Wind turbines join fungus as leading bat killers


From the Bat Conservation Society, a map depicting the rapid spread of the leath White-nose syndrome among America's bat population.

From the Bat Conservation Society, a map depicting the rapid spread of the lethal White-nose Syndrome among America’s bat population.

As we’ve noted before, a lethal plague is killing America’s bats, a fungal disease named for its most characteristic sign.

But there’s also another newly discovered bat killer, one hails as a major step to alleviating climate change.

But first, the lethal spread of White-nose Syndrome

From the Bat Conservation Society:

White-nose Syndrome (WNS) is a fungal disease that has killed millions of bats in North America. The disease is caused by a fungus from Eurasia, which was accidentally transported here by humans. The fungus, Pseudogymnoascus destructans, invades the skin of hibernating bats and disrupts both their hydration and hibernation cycles.

Hibernating bats awake repeatedly during the winter, burning up limited fat reserves. They often leave hibernation sites in late winter, dehydrated and in search of food, and ultimately dying.

The fungus is transmitted primarily from bat to bat. Today, WNS is found in 29 US states and 5 Canadian provinces. The fungus that causes WNS is found in three more US states.

WNS is known to affect hibernating bats, and 7 species of bats have been diagnosed with the disease. Five additional species (†) have been found with the fungus, but have not yet developed the disease.

So why be concerned about bats? After all, we in the West associate them with ghosts, goblins, vampires, and other creepy things.

We would argue that they have just as much right to be here as we do. And, besides, when you get over the initial cultural reactions, they really are marvelous critters.

But there’s also an economic argument.

As the Center for Biological Diversity notes:

Bats eat bugs, which is not only helpful for keeping mosquitoes and another annoying insects at bay for us humans but also has economic importance. A recent scientific paper on the economic value of bats to agriculture estimated that bats provided nontoxic pest-control services totaling $3.7 billion to $53 billion per year. This study did not even consider what the indirect costs of “replacing” bats with pesticides would be in terms of potential health and pollution threats from greater levels of toxins in the environment.

Bats provide other services to humans too, such as pollinating plants and distributing seeds, in tropical and subtropical habitats throughout the world. Some of these plants are useful to people, including a species of agave that is the source of tequila, a multimillion-dollar industry in Mexico. Bat guano has traditionally been used as fertilizer for crops in various parts of the world and is also sold commercially. However, mining of bat guano may also be harmful to cave organisms that depend on it as a source of food, and removal of guano is likely to be disruptive to bats themselves, if they are present.

But there’s another bat killer, a ‘green’ one

A new study reveals that a technology hailed as a major step in controlling carbon emissions is proving just as lethal to bats as it is to birds.

From the U.S. Geological Survey:

Wind turbine collisions and the deadly bat disease known as white-nose syndrome (WNS) can together intensify the decline of endangered Indiana bat populations in the midwestern United States, according to a recently published U.S. Geological Survey study.

Bats are valuable because, by eating insects, they save U.S. agriculture billions of dollars per year in pest control,” said USGS scientist Richard Erickson, the lead author of the study. “Our research is important for understanding the threats to endangered Indiana bats and can help inform conservation efforts.”

Wind energy generation can cause bat mortality when certain species, including the midwestern Indiana bat, approach turbines during migration. Meanwhile, WNS, which is caused by the Pseudogymnoascus destructans fungus, has killed millions of hibernating bats in North America and is spreading. The new study found that the combination of these two hazards has a larger negative impact on Indiana bats than either threat alone.

The researchers used a scientific model to compare how wind turbine mortality and WNS may singly and then together affect Indiana bat population dynamics throughout the species’ U.S. range. Findings from the model include:

  • Wind turbine deaths were localized and more likely to affect small sub-populations of bats, whereas WNS was more likely to devastate large winter colonies over the species’ entire range;
  • Together, the two threats reduced the sizes of all Indiana bat sub-populations;
  • WNS had the largest impact on population dynamics, with the most severe potential die-off scenario showing a population loss of about 95 percent; and
  • Despite killing fewer animals than WNS, wind turbines disrupted Indiana bat migration routes, which affected metapopulation dynamics more than WNS did in almost all modeled scenarios. A bat metapopulation consists of separated groups of the same species that interact during migration.

“These findings are useful for wildlife managers because they demonstrate the extra importance of protecting small Indiana bat colonies during the winter to help prevent extinction,” Erickson said.

WNS is not known to pose a threat to humans, pets, livestock or other wildlife.

The USGS partnered with the U.S. Fish and Wildlife Service on the new study, which is published in the journal PeerJ.

For more information about bats, wind energy and WNS, please visit the USGS Upper Midwest Environmental Sciences Center, the USGS Geosciences and Environmental Change Science Center and the USGS National Wildlife Health Center websites.

Visit whitenosesyndrome.org to learn about the coordinated response to WNS, led by the USFWS.

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