It is International Bat Appreciation Week! This week, we celebrate the 1,400+ species of bat found worldwide including the eight... that's right, eight!... species of bat that can be found here in the state of Maine!
Big Brown Bat in care at Center for Wildlife
Bats are incredible animals that have developed some of the most specialized adaptations of any mammal over the course of roughly 50 million years. The most unique adaptation of our friend the bat, which sets them apart from all other mammals, is their ability to fly. The reason this adaptation is so unique is because they are the only mammal currently kicking around that has ever developed the ability to do so! We have other mammals, including the "flying" squirrel found here in our region, that have evolved to glide through the tree canopy. Our bats hold the distinction of being the only mammalian animal to truly fly (i.e. sustain flight as opposed to gliding).
What is equally fascinating about bats is that this ability to fly currently stands as a bit of a mystery from an evolutionary standpoint. Due to lack of a substantial fossil record for bats, biologists have little evidence to trace the lineage of their evolution back to the early terrestrial mammals that bats (and all mammals) are believed to have evolved from. Why no fossils? Think of those tiny bones! Bats' bones are so small that it is rare for them to sustain the time and environment needed for fossilization. We have no "proto-bat" fossils but do have fossils that go back to the time of some of the earliest bats who had already developed this incredible feat of flight. Those early fossils (the oldest of which was found in Wyoming!) show claws on all digits which suggests these early bats spent as much time climbing as they did flying.
credit: Arizona State University
The Roles They Play
Today, bats are found throughout the world and have evolved to be equipped for a wide range of environments from deserts to tropical rainforests. Bats are now so widespread and varied that they are the second largest order of mammal behind rodents! While evolving to their habitats, bats also evolved to rely on a range of food sources from insects, to fruit, to the nectar of flowering plants. Bats are one of the most important animals for overall ecosystem health through the insect control they provide, seed dispersal carried out through the consumption of fruits and the pollination of flowering plants!
In the United States alone, bats provide roughly 3 billion dollars in insect control annually. Our insectivorous bats use one of the most efficient systems of echolocation found in the animal world to track down the tiniest of insects including mosquitos, beetles and more. A single bat can consume 1,000 mosquito-sized insects in an hour, with pregnant females consuming up to 4,000 insects in a single night. Most insectivorous bats will spend a couple hours feeding, find a nice spot to digest throughout the night and then return to their daytime dwelling before sunrise.
Bats Under Threat
The topic of bat conservation is more important than ever as bats continue to face the challenges of habitat loss, emergent disease and an ever-changing climate. According to the IUCN and Bat Conservation International, of worldwide populations: 23 species are critically endangered, 85 species are endangered, 113 species are considered vulnerable and 236 species are “data deficient” to determine health of populations.
To complicate things further, bats are the slowest reproducing mammal relative to their size and on average only give birth to one pup a year. This means that even minor disruptions can cause major issues for overall bat populations.
Bats of Maine
Our eight bat species found in the state of Maine are listed into two categories. Hibernating Bats and Tree Bats. To simplify this breakdown, hibernating bats listed below spend the entire year with us (hibernating in the winter months) and tree bats historically travel further south in the winter.
Hibernating bats (year-round residents):
Big brown bat (Eptesicus fuscus)
Little brown bat (Myotis lucifugus)
Northern long-eared bat (Myotis septentrionalis)
Eastern small-footed bat (Myotis leibii)
Tri-colored bat (Pipistrellus subflavus)
Tree bats (migratory):
Hoary bat (Lasiurus cinereus)
Silver-haired bat (Lasionycteris noctivagans)
Eastern Red bat (Lasiurus borealis)
Eastern Red Bat
Our most common bat in our area is the Big Brown Bat but many of these varying bat species are admitted to our Wildlife Medical Clinic at Center for Wildlife including an Eastern Small-footed Bat, Silver-haired Bats and a couple Eastern Red Bats just this year!
Many of our regional bats, particularly the Little Brown Bat have seen population declines in years past due to diseases such as white-nose syndrome (a fungal infection that can spread through large colonies like wildfire) as well as habitat loss.
That Maternal Instinct
In the world of bats, caring for young truly takes a village. When bat species like the Big Brown Bat (and others found in our region) are giving birth, they will form maternal colonies. During this time, males will typically break off into their own smaller groups. These maternal colonies quickly turn into highly efficient birthing and daycare systems. When first-time mothers are giving birth, more experienced females will take up midwife roles and assist in the birthing process, even showing new mothers correct positions to be in while giving birth! The entire maternal colony will take up responsibility for young, collecting any stragglers, assisting young that may fall from cave or cavity ceilings and watching over young as mothers take turns foraging for food. When mom returns from her round of feeding, she is able to distinguish the calls of her young from what can often be groups of thousands.
A maternal colony. Source: merlintuttle.org
Waiting Out the Cold
During the cold winter months, our hibernating bats will form what is called a hibernaculum, congregating in groups that can number in the thousands in a temperate dwelling (most commonly caves, tree cavities and man-made structures). During the winter months when their insect food source is scarce or nonexistent, bats will slow down their metabolisms and put themselves into a state of torpor. This allows them to stay inactive and only move areas of shelter or seek out sustenance in period of milder weather.
Bats in Media
Unfortunately, our friend the bat is commonly portrayed as a villainous critter in western media including movies and television. In many eastern cultures, bats represent good fortune! From their association with the fictional vampire to their use as scary frights throughout horror media, a negative light has been shed on bats. We are here to help champion these incredible, docile, maternal and ecologically critical animals!
What You Can Do To Help
There are a few simple ways you can help bats in your backyard and encourage this flighted friends to help rid your property of pesky insects.
Eliminate the use of pesticides. Pesticides that infect insects will work their way up the food chain and can cause extreme harm to insectivores like bats.
Leave standing deadwood trees on your property that do not pose a threat to your safety. Deadwood trees provide habitat for many cavity dwelling species including bats. If you have to take a tree down, don't forget to do so outside of nesting season (Oct-Feb).
Build a bat house! Bat houses can be a great way to provide for bats that may have limited natural habitat options in your area. For more info, check out National Wildlife Federation!
Happy bat appreciation week from all of us at Center for Wildlife! Don't forget to check out our educational programs that feature more learning opportunities about bats and get the chance to meet our resident ambassador bats in person!
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