Black Oystercatchers are a charismatic bird, with their medium-sized black bodies and bright orange beaks that resemble a bird smoking a big orange cigar. Their high-pitched, piping calls ring out across the rocky shores they call home, making them a signature bird of the rocky intertidal. 

These shorebirds occupy a narrow band of habitat, below the high tide mark and above the low tide mark, that is crucial for their foraging, nesting, and roosting. This limited habitat, stretching from Alaska to Baja California, supports a global population of only 12,000-17,000 birds. The main breeding areas are located north of Point Conception in California, with rare breeding occurrences south of that point. While not officially listed as a threatened species, Black Oystercatchers are considered a species of conservation concern due to their habitat limitations and increasing threats from climate change. 

Collaborative Conservation 

Starting in 2012, a collaboration between nearly 200 Audubon community scientists, agency staff, and science NGOs began assessing Black Oystercatcher populations and breeding productivity in California, spanning from Mendocino through San Luis Obispo counties. Key partners include Oikonos Ecosystem Knowledge and Mendocino Coast, Madrone, Golden Gate, Marin, and Monterey Audubon Chapters. Bird Alliance of Oregon launched a similar statewide monitoring program in 2015, working with U.S. Fish and Wildlife, U.S. Geological Survey, coastal Audubon chapters, and more. 

Using 10 years of robust data from these efforts, a new research paper by Audubon California, National Audubon Society, and Oikonos Ecosystem Knowledge, published in Marine Ornithology, assessed productivity patterns and the variables affecting breeding success. The study broke down breeding areas in California and Oregon into three regions based on biogeographic information. Results showed a clear trend: productivity increases as you move north, with southern regions averaging below the 0.5 threshold needed to sustain a stable population, while the most northern regions hover at or above this threshold. Although the global population is thought to be stable, more productive nests in the north may help replenish less successful southern populations. 

Key Factors: Nest Location, Climate Change, and Human Disturbance 

The research found that nesting success is closely linked to nest location. Nests placed higher up onshore or on offshore rocks were more successful, as lower nests are more susceptible to being washed out by waves during storms. As climate change leads to larger, more frequent storms, nesting could become increasingly challenging for Black Oystercatchers. 

Disturbance was also identified as a significant factor impacting nesting success. Human activity near nesting sites had a large negative effect, making onshore nesting sites that are higher up, though safer from waves, more vulnerable to human disturbance. This highlights the broader issue that species not classified as threatened can still be at serious risk, especially when facing climate change. 

The Future of Black Oystercatchers in a Changing Climate 

The narrow band of intertidal habitat that Black Oystercatchers depend on is expected to shrink as sea levels rise, and as storms become more intense, nesting habitats, already narrower than foraging and roosting areas, are increasingly threatened. Conservation efforts must account for how a changing climate will impact the habitats that support these birds. 

While reducing the impact of climate change on Black Oystercatcher habitat is a complex challenge, long-term monitoring programs like this one are crucial. Without ongoing monitoring efforts, we may not realize the full extent of the threats these birds face until it is too late. To help secure their future, reducing human disturbances at nesting sites and protecting offshore rocks and islands could be key strategies to the longer-term success of Black Oystercatchers. 

Supporting Conservation Efforts 

The success of these conservation efforts has been made possible through funding from the Marisla Foundation, Resources Legacy Fund, Bureau of Land Management, and private donations. Ongoing monitoring and community science initiatives will continue to play a critical role in protecting this coastal icon. 

For more information on Black Oystercatchers and to dive into the study, check out the report here.