Fungus threatens state bats
Guess how many species of bats are found in Alabama? As Ben Stein asked: “Anyone, anyone?”
To most people, a bat is a bat is a bat – a much-maligned creature with a face that only a mother could love. However, the 15 species of bats that inhabit our state – that’s right, 15 – play a vital role in the natural world, according to Keith Hudson, known as the Alabama Department of Conservation and Natural Resources’ “bat man.”
“Bats are tremendously important worldwide to ecosystems,” said Hudson, wildlife biologist with the Wildlife and Freshwater Fisheries Division. “Probably their greatest importance is they are pollinators. Some food sources important to man are dependent on bats for pollination. Another reason they’re important is some bats eat fruit and disperse seeds through their droppings and are important for reforestation in many tropical regions.
“Our bats we have in the Southeast are all insect eaters. We don’t have some of the pollination benefits as do the Western bats. Our Eastern bats are important as a natural insect control. They eat a tremendous amount of night-flying insects every night. They can eat half their body weight in insects each night. Those include mosquitoes. They do not exclusively eat mosquitoes. I use the example – would you rather eat a thousand Rice Krispies or one big, ol’ steak? It’s the same with bats – would they rather eat a thousand mosquitoes or one big, juicy moth?”
Unfortunately, there is a real threat to the bats species in North America in the form of White-nose Syndrome, a fungus that affects bats that hibernate in caves.
The latest update on the spread of the fungus is that it has now spread northward into Canada and as far south as Tennessee.
“It is in a border state of Alabama now,” Hudson said. “We did not find any when we surveyed the caves this winter. And we did an elaborate survey. But we think it’s just a matter of time, maybe next winter, before the stuff gets here.”
The frustrating part for biologists like Hudson is there is apparently nothing anyone can do. And when a colony is infected, the mortality rate can be as high as 95 percent.
“We don’t know anything to do to stop it or anything to do to treat it,” he said. “We think it’s coming. We don’t even think we can slow it down. If it gets in some of our species of bats, notably the endangered gray bat, it’s probably going to devastate that species, as it’s done with other species.
“This stuff is big news in the bat world. There’s a lot of work going on with it. It has the potential to really be a significant affliction that could affect our bats here.”
Of the 15 confirmed bat species in Alabama, Hudson said they live a varied existence. Some bats live in caves, while other seldom visit caves and live most of the time in forests or other habitat.
The ones affected by the White-nose Syndrome are the colonial cave-dwelling bats. According to the best evidence bat biologists have developed, this is a new fungus for which bats in North America have no resistance. Evidence suggests bats in Europe have developed a resistance
“The fungus grows while they’re hibernating in the winter time,” Hudson said. “The pathology is not well known. Apparently, it causes the bats to wake up early and use up their fat resources. They’re flying around the mouths of caves with snow on the ground up north, and there’s nothing for them to eat. Plus, it’s likely the fungus is working on them directly, as well.”
The main concentrations of colonial cave-dwelling bats are found in about two dozen caves mostly in north Alabama. Of those, most are along or near the Tennessee River. There are two species that are endangered, and both are colonial cave-dwellers – the gray bat and the Indiana bat.
Although the majority of caves containing these endangered bats are already under some type of conservation measure, Hudson said there are a few caves where the public has access. Although it isn’t required, Hudson said it is a good idea to go through a decontamination process to ensure humans play no role in the spread of any detrimental pathogen.
“We encourage cavers to decontaminate to be safe,” he said. “In my biological opinion, it’s being spread mainly bat to bat. But because this is so devastating, we want to do everything possible to make sure humans do not contribute to the spread of the syndrome. And we can’t just go in and decontaminate the whole cave because it may destroy beneficial fungus.”
Other creatures may also be affected by any efforts to stop the bat malady.
“Each species is important to the ecosystem to keep it healthy,” Hudson said. We can’t defend presence or absence of a species whether it’s beneficial to man or not. What benefit are bats? Well, it’s more than just human benefit. You’ve got bats that drink blood, bats that eat fish, bats that eat frogs, bats that eat fruit. Just like you can’t put birds in a group, each bat species has its own lifestyle.”
Other than the portrayal of bats as hosts to evil, supernatural beings in movies and literature, bats also suffer from a perception that rabies runs rampant in the population.
“They have a reputation of being rabid,” Hudson said. “They can and do contract and transmit rabies, as do many species of mammals. But the incidence of rabies in bats is very low. The ones that have rabies are not the ones flying around at night. Usually, it’s the sick ones that can’t fly that may have rabies.”
Should anyone come in contact with a bat, Hudson suggests it’s best to just walk away.
“They should just leave it alone unless they suspect that the bat has bitten someone or been handled in such a way that could conceivably transmit rabies,” he said. “In that case, it should be turned over the health department so it can be tested for rabies.
“If someone finds a sick bat or a bat that can’t fly, the best thing to do is nothing at all. Just leave it alone. Don’t mess with it; don’t touch it; don’t poke it; don’t prod it. Just leave it alone.”