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Bird's Eye View of the Bay

An obscure brown sparrow may be telling us how healthy the Bay's wetlands are-and could even offer restorationists a "short-cut" alternative to expensive, long-term monitoring programs, according to Dr. Steve Zack of the Point Reyes Bird Observatory and Wildlife Conservation Society.

In contrast to endangered salt marsh species (like the clapper rail), salt marsh song sparrows are a good indicator species because they live and breed in almost all of the Bay's salt marshes, and because they use the marsh in a "compelling" way that correlates with the health of the marsh, according to Zack, probing marsh channels with their bills at low tide for food. By examining song sparrow distribution and numbers in the marshes around the Bay, Zack thinks we can develop a picture of marsh health.

After censusing song sparrows for the past year, Zack and his colleagues have confirmed their suspicion that where marshes are better developed-with numerous dendritic channels-song sparrows are more prevalent. Mature marshes with intricate channel development offer more vegetation and food resources for the estuary's food chain, and better filter out pollutants and sediments-making them "healthier" or better-functioning than less-developed or disturbed marshes.

"At sites that have been leveed and where the channels have been straightened-where there is poorer quality marsh-we are seeing fewer song sparrows," says Zack. For sites in San Pablo Bay, Zack estimates sparrow density at approximately 68 birds per hectare, for example, while in Suisun Bay, the number drops to 25 birds per hectare, and in the South Bay, to between 3 and 5 birds per hectare.

Contact: Steve Zack (916)223-4899

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