The Lives of Bats, and Why They Matter

Blanchcard Springs is one of the most beautiful caves in the U.S.Blanchard Springs Caverns, located on the Sylamore Ranger District of the Ozark-St. Francis National Forest in Arkansas, is one of the premier caves in the country. This limestone cave, which first opened to the public in 1973, is known for its stunningly beautiful formations called speleothemsthat tower above like nature’s grand cathedrals, inspiring awe in those who venture into this dark, humid terrain that begins more than 200 feet below the Earth’s surface.  [1]

The only cave administered by the U.S. Forest Service with a visitor’s center, Blanchard Springs Caverns is a popular destination for tourists because it provides a variety of trails that are open at different times of the year. The cave is not only a place for exploration; its also a place of residence for a variety of plant and animal species such as salamanders, frogs, crickets, mosses, ferns and bats.  Some of these animals spend their entire lives in this cave, such as the native Ozark blind salamander. In fact, the cave is a very complex ecosystem that provides very specific habitats for its inhabitants.

A pair of gray batsBlanchard Springs is also well known as one of the few caves in the South that plays host to the endangered gray bat . Like some other species that reside in the cave, the gray bat requires highly specific requirements such as a defined temperature range and protection from the elements during hibernation in the winter. Male gray bats form summer bachelor colonies in the cave with populations up to 20,000. These bats feed mostly on mayflies over water along rivers, streams and lakes. Maternity colonies are usually found in the larger relatively warm cave areas with temperatures of 58-77 degrees. Gray bats hibernate in tight clusters that can include as many as several hundred thousand bats in areas with temperatures of 42-52 degrees [2].

A bat flight is a spectacular event to watch.Visitors who are lucky enough to be standing in front of a cave at dusk are in for a visual treat. As daylight fades, a monstrously huge and highly-charged cloud of hungry bats swarm erratically out of the cave, taking charge of the night. These early evening events—called bat flights—are often startling; folks become transfixed on this natural show. This almost unending swarm of bats—their black silhouettes fluttering against a pale blue darkening sky—leaves an indelible impression on the eyes. Similar to bird or whale watching, watching a bat flight is a worthwhile attraction for anyone with a keen interest in observing nature in action.

Unfounded Fear and a Misunderstood Group

Bats are nocturnal animals; they roost during the day and hunt at night. Having the opposite schedule from most birds probably gives bats an advantage in competing for food sources such as insects [9]. But because of their nocturnal behavior, bats are also much less visible than other animals and thus carry an aura of mystery and fear about them. Indeed a wealth of folklore, superstition and gothic literature conjures up bats in mysterious and fearful terms, often associated with the word vampire.  Contrary to popular folklore, only three bat species feed on blood, all of which live in Latin America [9].

Throughout the centuries bats have gotten bad press from humans. When most people hear the word bat they often think of vampires, blood, Halloween and maybe those awful grade B horror movies starring Bela Lugosi as Dracula. Given the wave of vampire movies and television shows that have deluged the airwaves in the past few years, it’s almost impossible to think of anything else. And for some reason the South seems to be a fertile breeding ground for these nocturnal blood-sucking characters, thanks to the Southern gothic writer Anne Rice and the HBO producers of “True Blood.”

Some Little Known Facts about Bats

  • Bats are more closely related to humans and other primates than they are to rodents. Several studies indicate that the old world fruit bats and flying foxes may actually descend from early primates such as lemurs.
  • Most female bats give birth to only a single pup each year, making them very vulnerable to extinction. Bats are the slowest reproducing mammals on Earth for their size.
  • Contrary to popular myths, most bats have very good eyesight, have excellent echolocation so they do not become entangled in human hair and seldom transmit disease to other animals or humans.
  • Bats are very clean animals and groom themselves almost constantly (when not eating or sleeping) to keep their fur soft and clean, like tiny cats.
  • Vampire bats adopt orphans, and are one of the few mammals known to risk their own lives to share food with less fortunate roost-mates.
  • All mammals can contract rabies; however, even the less than 0.05% of bats that do normally bite only in self-defense and pose little threat to people who do not handle them.
  • Bat droppings in caves support whole ecosystems of unique organisms, including bacteria useful in detoxifying wastes, improving detergents and producing gasohol and antibiotics.

Source:  BatRescue.org

Our fear of bats may not just come from the movies, but possibly because we encounter them when we least expect, often without warning which leaves us startled by their presence as they dart swiftly near us through the evening air. Their stealth appearance of dark wings and fur make them hard to recognize at night, unless we happen to catch them darting for insects under street lights. Regardless of how this irrational fear of bats (also known as chiroptophobia) came about, its clear bats suffer from a poor reputation. Maybe it’s time to view these nocturnal creatures from a different perspective.

The Benefits of Bats: Ecosystem Services

So why should we care about bats? Besides being an occasional vector for rabies or inspiration for gothic horror flicks, why do they matter to us? To ask such a question possibly implies that we are guilty of speciesism, the belief that humans are superior to other species and thus more valuable.  Admittedly this is a rather anthropocentric attitude, but we can use this self-interested perspective to argue why bats are important.

Bats benefit humans by providing important ecosystem services, the “benefits obtained from the environment that increase human well-being” [1].  Unfortunately “bats are among the most overlooked, yet economically important, nondomesticated animals in the world and their conservation is important for the integrity of ecosystems and in the best interest of both national and international economies” [2].  Examples of ecosystem services provided by bats include:

  1. Some bat species provide biological pest control with their voracious appetites for nocturnal insects, including crop and forest pests. For example, by one estimate a single colony of 150 big brown bats in Indiana can eat nearly 1.3 million pest insects each year [2]. A recent study published in Science states that bats provide more than $3.7 billion in pest control services every year [8].
     
  2. Since many bats help keep insect pests in check, expensive and toxic pesticides become less necessary [1]. Thus bats help reduce the amount of chemicals in the environment.
     
  3. Other bat species that subsist on fruit and nectar also act as pollinators and seed dispersers, thus benefiting our agricultural systems as well. Some of the most important crops that rely on bats include bananas, peaches, bread-fruit, mangoes, cashews, almonds, dates and figs [10].

A Crisis in the Colonies: White Nose Syndrome (WNS)

A bat infected with White Nose Syndrome (WNS)Today, bats face a critical challenge—white nose syndrome. The telltale sign is a white dusty powder that forms on the noses of hibernating bats. This powder, which is actually a fungus called Geomyces destructans, threatens to destroy entire bat colonies and thus put entire species at risk for extinction. This newly discovered epidemic is causing the most dramatic decline of wildlife seen in the past century. Since it was first discovered in a New York cave in February 2006, more than a million bats have succumbed to this deadly infection [7].

A small cluster of bats showing symptoms of White Nose Syndrome (WNS).Scientists are still not sure what causes this syndrome, or how it has spread so quickly during the last four years throughout the Eastern U.S. and Canada.  They also are not sure if the fungus causes WNS or if it is merely an opportunistic pathogen that takes advantage of weakened immune systems caused by some other biological or environmental factor. Although the fungus mostly infects the skin of bats, some infected bats show no physical symptoms; instead they display unusual behavior such as coming out of hibernation too early and flying around in winter conditions that can kill them [7]. Since the fungus thrives in cool temperatures, it may attack bats during hibernation when their immune systems are more vulnerable.  When bats leave hibernation in the spring, the fungus may persist on the cave walls or floors, waiting to infect the next colony in the fall causing the cycle to repeat itself [8].

Scientists know that the disease can spread between bats; they also suspect that humans may play a role in transmitting the disease from cave to cave by a process called pathogen pollution. As a precaution, many caves have been closed to visitors out of fear that humans may be spreading the fungus on their clothes and equipment. Scientists are encouraging visitors and cavers to clean and decontaminate their clothes and gear before entering a cave [7].

The long-term consequences of this rapidly advancing epidemic are far from certain at this point, but this much is clear: a declining bat population in the U.S. will cause a ripple effect throughout the nation’s agricultural system, leading to more expensive and toxic pest control alternatives. For example, one million bats –the number of bats who have already died from WNS—consume 700 tons of insects each year in the U.S., many of them pests [8]. The economic impact of extinction of common bat species such as the northern long-eared bat or little brown bat  could affect our ability to manage crops effectively and efficiently, probably resulting in higher food costs. 

Southeastern Bat Diversity Network (SBDN)

Most people are unaware that a regional bat network is working to help protect these valuable and fascinating creatures. Max Silvera, a public affairs specialist for the US Forest Service Southern Region ,  talks about how he first met members of the bat network when he found a roost of baby bats, or pups, in a tree he cut down in his backyard. The four tiny pups—about two inches long—were wedged underneath pine tree bark, and had apparently fallen out when the tree was removed.

Max’s wife, Janet, a science teacher at a local private school, took the pups to work in hopes that her science class could take care of them until they could be released as adults. Luckily for the bats and for everyone who handled them, Max spoke to Dennis Krusac—the Forest Service’s resident bat expert —who put Max in touch with the Southeastern Bat Diversity Network (SBDN). That evening a specialist from the Fernbank Museum called Max and cautioned him not to feed cow’s milk to the bats and not to let the school children touch them. The next day this SBDN volunteer came to the school to collect the pups to test them for rabies.  Fortunately none of them were infected. About six weeks later the SBDN volunteer returned the matured bats to Max and Janet who released them in their backyard, allowing the bats to continue their important roles in the local ecological community.

Southeastern Bat Diversity NetworkSBDN is a partnership program that includes members from 16 states throughout the Southeast [3].  The organization was formed in 1995 “to facilitate communication within the region, identify priorities and needs specific to the southeastern U.S. and develop and implement programs that address regional bat conservation needs” [3].

One important program the SBDN hosts includes regularly scheduled bat blitzes throughout the Southeast. These blitzes have created a strong community of expert volunteers who have made it their mission to actively participate in these surveys. Participants include volunteers from universities; federal, state and local agencies; non-profits; private companies; zoos; and museums, as well as individuals with an active interest in protecting bats.

The Bat Blitz: A Success Story in Cooperative Science

A bat blitz is “an intensive, short-duration survey of local bat communities using experienced volunteers” [4]. A bat blitz is designed to obtain baseline data on local bat populations that the SDBN can share with other natural resources agencies, universities and non-profits with an interest in bat conservation.

A wildlife tech catches a bat using a mist net.These blitzes are very efficient: data is collected by an army of volunteers over three consecutive nights, a process that would normally take an entire season. Each survey is conducted from dusk until 2 a.m. the following morning. These blitzes normally occur between mid-July and mid-August using standard survey protocols to ensure data compatibility. An experienced bat biologist leads the team and is responsible for providing equipment, locating exact sites, placing bat nets, collecting data and training other team members.

Volunteers capture bats with mist nets and harp traps and record their echolocation calls with acoustic monitoring equipment. They identify bats by species, reproductive condition, age, sex, weight and other factors. Endangered or rare bat species are often banded to aid in population monitoring efforts. Lactating or juvenile bats have been monitored by radio telemetry to locate maternity roosts, which is extremely important since little is currently known about bats’ maternity habitats.

Once volunteers have recorded the data, the bats are released at the capture site. 

The bat blitz idea came to life at the 2002 All Taxa Biodiversity Inventory (ATBI) conference at the Great Smokey Mountains National Park. The intent of ATBI was to inventory all living things in the park. Three individuals—Jackie Belwood, Mick Harvey and Dennis Krusac—made the bat blitz a reality. So far, ten bat blitzes have taken place in the Southeast, mainly on national forests. In those ten years, more than 120 partners have donated $10,000 and more than 18,000 volunteer hours; this impressive grassroots efforts has an estimated value of $600,000.

These surveys have recorded more than 3,000 bats representing 14 species, including two endangered and three U.S. Forest Service sensitive species.  The wealth of information gleaned from these cooperative surveys has helped scientists understand the needs and threats bats are facing in the Southeast.

How You Can Help

Here are a few things you can do to help us save our bats:

  • Honor all cave closures.  Check with your local state or federal parks for the status of caves in your area.
  • Follow all decontamination procedures should you decide to go caving.
  • Report unusual bat behavior or bats that show signs of disease to your local wildlife agency. Some symptoms to look for include: daytime flight, especially during cold weather; dead or dying bats found on the ground or in trees.
  • Volunteer in a bat blitz. Contact the SBDN to find out more about how you can participate. These bat blitzes usually take place in the late summer.

 

References

[1] Encyclopedia of Arkansas History and Culture

[2]  Bat Facts, U.S. Forest Service

[3] “Ecosystem services provided by bats,” Annals of the New York Academy of Sciences  1223 (2011) 1-38.

[4]” Economic Importance of Bats in Agriculture,” Science, Vol. 332, April 1, 2011.

[5] Southeastern Bat Diversity Network; June 27, 2011.

[6] Data provided by Dennis L. Krusac, TES biologist, who works for the U.S. Forest Service at their regional office in Atlanta, Georgia.

[7] BATFAQ, “White-Nose Syndrome, a Crisis for America’s Bats”, www.batcon.org/wns/.

[8] “Crisis in the Caves,” Smithsonian Magazine, July-August 2011.

[9] Wikipedia (http://en.wikipedia.org/wiki/Bat)

[10]  BatRescue.org