New Peer-Reviewed Science Suggests Potential Significant Negative Impact of Industrial Solar Facilities on Threatened/Endangered Bat Populations in Michigan’s Western Upper Peninsula
Summary
There are many well established economic and health benefits in preserving slow reproducing, endangered/threatened bat populations in the Western U.P (they are important insect eaters, pollinators, and seed dispersers).
The Western U.P. is critically important destination for migratory tree bats and especially hibernating cave bats that utilize abandoned mines as winter hibernacula. Cave bats hibernating in abandoned mines may travel up to 250 miles away, thus making the Western U.P. critically important in protecting bats in the Upper Great Lakes region.
A recently released peer reviewed scientific journal article concluded “ground-mounted solar photovoltaic developments have a significant negative effect on bat activity.”
This new study (and others) point to potential adverse impacts from the proposed 300+ acre Groveland Mine industrial solar installation on threatened/endangered bats that hibernate, roost, forage, and commune within proximity to the proposed development location. This is because of the established risks of bats not tolerating human disturbance (that now include ground-mounted industrial solar photovoltaic developments).
Ground-Mounted Solar Photovoltaic Systems were recently found to have a Significant Negative Effect on Bat Activity
Only recently have studies been conducted to assess the impact of industrial solar farms on bat activity. A 2023 peer reviewed research study published in a high quality scientific journal used bat echolocation call recordings to conclude “ground-mounted solar photovoltaic developments have a significant negative effect on bat activity” (Tinsley et al., Renewable energies and biodiversity: Impact of ground‐mounted solar photovoltaic sites on bat activity. Journal of Applied Ecology, 2023, doi: 10.1111/1365-2664.1447).
In fact, the activity of six of eight species/species groups analyzed was negatively affected by solar photovoltaic panels. The authors report their findings share similarities with a 2023 study (Szabadi et al., The use of solar farms by bats in mosaic landscapes: Implications for conservation. Global Ecology and Conservation, 44, e02481, 2023).
How do Ground-Mounted Solar Photovoltaic Systems Impact Bat Activity?
Tinsley et al. (2023) summarize that bats are known to be adversely impacted by anthropogenic noise, development associated with urbanized environments, the presence of smooth surfaces, and habitat fragmentation (i.e.., cutting of trees as proposed at the site). All of these factors are associated with ground-mounted industrial solar photovoltaic sites. In the Western U.P., industrial solar facilities can lead to habitat fragmentation and present acres upon acres of smooth surfaces that bats perceive as water.
“The alteration of land use, land cover, soils and water resources result in changes to microclimate and hydrological conditions, which have direct and indirect impacts on bats.”
“Indirect impacts include bat collisions “with solar panels, as bats perceive smooth, horizontal surfaces as water, and will approach such surfaces attempting to drink.”
“Indirect impacts of solar panels on bats may be subtler, with panels potentially increasing reflective temperature at night following a day of hot weather and also altering microclimate by blocking sunlight, rainfall and affecting drainage potentially reducing the availability of invertebrate prey. In addition bats may actively avoid solar photovoltaic sites, as a consequence of habitat loss and fragmentation as industrial solar energy can require large land footprints.”
Endangerment Status of Bats in the Western U.P.
The following text documents the endangerment status of four hibernating cave bat species reported in the Western U.P. Three of the four are listed by U.S. Fish and Wildlife Service as threatened or endangered. All four have been reported in peer reviewed scientific studies to be present in abandoned Western U.P. mines (Kurta and Smith, Northeastern Naturalist, 27(4):763-772, 2020).
The four cave/mine dwelling bats important to our area are:
Myotis lucifugus (LeConte) (Little Brown Bat) - The U.S. Fish and Wildlife Service is currently reviewing the status of the little brown bat as a result of several described threats. It was identified at 94% of sampled locations in the Western U.P.
Myotis septentrionalis Trouessart) (Northern Long-eared Bat) - The northern long-eared bat is listed as an endangered species by the U.S. Fish and Wildlife Service. It was identified at 94% of sampled locations in the Western U.P.
Eptesicus fuscus (Palisot de Beauvois) (Big Brown Bat) - Currently not under any special conservation status though temperate North American bats are now threatened by “white-nose syndrome” with mortality rates at some hibernation sites reported as high as 90%. https://www.michigan.gov/dnr/education/michigan-species/mammals/bats). It was Identified at 55% of sampled locations n the Western U.P.
Perimyotis subflavus (Cuvier) (Tricolored Bat) (formerly known as the eastern pipistrelle) - On September 13, 2022 the U.S. Fish and Wildlife Service announced a proposal to list the tricolored bat as an endangered species. It was identified at 28% of sampled locations in the Western U.P.
Location of Hibernating Bats in the Western U.P.
Scientists know of the importance of the Western U.P. in supporting migratory tree bats and especially, hibernating cave bat populations. For cave bat populations a 2020 study found 69% of 119 Western U.P. mines sampled contained at least one hibernating bat.
The two maps below show potential locations that support hibernation of Western U.P. bat populations. Proposed industrial solar wind developments in areas such as the Groveland Mine can have a potential negative impact at all these locations.
The map on the left shows locations of a mine or an exploration in the Western U.P. (reprinted from the Michigan Abandoned Underground Mine Inventory, https://www.mg.mtu.edu/mining/mining/ab.htm).
The map on the right shows the location of 82 mines known to be used for hibernation by bats in the Western U.P. (reproduced from Kurta and Smith, Hibernating Bats and Abandoned Mines in the Upper Peninsula of Michigan, Northeastern Naturalist, 21(4):587-605, 2014). Also on this map is a red box indicating the location of the proposed Groveland Mine ground-mounted industrial solar photovoltaic development which is located near several abandoned mine sites that serve as critically important hibernacula for cave bats.
When reviewing the map on the right, be aware that biologists know there are many more hibernating sites than those sampled for that study and shown on the map. Also, hibernating bats may travel significant distances from an abandoned mine they utilize in the winter (thus making the Western U.P. important for survival of bats in the Upper Great Lakes).
