The Andover Conservation Commission is tasked to ‘conserve and protect Andover’s rural character and ecological health.’ Every now and again the ACC hosts a guest speaker or presentation on pertinent and important topics to better inform each other about ways and means to conserve and protect our town’s natural systems.

During the last week of May, the ACC hosted Jesse Mohr of Native Geographic. Mohr is a wildlife biologist, licensed forester, owner of NativeGeographic LLC and enthusiastic educator. Mohr visited Andover to discuss bats.

Bats are a class of mammals that are largely a mystery to us, due to their nocturnal activities and secretive ways. However, most of us know the basics, that they are true flying mammals, they are active at night, and they eat lots of insects.

We learned from Mohr, that there are 8 species of bat that have historically been found in New Hampshire and Andover. The Red bat, Hoary bat, and Silver-haired bat all enjoy New Hampshire forests in warmer seasons and migrate south for the winter. The Tricolored bat, Northern long-eared bat and Eastern small-footed bat are year-round residents that hibernate in caves and mines, and are listed as endangered of extinction in the state. The big brown bat and the little brown bat, are the most common and likely the species you have maybe seen foraging the skies near your favorite pond. Each are year-round residents and hibernate.  

Mohr’s presentation took some time to focus on the functional role of bats in our local ecosystem. For centuries, bat populations have helped manage and control insect populations. Many of us know that management of insect populations can be time consuming and expensive (Emerald ash borer, mosquitoes, and beetles). Thankfully bats, and other insect eaters, can provide this service as long as they have adequate habitat space to thrive and maintain healthy populations within. However, most of our NH bat populations have not been thriving. Over the last decade bat populations have crashed.

In 2006, an invasive fungus, native to Europe, found its way into the caves and crevices that bats use for communal hibernating. The fungus spread to the bats quickly, causing them to develop White-Nose Syndrome (WNS), a respiratory disease that kills hibernating bats by aggravating their breathing. The breathing difficulty caused by WNS leads to incomplete and disrupted hibernation which uses up fat stores (energy) that the bat cannot regain, leading to its death by starvation.

During a 2008 survey of hibernacula (place where bats hibernate – caves or mines) for little brown bats, researchers counted a total of 3,135 little brown bats hibernating. In 2018 researchers surveyed the same hibernacula, and found only one individual little brown bat (reported on by WMUR on April 5, 2018). The prime suspect for the tragic loss, White-Nose Syndrome. Even though research is never flawless, that reported loss follows trends witnessed all over New England by wildlife biologists. Many species of bat have suffered tragic declines in population. Little brown bat populations, once the most common bat species in the New England area have dropped 99% since 2008. Imagine that scale of loss. Our town’s population is roughly 3,000 people. A 99% decline would leave the town with 30 people.

Mohr reminded our audience, that bats need some friendly help.  The key to getting bats back as functioning players (insect control) in our local habitats is to increase their populations. Understanding the reproductive potential (or rates) of any species is vital to managing their populations. Rodents, like mice and chipmunks, reproduce quickly by having many young several times a year. Bats, although small, are not rodents. In fact their reproductive rates are low. Bats typically only have one or two (often twins) pups a year.

Most of the pup rearing occurs in the summer, and the young are raised in large communal roosts. These maternal roosts are essential in raising future generations of bats. Many bats will use dead standing trees (snags) as roosting sites. However, attics or barns make for great alternatives when other sites are not available.

Mohr then made the point to acknowledge the annoyance bats can be to live with. “They foul up our buildings and they can really stink up the place,” says Mohr. Yet, we should not simply eradicate them from our homes. Mohr stressed that bats found living in buildings are not hibernating there. Usually issues arise in the summer months, because bats have found buildings spaces that meet their maternal roosting needs. Because bat populations are in such serious trouble, maternal roosting sites are vital for restoring a healthy bat population. Therefore, a little tolerance is required. In fact, communication with the right people can help, seal up spaces after the bats have left for winter sites. Mohr invited us to contact him about any such issues (his info is at the end of the article). He wants to be involved, because understanding where bat roosting spots are important, and he knows best practices for living with the bats until they leave for wintering sites. The trouble with bats

Mohr’s conclusion to his presentation focused on the importance of property owners knowing about the critical status of bat populations, as well as, ways and means to help and enhance our local wild populations. Below is a list of land management techniques that can help bats recover and provide the great functions and services they can provide.

Keep forests intact.

If you have to cut, avoid the months of June and July to minimize the impacts on young bats roosting in trees.

Keep snags and dead trees to promote roosting sites for bats.

Bats forage in openings and fields surrounded by forest.

Bats prefer openings whose edges are varied and irregular.

More diverse plants in the openings can increase diversity of bat species.

Best field management practices for bats include mowing after September 15 and rotating the mowing schedule each year.

Bats need slow moving water bodies in order to drink from on the wing.

Maintaining wetland buffers around ponds can increase bat activity.

If you have bats in your house or on your property contact Jesse Mohr. He can help provide an affordable and supportive means to get the bats our of your home safely. Contact: nativegeographic@nullgmail.com

Written by Alan D. McIntyre

Andover Conservation Commission member, and science teacher at Proctor Academy.