The Sierra Foothills are one of California’s most dynamic bird landscapes. Oak woodlands, chaparral, riparian corridors, reservoirs, and working ranchlands create a mosaic of habitats that support remarkable breeding diversity. It is also a region in flux. Fire regimes, drought cycles, development pressure, and vegetation change are already influencing where birds nest and how successfully they raise young.

If California is going to make smarter conservation decisions in the decades ahead, we need a clearer picture of which birds are breeding where and when. That is the purpose of California Bird Atlas (CBA), a new independent nonprofit coordinating the state’s first-ever statewide Breeding Bird Atlas.

A Breeding Bird Atlas focuses specifically on breeding evidence. Instead of simply recording that a species was observed, participants document behaviors such as singing on territory, courtship, nest building, feeding young, or recently fledged birds. Those records are organized within a consistent statewide grid, producing a fine-scale map of where birds are actually nesting.

Forty-four states have completed at least one statewide Breeding Bird Atlas, making California an unexpected outlier. Instead, the state has relied on county-level atlases, but only 15 of 58 counties have ever published one. With the exception of Nevada County, nearly all have focused on coastal or densely populated areas, leaving more than 80 percent of California’s land area without comprehensive breeding data. As of January 1, 2026, that gap is being addressed with the launch of California’s first statewide Breeding Bird Atlas, built on a dedicated eBird platform designed for standardized, long-term data management.

Fieldwork runs year-round through 2030. The goal is straightforward: create the most complete record ever assembled of the distribution and breeding status of California’s birds. Participation is open to anyone. If you bird in the Sierra Foothills, you are already observing breeding behaviors each spring and summer. The Atlas provides a simple structure for turning those observations into information that can inform restoration priorities, land protection, and habitat management.

To ensure consistency statewide, California is divided into approximately 16,500 atlas blocks, each roughly three miles by three miles. This framework allows meaningful comparisons across foothill oak woodlands, Central Valley riparian systems, coastal habitats, and desert landscapes.</

For the Sierra Foothills, the opportunity is especially important. Many species here occur along elevation and climate gradients, making this region particularly sensitive to change. A clear statewide baseline will allow us to detect shifts upslope, range contractions, and new breeding expansions with precision.

If you would like to participate, learn more and submit Atlas checklists at www.californiabirdatlas.org or ebird.org/AtlasCalifornia.