Going batty for bats

HOLLIS – Bats are among the unloved members of the animal kingdom. Most people find these flying mammals downright ugly, and some of their species are indeed blood eaters, which has never helped their reputation. But science is changing human attitudes, especially as it relates to insect control.

Knowing what kind of insects bats eat can be highly useful in conservation and ecological studies and in managing insect pests. But getting that information is tricky.

Devon O’Rourke was at the Hollis Social Library recently to explain his research at the University of New Hampshire, where he is a Ph.D. student in molecular and evolutionary systems biology.

Before DNA sequencing came into use, O’Rourke said, scientists tried to learn about bats’ diet by using tweezers to extract undigested material in guano, otherwise known as bat poop. They would pull out things such as insect antennae or legs, but that wasn’t very useful, because it only let them identify insects that have parts that aren’t digested.

It’s the same problem with trying to find out what birds eat, O’Rourke said. Birds also digest their food too well.

But now with DNA, scientists have laboratory tools to learn, for example, whether bats that are native to New England eat pests that ecologists and the forestry industry are concerned about – pests such as the emerald ash borer, which has been decimating ash trees and is now moving into New Hampshire. Some were found in Concord in 2013 and in Mont Vernon in 2015.

O’Rourke, whose research topic is “Pest management strategies using bat guano as a invasive species surveillance tool,” said research findings can be useful in devising pest management and land-use strategies in forests affected by woodland pests.

But “tracking animals that fly, fly at night and go away seven months of the year” is still not an easy task, he said.

So the university scientists have enlisted the help of volunteers, who collect the guano and send it to UNH. Scientists such as O’Rourke can sit in labs and process it, using chemical tools to extract evidence of insects and spiders in bats’ diets.

So far, they’ve learned the flying mammals are good at eating lots of things – they are “flying vacuums,” O’Rourke said, eating what happens to be in abundance.

But for the key question – Do bats eat invasive species that the forestry industry worries about? – the answer seems to be no, O’Rourke said.

The good new is that they do eat other unwanted bugs, including several species of tent caterpillars, pests of fruit trees and some other hardwood species.

Than again, O’Rourke said, they also eat good bugs – bugs that eat bugs that damage crops and forests.

For many people, it’s mosquito control that draws them to bats. But mosquitoes are so small and so thoroughly digested, it’s hard to detect them, O’Rourke said, although he has detected evidence in bat guano of four species of mosquitoes.

One man in the audience said bat populations on his Nashua property are down by a tenth of what they used to be.

But O’Rourke said it seems like bats “are no longer dying in droves.”

White nose syndrome has decimated the population of little brown bats and is estimated to have killed millions in the Northeast and Canada. The disease doesn’t kill them directly, but attacks while they’re hibernating, making them itchy and driving them out of their caves, where they starve.

The Hollis presentation was co-sponsored by the library and the Beaver Brook Association. One person in the audience won a raffle of a wooden bat house donated by Beaver Brook.

Kathy Cleveland can be reached at 673-3100 or kcleveland@cabinet.com.