Fringed Myotis (Myotis thysanodes)

Protection Status Notes
M. thysanodes is ranked as 'rare or possibly rare' in Texas. It is a former category 2 candidate species.
Description
Myotis thysanodes is a rather large Myotis with long ears and reddish‑brown hair. It can be distinguished from all other species by a conspicuous fringe of hair along the posterior edge of its interfemoral membrane.
Life History
The fringed bat is a colonial-roosting species with colonies ranging anywhere from 10 to 2,000 individuals, although large colonies are quite rare.

Copulation occurs in the fall following break‑up of maternity colonies. Ovulation, fertilization, and implantation occurs from April to May. Gestation averages 55 days. One young per female is born from May to July. Young are capable of flight at 16 days and fully volant at 20 days.

Not much is known about the diet of the fringed bat. Their diet is based on insects. Some studies have shown that beetles are their preferred prey, while others show that moths or crickets are eaten more often than anything else.
Habitat
This species has been found in hot desert scrubland, grassland, xeric woodland, sage‑grass steppe, mesic old‑growth forest, and multi‑aged subalpine coniferous and mixed‑deciduous forest. Xeric woodlands (oak and pinyon‑juniper) appear to be the most commonly used.

Where available, caves, buildings, underground mines, rock crevices in cliff faces and bridges are used for maternity and night roosts, while hibernation has only been documented in buildings and underground mines. Tree-roosting has also been documented in Oregon, New Mexico, and California.
Distribution
M. thysanodes ranges through much of western North America from southern British Columbia, Canada, south to Chiapas, Mexico and from Santa Cruz Island in California, east to the Black Hills of South Dakota.

This highly migratory western bat is known in the Trans-Pecos region in Texas, where they arrive by May and form nursing colonies and have their young. They stay till October then move on to winter locations.
Threats and Reasons for Decline
Abandoned mine closures, recreational caving and mine exploration, renewed mining at historic sites, and building and bridge conversion pose threats to roosts. Toxic material impoundments and pesticide spraying can have direct poisoning effects on M. thysanodes populations. Vegetative conversion, livestock grazing, and timber harvest can modify the insect prey base and affect bat populations.
Ongoing Recovery
Abandoned mines should be surveyed for the presence of bats before closing. If bats are present, bat-friendly gates should be installed. Toxic material impoundments should be inaccessible to any wildlife. More information regarding distribution and ecology is required for effective species conservation and management.
Other
Seasonal abundance differences within and between geographic, altitudinal and habitat boundaries are unknown. Other basic life history information such as roost requirements, generational turnover, longevity, and adult male life history is lacking.
For more information
  • Refer to the online version of The Mammals of Texas for additional details on the Fringed Myotis.

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