The recent decline of bird populations due to habitat loss, climatic changes, and other anthropogenic factors is a global concern, but especially relevant for California. California is a biodiversity hotspot and changes in climate can negatively impact fragile ecosystems and species. Riparian habitats are one of the most important ecosystems for bird species; however, about 95% of these ecosystems in California have been degraded. The impact of recent, record-breaking climate events in California and changes in riparian habitat in relation to bird populations has not been fully established. In response, we utilize long-term bird monitoring datasets in California, from eBird and the Coyote Creek Field Station (CCFS) in San Francisco Bay Area, to investigate how the changes in migratory, wintering, and nesting bird populations from 1980 to 2020 are related to changes in climate and habitat. The changes in climate and land cover are calculated from large-scale datasets (PRISM, CHIRPS, MODIS, USGS DEMs) and are then correlated with bird population data. Furthermore, future predictions about the relationship between climate change, habitat availability, and bird populations are estimated with a machine learning algorithm that utilizes climate, land cover, and topographic data as factors to predict avian populations.
Results/Conclusions
For the long-term bird monitoring dataset from CCFS our preliminary results indicate that, as measured by abundance, the bird population in the South San Francisco Bay Area has seen some increases from 1993 to 2018. Most of this increase might be related to increases in nesting species, while wintering and migratory species appear to have experienced a decline. Given the declines in bird populations, across the United States and globally, the increase in bird abundance at CCFS indicates relative success for this area of riparian habitat. Further investigation into state-wide changes in bird populations, utilizing the eBird dataset, will better contextualize results from the San Francisco Bay Area.
Our preliminary results also indicate that warmer temperatures and precipitation shifts throughout California, from 1980 to the present, are related to a concurrent decline in migratory and wintering bird species regardless of riparian habitat restoration efforts. The connections between habitat changes, climatic shifts and bird populations needs to be better understood to support avian conservation within California and beyond.