Bats and White-Nose Syndrome

Indiana Bats in Fitton Cave.

NPS

Bats, mammals of the Chiroptera order, are essential to the stability and promotion of biodiversity in above ground and subterranean ecosystems. With over 1,400 species identified, bats make up about twenty-one percent of the planet’s mammal population. Although they are severely underappreciated in modern Western culture, bats are revered elsewhere in the world because of the many ways in which they benefit the planet. Understanding bats and their importance is crucial to their survival here and around the world as many face extinction because of disease and human abuse.

Importance of Bats

Bats are divided into megabat and microbat suborders based on characteristics such as size, diet and habitat location. Megabats, or Old World fruit bats, live in subtropical and tropical areas and typically consume fruit and nectar. Along with select types of microbats, they are important agents of seed and pollen dispersal. Bats contribute to the pollination of over 500 plant species worldwide, and play a vital role in spreading seeds that promote the regrowth of tropical forests.

Microbats inhabit every continent except Antarctica and comprise over 80 percent of all bat species. Predominately insectivores, microbats can consume half their weight in bugs each night and are a keystone species in above ground ecosystems as predators of nocturnal flying insects. The presence of bats within terrestrial ecosystems was conservatively estimated to reduce agricultural costs in the United States by several billion dollars a year, accounting for factors such as potential crop loss and reduced use of pesticides. Of the sixteen species found in Arkansas, Buffalo National River is home to twelve types of microbats; three species at Buffalo National River are listed as endangered (Indiana, Gray, and Ozark Big-Eared bats), one threatened (Northern Long-Eared bat), and one currently pending review for protection under the Endangered Species Act (Tri-Colored bat). Historically substantial populations of these species have inhabited the region encompassing park lands.

While microbats of Buffalo National River feed above ground, many species roost, nest or hibernate in subterranean environments such as mines and caves. The presence of bats is the single-most defining characteristic of subterranean biodiversity. Bat excrement, or guano, is converted into food and nutrients by fungus and bacteria; this process provides the basis of many cave food chains. The cool temperatures and high humidity in caves also provides a suitable environment for a type of fungus that is currently decimating subterranean bat colonies.

 

Big Brown Bat

NPS/A. Smith

White-Nose Syndrome

White-Nose Syndrome is a devastating disease caused by the fungus pseudogymnoascus destructans (Pd). Pd is not native to the United States but has found ideal growth conditions on this continent in caves and cave-like environments. The fungus, which manifests itself in the form of thin white spores on a bat’s nose, wings, or ears, was first documented in the States in 2006, when scientists found thousands of dead bats on the floor of a New York hibernaculum. Research to determine how these bats died began immediately, and White-Nose Syndrome was named and catalogued shortly thereafter.

White-Nose affects bats in a number of ways. Like other animals that hibernate, bats’ body temperatures drop drastically when they hibernate. This creates an ideal host surface for Pd. Pd creates pockets in a bat’s skin, causing severe irritation which wakes the bat prematurely from hibernation. Premature emergence quickly leads to starvation as the bat uses its precious energy stores before it is able to replenish them. Furthermore, these pockets created by Pd in the bat’s wings result in the thinning and, in some cases, tearing of the wing membrane, which hinders the bat’s ability to fly and feed. White-Nose has also been proven to suppress a bat’s immune system. This is especially dangerous because a bat’s immunity is already weakened during hibernation; even if a bat survives hibernation without starving or wing deterioration, its immune system suffers immensely and the bat is left more susceptible to other illnesses after emergence from hibernation.

The ramifications of this disease are dire. An estimated 5.7 million bats were killed by White-Nose Syndrome between 2006 and 2016, and thousands more have died since. White-Nose is easily transferred by contact (environment-to-bat, bat-to-bat, and contaminated equipment-to-bat), sometimes resulting in mortality rates higher than ninety percent and leaving many colonies completely decimated. White-Nose is known to affect at least eleven bat species, three of which are endangered. Thirty-three states and seven Canadian provinces have confirmed the presence of White-Nose Syndrome in at least one bat habitat, and the disease continues to spread westward.

White-Nose Syndrome in Arkansas and Buffalo National River

White-Nose Syndrome was first confirmed in Arkansas caves in 2013. Cave closures at Buffalo National River were instituted beginning in 2009 to slow the spread of the pathogen and protect habitats for endangered bat populations; a substantial ban on entry was implemented the following year in an effort to further safeguard caves from the transmission of this highly communicable disease. In 2015, the disease was identified within Buffalo National River boundaries at a cave in Newton County. Both the Tri-Colored and Northern Long-Eared Bat have witnessed a steep decline in numbers due to White-Nose Syndrome since that time. The existence of the pathogen has been confirmed in eleven Arkansas counties, and its presence is suspected in an additional four as of 2018. In addition to cave closures, the National Park Service partners with conservation organizations as well as state and other federal agencies to study and learn more about the disease in an effort to slow its spread.

The Search for a Cure

Successfully combatting disease requires the alteration or elimination of one or more components of the disease triangle, which are a susceptible host, a toxin or pathogen, and a favorable environment. In the case of White-Nose, the host is hibernating bats, the pathogen is the fungus Pd, and the favorable environment is the cold, damp caves also favored by many North American bat species for hibernacula. Because Pd affects different species in varying degrees of severity, and because the reason for this is not yet understood, it is difficult to find a vaccine or cure that is universal. Additionally, individual administration is required for most vaccines or medication, a logistically challenging process at best. Most bats that hibernate in caves prefer temperatures between 39 and 59 degrees Fahrenheit, making environmental alteration tricky since Pd grows optimally between 55 and 60 degrees Fahrenheit. Artificially raising the temperature within the cave high enough to kill off the fungus would render the environment unsuitable for many bat species. A dedicated team continues to work toward a viable cure, but because White-Nose is a new and not fully-understood disease, the search for a cure is a difficult and ongoing task.

 

Gray bats in flight.

NPS

How to Get Involved

While there are many dedicated experts laboring to save bats from the deadly threat of White-Nose Syndrome, what bats really need is help from ordinary people. But how can you help?

First, change your own attitude. As with most areas of life, attitude is everything when it comes to bat perception and protection. There is such a negative depiction of bats in Western culture that most people aren’t aware of the many benefits that bats provide and are automatically “anti-bat.” Changing your own attitude can help others see that bats are beneficial, not scary, and that they need and deserve our help.

A positive attitude will help you take further steps; one such step may be building a bat house. Bat houses are very simple to make, or can be purchased online, and have been shown to help endangered bat colonies survive. Patience is key when putting up a bat house – bats may not find your new habitat for many months, even up to a few years, so don’t get discouraged if you don’t get any bat neighbors right away.

Perhaps you don’t live in an area where a bat house would be helpful, but you do come in contact with bats while caving. Caving is a fantastic way to learn about the world under our feet, but care must be taken to do it properly. White-Nose can be spread through contact with contaminated gear, so it is crucial to learn proper decontamination procedures for your gear and to never enter caves where White-Nose or Pd is known to be present. Being a responsible caver is one of the best ways to help protect bats.

Finally, learn more and share what you know. Sharing your concern with others when the opportunity arises may prompt them to get involved as well. Until a cure is found, prevention is the best solution for White-Nose, so it is vital that people are made aware of the crisis bats face. For more information and ideas about spreading the word, please visit the official White-Nose Syndrome website at www.whitenosesyndrome.org.

What would the world be like without bats? Let’s hope we never have to find out, because it’s not a pretty picture. Bats do so much to help the planet, and it is time that we return the favor. It’s time to step up and do what we can to preserve these amazing mammals for future generations.