Learning from real-world experience to understand renewable energy impacts to wildlife

The project team sought to use real-world data to understand adverse effects to wildlife
of renewable energy production that is critical to meeting California’s climate and clean
energy goals. The project had three main components. First, a systematic literature
review studied 20 peer-reviewed publications and 612 reports from other nonreviewed
sources from 231 wind and solar facilities in North America. Within California, 50
percent of facilities collected pre- and post-construction data, 30 percent had
experimental study designs, and fewer than 7 percent estimated detection probability
during habitat use surveys. Mitigation at wind power plants focused on repowering to
reduce risk to soaring birds and at solar facilities emphasized wildlife deterrence and
compensatory mitigation. Second, the authors developed a best-practices approach to
employ environmental isotopes (for example, hydrogen obtained from animal tissue)
and rescaling functions (a statistical approach to modeling the relationship between
variables) to assign individual birds or bats to their place of origin. The team applied
this approach to feathers from 411 individuals of 12 species killed at wind facilities and
515 individuals of 19 species killed at solar facilities. From 24 percent to 100 percent
(mean +/- SD = 49 percent +/- 33 percent) and 25 percent to 100 percent (73 percent +/-
25 percent) of birds grew feathers at a location outside the collection site at wind and
solar facilities, respectively. Third, the authors constructed Bayesian integrated
population models (probability models) for 29 focal species affected by wind or solar
energy generation in California. Species predominantly local in origin generally had
lower population growth rates than did species that were predominantly nonlocal in
origin. These patterns illustrate the complex linkages between behavioral ecology,
vulnerability to mortality, and population-level impacts to wildlife from fatalities at
renewable energy facilities. This project benefits the renewable energy sector by
providing a framework and specific tools for understanding environmental impacts of
renewable energy generation.