Bird community assembly in utility-scale solar farms of agricultural landscapes

Bird communities are facing heavy declines, especially in agricultural landscapes. An exponentially spreading landscape feature, photovoltaic solar farms, may offer an opportunity for their conservation. Compared to croplands and other disturbed areas, solar farms may provide stable food and nesting sources, but also pose challenges due to intensive vegetation management and the presence of artificial structures. We know little about how bird communities respond to these novel habitat characteristics, preventing the formulation of evidence-based guidelines to benefit birds in solar farms. Here, we aimed to unravel drivers of bird community patterns in solar farms embedded in transformed, agricultural landscapes. Using data from 32 farms and surrounding landscapes, we found that birds in the farms form distinct communities compared to the surrounding landscape, and the bigger the farm, the more distinct the community. Indicator species of solar farms include urban and open-habitat species, while forest species only spill over to the farms from adjacent woody habitats. Although some open-habitat species regularly occur in solar farms, those that require a clean skyline avoid the farms. In addition, if better-quality grasslands are available around, open-habitat birds do not enter in higher numbers but tend to lower their preference on the farms. Birds showed seasonal variation in solar farm use; they were more common during the breeding season than in the fall. These findings highlight the potential (e.g., for open-habitat bird conservation) and the limitations (e.g. unfavourable off-season conditions) of solar farms, which we could strategically exploit and should navigate with targeted interventions, respectively.