Working for a Better Future for Phalaropes

By Director of Waterbird Science Nathan Van Schmidt

​On March 28th this year, I co-authored and signed a petition for the U.S. Fish and Wildlife Service to list Wilson’s Phalaropes as endangered under the Endangered Species Act. The petition was coordinated and submitted by the Center for Biological Diversity (read their press release here). 

This work is a culmination of two decades of waterbird surveys biologists at the San Francisco Bay Bird Observatory have conducted in San Francisco Bay, including five years of focused summer phalarope surveys carried out with the help of our dedicated team of volunteer community scientists. In the 1980s, during days of peak migration San Francisco Bay had around 40,000 Wilson’s Phalaropes foraging on salt ponds here in order to gain enough fat reserves to continue their migration to wintering grounds to South America.

​Our efforts documented a 98% decline in the species locally, with 1,000 or fewer birds in recent years. Though these birds have declined at other sites across the Great Basin and South America, this is one of the most severe declines that has been documented. These worrying results were communicated to the U.S. Fish and Wildlife Service in the petition. The biggest concern, however, is falling water levels within Great Salt Lake, which faces unsustainable water diversions for agriculture as well as worsening droughts under climate change, which lead to populations of brine flies (phalarope’s main prey item) nearly collapsing last year.

​If populations in San Francisco Bay could be recovered, it may be able to increase the species’ resilience and long-term survival by providing a safe haven during droughts. This winter, SFBBO's Waterbirds team also did their first-ever analysis to test what drove this decline—the two leading hypotheses being either habitat changes or climatic conditions—to help guide managers of the South Bay Salt Pond Restoration Project to manage habitats for their recovery. Surprisingly for a salt-loving species, Wilson’s Phalaropes seem to have locally increased at ponds as their salinity has fallen in South San Francisco Bay. This very unexpected result has led to even more research plans to try and disentangle the complicated drivers of their decline!
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In March, I traveled to Laguna Mar Chaquita in Argentina, the biggest wintering site for Wilson’s Phalaropes, to participate in an international working group meeting across this species intercontinental range (see photo below). The 39 attendees shared data, findings, and most importantly, designed collaborative research goals for the next five years. We have big plans, including studying their foraging ecology and invertebrate prey abundance, trying to catch and tag phalaropes with tracking devices, and remote sensing mapping of habitat changes and stopover sites across North and South America. By donating to SFBBO, you provide seed money we can use to get grants to pursue that work, and support our other conservation and education programs.

To read more about our phalarope research, please visit our website.