What Birds Can Tell Us About the Health of San Francisco Bay

A new website, the San Francisco Bay State of the Birds, created by the San Francisco Bay Joint Venture and Point Blue Conservation Science, provides scientists, policymakers, and the public with an up-to-date look at which Bay Area bird populations are thriving and which are declining, and what that says about the health of San Francisco Bay’s wetlands and waters.

The findings suggest that the populations of Bay Area marsh birds and wetland ducks are doing well, shorebirds and diving ducks are declining, indicating that some habitats are rebounding from “rapidly evolving climate change and biodiversity challenges,” according to the project researchers, while others still need conservation attention.

The website compiles years of bird monitoring data, restoration success stories, and recommended conservation actions, and builds on a similar report from 2011.

“Birds are good visual indicators that the Bay and its ecosystems are healthy,” said Julian Wood, San Francisco Bay program leader at Point Blue Conservation Science.

Because birds react quickly to habitat changes, shifts in their populations can reveal whether the Bay’s wetlands, tidal flats, and open waters are under stress.

The site focuses on “indicator species” across four habitats — tidal marshes, tidal flats, subtidal zones, and non-tidal wetlands and waters — whose population trends reflect broader environmental conditions.

The launch follows a related effort by the San Francisco Estuary Partnership, which recently released its State of Our Estuary website. That project tracks estuary-wide health across multiple measures, from fish and freshwater flows to bird populations — some of which rely on data from the State of the Birds project.

“We hope this website helps people understand what’s happening with our bird community and promotes even more appreciation and care for birds and their habitats,” Wood said.

The latest monitoring results tell a mixed story. Song sparrows, common yellowthroats, and black rails — all residents of tidal marshes — are seeing increases in their populations, as are the wintering dabbling ducks like mallards and American wigeons, which depend on non-tidal wetlands.

But other groups aren’t doing as well. Diving ducks such as surf scoters and common goldeneyes have dropped in number across open waters in the North Bay and Central Bay.

At the same time, the populations of shorebirds like sandpipers and curlews have declined baywide, signaling that tidal flats and shallow-water habitats need more protection and restoration.

“The decline definitely raises concerns about the amount and quality of our tidal flats and the other habitats that they depend on,” Wood said.

Local restoration projects are already showing what’s possible. The Hamilton Wetlands Restoration Project, once an army airfield, is now a 650-acre refuge supporting 100 bird species, including endangered ridgway’s rails and threatened Western snowy plovers.

Other success stories featured on the website include the South Bay Salt Pond, Sears Point, and Sonoma Baylands restorations. Since 2017, more than 7,800 acres have been restored using funds from Measure AA, approved by Bay Area voters to support wetland recovery.

“Birds are so tightly linked to habitat health,” Wood said. “When we invest in on-the-ground conservation that’s guided by science, we see the positive results. And that is really impactful. With our long-term monitoring, we can see these diverse bird communities coming back and thriving. So that’s pretty exciting,” he added.

Healthy wetlands don’t just benefit wildlife. They filter pollutants from water, reduce flood risks, and buffer shorelines against storms — while offering people recreation and access to nature.

The website lists over 30 concrete actions — from building island nesting habitats to expanding long-term monitoring and public-private partnerships — aimed at protecting birds and improving ecosystem health.

“The more that people learn about these birds and have an awareness about their role in the environment, the better we will be able to protect these populations and ensure that we have thriving bird populations in the future.”