Find northern bat information at Animal Diversity Web
6 to 9 g; avg. 7.50 g
(0.21 to 0.32 oz; avg. 0.26 oz)
78 mm (average)
23 to 26 cm; avg. 24.50 cm
(9.06 to 10.24 in; avg. 9.65 in)
Northern bats are medium sized bats best recognized by their long rounded ears, which extend beyond the tip of the nose when laid forward. Their fur is a dull yellow/brown. Their bellies are pale gray and the shoulders have dull, brown spots. Their heads are narrow with relatively long noses. The total body length of northern bats is 78 mm. Their tails measure 26 mm, their feet measure 9 mm, their ears measure 17 to 19 mm, and their forearms measure 35 mm. Northern bats have a wingspan ranging between 23 and 26 cm. These bats weigh 6 to 9 grams. The females of this species are generally larger and heavier than the males.
Northern bats are distributed across forested regions of the eastern United States. They range across southern Canada and up to Newfoundland. They extend down into Florida, through the south central states and through the Dakotas, into eastern British Columbia.
Northern bats live in boreal forests. These bats roost in buildings, under loose bark, and in the cavities of trees. Caves and underground mines are their choice sites for hibernating.
During mating, a male northern bat mounts a female from behind, occasionally grasping the female's neck with his teeth. Both male and female northern bats have many mates.
Mating occurs in autumn when groups of a few hundred are formed and pairs mate before going into hibernation.
The females store the males' sperm inside of them during hibernation; they do not become pregnant until they emerge in the spring. Pregnancy lasts 50 to 60 days, after which a single young is born. Young are born in late June or early July.
Northern bats are born helpless and completely dependent on their mothers. Female northern bats nurse their young for about a month. Males do not help care for the young.
Northern bats have been known to live up to 18.5 years.
During the summer northern bats are commonly found in higher numbers around the northern areas of their range, as they rely upon the richly forested habitats in the north around this time.
Occasionally, these bats may be found roosting with other bat species, although they are much less social than some of their close relatives. Males and females roost separately; however, females with offspring may form small maternity colonies of less than 60 individuals.
In late summer or early autumn the bats gather and move to the places where they will hibernate, traveling up to 56 kilometers from their summer habitat. They generally hibernate alone although they sometimes form very small groups. During hibernation these bats prefer moist, still, narrow crevices where temperatures may be as low as 1.6 degrees Celsius. Hibernation may last for 8 to 9 months in the northern latitudes; length of hibernation varies among the various latitudes and environments. These bats often hibernate in the same places more than once.
Nothern bats have good hearing and they often listen for sounds made by their insect prey. They also use echolocation to locate insects resting on leaves, tree trunks, or on buildings.
Northern bats come out shortly after sunset to hunt. Hunting occurs over small ponds, forest clearings and forest edges at a height of 1 to 3 meters above the ground. While hunting, northern bats take occasional rests (night roosting), followed by a second peak of hunting just before dawn.
In general, these bats eat a variety of smaller night-flying insects, but they may sometimes pick resting prey off of flat surfaces as well.
Foods eaten include: caddisflies, moths, beetles, flies and leafhoppers.
No predators are known.
Northern bats play an important role in their ecosystem by eating large quantities of insects.
As is the case with most bats, many humans consider northern bats to be pests. Bats often work their way into the attics of houses and may carry a threat of rabies, although this threat is often exaggerated.
Northern bats help control populations of potentionally harmful insects.
controls pest population.
Timber harvesting may interfere with these bats' ability to use trees for nursery colonies and day roosts. It also may negatively affect their foraging habits in forested areas. Use of chemical and biological insecticides is another source of concern affecting their food supply. A less important, yet very real threat to northern bats is the disturbance they face in the caves (where recreational "caving" is popular) or mines (which are often closed after being abandoned) where they hibernate. A solution to the problem of disturbance at caves and mines is to put up gates that permit the bats to pass while keeping out humans.
Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%.
Jessica Ollendorff, University of Michigan
Ondrej Podlaha, University of Michigan
Allison Poor, University of Michigan
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