By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM

Bats Dying: An Epidemic

A deadly disease is destroying native bat populations in North America. Unfortunately, the “white-nose syndrome,” as the disease is named, is spreading more quickly than scientists had anticipated.

The white-nose syndrome is just the latest threat to the world’s bat populations. It was first identified in late 2006 in caves in Albany, N.Y., where as many as 11,000 bats died. By 2008 researchers confirmed that the disease had also infected bats elsewhere in New York, as well as in western Vermont and Massachusetts. The disease had killed more than 90 percent of bats in caves in those areas in just two years.

Fresh outbreaks of white-nose syndrome were quickly located in Connecticut and eastern Vermont. Scientists suspected that the disease may also have been in caves in Pennsylvania and feared that it would wipe out some entire species of bats over the next few years.

By 2011, the syndrome had spread south and westward to North Carolina and Tennessee, across the Midwest and into Canada. This diffusion of the disease probably occurred with the migration of infected bats as they migrated as groups and as individuals to other existing bat habitats.

Bats are mammals, but such unique mammals that scientists have placed them in their own order, the Chiroptera. They are the only mammals in the world capable of natural flight, although other mammals, such as flying squirrels, gliding flying possums and colugos, can glide for limited distances. The word Chiroptera comes from the Greek words cheir “hand” and pteron “wing,” as the structure of the bat’s open wing is very similar to an outspread human hand with a membrane between the fingers that also stretches between hand and body.

Bats have been very successful at adapting to environments worldwide. Scientists estimate that over 1,100 species of bats exist, accounting for over 20 percent of all mammal species. About 70 percent of bats are insectivores, while most of the rest are fructivores, eating only fruits. Only a few species are carnivores.

Bats are not only interesting mammals, but they perform vital ecological roles throughout the world as well. Bats keep populations of night-flying insects in balance. Just one bat can catch hundreds of insects in an hour and large colonies catch tons of insects nightly. These insects include mosquitoes, moths, locusts, grasshoppers and beetles. Some of these insects can destroy crops and forests and spread disease among humans and animals.

One of the American farmer’s biggest pests is the corn earworm moth. One small bat can eat 20 female moths a night, thus reducing the number of crop eating caterpillars. In another example, the 20 million free-tailed bats living in the Bracken Cave in Central Texas can eat more than 200 tons of insects in a single mid-summer night.

Bats also play an important role in pollinating some flowers and in seed dispersal. In fact, many tropical plants are totally dependent on bats. In the rainforest, many plants bloom at night using unique odors and special flower shapes to attract bats that then assist in pollination. Bananas, avocados, dates, figs, peaches, mangoes, cloves, cashews and agave (the plant from which tequila is derived) are other plants that benefit from bats as the animals pollinate or spread their seeds.

The value of tropical bats in reforestation alone is enormous. Seeds dropped by bats can account for up to 95 percent of forest re-growth on cleared land. Performing this essential role puts these bats among the most important seed-dispersing animals of the tropics.

As important as bats are, they now face a terrible threat from white-nose syndrome in the eastern United States. White-nose syndrome is a mysterious disease, resulting in many of the infected bats experiencing a white fungus growing on the muzzle. Other infected bats may have no white fungus, but rather look emaciated or act disoriented. Biologists are uncertain if the bats are spreading the disease among themselves or if humans or other animals are helping to spread it from cave to cave. Circumstantial evidence, however, points strongly toward bat-to-bat transferal of the virus being the major route.

Scientists initially hoped that the disease would burn itself out or be limited to remote caves, but the disease’s geographic expansion is increasing, seemingly affecting every species of bat in its path. For now, puzzled researchers can only dissect bat carcasses searching for clues as to the cause while closely monitoring as many bat caves as possible.

Because female bats produce just one pup a year, the loss of as much as 90 percent of the bat population in some hibernacula translates into a crisis in in four states initially in 2008 and to twelve U.S. states and four Canadian provinces in 2011 with no end in sight. The decline in bats has potentially far-reaching effects and may be an ecological disaster in the making.

And that is Geography in the News.

Sources: GITN 939, “Bats A-dying,” Maps.com, May 30, 2008; http://www.npr.org/templates/story/story.php?storyId=89852947;http://www.batcon.org/home/default.asp; and http://www.fws.gov/northeast/white_nose.html

Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.