LITTLE BROWN MYOTIS
Myotis lucifugus
(LeConte, 1831)


mI-O-tis lU-ce-fU-gus




An adult Little Brown Myotis.
Image © by Greg Sievert.
Image © by Greg Sievert.
An adult Little Brown Myotis.

Description:
Myotis lucifugus is a relatively small bat with sleek and glossy pelage. On the dorsum, it varies from dark brown (often with a metallic coppery sheen) in the East to buffy brown in the West. The venter is slightly paler and less glossy. The calcar usually lacks a keel. Long hairs on the hind foot extend beyond the toes. The tragus is blunt.
The species of bat that has been documented occurring in Kansas and can be confused with Myotis lucifugus is Myotis septentrionalis. The easiest way to differentiate between these species relates to the tragus, which is relatively short and blunt in Myotis lucifugus but long and pointed in Myotis septentrionalis. Also, the ears are much longer in the latter, extending beyond the tip of the nose when laid foreward. Potentially confusing species that have not been documented in Kansas yet but might occur here are Myotis sodalis and Myotis yumanensis. From Myotis sodalis, Myotis lucifugus differs in lacking a keel on the calcar and in long hairs on the hind feet. Myotis lucifugus differs can be distinguished from Myotis yumanensis by the glossy pelage in the former (the pelage is dull in the latter).

Distribution:
This species ranges from Alaska and the southern half of Canada south to Arizona in the West, Nebraska on the Great Plains, and the Gulf Coast in the East. It is known from the eastern two-thirds of Kansas. During winter, the little brown myotis hibernates in draftless caves where temperatures are low but above freezing and humidity is high. In summer, this bat occupies buildings or roosts under the loose bark of trees, in hollow trees, and in shallow crevices in cliffs. Eastern Kansas is at the western periphery of its distribution on the Great Plains, and it probably was never abundant here because of the lack of suitable caves in which to hibernate. It is possible that, before the mid-1960s, all or most bats of this species in Kansas hibernated in just one location: the large gypsum mines in Marshall County. The owner and operator of those mines, National Gypsum, no longer permits anyone to enter the mines and check for bats. It is perhaps informative that no specimens of Myotis lucifugus have been collected in Kansas since 1967. Therefore, it is possible that the species has been eliminated from the state's fauna. Even if a few individuals are found in Kansas in the future, it seems appropriate to list the species as endangered in the state.
Fossils of this species were found in a Holocene cave deposit in Kentucky.

(, Museum Voucher) (, Observation) (, Literature Record)
Open icons are questionable records; Click on a marker to view details.
  • Occurrence Summary:  
  • 82 Total Records 
  • 81 Museum Vouchers 
  • 1 Other Observations 
Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):
Barber (1); Comanche (1); Crawford (11); Douglas (7); Leavenworth (7); Marshall (54); Pratt (1);

Natural History:
This species is abundant in the eastern United States, where it forms large colonies and is known as a "house bat." Consequently, its physiology, ecology, and natural history are relatively well known. The little brown myotis, like most other bats, has a system of echolocation for evaluating the distance, size, and movement of flying prey and for evading obstacles. The ultrasonic calls are broadcast from the larynx through the mouth and echoes are reflected from objects back to the bat's ears. The ability to acoustically "see" objects is best demonstrated in total darkness of caves where little brown bat are able to fly about in close quarters with colliding. Echolocation functions with such a high degree of accuracy that the chance of a bat accidentally contacting a human in nature is negligible; the idea of bats attacking humans and becoming entangled in their hair is unfounded. Specializations in bats' ears permit reception of echoes with the least amount of interference from the high frequency calls being emitted. Partial separation of the bony capsule housing the middle and inner ear from the rest of the skull bones also reduces interference. In autumn, these bats move into their hibernacula and enter a torpor that may last all winter. While in the torpor, the rate of breathing and the pulse rate are greatly suppressed and the body temperature drops to just above freezing. If the ambient temperatures of a hibernaculum is too cool or too warm, hibernation is interrupted and the bats become active, searching for new roost sites where optimal conditions are found. Disturbance of bats in caves by humans, especially in winter, is a major factor in bat mortality.
Adults may attain the following dimensions: total length 85-100 mm; length of tail 33-40 mm; length of hind foot 8-11 mm; length of ear 14-16 mm; weight 5.5-8.5 g (in summer). Bats of this species commonly live more than 10 years, and 1 individual was documented as having lived more than 31 years. However, because of a high rate of mortality, the average longevity is about 2 years.
Little brown myotis fill an important ecological niche, taking over the insect foraging activity of birds at night. Their food consists entirely of insects, especially aquatic isects but also small beetles, moths, and gnats, as well as mosquitoes. Quantities sufficient to maintain flight metabolism require these bats to eat up to half their weight in a night's foraging. A study conducted in a laboratory revealed that a flying little brown myotis caught and ate 12 fruit flies in 1 minute. Insects larger than those which can be consumed in flight are carried to perches where they are eaten at leisure. The most undigestible parts are dropped to the ground and are telltale signs of feeding perches. In late autumn, fat is accumulated for the 6 to 7 months of hibernation.
A variety of predators feed on little brown myotis, including small carnivores, birds, mice, and snakes. Accidents may cause even more mortality than predators. Examples include bats impaled on barbed wire or burdock and animals killed in hibernacula by flood waters. Exposure to pesticides is another major cause of mortality. Finally, disturbance of hibernating bats by cavers, scientists, mining operations, or others can decimate colonies.
Breeding takes place in late autumn or winter, the latter in the hibernacula. Females are promiscuous and mate with several males. Males sometimes mate with torpid females that already have entered hibernation. The sperm remain dormant in the uterus until the single egg is released from the ovary. The egg is then fertilized in the right uterus. In 50 to 60 days, the young is born, sometime during May, June, or July. The naked newborn is one-fourth the weight of the mother. The eyes open on the second or third day. The young hold onto the mother's hair or nipples with claws and special hook-shaped temporary teeth. While females are foraging, the young remain in the nursery colony. They can fly at 3 weeks of age, and by the fourth week they are weaned. At 2 months they are capable of breeding. Males are not sexually mature until the next year. Juveniles can be distinguished from adults by the elongated cartilaginous joints of the fingers.

Occurrence Activity:
Remarks:
These bats have a low incidence of rabies. Throughout the northeastern United States, hibernating colonies of this bat (and at least one other species) are being decimated by a mysterious ailment that has been termed "white-nose syndrome" because of a white fungus that grows on the faces (and elsewhere) of hibernating bats. Tens of thousands of these bats are dying as a result. No one yet knows the cause of this mortality.
Populations of the little brown myotis that occur in Kansas are referrable to the subspecies Myotis lucifugus lucifugus.

Bibliography:
1934 Hibbard, C. W. Notes on some cave bats in Kansas. Trans. Kansas Acad. Sci., 37:235-238. ():
1967 Jones, J. K. Jr., E. D. Fleharty, and P. B. Dunnigan The distributional status of bats in Kansas. Univ. Kansas Mus. Nat. Hist. Misc. Publ., 46:1-33. ():
1980 Fenton, M. B., and R. M. R. Barclay Myotis lucifugus Mammalian Species 142():1-8
1983 Jones, J. K., Jr., D. M. Armstrong, R. S. Hoffmann, and C. Jones University of Nebraska Press, Lincoln, NE. 1-379pp.
1999 Wilson, D. E., and S. Ruff Smithsonian Institution Press, Washsington, DC. 1-750pp.
2000 Sparks, D. W., and J. R. Choate Distribution, natural history, conservation status, and biogeography of bats in Kansas Pages 173-228 in Reflections of a Naturalist: Papers Honoring Professor Eugene D. Fleharty Fort Hays State University, Hays, KS. pp.
2000 Sparks, D. W., K. J. Roberts, and C. Jones Vertebrate predators on bats in North America north of Mexico. Pages 229-241 in Reflections of a naturalist: Papers honoring Professor Eugene D. Fleharty. Fort Hays Studies, Special Issue 1, Hays, Kansas. pp.
2008 Timm, R. M., G. R. Pisani, J. R. Choate, N. A. Slade, G. A. Kaufman, and D. W. Kaufman http://www.ku.edu/~mammals, . pp.
Account Last Updated:
8/21/2018 7:55:03 PM


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