ArrayOctober 27, 2020 at 9:27 am
By Wildlife Promotional Coordinator Lauren McPherson
In celebration of bat week, coinciding perfectly during the week of Halloween, Maine Department of Inland Fisheries and Wildlife is exposing some of the scary truths about Maine’s bats. While some may know that bats have a common ancestor with humans, many of their unique adaptations like thermoregulation, bone structure, and senses have some spookily similar comparisons. As mammals, bats have hair, breath air, have mammary glands and nurse, and give live birth along with a number of other mammalian characteristics. While we obviously share some basic similarities, through millions of years of slight modifications, or adaptations, bats have evolved to use echolocation as a sixth sense, flight as their method of transportation, and fulfill a niche of a nighttime predator. Bats are a unique example of a same but different scenario, each thing more extraordinary than the next.
During warm summer nights, you may have noticed birds flying eerily close to your head, only to realize it isn’t a bird at all. You may watch in fear, covering your head to prevent the bats from flying into your hair or landing on you. While those rumors of bats being blind blood suckers served well for scare factor in Hollywood movies, the reality couldn’t be further from the truth.
"Blind as a bat" is a commonly used saying, but one that should be tossed. These unique mammals actually use vision to orient themselves in long-distance navigation, to differentiate day from night, and to synchronize their internal clocks with the cycle of daylight and darkness in their immediate surroundings, very much like humans do. In addition to their sight, their sense of smell and taste relate closely to ours as well, though slightly enhanced. Smell can be used to detect certain prey, locate roosts, identify members of the same species, and recognize the sex of other individuals based on pheromones, and touch is felt with small hairs that cover much of their bodies acting as whiskers, aiding in contact with rock surfaces or other bats in a roost. While hair may provide a very slight benefit for heat retention, much like humans, there isn’t enough hair to truly stay warm. Bats have a body temperature of about 98.6 degrees Fahrenheit. Sound familiar? Bats maintain body temperature by sustaining their metabolism through eating, removing thousands of insects every night, positively impacting agricultural crops and human outdoor activities. Unlike humans though, some bat species use hibernation to survive our cold winters. Five species of bats remain in Maine during the winter months, finding caves or cave-like structures where they use stored body fat, lower their body temperature, and become inactive for months. Some species, like the big brown bat and little brown bat, are nicknamed “house bats” because of their affinity for attics, camps, and other manmade structures.
If you aren’t impressed by their exclusive adaptations or uncanny similarities to humans yet, learning that bats have homologous structures to humans might give you the final freaky fact to convince you. Homologous structures are organs or skeletal characteristics of animals, demonstrating similarities in physical structure, but vast differences in function. Below is a comparison between the arm of a human and the wing of a bat. Both exhibit a humerus, radius, ulna, carpals, metacarpals, and phalanges which have been modified for function, in a bats case, as the only true flying mammal. Elongated metacarpals and phalanges allow for a thin wing membrane to span between each structure, while the chest and shoulders have large muscles attached to a reduced humerus and radius to provide power to the wings.
Last, but not least, bats are one of the few mammals that use echolocation to navigate surroundings and locate prey by acquiring detailed information such as size, speed, and direction of a prey’s flight. While mammals all have three inner ear bones, bats contract a muscle to separate their three inner ear bones in order to reduce hearing sensitivity temporarily so the bat can receive the return of their own calls. Most bat calls exist in lower and higher decibels than humans can hear, and vary slightly in both duration and sound frequency on individual bats. Regardless of each bat’s method, the brains and ears of bats are uniquely adapted to tune into frequencies of the sounds they emit, fulfilling a niche exclusive to any other wildlife.
With Halloween right around the corner, you might notice that bats are no longer out and about foraging in the night sky. This is the time of year when bats, depending on the species, have either migrated to warmer areas or they have returned to a hibernacula for the winter. While you may feel creeped out by the idea of bats, the fear of species decline is a true threat that should be on the forefront of our minds. To learn more about some challenges facing bats or how you can help bats in Maine visit mefishwildlife.com/bats.