Myotis septentrionalis
northern long-eared myotis

Myotis septentrionalis is widely but sparsely distributed across forested regions of the eastern United States. It ranges across southern Canada and up to Newfoundland. It extends down into Florida, through the south central states and through the Dakotas, into eastern British Columbia. In the Columbia Basin M. septentrionalis inhabits several different regions including Cranbrook, Invermere, Golden and Revelstoke forest districts (Trouessart, 1999). It has also been found scattered throughout eastern, central and northern British Columbia including the Peace River, Revelstoke and Liard River areas (Bat Conservation International, 2001). (Bat Conservation International, Inc, 2001; Trouessart, 1999)

Northern bats are associated with boreal forests. In British Columbia they are found in the wet forests of the interior cedar-hemlock biogeoclimatic zone. In areas of North America and Canada these bats choose maternity roosts in buildings, under loose bark, and in the cavities of trees. Caves and underground mines are their choice sites for hibernating. (Trouessart, 1999)

Myotis septentrionalis is a medium sized bat best recognized by its long rounded ears, which extend beyond the tip of the nose when laid forward. It has a comparatively longer tail and larger wing area than Myotis species of similar size; these structural adaptations are associated with its gleaning foraging strategy (Altenbach et. al., 2001).

The total body length of northern bats is 78 mm. The tail measures 26 mm, the foot measures 9 mm, the ears measure 17 to 19 mm, and the forearm measures 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 (Altenbach et. al., 2001).

The pelage is a dull yellow/brown, with a pale gray ventral side, and dull, brown shoulder spotting (Trouessart, 1999). Myotis septentrionalis has a long, narrow, sharp-pointed tragus, and the calcar lacks a keel (Texas Technical University, 1997). Its skull is narrow with a relatively long rostrum. Its dental formula is that of M. californicus: I 2/3, C 1/1, Pm 3/3, M 3/3 X 2 = 38. (Altenbach, J. S. and Harvey, M. J., 2001; Texas Technical University, 1997; Trouessart, 1999)

During copulation, a male northern bat mounts a female from behind, occasionally grasping the female's neck with his teeth (Barclay et. al., 2000). Northern bats are promiscuous. (Barclay, Robert M. R., May 12, 2000)

Mating occurs in autumn when groups of a few hundred are formed and pairs copulate before going into hibernation (Trouessart, 1999).

The females store sperm in their uteri during hibernation; ovulation will not occur until they emerge in the spring. Gestation lasts 50 to 60 days, after which a single young is born. In British Columbia limited breeding information suggests that young are born in late June or early July. (Trouessart, 1999)

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.

Individuals have been known to live up to 18.5 years. (Bogan, M. A. and Valdez, E. W., December 14, 2000)

During the summer northern bats are commonly found in higher densities around the northern areas of their range, as they are especially reliant upon the richly forested habitats in the north around this time (Altringham, 1996).

Occasionally, these bats may be found roosting with other bat species, although they are much less social than other members of the genus Myotis. The sexes roost separately; however, reproductive females may form small maternity colonies of less than 60 individuals (Altringham, 1996).

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. The same hibernacula are often inhabited more than once although not necessarily in sequential seasons. (Altringham, John D., 1996; Barclay, Robert M. R., May 12, 2000)

Nothern bats use passive listening and echolocation to locate insects resting on leaves, tree trunks, or on buildings. (Bogan, M. A. and Valdez, E. W., December 14, 2000)

Myotis septentrionalis emerges shortly after sunset to hunt. Hunting occurs over small ponds, forest clearings and forest edges at a height of 1 to 3 meters. Hunting is coupled with periodic rests (night roosting), followed by a second peak of hunting just before dawn (Trouessart, 1999).

In general, these bats consume a variety of smaller night-flying insects, but they may sometimes glean sitting prey as well.

Foods eaten include: caddisflies, moths, beetles, flies and leafhoppers. (Bogan, M. A. and Valdez, E. W., December 14, 2000; Trouessart, 1999)

No predators are known.

Northern bats play an important role in their ecosystem by eating large quantities of insects.

Due to its insectivorous feeding style, M. septentrionalis helps control populations of potentionally harmful insects. (Altringham, John D., 1996)

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. (Altringham, John D., 1996)

Timber harvesting may interfere with these bats' ability to utilize trees for nursery colonies and day roosts. It also may prove detrimental to their foraging habits in forested areas (Thomas, 1993). Use of chemical and biological insecticides is another source of concern affecting their food supply. A less vital, yet very real threat to M. septentrionalis 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 hibernacula is to put up gates that permit the bats to pass while excluding humans. (Thomas, Donald W., 1993)

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%. (Cryan, 2010; National Park Service, Wildlife Health Center, 2010)

Myotis septentrionalis was formerly classified as a member of the species keeni (Barclay et. al., 2000).

Myotis is a derivative of the Greek word for "mouse-eared" (Barclay et. al., 2000).

Septentrionalis comes from the Latin word for "northern". (Barclay, Robert M. R., May 12, 2000)