Bats! Bats are amazing little creatures, not least because they’re the only mammal with true flight ability. (The flying squirrels of Connecticut are gliders. Did you know about these little guys? They’re nocturnal, so few people see them.) Bats are not flying mice; they’re not even rodents. In fact, bats share a common ancestor with the mammals that evolved into whales, horses, pangolins, and dogs.
The bats of Connecticut are nocturnal and primarily insectivorous. They often eat their weight in insects; a single bat can consume 1,000 insects in one hour! One popular nocturnal target? Mosquitos! Bats are excellent allies in suppressing mosquito populations. To discover their target, these bats use echolocation: they send out sound waves that bounce off of objects, and their large ears pick up these sound waves, allowing them to create an image of what’s in their surrounding environment.
Connecticut has nine species: the hoary, Indiana, northern long-eared, eastern small-footed, tri-colored, little brown, eastern red bat, big brown, and the silver-haired. All are on the CT list of endangered, threatened, or species of greatest conservation need. While three of these species dwell in caves and white-nose syndrome (a fungal infection killing bats) has affected their populations, others are tree-dwelling, and insecticides and habitat destruction threaten their safety.
When the winter arrives, some of these species migrate, and others hibernate. Bats and groundhogs are the only hibernating species in Connecticut. (Bears enter a state of torpor, not true hibernation.) In hibernation, the metabolic rate, heart rate, and respiratory rate drop dramatically. A bat’s heart rate can drop from 200-300 beats per minute to 10 beats per minute. With such low energy expenditure, bats can survive the winter in hibernation. The small brown bat can remain in hibernation for up to six months!
Bats can enter a similar state called torpor for a few hours at a time during the periods where the days are warm and the nights freeze. Torpor has similar characteristics: a drop in metabolic, heart, and respiratory rates. However, torpor occurs for much shorter periods, and we can rouse an animal from torpor fairly quickly, unlike hibernation. Animals coming out of hibernation rely on specific environmental indicators to begin their emergence.
Migrating species like the eastern red and hoary bats leave as the months grow colder. However, it’s a good idea to leave your leaves in the yard! On especially chilly nights, these bats will enter torpor while wrapped in the brown leaves on the ground.
In hibernation, bats find nooks and crevices to sleep in, called hibernacula. Hibernating species include little brown, Indiana, northern long-eared, eastern small-footed, and tri-colored bats. Typically, the big brown bat migrates from northern areas but may hibernate during the coldest parts of the winter while in southern areas.
If you’d like to help bats in their survival, you can put up a bat house! And equally important: lay off the use of pesticides, and let a part of your yard go wild where you can leave your leaf litter. This helps local pollinators and birds, not just bats! It’s easy to benefit biodiversity with some simple acts in our own backyards.