Myotis thysanodes
fringed myotis

The fringed myotis is found across the western United States. It has been found as far east as the Trans-Pecos region of Texas during summer months, as far north as British Columbia and as far south as Mexico.

(Davis and Schmidly 1994, Nowack 1994)

This is a highly migratory species that roosts in caves, mine tunnels, rock crevices and old buildings. Their winter habitat is largely unknown.

(Davis and Schmidly 1994)

Myotis thysanodes is one of the larger species of the Myotis genus and has a total body length of 85mm, tail length of 37mm, foot length of 9mm and ear length of 16.5mm. Its name comes from the fringe of short hairs that line the interfemoral membrane. This species has a full pelage of light brown on its back and off -white underparts. It has a dental formula of I 2/3, Ca 1/1, Pm 3/3 and M 3/3.

(Schmidly 1991, Davis and Schmidly 1994)

After a gestation period of 50 - 60 days, a single young is born in late June or early July. Young bats are not entirely precocial, but are able to fly in about 16 days.

(Schmidly 1991)

In the southern United States, this species usually arrives around mid-May to begin nursery colonies which may contain hundreds of individuals. Female "nurse bats" remain at the roost to care for the young while other adults are out foraging. Males and females usually do not associate with one another during summer months and males are not normally found within the maternity roosts. The colonies have usually dispersed by the end of October.

(Davis and Schmidly 1994, Schmidly 1991)

Myotis thysanodes feeds mainly on beetles and other insects and appear in the late evening. Observations indicate that this species uses its ability for highly maneuverable flight to forage close to the vegetative canopy. It has been suggested that the fringe of hairs along the uropatagium is used to trap small insects.

(Davis and Schmidly 1994, Glass and Gannon 1994)

Bats act as an essential past control by eating hundreds of pounds of insects each night that they forage. They are of great interest to farmers for this role in preventing crop destruction by the insects without the use of harmful chemicals and pesticides.

(Schmidly 1991)

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%. While there are currently no reports of Myotis thysanodes mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America. (Cryan, 2010; National Park Service, Wildlife Health Center, 2010)