Like most animals, bats face threats from natural predators such as owls, hawks, and snakes ("13 Awesome Facts About Bats"). Bats also struggle with deforestation because it leads to loss of foraging habitat, maternity colony structures, and roosting Habitat loss in general is a big threat to bats. Many insects, the main prey of most bats, live as juveniles in the water, so clean water is also important to bats. Bats also are impacted by humans because buildings are torn down or sealed to prevent use by bats.
Homeowners and barn owners often do not like bats in their buildings, but this means bats don't have enough roosting habitat to sleep. Excluding bats from human structures also can kill the baby bats if it is a maternity colony, and this often happens in our area. Additionally, wind turbines are a danger to bats. The turbines can either indirectly or directly kill thousands of migrating bats a year as they move to hibernacula or migrate. Turbines can attract bats who are curious about this strange structure on the landscape. Bats die after being hit by blades and also by barotrauma, which is when the changing air pressure caused by the moving blade causes the blood vessels in the bats to rupture. Bat deaths appear to be more common at low wind speeds, so stopping turbine blade rotation at slow wind speeds may save many bats (NH Department of Fish and Game).
One huge problem that is devastating the bat population is a mostly fatal new fungus called White Nose Syndrome (WNS). WNS is caused by a fungus called pseudogymnoascus destructans, which was unknown to science until 2006-2007 when it began killing bats. It was first discovered in 2006 by cavers near Albany, New York. After that, it quickly spread. In NH it was detected in 2009. By 2015, WNS was found in 24 states and 4 Canadian provinces. Unfortunately, the fungus's best conditions for growth are the same that bats need to hibernate. The distinctive white fungus grows into the wings, muzzles and ears of the bats while they sleep. When bats are in hibernation they do not mount an immune response to the disease. WNS disrupts metabolic capacities and wakes the bats up from hibernation more frequently and stay awake longer than uninfected bats. When they do this, they use up all their stored energy that would normally keep them alive during hibernation. Bats can't replenish these energy stores during the winter because they have no food sources until late spring and summer. Often, they die from starvation in the hibernacula or in the spring, but some bats fly out of the hibernacula mid-winter searching for food and freeze to death. Basically, the infection makes them use up their fat stores and then they die (NH Department of Fish and Game).
WNS is believed to have originated in Europe where it grows on bats but does not kill them. It was likely brought to the U.S by cavers. The rapid rate of WNS's spread throughout the northeast and the rest of the country also has human connections. The fungus was originally spread by humans, as the jump from NY to VA in 2009 was too far a distance for bats to normally fly. Cavers ended up informing the government that they had explored the affected caves in NY and then went to other states and explored those caves. Since WNS attaches to clothes and gear, humans spread it between the caves with devastating consequences (NH Department of Fish and Game).
Unfortunately, 90% of northern long-eared, little brown and tri-colored bat populations have been killed by WNS in fewer than 10 years (Huang and Flatow). This is over 6.5 million bats in the northeast and Canada alone since 2007 ("13 Awesome Facts About Bats").
Mortality rates at hibernacula in New Hampshire have ranged from 79 to 100% since WNS was first documented in NH (NH Department of Fish and Game). Some caves and mines are now COMPLETELY EMPTY. NH does not have a lot of places for our hibernating bats, as there are only seven hibernacula (areas like caves and mines and bunkers where bats hibernate for the winter) and many fly out of state. However, of the seven New Hampshire hibernacula surveyed in 2009, five already had WNS. By 2011, the disease had killed most of NH’s hibernating bats, with only 16 found in four of the biggest hibernacula, down from 3,230 bats in 2009. More recent surveys have shown no sign of recovery (NH Department of Fish and Game).
Bats face many challenges as a species and soon we as humans will be seeing the environmental impacts of their loss in the world. However, there is things you can do to help out. Check out my helping bats page on the main website and please read my infographic to get a deeper knowledge of bats in NH.
Works Consulted
Huang, Lucy, and Ira Flatow. “Northeastern Bat Populations Haven't Recovered From White-Nose Syndrome.” Science Friday, 6 Nov. 2019, www.sciencefriday.com/segments/sos-for-new-england-bats-its-been-a-decade-of-carnage/.
New Hampshire Department of Fish and Game. “White-Nose Syndrome: A New Threat to New Hampshire's Bats.” New Hampshire Fish and Game Department, www.wildlife.state.nh.us/nongame/white-nose-syndrome.html
New Hampshire Department of Fish and Game. “White-Nose Syndrome.” New Hampshire Fish and Game Department, www.wildlife.state.nh.us/nongame/white-nose-syndrome.html.
“13 Awesome Facts About Bats.” U.S. Department of the Interior, 28 Oct. 2019, www.doi.gov/blog/13-facts-about-bats.
