 | 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. Desert red bat (Lasiurus blossevillii) with young roosting in grape leaves
(#1 of 10)
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All western bat species rely on forested habitats to some extent, especially where forests are associated with permanent water sources or rocky terrain containing cliff crevices or caves. Several species occupy a wide variety of habitats throughout most of North America. The big brown bat (Eptesicus fuscus), hoary bat (Lasiurus cinereus) and silver-haired bat (Lasionycteris noctivagans) are found coast-to-coast, while species like the desert red bat (Lasiurus blossevillii) and Keen's myotis (Myotis keenii) have a regional distribution. When people think of bat shelters, caves most often come to mind, but many bat species rarely, if ever, enter caves. Several in the genus Lasiurus are commonly referred to as "tree bats" because they roost only in tree foliage. The desert red bat is a typical tree bat, which is closely associated with cottonwoods in riparian areas at elevations below 6,500 feet (1,980 m.). Favored roosts are found where leaves form a dense canopy above and branches do not obstruct the bats' flyway below. Desert red bats are also known to roost in orchards, especially in the Sacramento Valley of California. Despite their bright amber color, these bats are actually rather hard to see, resembling dead leaves when they curl up in their furry tail membranes to sleep. Like other tree bats, this species is solitary, coming together only to mate and to migrate. Tree bats often give birth to twins, and red bats can have litters of up to four pups, though three is average. Red bats typically feed along forest edges, in small clearings or around streetlights where they can catch moths. It is not known exactly where desert red bats hibernate, though they may burrow into leaf litter or dense grass like their eastern counterparts, and they do move to milder coastal areas in the Pacific Northwest. Although largely undocumented, red bats appear to have declined markedly in the West due to the loss of lowland riparian forests. |
| 2. Typical Pacific Northwest forest with inset of a Keen's myotis (Myotis keenii) portrait
(#2 of 10)
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The Keen's myotis (Myotis keenii) is one of several species of long-eared bats in its genus. It is found from Alaska south to the coast and coastal islands of British Columbia and the area of Puget Sound in Washington. It is rarely encountered by biologists, and little is known about its behavior or population status. It is believed to rely on old-growth forests, apparently roosting in tree cavities, although a population of about 70 individuals is known from rock crevices heated by a natural hot spring in the Queen Charlotte Islands. At dusk, these bats have been observed traveling quickly to dense evergreen canopies where they apparently feed. Due to the mild coastal climates in which these bats occur, they most probably live in tree cavities year-round. This species has been placed on the Provincial Red List by the Canadian Ministry of Environment, indicating a proposed endangered or threatened status. |
| 3. Arizona white oak with inset of a southwestern myotis (Myotis auriculus) portrait
(#3 of 10)
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The southwestern myotis (Myotis auriculus) is another "long-eared" species. It is found from the southern two thirds of Arizona and New Mexico south into central Mexico. This bat often lives in ponderosa pine forests, oak woodlands, mesquite, chaparral and pinyon-juniper scrub. It is especially abundant where these habitats occur near rocky cliffs and water. Radio-tracking studies in the Chiricahua Mountains of southeastern Arizona revealed maternity roosts of up to 30 individuals living in small tree hollows, predominantly in sycamore. Other roosting cavities were in Arizona white oak and ponderosa pine, and most roosts were in riparian habitat adjacent to water. Winter roosting requirements are largely unknown. However, the southwestern myotis’ apparent preference for habitat adjacent to cliffs suggests possible reliance on cliff-face crevices for hibernation. |
| 4. California myotis (Myotis californicus) emerging from a rock outcrop crevice
(#4 of 10)
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The California myotis (Myotis californicus) ranges throughout western North America from southern Alaska south into Guatemala, and is one of the most abundant bats in desert scrub habitats, though it also can be found in oak and ponderosa pine woodlands. Throughout its range it roosts beneath loose bark and in crevices of old snags, as well as in cliff crevices, buildings and bridges. Like many species, California myotis switch roosts on a regular basis, sometimes within a few feet (less than 1 m.), sometimes up to a mile (1.6 km.) apart. Roost switching may aid in finding ideal roost temperatures as well as in avoiding predators and parasites. In most cases, roosts are located near feeding areas. These bats are among North America's smallest, enabling them to feed on especially tiny insect prey. It was not until miniature radio-transmitters could be outfitted to weigh less than 0.02 ounces (0.5 g) that these bats could be tracked and their roosts identified. |
| 5. Ponderosa pine habitat with inset of a lappet-browed bat (Idionycteris phyllotis)
(#5 of 10)
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The lappet-browed bat (Idionycteris phyllotis) is found in extreme southern Nevada, the southern third of Utah, throughout Arizona, in the southwestern quarter of New Mexico and south through the interior of Mexico. It is most often encountered in ponderosa pine, pinyon-juniper, pine-oak woodland and riparian habitats above 3,000 feet (915 m.). Maternity colonies of 30 to 150 individuals have been found in mine shafts, boulder piles, lava beds and beneath the loose bark of large ponderosa pine snags. They typically live in rocky areas and feed on moths, soldier beetles, dung beetles, leaf beetles, roaches and flying ants. They catch prey in flight or by gleaning them from foliage. This bat’s enormous ears, combined with unique skin folds at brow level called lappets, easily distinguish it from all other species. Some of its echolocation calls are audible to humans as a series of "cheeps" or "clicks." Vandalism in caves and closures of abandoned mines threaten maternity roosts, as does loss of old snags. The lappet-browed bat is a species of concern due to its limited distribution. |
| 6. Western long-eared myotis (Myotis evotis) resting on an aspen trunk
(#6 of 10)
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Western long-eared myotis (Myotis evotis) are endemic to the West, ranging from southwestern Canada, south through California into Baja California, eastward through northern Arizona and New Mexico and north into the Dakotas. These bats are found predominantly in coniferous forests, typically at higher elevations (7,000-8,500 feet or 2,100-2,600 m.) in southern areas. From British Columbia to northern Arizona, they have been found roosting in tree cavities and beneath exfoliating bark in both living trees and dead snags. Pregnant western long-eared myotis often roost at ground level in rock crevices, fallen logs and even in the crevices of sawed-off stumps, but they cannot rear young in such vulnerable locations. The only other western forest bat regularly to be found roosting at ground level is the western small-footed myotis (Myotis ciliolabrum). Western long-eared myotis capture prey in flight, but also glean stationary insects from foliage or the ground. Their main diet appears to consist of moths, and their relatively quiet echolocation calls are well suited for sneaking up on prey undetected as well as for maneuvering through cluttered habitats. |
| 7. Yuma myotis (Myotis yumanensis) in flight with moth
(#7 of 10)
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The Yuma myotis (Myotis yumanensis) is found throughout western North America, from British Columbia through Washington, Idaho, and western Montana, southern Wyoming, Colorado, New Mexico, West Texas and into Mexico. Occasionally roosting in mines or caves, these bats are most often found in buildings or bridges. Bachelors also sometimes roost in abandoned cliff swallow nests, but tree cavities were probably the original sites for most nursery roosts. These bats typically forage over water in forested areas. A study in western Oregon showed that feeding activity was up to eight times higher along forested edges of streams compared to those in logged areas, apparently because the wooded areas contain greater insect diversity. Although Yuma myotis feed predominantly over water, they eat a variety of insects that includes moths, froghoppers, leafhoppers, June beetles, ground beetles, midges, mosquitoes, muscid flies, caddisflies and crane flies. The Yuma myotis is threatened by loss of riparian habitats and the decline of permanent water sources in the Southwest and is a species of concern. |
| 8. Mexican free-tailed bat (Tadarida brasiliensis) emergence from cave
(#8 of 10)
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Mexican free-tailed bats (Tadarida brasiliensis) occupy a wide variety of habitats ranging from desert communities through pinyon-juniper woodland and pine-oak forests at elevations from sea level to 9,000 feet (2,740 m.) or more. The largest U.S. populations of free-tailed bats live in the West, with the densest concentrations found in Texas, where they form maternity colonies numbering in the millions. They are found throughout Mexico and most of the western and southern U.S. The largest maternity colonies are formed in limestone caves, abandoned mines, under bridges and in buildings, but smaller colonies also have been found in hollow trees. It is estimated that 100 million Mexican free-tailed bats come to Central Texas each year to raise their young. They consume an estimated 1,000 tons (907 metric tonnes) of insects nightly, a large proportion of which are agricultural pests. Doppler weather radar documents these bats ascending to altitudes of 1,000-10,000 feet (300-3,000 m.) to intercept and feed on migrating cotton bollworm moths, army cutworm moths and other costly agricultural pests as they arrive from Mexico. The cotton bollworm moth (also known as the corn earworm moth) alone costs American farmers approximately $1 billion annually. Mexican free-tailed bats also consume enormous quantities of insects over woodlands and forests, likely including many additional pests. Although this species is still abundant, it is highly vulnerable and has declined alarmingly at important roosts in Mexico, Arizona and New Mexico. |
| 9. Arizona little brown myotis (Myotis lucifugus occultus) roosting in tree bark
(#9 of 10)
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The little brown myotis (Myotis lucifugus) is abundant throughout forested areas of the U.S. as far north as Alaska. In the West it is found mainly in mountainous and riparian areas in a wide variety of forest habitats including tree-lined xeric scrub, aspen meadows and coniferous rain forests of the Pacific Northwest. This species is especially associated with humans, often forming nursery colonies containing hundreds, sometimes thousands, of individuals in buildings, attics and other man-made structures. Although the little brown myotis is poorly studied in the West, nursery colonies of 50-100 bats each have been documented in northern Arizona beneath loose bark on ponderosa pine snags. While eastern populations of little brown myotis hibernate in caves and mines, the winter habitats of the Arizona little brown myotis remain a mystery. Only a handful of hibernating individuals have been found in the West, where few caves or mines contain appropriate temperatures or humidity for hibernation. Hollow tree cavities are a likely choice in moist coastal areas or in deep cliff-face crevices further inland. Little brown myotis forage over water, eating aquatic insects such as midges, mosquitoes, mayflies and caddisflies. They also feed over forest trails, cliff faces, meadows and farmland where they consume a wide variety of insects, from moths and beetles to crane flies. Individuals can catch up to 1,200 insects in just one hour during peak feeding activity. Little brown myotis are relatively abundant, though status trends are undocumented. |
| 10. Ponderosa pine snag with inset of a long-legged myotis (Myotis volans) portrait
(#10 of 10)
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The long-legged myotis (Myotis volans) is one of western North America's most widely distributed bats. It is found from the Tongas National Forest in Alaska south through all of the western U.S., into Baja California and also along the Sierra Madre Occidental in Mexico. Long-legged myotis are especially dependent on wooded habitats from pinyon-juniper to coniferous forests, usually at elevations of 4,000 to 9,000 feet (1,200-2,700 m.) in southern areas. Radio-tracking studies have identified maternity roosts beneath bark and in cavities of snags. Most nursery colonies live in trees at least 100 years old, which provide crevices or exfoliating bark. These trees typically are located in openings or along forest edges where they receive a large amount of daily sun. Though maternity colonies are most often formed in tree cavities or under loose bark, they also are found in cliff crevices and buildings. Long-legged myotis forage over ponds, streams, water tanks and in forest clearings, primarily feeding on moths. This is one of the West’s most abundant species, though population trends have not been monitored. Because these and many other forest bats are widely dispersed in low numbers across rugged landscapes, population monitoring is a unique challenge. Mature trees and old snags provide essential roosts for many bat species, and small clearings and multi-age stands with a healthy mosaic of forested areas provide critical foraging habitat. In many cases, the most serious limiting factor appears to be a shortage of trees with cavities or exfoliating bark for roosting. In arid areas, bats are further limited by the availability of open water drinking sites. In summary, forested habitats including desert scrub, oak woodlands, pinyon-juniper, pine and mixed conifer forests are vital to the survival of nearly all western bat species. Because of their widely differing roosting and foraging behaviors, it is impossible to prescribe one set of management recommendations that will address the needs of all western bats. However, forest bat research conducted to date clearly demonstrates the importance of large dead or partially dead trees that provide cavities, exfoliating bark and crevices that are essential roost sites. Because of the ephemeral nature of snags and dying trees, large green trees must also be maintained as future replacement snags. Bat conservation and management concerns should be addressed whenever forest management practices such as timber harvest or prescribed fire will significantly affect the abundance and distribution of snags. Many forest-dwelling bats forage along edge habitats and in small openings. The availability of free-standing water is also critical for bats in many areas of the arid West, and riparian areas are particularly important. Therefore, the most abundant and diverse bat populations are often found in forested areas that provide large trees and snags, small openings and edge habitat, access to pooled water and proximity to cliffs, crevices, caves or mines. |
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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