The wetlands of south San Francisco Bay extend in a U-shaped band from near Milbrae (vicinity of San Francisco International Airport) southeast through the "Silicon Valley" cities of San Mateo County (Redwood City, Palo Alto) to Milpitas/Alviso (Santa Clara County), then north up the East Bay into Alameda County (Newark, Hayward) to Alameda (vicinity of Oakland International Airport). Over 20,000 acres of habitat is protected as the Don Edwards San Francisco Bay National Wildlife Refuge, where many of the bird habitats of this Important Bird Area are represented, including tidal marshes at creek deltas, tidal flats, salt pans (barren areas, either naturally formed within salt marshes, or left after salt evaporation ponds have dried), diked wetlands (including both brackish and freshwater marshes) and open water. Smaller areas of protected habitat (e.g. Martin Luther King, Jr. and Coyote Hills regional parks; Hayward Regional Shoreline) are scattered throughout. Vast, shallow salt evaporation ponds, located mainly on private lands, are the focus of much conservation and restoration attention. Massive salt pans with interwoven fingers of tidal marsh dominate the area near the western end of the Dumbarton Bridge (Highway 84 in East Palo Alto), and from Sunnyvale east through Coyote Creek north up the East Bay. The broad tidal flats of San Francisco Bay form a band around the entire edge of the Important Bird Area, and major blocks of marsh habitat include Bair and Greco Islands (vicinity of Redwood City) and Palo Alto Baylands (vicinity of Mountain View), which feature diked wetland, tidal marsh and tidal flats. The southeast edge of the Bay also features some of the most substantial upland habitats within this Important Bird Area, including a remnant vernal pool/grassland area south of Fremont (now nearly eliminated) and the Coyote Hills north of Newark (see Goals Project 1999 for a complete description of the area).

Ornithological Summary

Most of the global population of the endemic Alameda Song Sparrow falls within this Important Bird Area. Surveys in the tidal marshes on Don Edwards S.F. Bay NWR lands have estimated 600 California Clapper Rails (at least 60% of the global population of this taxa, M. Kolar, in literature). These are now limited to the handful of protected lands where Red Fox is being controlled. Snowy Plovers winter and occassionally breed in scattered sites, mainly near Redwood City and in the Alameda County section of this Important Bird Area, where they are joined by thousands of pairs of California Gull (11-14% of California?s breeding population, Shuford and Ryan 2000) and Forster?s Tern, with smaller numbers of Caspian Tern. Least Terns currently breed only at Hayward Shoreline, but utilize salt pans throughout for post-breeding staging, and Black Skimmer has recently bred successfully at several sites. Carefully monitored by the San Francisco Bay Bird Observatory, a heronry near Alviso is one of the state?s largest, and has recently included a handful of White-faced Ibis (Mike Rogers, via email). This Important Bird Area is a critical migration and wintering area for shorebirds, with an estimated half-million individuals (mainly Western Sandpipers) pouring through during spring migration, and large numbers in fall and winter. Other shorebirds are also well-represented, with spring Dunlin and Marbled Godwit numbers estimated to exceed 10% of their global populations (Page and Shuford 2000). Over 75,000 ducks have been counted wintering on the open water of the refuge, with Ruddy Duck and Northern Shoveler dominant (Accurso 1992). Other significant birds include Black Rail (winter only, fide Evens and Nur, in press) and even the occasional winter sighting of Yellow Rail, a species that has been nearly extirpated from the state (fide Mike Rogers). Northern Harrier, Short-eared Owl (mainly winter), Burrowing Owl and Loggerhead Shrike maintain small populations in grassy portions of the Important Bird Area, and have been essentially eliminated from inland areas by development.

Help us learn more about the birds at this IBA! Enter your birding data online at Calfornia eBird! (http://ebird.org/california/)

Conservation Issues

The remaining open space within this IBA is under threat of development. Redwood City, Newark, Fremont, and Oakland all face development pressure for housing, golf courses, industrial parks, and sports stadiums. Protected conservation areas are also under threat from pollution impacts such as light, noise, air, and water pollution originating in adjacent habitas.

Millions of dollars are being sought to restore and enhance diked former wetlands. In 2002, the USFWS and CA DFG purchased 15,100 acres of salt evaporator ponds in South San Francisco Bay. Because of concerns regarding the conservation of tidal-marsh dependent wildlife species, a massive effort has begun to restore much of these salt ponds to tidal marsh. However, the salt pond complexes currently provide valuable breeding and wintering habitat for Snowy Plovers and other non-tidal marsh species. Adaptive management during salt pond restoration will be critical to ensuring that a diverse suite of species needs are preserved and enhanced so that the site remains viable for species inhabiting marsh, shallow open water, deep open water, and managed mostly dry ponds.

Mercury contamination of wildlife is currently under extensive scrutiny.

Increased recreation along new public access trails through the Salt Pond Restoration project poses another conservation and management concern. Impacts from public access will be continually assessed and managed to minimize impacts to natural resources.

Invavise species control remains a pressing conservation issue, with non-native chord grass, and Pepperweed among the more serious invaders. Red Fox entered the system in the mid-1980s, and has been decimating the rail population, as have feral cats (colonies fiercely defended in area by local residents) and exotic rats. Finally, urban encroachment and its associated threats (including urban runoff, off-leash dogs) continue to pose a constant (and likely permanent) threat.

Ownership

Over 20,000 acres of habitat here is protected as the Don Edwards San Francisco Bay National Wildlife Refuge. Smaller areas of protected habitat (e.g. Martin Luther King, Jr. and Coyote Hills regional parks; Hayward Regional Shoreline) are scattered throughout.

Habitat

Over 20,000 acres of habitat here is protected as the Don Edwards San Francisco Bay National Wildlife Refuge, where many of the bird habitats of this IBA are represented, including tidal marshes at creek deltas, tidal flats, salt pans (barren areas, either naturally formed within salt marshes, or left after salt evaporation ponds have dried), diked wetlands (incl. both brackish and freshwater marshes) and open water. Vast, shallow salt evaporation ponds, located mainly on private lands, are the focus of much conservation and restoration attention. The broad tidal flats of San Francisco Bay form a band around the entire edge of the IBA, and major blocks of marsh habitat include Bair Isl./Greco Isl. (vic. Redwood City) and Palo Alto Baylands (vic. Mountain View), which feature diked wetland, tidal marsh and tidal flats. The southeast edge of the Bay also features some of the most substantial upland habitats within this IBA, including a remnant vernal pool/grassland area south of Fremont (now nearly eliminated) and the Coyote Hills north of Newark.

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