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Conserving bird populations is a key goal for management of the Sacramento–San Joaquin Delta ecosystem and is likely to have effects well beyond its boundaries. To inform bird- conservation strategies, we identified Priority Bird Conservation Areas for riparian landbirds and waterbirds in the Delta, defined as the most valuable 5% of the landscape for each group. We synthesized data from 2,547 surveys for riparian landbirds and 7,820 surveys for waterbirds to develop predictive distribution models, which then informed spatial prioritization analyses. We identified a total of 26,019 ha that are a high priority for conserving riparian landbirds, waterbirds, or both, representing the most important places in the Delta to protect and manage, as well as strategic areas where adjacent restoration could expand valuable habitat. These Priority Bird Conservation Areas include the Yolo Bypass Wildlife Area, Cosumnes River Preserve, Stone Lakes National Wildlife Refuge, and bufferlands that surround the Sacramento County Regional Sanitation District. However, we also found that over 60% of the Priority Bird Conservation Areas are not currently protected, indicating a vulnerability to changes in land cover or land use. We recommend advancing strategies for bird conservation in the Delta by developing more specific objectives and priorities, extending these analyses to include other bird species, and planning to mitigate the loss of Priority Bird Conservation Areas where they are most vulnerable to land cover change. The predictive models and analysis framework we developed represent the current state of the science on areas important to bird conservation, while also providing a foundation for an evolving bird-conservation strategy that reflects the Delta’s continuously evolving knowledge base and landscape.

Many bird populations have experienced population declines across North America over the past several decades. The establishment of protected areas has been used as a conservation action to maintain or help in the recovery of these populations; however, the effectiveness of protected areas in safeguarding bird populations within their borders from negative impacts to populations in surrounding unprotected areas has rarely been evaluated. Our study aimed to evaluate the effectiveness of protected areas in the San Francisco Bay Area of California for landbirds. We conducted point count surveys along riparian corridors in coastal Marin County in protected areas, predominately national parks, and estimated the population growth rates for 14 species over 23 years. We compared these growth rates to North American Breeding Bird Survey growth rate estimates from the Coastal California and the Northern Pacific Rainforest Bird Conservation Regions, which comprise larger, regional populations. A safeguarding effect was detected for 9 of the 14 species. We expected an effect on species strongly associated with riparian vegetation, which has incurred significant loss and degradation in the region; however, we instead observed benefits to general riparian users that were at least as great as the benefits to strong riparian specialists. We also expected that populations of resident species might benefit more than migrants; however, we found strong support for a safeguarding effect for both groups. Species with increasing growth rates in coastal Marin County protected areas in comparison to regionally stable or decreasing populations demonstrate the potential for protected areas to not only maintain populations despite declines outside their boundaries but also to help them recover from current and previous losses. Continuing long-term monitoring and associated full life cycle research will help identify if and when other drivers (e.g., climate change) may weaken these safeguarding effects, or when additional conservation and management is warranted. [ABSTRACT FROM AUTHOR]