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LOS ANGELES, CA — Conservation groups, bird organizations, and community scientists across California are preparing for the inaugural California Bird Atlas Big Weekend, a four-day effort taking place June 4–7, to document breeding birds as part of the first-ever statewide Breeding Bird Atlas (BBA).

Thousands of Californians will spread out across the state’s coastline, deserts, forests, wetlands, valleys, and cities to document as many breeding bird species in as many parts of the state as possible. Dozens of community events are being organized by local bird and conservation groups.

California is one of only six states that has never completed a statewide Breeding Bird Atlas, despite supporting more breeding bird species than any other place in the country. BBAs are large-scale, multi-year efforts to document the distribution and breeding status of all nesting bird species across a region, creating an essential baseline for tracking ecological change over time. Because breeding birds respond quickly to shifts in climate, habitat, and land use, they are among the most effective indicators of overall ecosystem health. By building this baseline now, Californians will help create one of the most important biodiversity datasets in state history and provide a powerful tool for guiding conservation decisions for decades to come. 

“California could arguably be called the birdiest state, but we’ve fallen far behind on pursuing this crucial tool,” said Van Pierszalowski, Director of California Bird Atlas, a new nonprofit organization dedicated to establishing the state’s Breeding Bird Atlas. “The birding community here has exploded in recent years, becoming younger and more diverse than most people realize. It’s been inspiring to see all these folks come together for a shared mission, directly adding to community science that will inform conservation decisions for years to come.”

“As champions for all of California’s 600+ bird species and our state’s incredible biodiversity, we are thrilled to help launch our state’s first and only Breeding Bird Atlas,” said Andrea Jones, vice president of ̽����ѡ California, a founding partner organization of California Bird Atlas. “This community-powered initiative is one of the most exciting opportunities to advance avian science and conservation planning for the millions of birds that rely on California to breed, feed, and rest during their remarkable migrations.”

The effort comes at a pivotal moment for California. Wildfires, climate change, habitat loss, and increasing pressure on land and water resources are rapidly reshaping landscapes across the state. Scientists and land managers increasingly need long-term data to understand how wildlife populations are responding.

“Breeding Bird Atlases provide an essential scientific baseline for understanding how ecosystems are changing over time,” said Morgan Tingley, Professor of Ecology and Evolutionary Biology at UCLA and chair of CBA’s Science Advisory Committee. “At a time of rapid environmental change and growing ecological uncertainty, establishing a statewide baseline for California’s breeding birds is urgently important for both conservation and science.”

The nonprofit California Bird Atlas officially launched the project on January 1, 2026, with data collection scheduled to continue through 2030. The response from the birding community was immediate. By late May, more than 4,000 individuals had already contributed to the project, collectively submitting over 110,000 Atlas checklists through a custom-built eBird platform. 

To learn more, find events, or host an outing, visit: .

About California Bird Atlas
California Bird Atlas is a nonprofit organization dedicated to establishing California’s first statewide Breeding Bird Atlas while deepening the public’s connection to nature. California Bird Atlas is supported by ̽����ѡ California, the Cornell Lab of Ornithology, UCLA, state agencies, 28 local ̽����ѡ chapters, and other conservation organizations.

About ̽����ѡ California
̽����ѡ California is a regional office of the ̽����ѡ, a leading nonprofit conservation organization with 120 years of science-based, community-driven impact, dedicated to protecting birds and the places they need, today and tomorrow. Learn more at  and follow us on and �����ܻ�ܲ��Dz԰䴡. �į�į�į&�Բ�����;