A summary of bird mortality at photovoltaic utility scale solar facilities in the Southwestern U.S.

Abstract

Recent trends in renewable energy development in the United States (U.S.) show that new installed capacity of utility-scale solar energy has exceeded 30% of total installed capacity of all sources per year since 2013. Photovoltaic solar energy provides benefits in that no emissions are produced; however, there are potential impacts from photovoltaic solar development on birds that include habitat loss and potential for collision mortality. Only 2 papers in the peer-reviewed literature present fatality information from fatality monitoring studies at a photovoltaic utility-scale solar energy facility; however, more data exists in unpublished reports. To provide a more comprehensive overview of bird mortality patterns, we synthesized results from fatality monitoring studies at 10 photovoltaic solar facilities across 13 siteyears in California and Nevada. We found variability in the distribution of avian orders and species among and within Bird Conservation Regions, and found that water-obligate birds, which rely on water for takeoff and landing, occurred at 90% (9/10) of site-years in the Sonoran and Mojave Deserts Bird Conservation Region. We found that a cause of mortality could not be determined for approximately 61% of intact carcasses, and that approximately 54% of all carcasses were feather spots, introducing uncertainty into the interpretation of the fatality estimates. The average annual fatality estimate we calculated for photovoltaic solar (high-end estimate of 2.49 birds per megawatt per year) is lower than that reported by another study (9.9 birds per megawatt per year) that included one photovoltaic facility. Our results provide a summary of fatalities in bird conservation regions where the facilities are located, but expanding our conclusions to new regions is limited by the location of facilities with fatality monitoring data.

Mitigating biodiversity impacts associated with solar and wind energy development: guidelines for project developers

“…Aquatic insects can also be attracted to the polarised light reflected by PV panels, and display maladaptive behaviour mistaking the panels for water surfaces. 85 Kosciuch et al (2020). Kagan et al (2014).…”

Aquatic Habitat Bird Occurrences at Photovoltaic Solar Energy Development in Southern California, USA

“…In a summary of bird carcasses that were opportunistically obtained from three USSE solar facilities (two concentrating solar power and one PV) in California, U.S., Kagan et al [3] determined that 48% (27/56) of identifiable remains found at the Desert Sunlight PV USSE facility (hereafter Desert Sunlight) in California, U.S., were of aquatic habitat birds that foraged in water. The carcasses from Desert Sunlight included species that rely on water for takeoff and landing (e.g., family Gaviidae) and those that use water for some aspect of their life history (e.g., family Charadriidae); these groups are defined by Kosciuch et al [4] as water obligates and water associates, respectively.…”

“…Further, as the LEH was developed based on one PV USSE facility, it was unknown whether the occurrence of aquatic habitat birds was unique to Desert Sunlight or whether the pattern was widespread among PV USSE facilities in southern California, U.S. In a summary of 13 studies at 10 PV USSE facilities in the Southwestern U.S., Kosciuch et al [4] determined that carcasses of water-obligate birds were documented in 90% (9/10) of studies in the Sonoran and Mojave Desert (SMD) Bird Conservation Region (BCR), the region where Desert Sunlight is located. However, Kosciuch et al [4] found that water obligates were detected in only one of three studies outside the SMD BCR.…”

“…In a summary of 13 studies at 10 PV USSE facilities in the Southwestern U.S., Kosciuch et al [4] determined that carcasses of water-obligate birds were documented in 90% (9/10) of studies in the Sonoran and Mojave Desert (SMD) Bird Conservation Region (BCR), the region where Desert Sunlight is located. However, Kosciuch et al [4] found that water obligates were detected in only one of three studies outside the SMD BCR. Thus, uncertainty remains in how broadly the LEH can be applied and whether the LEH applies to all aquatic habitat birds or is limited to specific species.…”

“…It is unknown how the aquatic habitat bird diversity and abundance at PV USSE facilities compares with that at a regional waterbody; thus, our objective was to understand whether a local lake could provide context for our findings at the PV study sites. Our final objective was to determine whether there was support for the alternative hypothesis that exhausted or sick aquatic birds landed broadly on the landscape and died, but were only detected at PV USSE facilities because researchers did not search outside the facilities (e.g., [4]). Searching for aquatic habitat bird carcasses in reference areas outside the PV solar sites would allow us to determine whether there was support for an alternative hypothesis that posits mortality was not predicated on birds being attracted to the PV solar facility.…”