Fringed Myotis
The fringed myotis is distinguished by its relatively long ears and a conspicuous fringe of stiff hairs on the trailing edge of the uropatagium (tail webbing).
About This Species
The pelage varies in color from pale to rich brownish, individual hairs being lead-gray at their bases. The membranes are dark. The only other medium-sized myotis with long ears is the long-eared myotis, a species in which the ears are 21-24 mm long (by contrast with ears 17-20 mm long on the fringed myotis).
Living with Bats
There are 18 species of bat that call Colorado home. These amazing mammals are not only fantastic insect control, but are also valuable pollinators. Learn more about how humans and bats can live in harmony in our guide.
Bat Conservation
Bats remain one of the most mysterious land mammals, especially in Colorado, where 18 species spend at least part of the year. For example, the little brown bats in our state seem to hibernate differently than those on the east coast, and we are constantly learning about their whereabouts, habitats and behaviors. Our current research suggests that bat populations in Colorado are doing quite well.
One little brown bat can eat up to 18,000 small insects (like mosquitoes) each night. Their economic impact is estimated to be billions of dollars, and much of the agricultural industry relies on their insect control.
Beyond their economic impact, bats flaunt some impressive adaptations. They are the only mammal that truly flies, which requires a very unique anatomy. Their upside-down lifestyle requires adaptations in their “feet” to consistently grip. If people hanged upside down for even an hour, we’d lose consciousness; bats have developed amazing blood pressure accommodations to fit the lifestyle.
We are currently involved in a monitoring partnership called the North American Bat Monitoring Program (NA Bat). The program utilizes acoustic surveys to collect information on bat populations without interfering with their behaviors. We also are using PIT tags, like the chips put in household pets, to monitor a number of maternity sites. While data collection will take years, we’ve already learned new information about Colorado’s bat population, the most heartening of which is that the population appears larger and more widespread than we’d thought. This is an excellent start to learning more about the species, but we’ve got lots of problem-solving and technological innovation left to do.
Our priorities also include learning more about bats so that we are prepared for the potential spread of White-nose Syndrome. Finding and monitoring bats is crucial to this effort, but also comes with its own challenges. Because bats are small, flying mammals, much of the equipment used to track other species is too heavy for them. And during the winter, Colorado bats are very elusive, choosing to hibernate in small groups often in locations that are inaccessible to people.
More Information:
Physical Characteristics
Total length of five individuals from northwestern Colorado averaged 86.8 mm; length of forearm averaged 40.1 mm: and weight averaged 7.5 g. The wingspan is 265-300 mm.
Range
This is a western North American species, ranging from the Isthmus of Tehuantepec in Mexico north to British Columbia, Montana and Wyoming. The animals apparently occur as scattered populations at moderate elevations on the Western Slope, along the foothills of the Front Range and the mesas of southeastern Colorado. Maximum elevation is 7,500 feet.
Habitat
The fringed myotis is a species of coniferous forest and mixed pine woodland at moderate to low elevations in Colorado. Records of occurrence are few with, the species thought to be rare in the state, but perhaps it is simply widely distributed. Typical vegetation of the habitat includes ponderosa pine, pinyon, juniper, greasewood, saltbush and scrub oak. The animals roost in rock crevices, caves, mines, buildings and trees. They are known to hibernate in caves and buildings, and may use rock crevices as well. Where this species has been studied well, migration seems not to be extensive.
Diet
The fringed myotis feeds on such arthropods as moths, daddy longlegs and beetles. They forage along water, above shrubs and woodlands or low over meadows (apparently in more open areas than the long-eared myotis), emerging to feed about two hours after sunset. Flight speeds average about 9 miles per hour.
Reproduction
Breeding takes place in fall; ovulation, fertilization, implantation and gestation occur in spring, as sperm are stored over the winter in the female's uterus. Up to several hundred females can aggregate in nursery colonies but are more likely to occur in smaller groups (10-20). Males are solitary while the young are reared. In a typical season, all mature females breed. A single young is produced after a gestation of 50 to 60 days. Newborn young are hairless and pinkish, and their eyes are closed. Growth is rapid, however, and they can fly by 20 days old. Maximum known longevity is 11 years, although some individuals may live even longer.