Belding's Savannah Sparrows Passerculus sandwichensis beldingi are endemic to southern California's and Baja California, Mexico's coastal salt marshes. They live and prefer to nest in the mid- to upper-littoral zones of coastal salt marshes and have adapted to drinking saltwater. They eat insects, seeds and some vegetation.
Belding's Savannah Sparrow has suffered population declines with the loss of suitable high pickleweed marsh: in California, over 75% of the presettlement acreage of California's coastal wetlands have been lost to human development. They are nonmigratory and are therefore dependent on salt marsh habitat during all months of the year. Listed as endangered by the State of California, statewide censuses of Belding's Savannah Sparrows reveal wide fluctuations in local population sizes, with local extinctions occurring in some years (Zembal et al. 1988). Thus, the population dynamic's of Belding's Savannah Sparrow may reflect the effects of fragmentation.
(Further info: "Populations of Belding's Savannah Sparrows in California are weakly correlated with habitat area, but there are few large wetland fragments remaining within their range. We conducted research in a fragmented wetland complex, and measured territory sizes and reproductive success of sparrows as well as habitat characteristics. We found no relationship between territory size and reproductive success, but all available habitat within the marshes was occupied, suggesting that even low quality habitat was being used. Although reproductive success was not strongly linked to vegetational characteristics, we found significant differences in reproductive success between birds nesting in large wetland complexes versus those nesting in small, isolated marshes. Sparrows nesting in a small, isolated salt marsh failed to produce fledglings over the course of the breeding season, but birds nesting in a small, connected wetland succeeded. Large wetland complexes are likely to be population sources, while small, isolated marshes act as population sinks. Because of the overall rarity of salt marsh habitats in this region, all sizes of remnant marshes are important, and therefore restoration planning should take place on a regional level". Powell , A.N. and C. L. Collier - 1998. Reproductive success of Belding's Savannah sparrows in a highly fragmented landscape. Auk 115:508-513.www.npwrc.usgs.gov/belding/belding.htm)