 | List of Images Audiovisual Program photos copyright: Merlin D. Tuttle Produced by: Bat Conservation International Inc. P.O. Box 162603 Austin, Texas 78716 |
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| List of Images Audiovisual Program photos copyright: Merlin D. Tuttle Produced by: Bat Conservation International Inc. P.O. Box 162603 Austin, Texas 78716 |
Updated 04/24/01
| IMAGES | REFERENCE INFORMATION |
| 1. Red bat (Lasiurus borealis) roosting in fall foliage
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Bats form a significant, yet often overlooked component of the mammalian fauna found in North American forests. For example, in just three national forests in Arkansas, bats constitute nearly a quarter of the state’s 70 species of mammals. But, because of their small size and nocturnal nature, the presence and contributions of bats to these environments often go unnoticed. Moreover, when we think of bats, we tend to think only of cave environments, but in reality, many species of bats rarely, if ever, enter caves at all. These species are referred to as “tree bats” due to their penchant for choosing forest roosts and habitats. Forests provide a plethora of potential roosts for tree bats. Some species form colonies in huge old hollow trees such as sycamore and cypress. Others choose smaller crevices in dead or dying wood, sometimes in natural hollows or in cavities excavated by woodpeckers. Many species roost under exfoliating bark or beneath thick convolutions in the furrowed bark of tree species like hickory, walnut, fir and some pines. A few species, like red bats (Lasiurus borealis), roost right out in the foliage of deciduous or evergreen trees. Despite their bright red color, these bats are actually rather cryptic, often resembling dead leaves or pine cones. Red bats are well camouflaged as they hang curled-up in their furry tail membranes, suspended from a single foot, twisting slightly in the breeze. For the most part, red bats are solitary, coming together only to mate and to migrate. Unlike most bats, red bats often give birth to twins and can have litters of up to five young, though three is average. Red bats typically feed around forest edges, in clearings or around streetlights where they mostly consume moths. In the fall they perform long-distance migrations using the same migratory routes along the Atlantic seaboard as many birds. Very little is known about their winter habitat or behavior. In some areas of the southeastern U.S., red bats have occasionally been encountered flying up out of the leaf litter on the ground in advance of prescribed burns done in winter. |
| 2. Typical eastern forest with inset of an eastern pipistrelle (Pipistrellus subflavus) portrait
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The eastern pipistrelle (Pipistrellus subflavus) is one of the most common species of bats found throughout the eastern forests of America from Nova Scotia and Quebec, south throughout the east coast of Mexico into northern Central America. But, surprisingly little is known about its daytime summer roosts. These bats are among the first to emerge at dusk, and their appearance at tree-top level indicates that they may roost in foliage or in high tree cavities and crevices. They are seldom found in buildings or in deep woods, seeming to prefer edge habitats, often near areas of mixed agricultural use. Where information about their foraging behavior is known, these bats have been found to feed on small leaf-hoppers, ground beetles, flies, moths and ants. Eastern pipistrelles cannot withstand freezing temperatures and are among the first bats to enter hibernation each fall and the last to emerge in spring. Hibernation sites are found deep within caves or mines in areas of relatively warm (close to 50EF or 10EC), stable temperatures. These bats have strong roost fidelity to their winter hibernation sites and may choose the exact same spot in a cave or mine from year to year. As with many forest bat species which spend their winters underground, far more is known about their hibernation habitats and behavior than is known about their summer needs. |
| 3. Hollow sycamore with inset of a Rafinesque’s big-eared bat (Corynorhinus rafinesquii)
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Bats, such as Rafinesque’s big-eared bat (Corynorhinus rafinesquii), are known to form nursery colonies in large hollow trees. Hollow tree roosts provide stable internal environments, protection from predators, and often contain well-insulated areas that form the hot-air traps essential for rearing young. These bats range throughout the southeastern U.S. from southern Kentucky and Virginia south and west to eastern Texas and northward along the Mississippi River valley to southern Indiana. Their range most closely approximates the historical range of great cypress swamps, indicating that they may have formed a traditional reliance on these areas for roosting and foraging sites. As these swamplands have been drained and trees have been harvested, big-eared bats have attempted to move their maternity roosts into old buildings or attics. Big-eared bats are slow, agile flyers and appear to forage on a wide variety of small nocturnal insects, especially moths. They hibernate near their summer foraging grounds in old mines, caves and cisterns. Though widespread in the eastern U.S., this bat is nowhere abundant and population levels appear to have declined severely in the past century due to loss of summer roosting or foraging habitat and disturbance at winter hibernacula. Big-eared bats are at special risk where they form nursery or hibernation colonies in caves that are susceptible to recreational disturbance and in abandoned mines slated for closure or reclamation. |
| 4. Indiana myotis (Myotis sodalis) roosting under exfoliating bark
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The Indiana myotis (Myotis sodalis) was one of the first bat species in the U.S. to be recognized as endangered by the U.S. Fish and Wildlife Service Endangered Species Act. This listing was largely due to declines recorded at winter hibernation caves, which, until very recently, were the only known roosts for this species. It is now known that in summer Indiana myotis roost and rear their young under loose bark or in small tree cavities. They are found throughout the eastern U.S. from the central Midwest and upper New England states, south to the northern Gulf States and into extreme northern Florida. In winter the largest hibernating populations of Indiana myotis occur in just three states: Kentucky, Missouri and Indiana, where they form large, highly vulnerable aggregations. Human disturbance and alteration of hibernation caves have caused the largest documented decline, though pesticide poisoning and loss of summer roosting and foraging habitat due to deforestation have also contributed to the reduction. Because nursery colonies roost mainly under exfoliating bark, their summer roosts are short-lived, requiring a mosaic of multi-aged trees to provide new roosts from year to year. Moreover, like many cavity- or crevice-dwelling bats, Indiana myotis switch roosts often throughout the summer maternity season. Maternity colonies appear to have at least one primary roost that is used by the majority of the colony. Over a dozen different alternate roosts may be used by portions of the colony intermittently. One reason for this roost-switching may be due to differing thermoregulatory needs at different stages of the reproductive process for individuals or as a result of environmental deviations from normal climatic patterns. Bats may also switch roosts due to increased parasite loads or unstable food resources brought on by drought or unusually heavy rains. Detailed investigation into the habitat needs of this bat throughout its large summer range is warranted, including a greater understanding of food habits. Many important hibernation sites remain unprotected or unacceptably altered, and these problems must be remedied. |
| 5. Eastern long-eared myotis (Myotis septentrionalis) roosting under exfoliating bark
(#5 of 10)
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The eastern long-eared myotis (Myotis septentrionalis, formerly M. keenii, in part) is widely distributed in eastern North America from Manitoba across southern Canada to Newfoundland, south to northern Florida, west through the south central states and northwest to the Dakotas. It is found in dense forest stands and chooses maternity roosts beneath exfoliating bark and in tree cavities, much like the Indiana myotis. And, like the Indiana myotis, the eastern long-eared myotis relies upon caves and underground mines for hibernation sites, where it typically chooses cooler sites than eastern pipistrelles (Pipistrellus subflavus) and little brown myotis (Myotis lucifugus). This species is generally found alone or in small nursery colonies. During the summer, the eastern long-eared myotis appears especially reliant upon forested habitats and is found in greater densities in the northern areas of its range than in the south. Eastern long-eared myotis are slow, maneuverable flyers, perfectly adapted for foraging in cluttered forest environments, and they often have been observed gleaning insects directly from foliage. These bats are suspected to forage exclusively beneath the forest canopy where they feed on beetles, moths, caddisflies and mayflies. |
| 6. Evening bat (Nycticeius humeralis) portrait
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The evening bat (Nycticeius humeralis) is abundant throughout the southeastern U. S., northward to the upper Midwest and Ontario. It ranges along the Atlantic Seaboard south to Florida and Veracruz, Mexico. The evening bat is almost never encountered in caves. It forms nursery colonies in hollow trees, behind loose bark and sometimes in buildings and attics. Some colonies contain several hundred individuals. Evening bats emerge soon after dusk and forage on a large array of small nocturnal insects including flying ants, spittle bugs, June beetles, Japanese beetles and moths. In the fall, evening bats store large amounts of fat indicating a lengthy migration to southern parts of its range. In a banded bat recovery study, bats were found as far as 340 miles (547 km.) south of their banding sites. Yet, little research has been done to learn exact migration movements of this species. It never has been found hibernating in caves and simply disappears from summer habitats each fall. Once these bats arrive at their over-wintering sites, they are thought to remain active throughout the winter. |
| 7. Southeastern myotis (Myotis austroriparius) in flight
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Southeastern myotis (Myotis austroriparius) range in a broad band from Indiana and Illinois south along the Mississippi River and around the southeastern coastal plain to North Carolina. Yet, despite this rather wide distribution, few maternity colonies have been discovered outside of Florida. This bat uses a variety of roosts in a variety of habitats including hollow trees in forested areas but also bridges, buildings and culverts. Southeastern myotis are most commonly associated with caves, where they form large maternity colonies, sometimes containing tens of thousands of individuals. This bat appears to remain active for much of the year in the southern portions of its range, feeding predominately on a variety of aquatic insects. This species is known to live only in forested areas, and recent radio-tracking studies have documented maternity colonies in large hollow trees of hardwood swamps far from the nearest caves. The southeastern myotis appears to be in steady decline, and it is considered a species of concern. |
| 8. Big brown bat (Eptesicus fuscus) in flight with a beetle
(#8 of 10)
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The big brown bat (Eptesicus fuscus) is found in virtually every North American habitat, ranging from timberline meadows to lowland deserts, though it is most abundant in deciduous forests. It is also abundant in suburban areas of mixed agricultural use. This species ranges from extreme northern Canada, throughout the U.S. and south to the extreme southern tip of Mexico. Traditionally, these bats have formed maternity colonies beneath loose bark and in small cavities in pine, oak, beech, bald cypress and other trees. Common maternity roosts today can be found in buildings, barns, bridges and even bat houses. Small beetles are their most frequent prey, yet big brown bats will consume prodigious quantities of a wide variety of night-flying insects. They are generalists in their foraging behavior and habitat selections, seemingly showing little preference for feeding over water vs. land, or in forests vs. clearings. Like all insect-eating bats, big brown bats contribute mightily to a healthy environment and are vital players in the checks and balances of insect pests. Numerous feeding studies of big brown bats exist, indicating that they consume significant crop and forest pests including ground beetles, scarab beetles, cucumber beetles, snout beetles and stink bugs, in addition to numerous species of moths and leafhoppers. Like many bat species, reproductive females often can consume their body weight in insects each night. In fact, a colony of 150 big brown bats can consume enough adult cucumber beetles in one summer to prevent egg-laying that would produce 33 million of their root-worm larvae, a major pest of corn. Big brown bats clearly rank among America’s most beneficial animals. As they are forced out of traditional forest habitats due to encroaching human populations, logging and habitat modification, they will move into increasingly close human contact, taking up residence in buildings and other man-made structures. But, humans and bats can coexist peacefully. Sometimes bat houses are the best options to keep bats out of our homes, yet near enough so that we can continue to benefit from their insect-eating capabilities. Though many species, like the big brown, still rank among our most abundant and widespread bats, they nevertheless deserve attention from conservation and education initiatives for healthy environments. |
| 9. Silver-haired bat (Lasionycteris noctivagans) emerging from a woodpecker hole
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Silver-haired bats (Lasionycteris noctivagans) are among the most common bats in forested areas of North America, most closely associated with coniferous or mixed coniferous and deciduous forest types, especially in areas of old-growth. They form maternity colonies almost exclusively in tree cavities or small hollows. Like many forest-roosting bats, silver-haired bats switch roosts throughout the maternity season. Because they are dependent upon roosts in old-growth areas, managing forests for diverse age structure and maintaining forested corridors are important to their survival. It is estimated that these bats require snag densities of at least nine per acre (21 per hectare), though forest management practices have often fallen far short of this figure. Unlike many bat species, silver-haired bats appear to hibernate mainly in forested areas, though they may be making long migrations from their summer forest to a winter forest in a milder climate. Their typical hibernation roosts include small tree hollows, loose bark, wood piles and cliff crevices. Occasionally silver-haired bats will hibernate in cave entrances, especially in northern regions of their range. Even though they are highly dependent upon old-growth forest areas for roosts, silver-haired bats feed predominantly in disturbed areas, sometimes at tree-top level, but often in small clearings and along roadways or water courses. Though their diets vary widely, these bats feed chiefly on small, soft-bodied insects. Like big brown bats (Eptesicus fuscus), silver-haired bats have been documented to feed on many insects that are pests of humans, agriculture or forestry. They have been known to take flies, midges, leafhoppers, moths, mosquitoes, beetles, crane flies, lacewings, caddisflies, ants and crickets. |
| 10. Hoary bat (Lasiurus cinereus) roosting among foliage
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Many forest bats require tree roosts only in the summer, though some, such as this hoary bat (Lasiurus cinereus), rely on them year round. Hoary bats are capable of hibernating right out in the open on tree trunks, their grizzled gray fur providing perfect camouflage. Wherever forest bats occur, they are valuable allies and deserve protection. To date, much bat research and conservation has focused on threatened or endangered species or on bats that form relatively large, easy-to-study colonies in caves or mines. We are only now beginning to glimpse important insights to the secret world of bats in North America’s remaining forest ecosystems. In the 1870s red bats (Lasiurus borealis) were so common that great aggregations of them could be observed making diurnal migrations along the northern Atlantic coast. Today it is rare to encounter these bats during their southward treks. Forest bat populations have had to adjust to modern human activities that have dramatically altered the age classes and health of North American forests. Timber harvesting often has removed the large old trees that have hollows, loose bark and knot holes traditionally used as roosts. Bats are essential elements in maintaining forest health and they need help. Increasingly, wildlife-friendly timber practices are retaining snags and den trees for bat roosts, as well as protecting aged stands of trees that provide cavities and exfoliating bark for bats. Maintenance of permanent open water resources combined with protection of riparian areas as buffers or travel corridors between areas of rich vegetational diversity are also important to the conservation of North America’s tree-dwelling bats. By addressing the plight of forest bat habitats, we can begin to protect both bats and healthy forest ecosystems. |
Bats: Rainforest Allies Script
Mini Slide Set: Rare and Endangered Bats List of Images
Mini Slide Set: Common North American Bats List of Images
Mini Slide Set: Bats in Eastern North American Forests List of Images
Mini Slide Set: Bats in Western North American Forests List of Images
Mini Slide Set: Bats: Partners in Pollination List of Images
Los Murcielagos de America Latina
(English language script for review only)
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