Bird mortality at renewable energy facilities has impact on populations

Importantly, these impacts on populations often extend far beyond the area where the die-off occurred. While existing science has shown that renewable energy production can sometimes kill individual birds, this study is the first to assess the impacts on larger populations.

“The results of this study are important because nearly all environmental impact assessments conducted at renewable energy facilities focus on local subpopulations to estimate mortality consequences,” said Tara Conklin, a wildlife biologist with the U.S. Geological Survey.

The authors estimated the vulnerability of 23 priority species to bird deaths at wind and solar facilities in California. The priority species were identified by California wind and solar wildlife experts, managers, and conservationists. The scientists used a five-step framework that combined data on known population size and natural history, biochemical analysis to determine the source of the dead birds, and population models to estimate the vulnerability of the 23 species.

Of the 23 species studied, 48% were estimated to be highly or moderately vulnerable to mortality events at renewable energy facilities. Additionally, for some species, only local populations were vulnerable, while for others, vulnerable populations were far from California. Most vulnerable species came from subpopulations with narrow geographic ranges or were not locally abundant. Likewise, some vulnerable species came from habitats similar to where renewable energy sources are located. However, in the case of solar energy, populations of nocturnal migratory species were the most vulnerable, even though they are not generally associated with the deserts where the solar facilities studied are located.

“This study suggests that the cumulative effects of renewable energy may be more widespread than previously understood, especially for migratory species, because renewable energy can affect both native and non-native subpopulations,” Conklin said. “In the case of renewable energy, actions regarding the placement of facilities in the landscape and actions to reduce and mitigate mortality impacts may be more effective if managers consider impacts on both native and non-native populations and consider habitats far from where facilities are located.”