Richardson Bay is located just north of San Francisco in southeastern Marin County in the urbanized middle section of San Francisco Bay across from Berkeley. Much of the shoreline has been filled and rip-rapped, but a few sections are less disturbed. A small area in the northwest, Bothin Marsh, is managed by Marin County Open Space District. This wetland, along with the wetlands of Corte Madera, represents the majority of the tidal marsh habitat of west-central San Francisco Bay. Nine hundred acres of open water are protected as the Richardson Bay Wildlife Sanctuary under the management of the National Audubon Society, which has maintained a small interpretive center and sanctuary since 1958 on 11 acres of coastal scrub, riparian thicket and oak woodland.
The estuarine wetlands of San Francisco (which includes Richardson) and San Pablo Bays are recognized together as a Western Hemisphere Shorebird Reserve Network (WHSRN) Site of Hemispheric Importance for shorebirds - the highest possible ranking.
The large numbers of waterfowl during high tide and shorebirds during low tide that find refuge in the sanctuary make it an important link of habitat in an otherwise urbanized portion of San Francisco Bay between the extensive refuges to the north and south. Over 16000 scaup (Greater and Lesser) have been recorded within the Audubon sanctuary alone (K. Wilcox, M. Sundove, personal communication), although the area normally supports 2,000-4,000 ducks, mainly Scaup, Ruddy Duck, and Bufflehead (Meryl Sundove, personal communication). An Audubon survey on December 23, 2013 documented over 21000 birds on the sanctuary waters, more than 75% of which were diving ducks. Additionally, hundreds of shorebirds, especially Least Sandpiper and Dunlin, utilize the exposed mudflats of Bothin Marsh and the greater Richardson Bay daily during migration. Additionally, Elegant Terns often roost in the hundreds on Richardson Bay post-breeding using the islands just east of Strawberry Peninsula. p to 800 Elegant Terns have been recorded using the islands just east of Strawberry Peninsula (R. Hinz, K. Wilcox, unpublished data), and over 1300 recorded at Blackie's Pasture (eBird, 2016). Help us learn more about the birds at this IBA! Enter your birding data online at Calfornia eBird! (http://ebird.org/california/)
The Bay waters under the protection of the Sanctuary are closed to boat traffic from October 1 until March 31 of each winter in order to prevent disturbances to wintering and migrating waterbirds. Several species of waterfowl that were once more common on the Bay such as Canvasback and Surf Scoter have not been seen as frequently as in past years, and one species, Brant, has rarely been seen at all. The upland portions of this Important Bird Area are extensively invaded with exotic vegetation (e.g. French Broom, exotic plum trees, Cotoneaster, European annual grasses, etc.). Currently the Richardson Bay Sanctuary and Center is conducting experimental reintroductions of native eelgrass and oysters within Bay waters. Additionally, the Richardson Bay Sanctuary and Center is planning to enhance habitat on the dredged spoil islands within the Bay.
Though much of the shoreline has been filled and rip-rapped, Armaburu Island along Strawberry Peninsula's east side and marshland in the northwest is managed by Marin Co. Parks District. Nearly 900 acres of open water in the northeast is protected as the Richardson Bay Audubon Sanctuary by National Audubon Society which has maintained a small Center since the late 1950s.
Though much of the shoreline of Richardson Bay has been filled and rip-rapped, there is tidal marsh on the western arm of Richardson Bay in Mill Valley (Bothin Marsh). Nearly 900 acres of open water is protected as the Richardson Bay Audubon Sanctuary (formerly called "Richardson Bay Wildlife Sanctuary"). Audubon has maintained a Center since 1958 on 10 acres of coastal scrub, riparian thicket and oak woodland. Three small bay-fill islands line the eastern shore of Strawberry Peninsula creating some limited marsh habitat; one of them, Aramburu Island, has undergone enhancement to its uplands and shoreline.