Utility‐scale solar impacts to volant wildlife

Abstract

To reduce carbon emissions from fossil fuel combustion, United States government agencies, including those in California, initiated aggressive programs to hasten development of utility‐scale solar energy. Much of California's early development of solar energy occurred in deserts and annual grasslands, much of it on public land. Measurement of solar energy's impacts to wildlife has been limited to mortality caused by features of solar facilities, and has yet to include impacts from habitat loss and energy transmission. To estimate species‐specific bird and bat fatality rates and statewide mortality, I reviewed reports of fatality monitoring from 1982 to 2018 at 14 projects, which varied in duration, level of sampling, search interval, search method, and carcass detection trials. Because most monitors performed carcass detection trials using species of birds whose members were larger than birds and bats found as fatalities, I bridged the monitors' onsite trial results to offsite trial results based on the same methods but which also measured detection probabilities across the full range of body sizes of species represented by fatalities. This bridge preserved the project site's effects on detection probabilities while more fully adjusting for the effects of body size. My fatality estimates consistently exceeded those reported. Projected to California's installed capacity of 1,948.8 MW of solar thermal and 12,220 MW of photovoltaic (PV) panels in 2020 (14,168.8 MW total), reported estimates would support an annual statewide fatality estimate of 37,546 birds and 207 bats, whereas I estimated fatalities of 267,732 birds and 11,418 bats. Fatalities/MW/year averaged 11.61 birds and 0.06 bats at PV projects and 64.61 birds and 5.49 bats at solar thermal projects. Fatalities/km/year averaged 113.16 birds and zero bats at generation tie‐ins, and 14.44 birds and 2.56 bats along perimeter fences. Bird fatality rates averaged 3 times higher at PV projects searched by foot rather than car. They were usually biased low by insufficient monitoring duration and by the 22% of fatalities that monitors could not identify to species. I estimated that construction grading for solar projects removed habitat that otherwise would have supported nearly 300,000 birds/year. I recommend that utility‐scale solar energy development be slowed to improve project decision‐making, impacts assessment, fatality monitoring, mitigation efficacy, and oversight.

Solar Energy-driven Land-cover Change Could Alter Landscapes Critical to Animal Movement in the Continental United States

“…Research gaps pertaining to solar energy infrastructure’s influence on the movement of individual species persist, and solar energy development is likely to impact different species in different ways. , Some are less likely to be affectedvolant species, for example, can fly above or around facilities and may be less at risk for PV-driven disruption of their movement or migration. However, mortality of volant species due to direct impacts with solar energy infrastructure has been observed . Large mammals could lose access to all or portions of their home range and have migratory pathways disrupted, and are thus more likely to experience adverse effects from solar development.…”

The geographic extent of bird populations affected by renewable‐energy development

“…Renewable energy is a crucial part of strategies to mitigate climate change (Cole et al., 2019; Larson et al., 2021; Socolow, 2020), yet land‐use change related to renewable‐energy production also has consequences for wildlife (Allison et al., 2019; Marques et al., 2014; Schuster et al., 2015). Besides habitat loss and displacement associated with facility installation (e.g., Smallwood, 2022), estimates are that hundreds of thousands of individual birds die annually at wind‐ and solar‐energy facilities in North America (Erickson et al., 2014; Kosciuch et al., 2020; Loss et al., 2013a; Smallwood, 2013; Walston et al., 2016; Zimmerling et al., 2013).…”

Insectivorous bats alter their flight and feeding behaviour at ground‐mounted solar farms

“…Finally, solar farms can create sensory traps for flying vertebrates (birds and bats) leading to attempts to drink from the smooth, horizontal panels or collisions with smooth, vertical panels (Greif et al., 2017), potentially generating additional energy costs. Collisions with panels also pose fatality risks (Smallwood, 2022).…”

“…Despite the important synthesis and review work of Smallwood (2022), effects of the installation of solar farms on habitat use by vertebrates remain poorly documented. There have been only three studies: one shows that solar farms lead to reduced bird species richness and density (Visser et al., 2019), and two show that they lead to reduced activity of several insectivorous bat species (Szabadi et al., 2023; Tinsley et al., 2023).…”