies has a Global/State Rank of G5T3 S2, indicating it is vulnerable both globally as a subspecies and within California. The Suisun Song Sparrow is designated as a Bird Species of Special Concern by the California Department of Fish and Wildlife and is included in the U.S. Fish and Wildlife Service's Birds of Conservation Concern (2002). Primary threats include habitat loss and degradation from urban development, water management practices that alter marsh hydrology, invasive plant species, and sea level rise associated with climate change. The subspecies' restricted range makes it particularly vulnerable to environmental changes. Conservation efforts focus on protecting and restoring tidal marsh habitat within the Suisun Marsh, maintaining appropriate water levels and salinity regimes, and controlling invasive species that degrade marsh habitat quality.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.