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From Washington to California, Volunteers Answered the Call as Concerns Rose for California Brown Pelicans
How volunteer surveys along the west coast may be revealing changes in where California Brown Pelicans roost and feed in response to a changing climate.
By Dan Orr
Director of Geospatial Science, Audubon California
Published December 10, 2025
This article is from Audubon California
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It was a cool, overcast spring morning in Grays Harbor, Washington. Volunteer community scientists gathered to do a spring roosting count of California Brown Pelicans, a subspecies of the Brown Pelican that had been taken off the federal endangered species list just six years earlier. That same morning, nearly 900 miles south, another team of volunteers gathered at the warmer and sunnier Tijuana River near the U.S.–Mexico border. From a pelican’s eye view soaring above the water, one would have seen this identical scene playing out all along the coast, with dozens of bird lovers meeting up at the ocean equipped with clipboards and binoculars. Altogether, over 100 community scientists surveyed more than 80 roosting sites from Grays Harbor to the Tijuana River on this single day. And this impressive -coordinated effort happened not just once, but several times over 4 years, every spring and fall. The cause? To fill in critical data gaps about the inspiring California Brown Pelican population.
The Community Science Pelican Survey, which ran from 2016–2019 and leveraged the west coast Audubon network, responded to U.S. Fish and Wildlife Service concerns about poor reproductive success coinciding with sharp declines in Northern Anchovy and the crash of the Pacific Sardine fishery, the primary food sources for California Brown Pelicans.
This large-scale community science project was used to analyze patterns of abundance and age ratios, and to assess how environmental variables in the California Current Ecosystem may impact these patterns. It was also a successful proof of concept: carefully coordinated, broad-scale community science can be used to inform the management of a species. It can help us better understand a species’ distribution and demographics, as well as how environmental conditions and climate change may shape patterns of abundance and distribution. These outcomes are captured in a recently released paper in Marine Ornithology, “California Brown Pelican Pelecanus occidentalis Community Science Project: Potential for Population Monitoring.”
This iconic species was one of the first to be listed under the Endangered Species Act of 1970 by the U.S. Fish and Wildlife Service. Population declines associated with exposure to chemicals like dichlorodiphenyltrichloroethane (DDT), a pesticide once widely used to control insects in agriculture that weakened eggshells and reduced reproductive success, drove the steep declines that ultimately led to its listing.
Abatement of these synthetic pesticides led to a significant decrease in pollution and recovery of Brown Pelican populations, culminating in the delisting of the species in 2009. Although the species experienced a period of recovery, its populations were soon troubled again by poor reproductive output and nesting effort, as well as unusual mortality events. These impacts lined up with decreases in Northern Anchovy and the broader collapse of the Pacific Sardine fishery in 2015.
These new warning signs concerned the U.S. Fish and Wildlife Service enough that the agency funded a colony-monitoring program and worked with Audubon to activate the West Coast Audubon network, including Audubon California, Bird Alliance of Oregon, and many of the more than 20 Audubon chapters along California’s coast, to launch the Community Science Pelican Survey.
What Community Scientists Helped Us Learn
The program ran successfully for several years and ended due to the COVID-19 pandemic. During that time, data collected by community scientists proved useful for understanding how Brown Pelicans were responding to their environment and to climate change.
This impactful community science program provided a snapshot of the population during the spring and fall by simultaneously engaging over 100 volunteers on single survey dates to monitor up to 89 sites and count as many as 22,000 Brown Pelicans. A key strength of this study was that observers differentiated juveniles from adults across this large spatial scale.
About 76% of California Brown Pelicans nest on remote islands in the Sea of Cortez, while around 17% nest on California’s Channel Islands. During the nonbreeding season, the more southern pelican population moves north into the cooler waters off the coasts of California, Oregon, and Washington to forage. Because it is difficult to collect colony data across the entire range of the California Brown Pelican subspecies, this coordinated nonbreeding-season survey allows scientists to gain insight into age structure and breeding success for this charismatic West Coast species.
The surveys were able to capture important trends, highlighting the value of community science monitoring. Over the study period, the colony-monitoring and community survey data together showed an increase in nesting and fledging success. This trend followed an increasing trend in Northern Anchovy, a major food source for Brown Pelicans.
The conditions that originally gave rise to this study: a period of very low productivity and concerning die-offs, occurred when Northern Anchovy availability (biomass) was very low. When the study began, anchovy numbers were recovering, and that recovery was associated with improved nesting success for Brown Pelicans. This pattern is consistent with previous studies and was evident in both the colony monitoring and the Community Science Pelican Survey data.
This is encouraging, because it shows that a low-cost monitoring program that incorporates volunteers can be used to gain insights into year-to-year variation in nest success. It can also shed light on population distribution and how changing environmental conditions may influence where pelicans forage and roost. For example, in this study we found a notable shift northward in the nonbreeding population distribution compared to historical patterns, indicating the species is likely responding to climate change by shifting foraging northward.
A Shifting Population in Need of Long-Term Monitoring Support
However, detecting trends in overall population abundance requires long-term datasets. Those questions cannot be fully answered with the current data unless the program receives support on a more long-term basis.
The concerning recent trend of Brown Pelican die-offs over the last couple of years has unfortunately not been captured by this discontinued survey effort. One current hypothesis is that the anchovies that support pelicans have moved into deeper water, beyond the reach of foraging birds. This study showed that pelicans do respond to coastal upwelling conditions that could drive these kinds of shifts, and we know Brown Pelicans experience years of feast and famine that affect nesting success and juvenile survival.
Brown Pelicans may no longer be listed under the Endangered Species Act, but they remain vulnerable to rapidly changing ocean conditions. Programs like the Community Science Pelican Survey could continue to provide useful insights into these patterns and, if resumed and supported over the long term, could help uncover how they influence trends in abundance. In addition to answering management and conservation questions, investment in projects like this increase public awareness, generate interest and support for stewardship, and help advance coastal and marine conservation into the future.
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