The influence of native shrub density on bird communities in the southern drylands of California, USA.

Interactions between key landscape features in desert ecosystems such as shrubs and other foundation plants can influence avian community assembly. Bird species often use resources and microhabitats provided by these shrubs for food, perching sites, and as thermal refuges. Citizen science data are broadly accessible and can be used to examine fine-scale avian distribution. Coupling this accessible data with key factors, such as native shrubs, can be used for conservation practices. eBird data offers the opportunity to examine avian communities across regional ecological gradients. Using eBird, we tested the hypothesis that shrub density and relative differences in aridity among sites within this region shape the structure of bird communities throughout Central California drylands. Shrub density positively influenced the observation rates of avian communities sampled. Decreasing aridity increased the positive associations of birds with shrubs. Citizen science data such as eBird offers promise for testing predictions at fine spatial scales, and further research can explore availability and reporting of data for other regions - particularly in drylands subject to substantial pressures from climate change globally. Simple landscape features in drylands, such as native shrub density and cover, offer a viable path forward for avian community conservation and potential habitat restoration in drylands in the face of a changing climate and increasing desertification.