Checking in on Maine's Bats

ArrayJanuary 7, 2020 at 1:08 pm

By Wildlife Promotional Coordinator Lauren McPherson

As we Mainers forge our way through winter, enduring extreme colds and extended darkness, we often ponder things we miss about summer. For many, it’s the longing for warmth, or the memory of a long day out on a lake fishing. For myself, it’s the anticipated presence when the sun begins to set of one of our more underappreciated mammals, the bat. Often viewed as a nuisance, bats are surrounded by misconceptions and fears, however, the world’s only flying mammal provide critical contributions to both our environment and economy.

Worldwide, there are 1,296 bat species that fulfill an incredible number of ecological niches which are vital to the health of natural ecosystems and human economies. In Maine, we have eight species of bats that inhabit our state, each of which provide value to our lives. As numerous bats dance across the sky while you sit beneath enjoying a fire, one individual bat is capable of consuming 1,000 mosquito sized insects in just one hour, leaving you a little less itchy and helping to mitigate the potential spread of various mosquito borne diseases. Beyond that, bats help control agricultural pests in farmlands and orchards, greatly reducing the need for pesticides. Depending on location in the world, bats are also responsible for seed dispersal leading to the regrowth of deforested rainforests, and critical pollination for over 500 species of flowers and fruits such as bananas, mango and agave. Bats bring far more positive impacts than harmful ones to our everyday lives.

Last month I was provided the opportunity to participate in a bat count survey with Maine Department of Inland Fisheries and Wildlife’s furbearer and small mammal biologist, Shevenell Webb. The dedication and effort put forth by Shevenell, along with biologists Dave Yates and Caroline Byrne from the Biodiversity Research Institute, is no short of admirable to ensure they monitor our threatened bat population.

Caves and old mines provide ideal temperature and humidity conditions for hibernating bats – these types of places used by bats are called hibernacula. Biologists in Maine conduct hibernacula surveys when bats are inactive and more easily counted while clinging to cave walls. However, in 2006, a significant decline in bat populations was noticed across the eastern part of the U.S, finding its way to parts of Maine by 2009. White nose syndrome, named for the white fungus on the muzzle and exposed skin of a bat, is a cold-loving fungal pathogen that attacks hibernating bats, and has led to a 90% decline of some species of bats, like the little brown bat and northern long-eared bat. White nose syndrome is highly contagious, with spores that are easily spread from bat to bat or from surface of caves to bat. The spores can also attach to human clothing, shoes, and other material leading to transfer from people entering hibernaculum. Once the fungus has infected a bat, it irritates the bat causing it to wake more often during its hibernation and leading the bat to use vital fat storages.  Eventually, white nose syndrome causes bats to burn through stored fat reserves, ultimately resulting in death by starvation. There has been some indication that bats with higher fat stores contribute to higher survival.

Our bat count survey on December 19, 2019, was the first bat count since 2016. To minimize disturbing bats, staff conduct surveys every 3-5 years. On our arrival to the first bat hibernacula, we met with Josh Smith, the area’s game warden who has taken on the task of protecting these hibernacula from human traffic. As we parked our vehicle and exited to put on our gear, the wind exposed us to negative temperatures. The five of us began the hour-long hike through the snow to our first cave. Once there, we put on our dedicated decontamination gear and helmets. Once in the cave, it was obvious the water we thought would be frozen, was still liquid and had flooded much of the cave. Dave, Caroline and Josh made a sacrifice to trek through the water, submerging their boots in subzero temperatures, all in the name of an accurate bat count. Prior to white nose syndrome, this hibernaculum had over 300 bats. Unfortunately, since the devastating pathogen has swept through, only five bats were found in this cave, and six bats in the second cave. Those numbers are very similar to what biologists found three years ago, in 2016. The promising trend is that seeing the same number of bats years apart is suggesting the population has remained stable.

*Note: Asterisks (*) represent years with incomplete data as not all caves were visited. 2019 provides data from two of three bat hibernacula in Maine, the third will be surveyed in the coming weeks.

In order to continue the preservation of the current bat population and prevent further decline, we are careful to use protective equipment that is changed out for every new cave. It is also illegal for people to enter bat hibernacula from October 1 through April 30, ensuring bats can safely continue with hibernation. A bat gate was also installed at one of the sites last year to prevent people from entering the caves, disturbing the bats and potentially spreading further disease. If cave-dwelling bats can rebound from this pathogen, it will take a significant amount of time. Female bats only give birth to one pup every year on average, so recovery from losses is extremely slow.

A colony of big brown bats

While the image of bats has often been smeared as a sinister animal, they provide many overlooked benefits to our everyday lives. Promoting this animal might allow you to enjoy the many benefits they bring to our back yards. If you’re looking to support these critters, you can create a bat-friendly environment! Planting late-day blooming flowers or night scented flowers will attract night pollinators, like moths, that bats like to eat, encouraging their presence. Buy a bat house and place it somewhere near your yard, encouraging roosting near your home. Or, maintain old trees on your property that eventually become snags that host bats and a variety of other critters. Lastly, avoid using pesticides on your lawn and plants so bats aren’t consuming insects with toxins. If you’d like to learn more about living with bats and their benefits, go to, or for information on creating a bat-friendly environment, go to BatsLive!