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Black Rail, cont. the black rail was considered "extirpated" from coastal Southern California. Its status elsewhere was not well understood.
A statewide survey conducted in the 1970's suggested that the marshes of San Francisco Bay probably supported the bulk of the black rail population in California. Although small populations have also been found outside San Francisco Bay, (in outer coast tidal marshes, small pond margins and swales in the low Sierra foothills, freshwater marshes associated with the Colorado River and the Salton Sea) the habitat available at all these sites combined provides less that 10% of the marshland that occurs within San Francisco Bay. The total number of California black rails outside of San Francisco Bay must be low, perhaps several hundred individuals.
In the course of other avian research within the bay, shorebird biologist Gary Page, other associates at Point Reyes Bird Observatory, and I had encountered black rails fleetingly and had become curious about this mysterious little marsh dweller. We knew that because of the severe modifications imposed on shoreline habitats of San Francisco Bay over the past 150 years, it was likely that any species that was dependent on marsh habitats had suffered dramatic declines. Many of the same factors that have caused other marsh dependent species, such as the California clapper rail, salt marsh harvest mouse and soft bird's beak to be classified as "threatened" or "endangered," must also negatively influence the black rail population. Several other species, such as the salt marsh common yellowthroat, Suisun song sparrow and San Pablo song sparrow are candidates for the endangered species list.
In mid-1980's the Marin Audubon Society and the California Department of Fish and Game funded a few small studies to help us address some questions key to conservation biology. How many black rails reside in the San Francisco Bay estuary? Where exactly are they? What are their habitat requirements? |
Last updated:
May 27, 2008
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