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Smithsonian National Museum of Natural History, North American Mammals

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  Chiroptera · Vespertilionidae · Myotis thysanodes

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Myotis thysanodes



Fringed Myotis



Order: Chiroptera
Family: Vespertilionidae

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Credit: New Mexico Bat Call Library, W. L. Gannon
Image of Myotis thysanodes
Myotis thysanodes - inset shows trailing edges of tail membranes
Click to enlarge. (95 kb)

Conservation Status: Least Concern.


The fringed myotis belongs to the long-eared myotis group, all of which tend to be high-elevation forest bats. This species has the shortest ears and occupies the lowest elevation of the group. Its wings are short and broad, indicating maneuverable, low-speed flight, and it seems to be a specialist at gleaning small beetles from vegetation surfaces. Beetles may make up 70 percent of its diet. Fringed myotis have one baby a year, and it is huge in proportion to the mother's size. A newborn's weight is 22 percent, and its length is 54 percent, of the mother's. Newborn bats are left hanging in special roosts, where 2-10 adult females are always present to care for them. The other females fly out at dusk to forage and return at dawn, but are there as necessary to nurse their young.  Before they are three weeks old, the young can fly, and by three weeks, they are as large as adults.

Sexual Dimorphism:
Females are larger than males.

Length:
Average: 89 mm
Range: 80-99 mm

Weight:
Average: 8.8 g
Range: 6-11.8 g

References:

Miller, G.S., Jr., 1897.  Revision of the North American bats of the family Vespertilionidae, p. 80.  North American Fauna, 13:1-135.

Links:

Mammal Species of the World (opens in a new window).

Mammalian Species, American Society of Mammalogists' species account *
* PDF reader available here (opens in a new window).

Distribution of Myotis thysanodes

Image of Myotis thysanodes
Click to enlarge. (141kb)