Will large scale solar developments affect bat populations in the Southwest US?
Utility scale solar energy projects are being built at a fast pace in the Southwest United States, but little is known about their effects on bats. We hypothesized that the structural changes cause by the addition of arrays and perimeter fences could result in changes to bat activity in array areas, relative to conservation lands. We predicted that the majority of bat species would increase their activity in array areas, due to the edge structure provided, but we predicted that pallid bats (Antrozous pallidus), a species that specializes in low flight and gleaning ground dwelling insects, would decrease their activity inside array areas due to the presence of perimeter fencing. We deployed 26 passive acoustic bat detectors and recorded echolocation calls of bats from sunset to sunrise from July 2012-December 2014. We manually identified the calls to species using AnaLook. We applied log transformations and used generalized least squares models to analyze the effects of arrays on the activity of each bat species. To better understand any potential negative effects to at a regional level, we overlaid solar project footprints in the Southwest with the range of bat species.
Our preliminary investigation of the effects of an operating 250-megawatt solar photovoltaic (PV) project on insectivorous bats suggests that most species were not significantly affected by the construction or presence of solar PV projects. Canyon bats (Parastrellus hesperus) had lower activity in preconstruction and conservation lands, compared to within operating arrays (-0.08, SE= 0.04, P<0.05). Pallid bats decreased their activity in array areas (‑0.07, SE=0.02, P<0.05). Preliminary results suggest that acoustic deterrents will significantly reduce bat fatalities at solar flux project developments. Based on a GAP analysis, pallid bats’ range comprises 364.62 million acres over 6 southwestern states and pallid bats are expected to lose 219,481 acres of foraging area to solar developments, which represents less than one percent of their range. The southwestern development of solar projects is therefore not expected to negatively affect the foraging areas of bats.