Threats to Bats

White Nose Syndrome 
White nose syndrome is a new disease to North America. Caused by a cold-loving fungus, Pseudogymnoascus destructans, this disease has killed over 6 million bats since 2006. First diagnosed in a hibernating colony of bats in New York, the disease has spread to 26 eastern states and as far west as Missouri and as far south as Mississippi and Georgia. The fungus gets into skin tissues and disrupts cells' abilities to transport materials, causing the bat to be drained of energy and water. The bats are unable to mount a defense to the disease while they are hibernating, so awaken in the winter to replenish their energy. Unfortunately, there are no insects in flight that can replenish the energy reserves they have lost, and a tell-tale sign of White nose syndrome infection at a site is the abundance of dead bats and their carcasses at cave or mine openings. For the most current information on white nose syndrome, please visit www.whitenosesyndrome.org.

For more information, find:

  • D. S. Blehert et al. 2009. Bat white-nose syndrome: an emerging fungal pathogen? Science (volume 323, page 227)
  • W. F. Frick et al. 2010. An emerging disease causes regional population collapse of a common North American bat species. Science (volume 329, pages 679-681)
  • P. M. Cryan et al. 2010. Wing pathology of white-nose syndrome in bats suggests life-threatening disruption of physiology. BioMedCentral Biology (volume 8, issue 135)
  • D. Quammen. December 2010. Crash. National Geographic (pages 126-137)

Wind Turbine Collisions
Bat mortalities have been documented at all wind facilities that have been searched thoroughly. A majority of those mortalities are from the migratory tree-roosting bats (red bats, hoary bats, silver-haired bats) that travel great distances between North American and Central America during their migratory trips. It is unclear why these bats approach wind turbines, but some die as a result of collision, while others succumb because hemmorhaging of lung tissues (barotrauma) from the dramatic change in air pressure at the turbine blades. In 2012, it was estimated that 600,000 bats died because of interactions with wind turbines.

For more information, find: 

  • E. B. Arnett et al. 2008. Patterns of bat fatalities at wind energy facilities in North America. Journal of Wildlife Management (volume 72, pages 61-78)
  • E. F. Baerwald et al. 2008. Barotrauma is a significant cause of bat fatalities at wind turbines. Current Biology (volume 18, pages R695-R696)
  • M. A. Hayes. 2013. Bats killed in large numbers at wind energy facilities. Bioscience (volume 63, pages 975-979)

Habitat Loss 
Habitat loss for bats can arise in several ways. The most noted concerns for habitat loss for cave- and mine-roosting bats are closures at caves and mines. When there is fear of human injury at caves and mines, one solution has been to fill openings. Unfortunately, this usually precludes bat use. Installation of bat-friendly gates has prevented human access while allowing bat access. Additionally, frequent visitation by humans can preclude use of a cave or mine by bats. Another type of habitat loss can occur during timber harvest that eliminates roosting resources for tree-roosting bats. Although this is a known threat to bats because we know some species use trees as roost sites, it has been difficult to quantify because it is unclear how many species or individuals might be using particular trees or forest patches. In southeastern Asia, deforestation has led to some bat extinctions and designation of some species as endangered.

For more information, find:

  • G. F. McCracken. 1989. Cave conservation: special problems for bats. National Speleological Society Bulletin (volume 51, pages 49-51) but also in Bat Conservation International Bat Conservation and Management Workshop Course Booklet 2011 (pages 68-72).
  • M. D. Tuttle, and D. A. R. Taylor. 1998. Bats and Mines. Bat Conservation International Resource Publication No. 3
  • D. W. Lane et al. 2006. Dramatic decline in bat species richness in Singapore, with implications for Southeast Asia. Biological Conservation (volume 131, pages 584-593)

Pesticide Use
Historically, pesticide use had more dramatic impacts to bat populations, causing direct poisoning and population declines. Increased regulation on many of these chemicals has reduced some concerns. However, given the volume of insects eaten by individual bats and bat populations, there is concern bioaccumulation of such toxins in bats may have secondary impacts that are limiting bat populations.

For more information find:

  • S. Bayat et al. 2013. Organic contaminants in bats: trends and new issues. Environment International (volume 63, pages 40-52).
  • D. R. Clark, Jr. 1988. How sensitive are bats to insecticides? Wildlife Society Bulletin (volume 16, pages 399-403)