The Black Oystercatcher is the charismatic, signature bird of rocky intertidal, one of California’s and the west coast’s iconic habitats. Commonly seen yet globally rare, there is no mistaking the bright orange beak or distinctive call of California's only year-round resident rocky intertidal bird. It can be seen prying limpets, mussels, and other sea life from dynamic Pacific shoreline. There are thought to be no more than 12,000-18,000 of these birds ranging from the Aleutian Islands through Baja.
Until recently little was known of its status and distribution in California. This lack of information has constrained conservation activities that could help secure the species. Since 2011, a unique collaboration led by Audubon California has worked to collect baseline information, describe threats to its population, and develop conservation strategies.
In 2011 we designed and led the first-ever population assessment of Black Oystercatcher in California. The peer-reviewed results are available here. Over 150 participants drawn from coastal chapters and from agencies found more Oystercatchers in just a part of our state’s suitable habitat, than were previously estimated for the state as a whole. Over 1300 birds and over 170 nests were detected. This result combined with high densities of breeding Oystercatchers in certain areas has shone light on the importance of California to the species. This study went far to fulfill the rangewide conservation action plan developed by the US Fish and Wildlife Service and partners which called for more information on the species in California.
Starting in 2012, a collaboration of Audubon citizen scientists, agency staff, and science NGO staff working from Mendocino through San Luis Obispo counties have worked to assess oystercatcher population and breeding productivity in California Marine Protected Areas State Parks, and other rocky intertidal areas. Participating agencies and other science NGOs include the Bureau of Land Management California Coastal National Monument, California State Parks, and Oikonos Ecosystem Knowledge. Audubon chapters include Mendocino Coast, Madrone, Golden Gate, Marin, and Monterey. endocino COast au of Land Management California Coastal National Monument, and California State Parks.
From 2012-2016, between 50-110 individuals have conducted weekly seasonal surveys tracking nest success (through fledge or failure) of 85-130 pairs of birds. The program has been growing with an increase in participants and bird pairs tracked each year. Pairs that experience nest failure often re-nest requiring additional weeks of surveys. These efforts have resulted in a robust data set that is available in detailed reports at this website, and is being prepared for publication by Audubon national science team staff and collaborators. Additionally, we are committed to ensuring our data set is available through the Multi-Agency Rocky Intertidal Network platform:
Black oystercatchers exert substantial top-down influence on intertidal communities through their predation on limpets and other invertebrates. Researchers, managers, students and others interested in oystercatchers and/or the relationship of oystercatchers to the ecology of the intertidal community will have access to the locations of oystercatcher breeding territories, the density of birds in these areas, and productivity associated with each territory. This will allow enhanced understanding of the status and trends of the intertidal community in state marine reserves, state parks, and other areas in the context of rapid changes due to a changing climate.
Numerous conservation activities have been initiated by partners to help preserve the species. Signs, magnets, pamphlets, lectures, and conversations with coastal users and business owners has resulted in reduced disturbance and increased public awareness of oystercatchers. These outreach materials are available at this site for downloading and use in your area.
Funding for the program has been provided by the Marisla Foundation, the Resources Legacy Fund, the Bureau of Land Management, and private donations.
How are oystercatchers doing in California?
We estimate 4000-6000 oystercatchers in California, making our state a critical bastion for the species. Productivity monitoring from 2012-2016 has found a statewide fledge success (fledged chicks per pair per year) of between 0.41-0.49. This is comparable to published fledge rates in British Columbia and Alaska. Audubon will be developing a Population Viability Analysis which will use these fledging rates and other factors to understand the trajectory of the species. Our productivity results as well as trends data from the Christmas Bird Count suggest the species is stable in California. This is great news. However, the species is highly vulnerable to impacts from a rapidly changing coastal environment. This includes sea level rise, increased storms and king tides, ocean acidification, increased disturbance from coastal users, and increased predation from corvids and other avian predators.
State summaries and Regional results (productivity and maps)
Content coming soon
Printable outreach materials
Media, photos, video
Scientific Literature and reports (PDFs and links)
Click here for downloadable resources
How you can help, right now
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