Little brown bats can be golden, reddish, olive or dark brown with a dark brown or black face. (Garrett & Kitty Wilkins/Flickr)
The little brown bat is a small, mostly nocturnal flying mammal with long, brownish fur. It lives in buildings, trees, caves and similar areas throughout the Chesapeake Bay watershed.
Appearance:
Long, glossy fur that can be golden, reddish, olive or dark brown
Dark brown or black face, ears and wing membranes
Small ears that usually do not extend past the nose when laid forward
Large hind feet with long hairs that extend past the tips of the claws
Usually grows to about 3.5 inches with a wingspan of 9-11 inches
Usually weighs less than half an ounce
Females are slightly larger than males
Habitat:
Occupies different “roosts” depending on temperature and time of year
Spring, summer and autumn roosts include trees, buildings (mostly hot, dry attics or under shingles, shutters and siding), wood piles and under rocks.
Day roosts have little to no light and usually have a southwestern exposure to provide heat
Night roosts are typically confined spaces where many bats can cluster together to increase the temperature
Usually lives close to water
In winter, hibernates in caves and abandoned mines with high humidity and above-freezing temperatures
Nocturnal, like all other bats
Range:
Found throughout the entire Chesapeake Bay watershed
Feeding:
Mainly eats aquatic insects such as midges, mayflies and caddisflies
Also eat gnats, beetles, wasps, moths and crane flies
Feeds in fields, wooded areas, and near or over water while flying
Will also eat insects while they are on the water’s surface
Most feeding takes place about two hours after dark
Typically consumes half its body weight in insects every night. Nursing females may consume up to 110 percent of their body weight.
Uses echolocation – short, ultrasonic calls that humans cannot hear – to detect prey
Predators:
Domestic cats are a major predator
Other predators include small carnivores such as mice, owls, hawks, snakes, weasels, martens, fishers and raccoons
Flight:
Usually flies about 12 miles per hour, but can fly as fast as 21-22 miles per hour
Voice:
Uses echolocation to orient itself, as well as to locate, track and evaluate its prey
Calls typically last about 4 milliseconds
While cruising, emits calls about 20 times per second; quickens to 200 times per second when attacking airborne prey
Most bat calls are beyond the range of human hearing, so humans need bat detectors to hear them
Little Brown Bat courtesy of Bat Call: Acoustic Call Library and Species Accounts
Reproduction and Life Cycle:
Mating occurs between random adult bats during late summer and early autumn in two phases: active and passive
During the active mating phase, both partners are awake and alert. Females in this phase usually mate with more than one male.
During the passive mating phase, active males mate with torpid bats of both sexes
Females delay ovulation, storing sperm for seven months between insemination in autumn and fertilization in spring
Gestationperiod is 50-60 days, with pups born between June-July
During this time, females roost in nursery areas that are typically only occupied by females and their young
Males play no role in parental care
Females give birth to just one pup per year
Young spend their first few weeks clinging to their mother’s nipple using their teeth and claws
Young are able to hear by day 2 and develop adult-like sensitive hearing by day 13
After three weeks, young are able to fly, and within four weeks of birth young are independent from their mothers
Usually lives 6-7 years, but can live for 10 or more years
Other Facts:
Also known as the little brown myotis
Spends a large amount of time every day grooming its fur and wing membranes
During the day and throughout the winter hibernation, little brown bats enter torpor: a state of reduced body activity in which temperature, breathing, heart rates and other bodily functions are lowered to conserve energy.
