"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."

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Chiapas (Mexico) to Southwestern South Dakota (USA) and British Columbia (Canada) (Simmons 2005).

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)

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Western North America from southcentral British Columbia (low numbers, but known to breed; Balcombe, 1988 COSEWIC report) south through the western United States to Veracruz and Chiapas in southern Mexico. An apparently disjunct population occurs in the Black Hills region, Wyoming-South Dakota-Nebraska (O'Farrell and Studier 1980, Hall 1981). Winter range is little known.

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)

Range mass: 5 to 9 g.

Average mass: 6 g.

Length: 10 cm

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

Habitat and Ecology

Systems

• Terrestrial

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)

Terrestrial Biomes: savanna or grassland

Comments: Primarily at middle elevations of 1,200-2,150 m in desert, grassland, and woodland habitats; has been recorded at 2,850 m in spruce-fir habitat in New Mexico, and at low elevations along Pacific Coast. Roosts in caves, mines, rock crevices, buildings, and other protected sites. Nursery colonies occur in caves, mines, and sometimes buildings.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Known to migrate, but little is known about migration distances and destinations (O'Farrell and Studier 1980). Arrives in Trans-Pecos Texas in May (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)

Comments: Insectivorous; beetles are a common prey item. Wings have a high puncture strength, which is characteristic of bats that forage by gleaning from the ground or near thick or thorny vegetation (O'Farrell and Studier 1980). Often forages close to vegetative canopy.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: Has not been intensively surveyed across range, and occurrence information is not available from Mexico and portions of the United States. Therefore, the total number of occurrences has been estimated from available natural heritage program data, occurrence estimates, state ranks, and collection site maps. The Idaho Natural Heritage Program has recorded seven occurrences (Chuck Harris, pers. comm., 1998). In Oregon the heritage program has recorded 43 occurrences and believes about 35 occurrences are extant (Eleanor Gaines, pers. comm., 1998). Six occurrences dating from 1961-1992 have been recorded by the Montana Heritage Program (Paul Hendrick, pers. comm., 1998). The Arizona Heritage Program is aware of 14 extant occurrences (Sabra Schwartz, pers. comm., 1998). The Nevada Heritage Program has recorded 15 extant occurrences; the condition of Nevada occurrences is estimated to be good (Carrie Carreno, pers. comm., 1998). The Wyoming Heritage Program stated that occurrences have not been recorded, but there are approximately 75 verified observations. Based on this information, the Wyoming Heritage Program estimates that there are at least 6 but fewer than 100 occurrences (Mary Neighbours, pers. comm., 1998). The Washington Heritage Program has not recorded occurrences, but estimates 21-101+ occurrences (John Fleckenstein, pers. comm., 1998). In South Dakota the heritage program estimates 21-100 occurrences (Doug Backlund, pers. comm., 1998). The Colorado Heritage Program estimates 6-20 occurrences (Mike Wunder, pers. comm., 1998). Occurrences have not been recorded in Nebraska, but based on a 1995 bat survey 6-20 occurrences are estimated. The estimated condition of Nebraska occurrences is 10% excellent, 80% good, and 10% fair (Mike Fritz, pers. comm., 1998). Hasenyager (1980) listed 10 collection sites in Utah. Nagorsen and Brigham (1993) mapped approximately 10 collection sites in British Columbia. Schmidley (1977) mapped 17 collection sites in Texas and the state heritage program has assigned a rank of S3, typically 21-100 occurrences. The New Mexico Heritage Program has assigned a rank of S5, typically 101+ occurrences and/or secure.

10,000 to >1,000,000 individuals

Comments: Based on an analysis of state heritage program ranks and state listings (i.e., watch lists, threatened, endangered, etc.), the Western Bat Working Group (1998) concluded that this bat may be uncommon or rare through the bulk of the range, not merely at the periphery. Little quantitative data are available on abundance. However, Jones (1966) reported monthly changes in relative abundance of mist-netted bats. In addition, relative abundance values were obtained over a 10-year period by Jones and Suttkus (1972) in western New Mexico. Populations fluctuated over a 10-year period resulting in a small net gain in abundance; population lows occurred in 1962 and 1963, whereas peak abundance occurred in 1965 (Jones and Suttkus 1972). Colonial roosts range from 10 to 2,000 individuals, and large colonies are extremely rare (Western Bat Working Group 1998). According to Tuttle and Taylor (1994) mine colonies include dozens to hundreds of individuals.

Thysanodes is found with many other species including: M. EVOTIS, M. VOLANS, M. CALIFORNICUS, etc.

Comments: Known to be active April-September. During winter, hibernation may be periodically interrupted (O'Farrell and Studier 1980).

Average lifespan

Sex: male

Status: wild: 18.3 years.

Maximum longevity: 18.3 years (wild)

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)

Range number of offspring: 1 to 1.

Range gestation period: 50 to 60 days.

Average weaning age: 21 days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; sperm-storing

Average birth mass: 1.32 g.

Average number of offspring: 1.

Seemingly there is little variation in the timing of reproduction throughout the range. In northeastern New Mexico, copulates in fall; ovulation, fertilization, and implantation from late April to mid-May; gestation lasts 50-60 days; births late June to mid-July (O'Farrell and Studier 1973). Litter size is 1. Young can fly at 16-17 days. Colony size ranges up to several hundred; colonies begin to disperse by October.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Species: 2
Species With Barcodes: 1

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.

CITES: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N2 - Imperiled

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Widespread in western North America; well over 100 occurrences; abundance is apparently low; protected at a minimum of three locations; appears to be moderately threatened.

Other Considerations: Has been misidentified as M. EVOTIS (Mattson and Bogan 1993).

Population

Population Trend

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Specific population trend information is not available and can only be estimated. Statements regarding population trends vary from declining to stable. According to the Oregon Heritage Program, population trends are unknown, but bats in general are thought to be declining (Eleanor Gaines, pers. comm., 1998). The Nevada Heritage Program stated that populations are declining (Carrie Carreno, pers. comm., 1998). Believed to be stable at low numbers in Wyoming (Mary Neighbours, pers. comm., 1998). Appears to be stable in Arizona (Arizona Game and Fish Department 1997). The status of populations in Canada is uncertain. However, recent evidence of a breeding population in Canada indicates that it is still viable within a very restricted range (Balcombe 1988).

Major Threats

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: The greatest threat is human disturbance of roost sites, especially maternity colonies, through recreational caving and mine exploration (Western Bat Working Group 1998; George Oliver, pers. comm., 1998, Arizona Game and Fish Department 1993). Unprotected caves in South Dakota are heavily used and vandalized (Doug Backlund, pers. comm., 1998), and in Wyoming caves are threatened by recreational use (Mary Neighbours, pers. comm., 1998). Other threats include closure of abandoned mines, renewed mining at historic sites, toxic material impoundments, pesticide spraying, vegetation conversion, livestock grazing, timber harvest, and destruction of buildings and bridges used as roosts (Western Bat Working Group 1998). Also threatened by the disturbance or destruction of water sources and riparian habitat (George Oliver, pers. comm., 1998). The estimated degree of threat varies across the range, but is considered moderate through the majority of the range. The degree of threat is considered moderate by the Sonora, South Dakota, Utah, Oregon, Wyoming and Washington heritage programs (Andres Villareal Lazarraga, Doug Backlund, George Oliver, Eleanor Gaines, Mary Neighbours, and John Fleckenstein, pers. comm., 1998). However, the Nevada Heritage Program regards this bat as very threatened (Carrie, Carreno, pers. comm., 1998). Regarded as not very threatened in Nebraska (Mike Fritz, pers. comm., 1998).

Conservation Actions

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: The United States Forest Service has gated several South Dakota caves that are known hibernacula. Davenport Cave, Jewel Cave, and Badlands National Park are protected occurrences in South Dakota (Doug Backlund, pers. comm., 1998).

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)

Comments: See Manning (1988) for a description of the new subspecies VESPERTINUS from California, Oregon, and Washington.