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| Western Pipistrelle - Pipistrellus hesperus |  
Wingspread: 7.5-8.5 inches. Weight:0.14-0.21 oz.
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The western pipistrelle with its beautiful butterfly like flight is the smallest bat in Utah and the United States. It is a bat of the western deserts, occurring throughout the Southwest north to Washington and south into Mexico. The western pipistrelle emerges earlier and remains out later than any other bat in Utah. They may be seen out feeding well before sundown and after sunrise. The western pipstrelle is closely associated with rocky areas, depending on crevices and outcrops as day roosts. They typically roost singly or in very small groups.
Up to two young are born in the early summer and can fly after about one month. The winter habits of the western pipistrelle are not clearly understood. Although able to hibernate, these bats are sometimes found flying at temperatures below freezing. |
| | Big Brown Bat - Eptesicus fuscus |  Wingspread: 12.8-13.8 inches. Weight:0.38-0.70 oz.
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A medium-sized, common brown bat often closely associated with man, the big brown bat occurs from Alaska and Canada throughout much of the United States, south through Mexico into northern South America. In Utah it is found in mid and higher elevation forests and some lower elevations throughout the summer.
Big brown bats are known for their strong, straight flight patterns in search of insects. These patterns are often repeated night after night. Like many other bats, breeding occurs in the fall, and the female retains the live sperm in her body until spring when ovulation occurs. Young are born in the summer and can apparently fly within a months. Big brown bats roost in mine tunnels, caves, cavities or under bark in trees, and in buildings.
Big brown bats are found in virtually every American habitat ranging from timberline meadows to lowland deserts, though it is most abundant in deciduous forest areas. It is often abundant in suburban areas of mixed agricultural use. This species ranges from extreme northern Canada, throughout the United States and south to the extreme southern tip of Mexico. Traditionally, these bats have formed maternity colonies beneath loose bark and in small cavities of 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 (Whitaker, 1995). Big brown bats clearly rank among America's most beneficial animals. And, 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 designing bat-specific artificial roosts 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. |
| | Fringed Myotis - Myotis thysanodes |  Wingspread: 10.4-11.8 inches.
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In the summertime, this species in the southeastern portion of Utah and in western North America from British Columbia to Mexico.It is named for a conspicuous fringe of stiff straw-colored hairs on the trailing edge of the tail membrane. They are thought to emerge about two hours after sunset to feed on moths, daddy longlegs and beetles by foraging along waterways or above the canopy of the vegetation.
Females congregate in nursery colonies to give birth to a single young which is born hairless. Even though breeding occurs in the fall, the egg is not fertilized nor does development of the fetus begin until the spring. Amazingly, the young develop very rapidly and can fly within 20 days. The fringed myotis roosts in caves, abandoned buildings, rock crevices and trees. They apparently hibernate during the winter, but little is known about this species' winter habits.
The southwestern myotis, the long-eared myotis and the fringed myotis all use similar foraging patterns. They hover or fly slowly over the surface of vegetation, tree trunks, racks, or the ground and pick insects from the surface. |
| | Long-Legged Myotis - Myotis volans |  Wingspread: 10-10.5 inches. Body Lenth: 2- 2.5 inches.
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The long-legged myotis ranges throughout western North America with observations as far north as Alaska, south to central Mexico, and east to the Dakotas and Nebraska. It occurs in pinyon-juniper, oak and coniferous forests.
As for many species of bats, copulation may occur in August, with the sperm being stored during winter in the female's reproductive tract. Ovulation occurs sometime between March and May, with birth occurring between May and August. Females form summer maternity colonies in buildings, rock crevices, cliffs and trees. They have also been observed under loose bark on trees.
The long-legged myotis emerges in the early evening when it is still light to forage. They may be active throughout the night, but usually have a peak of activity during the three or four hours following sunset. These bats are believed to feed primarily on months. They have been observed flying10-15 feet over water and open meadows, as well as foraging in forest openings. This bat forages by skimming insects over water or pursuing insects in the open air.
The long-legged myotis is one of western America's most widely distributed bat species. It is found from the Tongas National Forest in Alaska, south, through all of the western U.S. and into the Baja peninsula, 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. Radio-tracking studies have identified maternity roosts beneath bark and in other cavities. Most nursery colonies live in at least 100 year-old trees that provide crevices or exfoliating bark. These 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 rock crevices, cliffs, and buildings. Long-legged myotis forage over ponds, streams, water tanks, and in forest clearings, often on moths. Few winter records exist in the West. Because these and many other forest bats are widely dispersed in low numbers, across rugged landscapes, population monitoring is a unique challenge. |
| | Western Small-Footed Myotis - Myotis ciliolabrum | Wingspread: 8-10 inches. Body Length:1.5-2 inches.
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Western small-footed myotis can be found throughout most of Utah. The geographic range of this bat encompasses a large portion of western North America, from southwestern Canada, spreading south to upper Baja California and western Oklahoma, and then extending south to Coahuila and Zacatecas, Mexico.
These small bats have tiny feet, usually measuring about 0.3 inches. The glossy fur varies from blond to dark brown. They also have dark ears and a black facial mask. They look very similar to the California myotis, however, the small-footed myotis has a flatter forehead and a longer thumb.
Habitat requirements for roost selection are poorly known. In summer, they can be found roosting in rock crevices, buildings, caves, mine tunnels, and even in loose tree bark.
The western small-footed myotis mates in the fall. The female retains the sperm until fertilization takes place in the spring. A single baby is born per year, with the birth taking place from late May to early July. Maternity colonies appear to be small, containing up to 20 individual females with young, and have been found in buildings and tree cavities.
As with many of the myotis bats, western small-footed myotis are insectivorous. Their diet includes moths, flies and flying beetles. This bat forages by skimming insects over water or pursuing insects in the open air.
The western small-footed myotis rears its young in cliff-face crevices, erosion cavities, and beneath rocks on the ground. Some females care for their pups alone, while others form small groups. These bats can also be found hibernating in caves or mines, but little else is known about them; they are among America's least-studied animals. Eastern and western species of small-footed myotis are distinct but closely related. The western species ranges from southwestern Canada to western Oklahoma and central Mexico. It is easily confused with the California myotis (Myotis californicus). |
| | California Myotis - Myotis californicus |  Wingspread: 9 inches. Weight: 0.1 oz. Body Length: 1.5-2 inches.
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California myotis occur throughout the state, but they do not extent into the northwestern portion of the state. The known range for California myotis includes the western United States south into Mexico.It is the smallest myotis found in Utah. The fur varies geographically and locally from pale buff to dark brownish black. The ears vary in color from light to dark, but usually dark. This species is easily confused with the western small-footed myotis. However, California myotis tends to have a more abrupt forehead and a shorter thumb.
The California myotis is an opportunistic rooster. They roost in any convenient shelter and do not regularly return to the same place everyday. Roost selection tends to be any available crevice, from rock fissures to loose tree bark. Maternity colonies are usually small and the young become self-dependent by mid-July. The single young is born usually in June. This bat forages by skimming insects over water or pursuing insects in the open air.
The California myotis ranges throughout western North America from southern Alaska south into Guatemala and is one of the most abundant bats in desertscrub 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 tree crevices. It also forms small maternity colonies in cliff crevices, buildings, and bridges. Like many species, California myotis switch roosts on a regular basis, sometimes within a few feet, sometimes up to a mile 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 half a gram that these bats could be tracked and their roosts identified. |
| | Long-Eared Myotis - Myotis evotis |  Weight: Less than 0.25 oz. Body Length:1.5 - 2 inches.
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This myotis has long, narrow, dark-colored ears. Its ears, nearly an inch from base to tip, average longer than any of the other 88 species of myotis bats in the world. During the summer months, it is found in forest areas through temperate parts of western North America. Long-eared myotis roost in small groups in day roosts which may include buildings, caves, mines, hollow trees, cracks in cliffs, sinkholes, or behind slabs of bark. Males and females roost separately in summer. Female long-eared myotis congregate in small groups and give birth to one young, probably in late June or early July.
Nothing is known about this bat's migration or winter habits and whereabouts. It is presumed to hibernate and probably migrates short distances from its summer range to caves or abandoned mines to spend the winter.
The southwestern myotis, the long-eared myotis and the fringed myotis all use similar foraging patterns. They hover or fly slowly over the surface of vegetation, tree trunks, racks, or the ground and pick insects from the surface.
The relatively long black ears of the long-eared myotis are distinctive and dramatic in contrast with its paler body fur. These bats are endemic to the west, ranging from southwestern Canada, south through California into Baja, eastward through northern Arizona and New Mexico and north into the Dakotas. They are found predominantly in coniferous forests, typically only at higher elevations in southern areas (between 7,000 and 8,500 feet). From British Columbia to northern Arizona, they roost in tree cavities and beneath exfoliating bark in both living trees and dead snags. Pregnant 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. Only one other western forest bat has been found regularly roosting at ground level, the western small-footed myotis (Myotis ciliolabrum). 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. |
| | Yuma Myotis - Myotis yumanensis |  
Wingspread: 9.25 inches. Body Length: 1.5- 2 inches.
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Have you ever seen bats flying close to the surface of a pond or lake? Chances are you were watching the Yuma myotis as it foraged over the water in search of moths, midges, caddis flies, or some other flying insect. It is one of two bats in Utah that prefer to forage over open water, most of the time flying within a few inches of the surface.
The Yuma myotis is a small bat with relatively large feet. I tis the smallest of the large-footed myotis bats. It has buffy brown fur and light colored ears with white or buff underparts.
This species can be found in the southeastern half of Utah. It has been found in desert, grassland, woodland and riparian communities. The range of the Yuma myotis is from British Columbia south to Mexico. The east-west distribution appears to be from Oklahoma and Texas to coastal California. These bats are known to winter along the Lower Colorado River in Arizona.
Yuma myotis appear to prefer to roost in buildings or under bridges, and rarely in mines or caves. Like other bats, they mate in the fall, with fertilization occurring in the spring. The females roost communally in small maternity colonies consisting of about 35 individuals. Birth occurs from late May into June, with a single young being born. Most of the young are able to fly by early July. Adult males usually roost singly during the maternity season.
Yuma myotis are 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. Yuma myotis are threatened by loss of riparian habitats and the decline in permanent water sources in the southwest. |
| | Little Brown Bat - Myotis lucifugus |  
Wingspread: 9.5 - 11 inches. Body Length:1.5 - 2 inches.
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The little brown myotis 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; from tree-lined xeric-scrub to aspen meadows and Pacific Northwest coniferous rain forests. 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. The little brown myotis is poorly studied in the West. In northern Arizona, numerous nursery colonies of 50-100 bats each have been documented beneath exfoliating bark on ponderosa pine snags. In addition to day roosts in tree cavities and crevices, little brown myotis seem quite dependent upon roosts which provide safe havens from predators that are close to foraging grounds. Unlike their eastern counterparts, the winter habitats of western little brown myotis remain a mystery. Despite summer nursery colonies numbering in excess of 1,000 individuals, only a handful of hibernating individuals have ever been found. In the West, where few caves or mines contain appropriate temperature or humidity for hibernation, these bats may hibernate in hollow tree cavities in moist coastal areas or in deep cliff-face crevices. Little brown myotis forage over water where their diet consists of aquatic insects, mainly 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 to1,200 insects in just one hour during peak feeding activity.
In the four-corners region of the west, research is being conducted on little brown bats to try to determine if Myotis lucifugus occultis is a subspecies or separate species from Myotis lucifugus. Evaluation by USGS bat biologist (Ernie Valdez) of individuals captured on the GSENM states that they have the physical characteristics of Myotis lucifugus, however the distribution and habitat more closely fit's that of Myotis occultis.More detailed study needs to take place before this mystery is solved. |
| | All Photos by M.Siders |
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