|The bats of Pennsylvania
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Big brown bats or the "Farmer's Friend" can be found during the day in certain barns and attics. At night they relentlessly feed over agricultural fields devouring crop pests.
Big Brown Bat (Eptesicus fuscus)
Big brown bats fly at dusk, and generally use the same feeding grounds each night. They fly in a nearly straight course 20-30 feet in the air, often emitting an audible chatter.
Among the last bats to enter hibernation, big brown bats seek out caves, buildings, mines, and storm sewers in October, November, or December. They hang close to the mouths of caves. They emerge in March and April. Females bear young in June, usually two per litter. As young mature and leave the nursery colony, adult males enter and take up residence. Big brown bats have lived up to 19 years in the wild. BatIndex
Tri-colored bat (Perimyotis subflavus)
Tri-coloreds take wing early in the evening and make short, elliptical flights at treetop level. In summer, they inhabit open woods near water, rock or cliff crevices, buildings, and caves. They hibernate from September through April or early May, deep inside caves and away from the openings, in zones where the temperature is about 52-55 F. They sleep soundly, often dangling in the same spot for months completely covered with water condensation.
Tri-coloreds eat flies, grain moths, and other insects. They breed in November, and young-usually two per litter-are born in June or July. Pipistrelles live 10-15 years. They are found throughout Pennsylvania, except in the southeastern corner. BatIndex
Hoary Bat (Lasiurus cinereus)
Hoary bats roost in trees-they prefer conifers, but also use deciduous trees-in woods, forest edges, and farmland. They choose protected sites 10-15 feet above the ground. Strong, swift fliers, they take to the air later than most other bats. They prey mostly on insects, but occasionally take pipistrelles.
Hoary bats migrate to warmer climates in winter. In spring, they return and raise young. The young are born from mid-May to early July, usually two to a litter. The female gives birth while hanging in a tree. Young grow rapidly and are able to shift for themselves in about a month. BatIndex
Indiana Bat (Myotis sodalis)
On right: Note less fur on muzzle of the Indiana bat, giving its face a more pinkish cast. The overall color of the fur also has a slight pink cast. Due to variations of the coloration of little browns and Indiana bats alike, the key to positive identification is careful inspection of the fine hairs on the feet and the edge of the tail membrane.
Indiana bats roost under the loose bark of trees in summer and have been found using buildings, roosting among common little browns. In winter, some 97 percent of the total species population hibernates in certain large caves in Missouri, Kentucky, Indiana, and Illinois. Pennsylvania is on the edge of the species' range. In our state in recent years, Indiana bats have been found wintering in only seven sites. The species has disappeared from all other known past localities. Populations of Myotis sodalis are dwindling throughout its range, and it is on the federal endangered species list.
The Indiana bat hibernates in clusters of about 250 bats per square foot on the ceilings and side walls of caves. In this formation, it is vulnerable to disturbance by cave explorers: when a bat on the edge of the cluster is awakened, it moves about, starting a ripple of activity that spreads throughout the group. A winter of repeated disturbances causes bats to burn vital fat stores, and they may run out of energy before spring.
Females of this species are believed to bear a single young in late June. Feeding habits are probably similar to those of the little brown bat. BatIndex
Little Brown Bat (Myotis lucifugus)
This bat eats a wide variety of flying insects, including nocturnal moths, bugs, beetles, flies, and mosquitoes. Insects are regularly caught with the wing or tail membrane, and transferred to the mouth. An individual emerges from its day roost at dusk, and usually seeks a body of water, where it skims the surface for a drink, and then hunts insects. The little brown bat makes several feeding flights each night.
In October and November, bats leave their summer roosts and move to tunnels, mine shafts, and caves. Here, clinging to the ceilings and clustered against one another, they hibernate. In spring, they emerge in April and May. They return to the same hibernation sites year after year, usually to the same exact spot in the cave or mine.
Females disperse from the hibernation roosts, and gather in summer nursery colonies of 10 to l,000 individuals in attics, barns, and other dark, hot retreats. Males are solitary, roosting in hollow trees, under loose bark, behind loose siding and shingles, and in rock crevices.
A single young is born to each female in June or early July. After four weeks the young bat is fully grown and ready to leave the colony. Females mature sexually at about 8 months of age, while males mature in their second summer. Little brown bats may live up to 25 years. BatIndex
Northern Long Ear Bat (Myotis septentrionalis)
Zoologists have learned little of the ecology and behavior of Northern long eared bat; although they suspect feeding habits are similar to those of the little brown. Long eared bats roost singly or in small colonies in caves, behind window shutters, under loose tree bark, in cliff crevices. Females gather in nursery colonies in attics, barns, and tree cavities. Probably a single young is born in July. Long eareds return to caves in fall, often sharing space with little brown bats, big brown bats, and tri-colored bats. BatIndex
Red Bat (Lasiurus borealis)
Red bats start flying early in the evening, preying on moths, flies, bugs, beetles, crickets, and cicadas, which they take from air, foliage, and ground. Strong fliers, red bats are considered migratory, although their migratory patterns are little known. The sexes may migrate separately. Red bats start flying south in September or October. BatIndex
Females bear 1-5 young (usually 2-3) in their treetop roosts. For the first few days, the young remain clinging to their mother when she flies out to hunt. Young are able to fly at 3-4 weeks, and are weaned at about 5-6 weeks old. Longevity is about 12 years . The red bat ranges across Pennsylvania.
Silver-Haired Bat (Lasionycteris noctivagans)
The silver-haired bat inhabits wooded areas bordering lakes and streams. It roosts in dense foliage, behind loose bark, or in a hollow tree-rarely in a cave. It begins feeding earlier than most bats, often before sunset. Silver-haired bats do not hibernate in Pennsylvania, migrating farther south. In summer, a few may breed in the cooler, mountainous sections of the state, but most go farther north. BatIndex
Small-Footed Bat (Myotis leibii)
The small-footed bat resembles the little brown bat, but has a golden tint to its fur. Besides somewhat ill-proportionated small feet and forearms, this bat has a distinctive black "raccoon mask". Feeding and breeding habits probably parallel those of the other small, closely related bats. The small-footed bat waits until November to enter caves for hibernating, and emerges in March. It hibernates in narrow cracks in the wall or roof, singly and in small groups. It usually stays close to entrances or in areas where the temperature is just above freezing. BatIndex
Note: The seminole bat (Lasiurus seminolus) and evening bat (Nycticeius humeralis) have been found a few times in Pennsylvania, but are considered incidental.
This information is adapted from the Pennsylvania Game Commission's Wildlife Note #175-35. Other Wildlife Notes on other animals are available through PGC, Bureau of Information and Education, Dept. MS, 2001 Elmerton Avenue, Harrisburg, PA 17110-9797.