Bats’ Demise: Climate Caused?

There is speculation (of course, and in the absence of a smoking gun bacterium or virus) that behavioral changes due to warmer winters is to blame for the so-called White Nose Syndrome in bats. The fungus is only taking advantage of bats so weak they can’t wipe their noses. Here’s one wildlife pathologist voicing the global warming explanation:

Stone said the bats are dying from starvation and weakened immune systems resulting from the unusually warm late fall and winters during the last several years, which has kept bats flying even when fewer insects are available to eat.

That has led bats to begin hibernation with insufficient fat reserves, prompting them to starve and sometimes leave the safety of caves in search of food during cold weather, which is usually fatal.

“The good news is, this is not going to wipe out all the bats. All the bats are not in tough shape, a number of them have enough fat,” said Stone. “There are a lot of bats that have died that don’t have any fungus.”

Does the theory hold water? Maybe. It seems possible that white-nosed northern state bats (NY, VT and MA) might be less well adapted to stay in winter hibernation when temps are still warm while southern state bats have long done so.

Also with average winter temperatures a few degrees warmer hundreds of miles south there are probably still at times enough cold-blooded insects on the wing for bat food. On a warm December day, the Asian Ladybird Beetle swarms alone could feed a legion of bats where we live in Southwestern Virginia and the cost of leaving the roost would well be compensated for by a good meal. Not so with warm winter spells to the north.

But early on, a strong correlation was noted between caves where WNS was found and those visited frequently by cavers. Here again, perhaps the added stress of hibernation disruption compounded the metabolic stress the bats were under.

My guess is that we’ll have a handle on WNS long before we understand CCD in bees. Stay tuned.