Maine’s Bat Monitoring

October 27, 2020 at 9:26 am

By Wildlife Promotional Coordinator Lauren McPherson

As Connor White, contract wildlife biologist, and I trek up the hillside, massive boulders surround us while we navigate through the rough terrain. These boulders may have been left behind millions of years ago as glaciers moved over the land, or formed by pieces of the mountain falling down to the base. The moss and fern covered boulders have provided a unique opportunity for organisms to find habitats in the mini caves and crevices, referred to as talus slopes.

It has become clear that a great deal of information is needed for proper bat monitoring in the state, so Maine Department of Inland Fisheries and Wildlife (MDIFW) has been conducting comprehensive acoustic surveys to gather bat species data across a broad area of Maine as well as a non-traditional hibernacula study.

Acoustic Survey

The acoustic survey results confirmed the widespread distribution of the more common bat species across the state, such as big brown, silver-haired, eastern red, and hoary bats. Species such as the little brown, eastern small-footed, northern long-eared, and tri-colored bats were less frequently recorded, possibly demonstrating the habitats sampled aren’t preferred for those species or that these species are less abundant. Long-term data collection will inform bat species management objectives, aid in environmental permit review to reduce the risk to bats from development, and provide baseline data to monitor the recovery of species affected by white-nose syndrome

Non-Traditional Hibernacula Study

It is well known that bats use underground caves and old mines to hibernate; biologists call these places hibernacula. Maine lacks large caves but does have a lot of rock piles. MDIFW, in collaboration with Acadia National Park (ANP) and The University of Maine in Orono, have been studying the locations and importance of non-traditional hibernacula, such as talus slopes described above. Time has been spent identifying course and fine-scale features that may influence bat activity and attempting to identify high probability sites of bats based on the Rogue Detection Dog Crew from Washington state. This organization trains dogs to smell the scat of very specific wildlife in order to perform non-invasive research. A team consisting of a handler and dog were taken to areas where bats were detected during two winters using acoustic surveys. Connor White, a MDIFW Contract Wildlife Biologist, spent the fall surveying the top six sites of over seven detections where the dog provided high probability ‘hits.’

Jack from the Rogue Detection Team identified this site last winter

On this particular evening, Connor and I arrived before dusk to set up a bioacoustics meter, a game camera, and infrared camera for a bat emergence survey, in order to collect data through sound, images, and body heat from bats while leaving a possible roosting area. While Connor and I didn’t have any luck seeing bats emerge from the talus that night, game cameras were successful at picking up bats at all five locations the dog identified. Connor’s hard work provided vital information to continue future research using dogs in wildlife surveys, as well as to understand habitats important for bats and seasonality of bat movements.

Photo of a bat flying in cave taken by a game camera

MDIFW will continue to evaluate habitat use of Maine's bat species and evaluate the effects of white-nose syndrome. While bats are attempting to make a very slow recovery after experiencing significant population declines since 2011, after the introduction of white-nose syndrome, monitoring these mammals requires a great deal of innovative methods to collect data and monitor populations. Collaborative efforts will continue to adapt and find new ways to assess populations across our state in hopes that we can see a recovery of our state’s species.

You can learn more about Maine's bats at