Bats comprise one-fourth of the world's 4,000 species of mammals. Fruit-eating bats are nature's most important seed-dispersing animals. Nectar bats pollinate many rain-forest trees, shrubs, and flowers and without their help the forest would be less diverse.
The ability of insect-eating bats is phenomenal--one little brown bat can eat 600 to 1,000 mosquitoes in an hour. Over-sized ears and nostrils help bats to use a sonar system that experts believe is a thousand times more sophisticated than the best airport radar invented to date.
Of the 43 species of bats that live in the U.S., nine insect-eating species of bats live in Michigan. All are nocturnal (active at night), and feed nearly exclusively on flying insects, including moths, beetles, and mosquitoes.
Bats in Michigan
1. The little brown bat is the most common and gentle bat found throughout Michigan and is the most seen species. A light brown bat with a wingspan of 8 1/2 to 11 1/2 inches, small ears, and large feet. In summer, colonies of the species live in hot attics and under shingles and siding or in manmade bat houses; in winter, they hibernate in caves, crevices, houses, hollow trees, or mines. Females form nursery colonies away from the males. Little brown bats like to feed on aquatic insects and are frequently seen dipping and diving over water but will also forage over lawns and pastures, among trees, and under street lights.
2. The big brown bat has a large nose, is reddish to dark brown in color, and sports a wingspan ranging from 12 1/2 to 13 1/2 inches. Its slow, steady flight, and large size make it fairly easy to identify. Beetles, wasps, mosquitoes and flies from pastures, lawns and vacant lots in the city make up its diet. They are late-dusk fliers that often swoop low to the ground. A colonizing species, big browns roost in buildings and under bridges in summer and hibernate in caves, mines, houses, hollow trees, and even storm sewers in winter. Efficient feeders, the species often roosts for a short nap after gorging itself. Porches, garages, and breezeways are good places to find them. The female gives birth to only one pup per year.
3. The hoary bat is Michigan’s largest with a wingspan of up to 15 inches and lives in the forest. It’s rarely encountered by people and migrates south in winter.
4. The red bat also migrates south and is a solitary bat of forests near water. Its long, pointed wings may stretch 12 inches, and it has short, rounded ears, and a furred tail. Color varies from a bright orange to a yellow-brown.
5. The silver-haired bat, considered scarce, lives in forested areas near streams and lakes. Similar in size to the red bat, it is black or dark brown with silver on the tips of its hairs.
6. The eastern pipistrelle bat does not migrate but hibernates in caves or abandoned mines through winter in the western Upper Peninsula year-round. A golden brown to reddish brown tiny bat with a wingspan of 10 inches or less.
7. The northern long-eared bat has very large ears make these bats easy to identify at close range. A brown bat with wings that stretch 12 inches, it typically roosts alone in buildings and under tree bark in the summer, small numbers hibernate together in caves, often with big brown bats.
8. The evening bat lives in extreme southern Michigan and is easily confused with the little brown bat except the evening bat has a curved, rounded fleshy protrusion (tragus) on the ear instead of a pointed tragus. Their wings span 10 to 11 inches. The evening bat flies low to the ground and is sometimes seen swarming around caves, which it rarely enters.
9. The Federally endangered Indiana bat in southern Michigan closely resembles the little brown bat.
Concerns: Scientific surveys of wild bats typically report rabies in less than 0.5% for most North American bat species. In addition, bats are not “carriers” of rabies; when a bat gets the disease it will die. Bats also tend to become paralyzed with the disease, often avoiding the aggressive form of rabies.
Bats prefer to live in dead trees during the summer. Without natural habitat, brown bats will take up residence in human-made buildings. Rather than killing these beneficial mammals, prevent entry into your home by locating and plugging potential entrance holes after sunset when they leave. Putting up a bat house nearby may discourage them from entering your home while keeping them in the area.
Original article: michigandnr.com
Sargent, M.S and Carter, K.S., ed. 1999. Managing Michigan Wildlife: A Landowners Guide. Michigan United Conservation Clubs, East Lansing, MI. 297pp.