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Jul 012009

By Christopher Peake
Green Right Now

Bats have creeped us out since man and bat first met. But not many of us know just how important bats are to mankind’s existence and fewer of us know that at least five species of bats are battling an epidemic that could have devastating consequences for both bat and man.

To quote the U.S. Fish & Wildlife Service, “Worldwide, bats play critical ecological roles in insect control, plant pollination and seed dissemination” (seed dissemination is critical to rain forest regeneration). There are 25 species of North American bat.

Barbara French, a biologist at Bat Conservation International (BCI) in Austin, gave this capsule on the bond between bat and farmer: “A colony of 150 Big Brown bats can protect farmers from up to 33 million rootworms, which are serious crop pests. Many bats feed on moths. The moths lay eggs that develop into caterpillars, like corn earworms and army worms, which feed on a huge variety of crops.” And bats love mosquitoes, too.

That something was terribly wrong in the bat world was first noticed in February, 2006 in Howe’s Cave, 40 miles west of Albany, N.Y. A photograph of hibernating bats showed many had an unusual white dust on their noses, ears and wings; the find was named White-Nose Syndrome (WNS) and in less than 12 months WNS had traveled 450 miles south from Howe’s Cave. The epidemic has now spread to more than 65 caves in nine New England and Mid-Atlantic states and several caves in Canada are suspected of harboring the fungus.

Gray bats and Virginia Big-eared bats are severely threatened: even before WNS they were federally listed as endangered species. Indiana bats are now losing population, nearly to the levels of the endangered Virginia big-eared bats.

Despite the continuing search to find the source of this condition by numerous laboratories and state and federal biologists, the cause of the bat deaths remains unknown.

There really isn’t much to go on; nobody knows what is causing WNS … cavers, pesticides, global warming and more may or may not be the cause. But we do know these three facts:

  • Bats hibernate in cool or cold caves and abandoned mines;
  • WNS is a cold-loving fungus; and
  • During hibernation bats, like all other hibernating mammals, live off their stored fat reserves.

Apparently WNS triggers a desire for food in bats, breaking their hibernation cycle; those that are strong enough to do so struggle to fly out into the cold winter environment in search of non-existent insects. Those bats, too weak to fly, die and fall to the ground. Again, the U.S. Fish & Wildlife Service: “We have found sick, dying and dead bats in unprecedented numbers in and around caves and mines from Vermont to Virginia. In some hibernaculum, 90 to 100 percent of the bats are dying.”

Melia Bayless, another biologist at BCI, says “WNS is a huge scientific mystery … it’s a puzzle. We don’t know yet whether the fungus is the cause (originating on the bat) or whether it’s opportunistic (picked up somewhere else) bu susceptible bats. We don’t know how the fungus is transmitted but we do know other fungus spores (in mammals and animals) can be transmitted and held for a long time.