From Washington to California, Volunteers Answered the Call as Concerns Rose for California Brown Pelicans
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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.