San Diego Management & Monitoring Program


Belding's savannah sparrow
Passerculus sandwichensis beldingi

Vertebrata

Vertebrata
Kingdom Phylum Subphylum Class Order Suborder Family

Current distribution rangewide

Nonmigratory; endemic to the coast of southern California and northern Baja California [1].


Known Populations in San Diego County

Occurs in MUs 1, 2, and 6 in the MSPA. Occur along the southern coast primarily in coastal salt marshes year-round. More specifically, San Diego Bay, Mission Bay, Santa Margarita River Estuary, Buena Vista Lagoon, Agua Hedionda Lagoon, Batiquitos Lagoon, San Elijo Lagoon, San Dieguito Lagoon, and Los Penasquitos Lagoon are localities with present populations [1].


List status

CE [2].


Habitat affinities

Prefer to build their nests on or near the ground, concealed from above, within habitats dominated by dense pickleweed, particularly Salicornia virginica. Nests have been located in pickleweed, shore grass, and saltwort [3]. Conducting an accurate survey can be difficult since they are secretive and forage throughout a marsh, many times away from nesting sites [4, 5].


Taxonomy and genetics

Belding’s savannah sparrow are one of the seventeen subspecies of the savannah sparrow [6]. Six of those subspecies live at least part of the year in wetlands such as salt marshes. Recognized by its heavily black-streaked underparts and dark olive-tinged upperparts, Belding’s savannah sparrow is a little brown and white streaked sparrow with a yellow eyebrow stripe. The three subspecies that migrate from the north as winter visitors have paler upperparts and defined brown streaks on their underparts. Males and females are similar in appearance [6].


Seasonal activity

Nonmigratory and endemic to the coast of southern California [7]. During the winter individuals may form loose flocks, which appear to be aggregations around food-rich patches rather than social groups [8].


Life history/ reproduction

Breeds from April into July, peaking in May and June [9]. Females lay an average of 2-6 eggs per clutch; often double-brooded. Incubation is 10-13 days with altricial young fledging in 7-14 days [10]. Incubation and brooding mostly by female [11]. The primary habitat is the upper marsh zone that is flooded infrequently by the tide. In order to sustain the pickleweed and prevent the invasion of upland plants, the marshes must be flooded regularly, but not so deeply or for so long to preclude the birds from nesting. The birds nest only in this zone, though they range outside it to forage. Nesting success is higher where the marsh plants are denser and taller [3, 12].


Diet and foraging

Belding’s savannah sparrows forage throughout the marsh, within the vegetation, along intertidal mudflats, and sometimes on neighboring sand dunes [1, 4]. Generally eat grass, seeds, insects, snails, and spiders. Invertebrates are the predominate food source in the breeding season, while seeds are more important the remainder of year. Scratches and gleans on ground, and picks food directly from low plants [9].


Dispersal

Limited dispersal and exists as a metapopulation with extirpation and recolonization of local populations [1, 13, 14].


Threats

Destruction or degradation to salt-marsh habitat due to the direct impact of urban development. Human impacts, such as trespassing into restricted areas, off-trail use in public areas, and feral animals entering into the marsh represent a serious threat to survival.


Special considerations:

Narrowly restricted to coastal marshes dominated by pickleweed [6]. Pickleweed habitats have been degraded by changes in tidal flow and freshwater inputs, invasion of nonindigenous plants, and fragmentation by trails and roads. Restoration of this habitat type is difficult and may not result in suitable nesting habitat for sparrows [15].


Belding's savannah sparrow sources