free-tailed bats
Molossidae /
Molossidae, or free-tailed bats, belong to the order Chiroptera. The family’s common name is derived from a length of “free” tail, projecting beyond the end of the uropatagium – the membrane that connects the base of the tail to the hind legs. The tail is usually best seen when resting. A special ring of cartilage slides up or down the tail vertebrae by muscular action to stretch or retract the tail membrane. This gives many species a degree of fine tuning in their flight maneuvers to rival their day-flying ecological equivalents, such as swifts, swallows, and martins. As a result, these animals include the fastest-flying of all bat species among their number.
Eumops perotis, a member of the Family Molossidae, has a disjunct distribution, with two subspecies confined to South America. The subspecies that occurs in North America, E. p. californicus, ranges from central Mexico across the southwestern United States (parts of California, southern Nevada, Arizona, southern New Mexico and western Texas). Recent surveys have extended the previously known range to the north in both Arizona (several localities near the Utah border) and California (to within a few miles of the Oregon border). Distribution in Nevada and Southern Utah is not well understood. Until recently, Nevada records were limited to a single record from Southern Nevada. A recent study in southern Nevada has acoustic records for E. perotis from June through October in 2004. The species has also been detected acoustically in southern Utah. Published information suggests that the species occurs only to 375 m in California, and 1,100 m in Texas. Recent surveys in California, however, have documented roosts up to 1,400 m, and foraging animals at > 2,700 m. Acoustic records of E. perotis in California document foraging or commuting at up to 3,050m in the southern Sierra Nevada. Recent surveys in northern Arizona have documented roosts at approx. 1,200 m, and foraging animals at >2,500 m. The distribution of E. perotis is likely geomorphically determined, with the species being present only where there are significant rock features offering suitable roosting habitat. It is found in a variety of habitats, from desert scrub to chaparral to oak woodland and into the ponderosa pine belt and high elevation meadows of mixed conifer forests
Global Rank – G5. National Rank – N3., State Ranks: AZ – S2S3; CA – S3?; NV – S2; TX – S3., former category 2 candidate species. A Species of Special Concern in California, where severe declines have been documented in the Los Angeles basin.
Like most other North American species of bat, the long term persistence of E. perotis is threatened by: low fecundity, high juvenile mortality, long generational turnover; loss of clean, open water; loss of riparian vegetation; pesticide application. Population trends for this species are difficult to assess in many areas because of an absence of historical roost records. Additionally, E. perotis in particular, are threatened by urban expansion. When colonies are within or in close proximity to human dwellings, they are vulnerable to disturbance, vandalism and the hysteria which often surrounds bat colonies, causing extermination by pest control operators and public health departments. Two colonies in buildings in the Los Angeles area (Norco and Rancho Cucamonga) were eradicated recently in the name of public health. Any construction activities (e.g., quarry operations, highway projects, water impoundments) that impact cliffs or boulders could also affect western mastiff bat roosts. Rock climbing may also disturb roosting bats, and is a rapidly-growing recreational activity in the range of Eumops. Communication with avid rock climbers suggest bat encounters do occur on climbs, and that hands or temporary climbing aids inserted into a roost crevice could cause abandonment of a site. Since E. perotis forage over a large area, the huge amount of pesticide applications in areas such as the Imperial and Colorado River Valleys could have far-reaching effects. Non-chemical methods, such as the lepidopteron-attacking E. perotis, can reduce the prey base for western mastiff bat populations, which rely heavily on moths. In general, the long term persistence of North American bat species is threatened by the loss of clean, open water; modification or destruction of roosting and foraging habitat; and, for hibernating species, disturbance or destruction of hibernacula. Chemicals in the environment that affect bats or their prey are also a threat. Because of low fecundity, high juvenile mortality, and long generational turnover, many bat populations may be vulnerable to human-induced pressures.
Morphologically distinct. Most roosts are in cliffs and are highly inaccessible; quite frequently in building roosts. E. perotis can sometimes be found by surveying for guano and listening for loud chatter along base of cliffs. Effectiveness of netting varies regionally. E. perotis have been netted where open flight paths are evident, or water is limiting. E. perotis forage at considerable heights and captured at drinking sites. E. perotis calls are diagnostic and in the audible range; easy to detect species acoustically (better with low frequency microphone). Flight is distinctive except in areas of overlap with E. perotis.
More surveys are needed, using acoustic techniques, to delineate the range of this species. More information is needed on distribution of breeding colonies, seasonal movements, roosting and foraging requirements. Methods need to be developed for assessment and on going monitoring of population size.
Arizona Game and Fish Department. 2002. Heritage Data Management System: Eumops perotis californicus. Accessed March 24, 2005.
Bat Conservation International. 2002. Eumops perotis: Greater bonneted bat. Accessed March 24, 2005.
Best, T. L., W. M. Kiser, and P. W. Freeman. 1996. Eumops perotis. American Society of Mammalogists, Mammalian Species, 534:1-8.
Brown, P.E. and R. D. Berry. 2003. Baseline surveys and the development of monitoring protocol for Lower Colorado River bat species. Report prepared for NFWF, Washington D.C. for the Lower Colorado River Multi-Species Conservation Program. Project # 2000-0304-002. 76pp.
Brown, P. E., and R. D. Berry. 2004. Roost surveys and habitat requirements of rare southwestern bats: California leaf-nosed and Allen’s lappet-browed bats, with observations on Townsend’s big-eared and western mastiff bats.
NatureServe. 2005. NatureServe Explorer: An online encyclopedia of life [web application]. Version 4.3. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. Accessed March 24, 2005.
Nevada Bat Working Group. Checklist of Bats of Nevada. Accessed March 24, 2005.
New Mexico Game and Fish Department. Biota Information System of New Mexico (BISON). Greater western mastiff bat. Accessed March 24, 2005.
Pierson, E. D., and W. E. Rainey. 1996. Distribution, habitat associations, status, and survey methodologies for three molossid bat species (Eumops perotis, Nyctinomops femorosaccus, Nyctinomops macrotis) and the vespertilionid (Euderma maculatum). Calif. Dept. of Fish and Game, Bird and Mammal Conservation Program Rep. 96-8, 46 pp.3
Rainey, W. E., E. D. Pierson, and C. J. Corben. 2003. Sacramento River Ecological Indicators Pilot Study. Contract Report for the Nature Conservancy, Chico, CA.
Schmidly, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, TX. 188 pp.
Siders, M.S., M.J. Rabe, T.K. Snow and K. Yasuda. 1999. Long foraging distances in two uncommon bat species (Euderma maculatum and Eumops perotis) in Northern Arizona. P 113-122 in van Riper, C., III, and M.A. Stuart, eds, Proceedings of the Fourth Biennial Conference of Research on the Colorado Plateau. U.S. Geological Survey/FRESC Report Series USGSFRESC/COPL/1999/16.
Snow, T. K., S. V. Castner, S. R. MacVean, C. R. Miller, and D. C. Noel. 1996. Spotted bat survey of the North Kaibab Ranger District (Coconino County, Arizona). Arizona Game and Fish Department, Phoenix, AZ, Technical Report, 102:1-26.
Steffensen, R. A., and M. S. Siders. 1997. Spotted bat and greater western mastiff bat surveys: North Kaibab Ranger District, Kaibab National Forest.
Texas Parks and Wildlife. Nature: Western Mastiff Bat. Accessed March 24, 2005.
Williams, D. F. Mammalian Species Of Special Concern In California. California Habitat Conservation Branch, Sacramento, California. Accessed March 24, 2005.
Original account by Elizabeth D. Pierson
2005 update by Melissa S. Siders
Eumops underwoodi, a member of the Family Molossidae, is known in the United States only from a few localities in Pima County, Arizona. This species’ range extends from southern Arizona through western Mexico, as far south as Honduras. The subspecies found in Arizona, E.u. sonoriensis, is limited to Arizona and Sonora, Mexico. It is found in sonoran desert habitat in Arizona, and has been found in pine-oak forest at 1,495-1,800 m elevation in Mexico.
Global Rank – G4. State Ranks: AZ – S1. Although this species can be predictably encountered at at least one locality in Arizona, its status and distribution are not well understood. A former category 2 candidate species.
E. underwoodi can be distinguished from all other North American molossid (=free-tail) species based on size. With a forearm of 65-77 mm, it is smaller than Eumops perotis (forearm = 73-83 mm) and larger than Nyctinomops macrotis (forearm = 58-64 mm). Eumops species have a smooth upper lip, in contrast to a wrinkled upper lip in Nyctinomops. In E. underwoodi the tragus is small and rounded, in E. perotis it is broad and square. While E. underwoodi is presumed to roost primarily in rock crevices on cliff-faces, the only identified roost was in a large, hollow tree in Jalisco, Mexico. E. underwoodi apparently gives birth to a single young in late June or July. No information is available on colony size. Based on limited samples, the diet of E. underwoodi appears to be predominantly beetles (scarabs and long-horned) and short-horned grasshoppers, with some leafhoppers and moths. No information is available on seasonal movements.
No threats have been identified. Assuming that this species is primarily cliff-dwelling, it could be threatened by any activities that disturb or destroy cliff habitat (e.g., recreational climbing, water impoundments, highway construction, quarry operations). Grazing and pesticide applications in agricultural areas could impact foraging habitat.
More surveys are needed to delineate the range of this species in the southwestern U.S. More information is needed on distribution of breeding colonies, seasonal movements, roosting and foraging requirements. Methods need to be developed for assessment and on going monitoring of population size. Call features need to be described to determine whether this species can be distinguished from other large molossids acoustically.
Barbour, R. W. and W. H. Davis 1969. Bats of America. Vol. University of Kentucky Press, Lexington, Ky. 286 pp.
Cockrum, E.L. and A. L. Gardner. 1960. Underwood’s mastiff bat in Arizona. Journal of Mammalogy, 41:510-511.
Constantine, D. G. 1961. Locality records and notes on Western bats. Journal of Mammalogy, 42(3):404- 405.
Hoffmeister, D.F. 1959. Distributional records of certain mammals from southern Arizona. Southwestern Naturalist 4:14-19.
Kiser, W. M. 1995. Eumops underwoodi. American Society of Mammalogists, Mammalian Species, 516:1- 4.
Account by Elizabeth D. Pierson
Nyctinomops femorosaccus, a member of the Family Molossidae, occurs in western North America, from southern California, central Arizona, southern New Mexico and western Texas, south into Mexico including Baja California. The species is thought to be non-migratory. The known altitudinal distribution is from near sea level to about 7,300 ft (2,250 meters). Breeding ppopulations have recently been identified in southern California.
Global Rank – G4. State Ranks: Arizona – S2/S3, California – S2/S3, New Mexico – S1, and Texas – S3. This species currently is not listed as Threatened or Endangered. It is a Species of Special Concern in California. There are no studies that elucidate the global population status of this species. Rankings should be re-evaluated as more information is available.
Like all molossids (=free-tailed bats), N. femorosaccus has a free-tail which extends beyond the edge of the interfemoral membrane. With a forearm of 45-49 mm., it is smaller than all other North American molossid species except Tadarida brasiliensis. It is slightly larger than T. brasiliensis and, unlike T. brasiliensis, has its ears joined at the midline. The pocketed free-tailed bat is colonial and roosts primarily in crevices of rugged cliffs, high rocky outcrops and slopes. It has been found in a variety of plant associations, including desert shrub and pine-oak forests. The species may also roost in buildings, caves, and under roof tiles. The species forms maternity colonies, and females bear 1 young in late June or July. Lactating females have been taken between 7 July and 8 August, and volant juveniles recorded on 7 August. N. femorosaccus forages mainly on large moths, but its diet includes small moths and beetles, with small amounts of a variety of other insects. Owls and snakes have been documented preying on this species. Little is known about population dynamics, seasonal movements, or ecology.
No known treats to the species have been identified to date. However, some of the general threats to bats could apply to N. femorosaccus. These could include impacts to foraging areas from grazing, riparian management, the use of pesticides, and in some places disturbance to roost sites.
Information is needed on N. femorosaccus regarding roosting ecology, foraging ecology, seaonal movements, and breeding colony distribution. Little appears to be known about the echolocation calls of this species, and documentation is needed for comparison with other molossid species. More information on the ecology of this species is required before threats can be more fully delineated.
Kumirai, A. and J. K. Jones, Jr. 1990. Nyctinomops femorosaccus. American Society of Mammalogists, Mammalian Species, 349:1-5.
Schmidly, D. J. 1991. The bats of Texas. University of Texas Press, Austin. 189 pp.
Account by Kirk Navo
Nyctinomops macrotis, a member of the Family Molossidae, ranges from most of South America northward to include Mexico, Arizona, New Mexico, southern and western Texas, southern California and southeastern Nevada, southern Utah, and north to central Colorado. The species is migratory, and there are some extralimital records from British Columbia, Iowa, Kansas, and South Carolina. The known elevational range is from near sea level to about 8,500 ft (2,600 meters).
Global Rank – G5. State Ranks: AZ – S2S3; CA – S2; CO – S1?; NM – S2; NV – S?; TX – S3; UT – S2.The Big-free-tailed bat was proposed as a federal candidate C2 species in 1994. This species is currently on the BLM’s special status species list for Utah and Colorado. It is considered a Species of Special Concern by the states of California and Utah.
N. macrotis can be distinguished from other molossids (= free-tailed bats) based on size. With an adult forearm of 58-64 mm it is larger than T. brasiliensis or N. femorosaccus, and smaller than either Eumops species. Also, it has dvertical grooves or wrinkles on the upper lip, which are lacking in Eumops. N. macrotis appears to be mainly an inhabitant of rugged, rocky habitats in arid landscapes. It has been found in a variety of plant associations, including desert shrub, woodlands, and evergreen forests. It appears to be associated with lowlands, but has been documented at around 8,000 ft in New Mexico. This species is a seasonal migrant, and a powerful flyer. It roosts mainly in the crevices of rocks in cliff situations, although there is some documentation of roosting in buildings, caves, and tree cavities. The species forms maternity colonies, and females bear one young in late spring or early summer. Lactating females have been taken in July, August and September, and volant juveniles recorded on 8 and 27 August. Maternity roosts have been documented in rock crevices, with evidence of long term use of the crevices reported. It appears that the return to the roost site by this bat involves ritualized behavior, including a general reconnaissance of the site and several landing trials before entry. N. macrotis forages almost entirely on large moths, but some data exists to document occasional foraging on other insects, including grasshoppers, beetles, crickets, leafhoppers and flying ants. Owls appear to be the only documented predator of this species. N. macrotis has an audible echolocation call, which is characterized as loud and with a frequency range of 17-30 kHz. Surveys based on echolocation calls for this species may be possible, as captures appear to be uncommon (outside of Big Bend National Park, where the most animals in North America have been documented). Easterla , however, reports that the populations at the Park fluctuate greatly from year to year. Little is known about the species population dynamics and ecology.
No known threats to the species have been identified to date. However, some of the general threats to bats could apply to N. macrotis. These could include impacts to foraging areas from grazing, riparian management, the use of pesticides, and in some places disturbance to the roost site (e.g., blasting of cliffs or water impoundments).
Information is needed on N. macrotis regarding roosting ecology, seasonal movement patterns, and breeding colony distribution. Current evidence suggests that the species breeds farther north than previously thought, including southern Utah and Colorado. Vocalization recordings are needed to help train researchers and managers that may attempt to survey for the species based on audible call detections. Reference calls need to be established and geographically verified, and made available at a depository, and/or establish a site where recordings can be sent for verification. It will be important for bat biologists to be able to distinguish between the different audible bats in the southwest.
Di Salvo, A. F., H. N. Newhauser and R. E. Mancke. 1992. Nyctinomops macrotis in South Carolina. Bat Research News, 33(2&3):21-22.
Milner, J., C. Jones and J. K. Jones, Jr. 1990. Nyctinomops macrotis. American Society of Mammalogists, Mammalian Species, 355:1-4.
Nagorsen, D. W. and R. M. Brigham. 1993. Bats of British Columbia. University of British Columbia Press, Vancouver, BC. 164 pp.
Schmidly, D. J. 1991. The bats of Texas. University of Texas Press, Austin, TX. 189 pp.
Account by Kirk Navo
Tadarida brasiliensis, a member of the Family Molossidae, is one of the most widely distributed mammalian species in the Western Hemisphere. There are nine recognized subspecies, two in the United States. T. b. mexicana is primarily western, occurring from southern Oregon to eastern Nebraska, and south through Mexico. T. b. cynocephala is primarily a southeastern species, from eastern Kentucky into South Carolina and south through Florida. T. brasiliensis ranges southward through most of Central America. In the western United States, T. brasiliensis is most commonly associated with dry, lower elevation habitats, yet it also occurs in a variety of other habitats, and is found up to at least 3,000 m. in some of the western mountain ranges.
Global Rank – G5. State Ranks: AZ – S3/S4; CA – S4/S5; CO – S1; NM – S2; NV – S?; OR – S2; TX – S5; UT – S3/S4; WY – S5. T. brasiliensis is widely regarded as one of the most abundant mammals in North America, and is not on any Federal lists. However, its proclivity towards roosting in large numbers in relatively few roosts makes it especially vulnerable to human disturbance and habitat destruction. Documented declines at some roosts are cause for concern. It is considered a Species of Special Concern due to declining populations and limited distribution in Utah.
Like other molossid (free-tail) species, T. brasiliensis has a tail which extends well beyond the back edge of the interfemoral membrane.T. brasiliensis can be distinguished from the other molossids occurring in the United States by the characteristic that its the ears are not joined basally at the mid-line. This species is highly colonial with maternity colonies ranging in size from a few hundred to 20 million. The most commonly used natural roosts are caves and rock crevices on cliff faces. This species also roosts in abandoned mines and tunnels, highway bridges and large culverts, buildings, and bat houses. Maternity roosts are usually warmer and larger than bachelor or non-reproductive female roosts.T. brasiliensis will, during spring cold snaps, take refuge in cliff swallow nests. Brazilian free-tailed bats often fly more than 50 km to reach foraging areas. Such flight is rapid, direct, and often involves gliding. Bats from one colony may cover areas as large as 400 km2 and move at speeds over 40 km/hour and at altitudes of 3,000 meters or more. Foraging occurs at high elevations and also at heights of 6 to 15 meters.T. brasiliensis consumes a large variety of agricultural pests, mostly moths, but also flying ants, weevils, stink-bugs and ground beetles. T. b. mexicana is primarily migratory, with large numbers of females returning to large, warm caves in Texas, New Mexico, Arizona, and Oklahoma each spring. Few adult males return northward; mating probably occurs in lower latitudes of the winter range. Seasonal patterns elsewhere in the west are less clear. Birth usually occurs between mid-June and mid-July. Adult mass is reached in as little as three weeks, and first flight occurs 2-3 weeks later.
Besides the human disturbance and habitat destruction, or alteration of suitable caves, mines, bridges, and old buildings noted above, there are problems with pesticide poisoning and deliberate eradication attempts. Human rabies deaths attributed to T. brasiliensis foster attitudes for the destruction of T. brasiliensis roosts and colonies.
Although most major maternity roosts in the United States are now protected, much remains to be done with winter roosts in Mexico. More documentation of the role of T. b. mexicana in agriculture, and the use of artificial roosts to attract them, is needed. Its ecology, distribution, and seasonal patterns are not well understood in some parts of its range, particularly California, Nevada, southern Oregon, and Utah).
Loughry, W. J., and G. F. McCracken. 1991. Factors influencing female-pup scent recognition in Mexican free-tailed bats. Journal of Mammalogy, 72(3):624-626.
McCracken, G. F. 1996. Bats aloft: a study of high-altitude feeding. Bats, 14:7-10.
McCracken, G. F., and M. K. Gustin. 1991. Nursing behavior in Mexican free-tailed bat maternity colonies. Ethology, 89(4):305-321.
McCracken, G. F., M. K. McCracken, and A. T. Vawter. 1994. Genetic structure in migratory populations of the bat Tadarida brasiliensis mexicana. Journal of Mammalogy, 75(2):500-514.
Schmidley, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, TX. 188 pp.
Wilkins, K. T. 1989. Tadarida brasiliensis. American Society of Mammalogists, Mammalian Species, 331:1-10.
Account by Bat Conservation International
mustached bats
Mormoopidae /
Mormoopidae, contains bats known generally as mustached bats, ghost-faced bats, and naked-backed bats. They are found in the Americas from the southwestern United States to southeastern Brazil. They are distinguished by the presence of a leaf-like projection from their lips, instead of the nose-leaf found in many other bat species. In some species, the wing membranes join over the animal’s back, making it appear hairless. The tail projects only a short distance beyond the membrane that stretches between the hind legs.
Mormoops megalophylla ,the only North American representative of the Family Mormoopidae, inhabits humid, semi-arid, and arid regions below 3,000 m. elevation from southwestern Texas and southern Arizona southward through Baja California and mainland Mexico into eastern Honduras and El Salvador. Records also occur for the Netherlands Antilles and Trinidad, along the Caribbean coast of Columbia and Venezuela, and along the Pacific coasts of Columbia, Ecuador, and northern Peru. In Arizona, it is known only from the southern end of the Santa Rita Mountains, and in Texas from the Trans-Pecos, South Texas Plains, and the southern edge of the Edwards Plateau. This species is found in a variety of habitats including desert scrub, mixed boreal-tropical forests (the transitional zone between pine-oak forest and tropical deciduous forest between approximately 1,475 and 2,185 m. elevation), tropical rain forests, and riparian areas with mature cottonwood, sycamore, and willow in oak- woodland habitat.
Global Rank – G4. State Ranks: AZ – S1; TX – S2. Although widely-distributed, M. megalophylla is not numerous anywhere in its range. It has neither federal nor state protection designation, but is listed as “Uncommon” in Arizona.
M. megalophylla can readily be distinguished from all other species by its unique facial ornamentation consisting of conspicuous folds of skin reaching from ear to ear across the chin. The ghost-faced bat roosts primarily in caves or abandoned mines, and occasionally in old buildings. Colonies of this species may contain 500,000 individuals and are spatially isolated from colonies of other species of bats roosting in the same structures. Conspecific individuals maintain a distance of approximately 15 cm. from each other. Nursing M. megalophylla roost in areas which minimize ventilation and maximize heat retention. These sites are usually the deepest and warmest (36EC) areas of occupied caves. Males and non-reproducing females use caves separate from those used by nursing females. In Falcon state, Venezuela, males form bachelor colonies in areas of caves having ambient temperatures of 30.6-34.2EC. Non-reproductive females use interior chambers with a temperature of 33.4-34.2EC, often roosting in nurseries of Leptonycteris curasoae. M. megalophylla emerges soon after dark, flying in dense, fast-moving formations. Once out of the roost, individuals fly quickly to foraging sites along canyons and arroyos. These bats are strong, fast flyers that travel at relatively high altitudes enroute to and from foraging sites. Foraging sometimes occurs over standing water. Individuals begin to return approximately seven hours after first leaving the roost. Stomach and intestinal contents collected from four individuals suggest this species feeds on large-bodied moths. Although seasonal patterns are not well understood, in Texas, winter records from the Edwards Plateau and summer records from the Trans-Pecos suggest that some seasonal movements occur.
No known threats to the species have been identified to date. However, some of the general threats to bats could apply to this species. These could include impacts to cave and mine roosts, use of pesticides, and alteration of foraging areas from timber harvest or agriculture.
Apparently this species does not hibernate, but very little is known of its seasonal movements. Likewise, little is known of its foraging habits and food preferences, and virtually nothing is known on its reproductive habits. Status of historic roosts and active searching for unreported roosts should be undertaken.
Rezsutek, M., and G.N. Cameron. 1993. Mormoops megalophylla. American Society of Mammalogists, Mammalian Species, 448:1-5.
Account by Bat Conservation International
leaf-nosed bats
Phyllostomidae /
Phyllostomidae, i.e., New World leaf-nosed bats, represents one of the most morphologically diverse families, comprising approximately 227 species of 61 genera. These extraordinary bats, whose scientific and common names derive from their ‘leaf-shaped’ noses, occur throughout Central and South America, from Mexico to northern Argentina.
Choeronycteris mexicana, a member of the Family Phyllostomidae (leaf-nosed bats), is found in the southwestern United States through Mexico to El Salvador and Honduras. In the United States, it occurs primarily in southern California (the San Diego area), southern Arizona, southwestern New Mexico, and the southern tip of Texas (Figure 1). Extralimital records exist from Grand Canyon National Park in northern Arizona and Las Vegas, Nevada. This bat occurs in a variety of habitats, including thorn scrub, Palo Verde-saguaro desert, semi-desert grassland, oak woodland and tropical deciduous forests. In the southwestern United States, Choeronycteris is typically observed in oak-conifer woodlands and semi desert grasslands. Most of the historical sites occupied by this species in southern Arizona and New Mexico were associated with streams and riparian vegetation.
Global Rank – G4. State Ranks: AZ – S1S2; CA – S2; NM – S1; NV – SA; TX – S1. The Mexican long-tongued bat is currently listed by the U.S. Fish and Wildlife Service as a Species of Concern. This classification describes an entire realm of taxa whose conservation status may be of concern to the Service (former C2 species). This designation carries with it no official status. This species is also considered Sensitive by the U.S. Forest Service, is considered to be Rare in Mexico, is proposed as a Species of Special Concern in California, and is included in Arizona Game and Fish Department’s Wildlife of Special Concern in Arizona. Fewer than 1,500 individuals of this species have been documented since its discovery. In Arizona, all bats are protected from take by Arizona Game and Fish Commission Order #14.
Like other phyllostomid (=leaf-nosed) bats, C. mexicana has a leaf-like projection at the tip of its nose. It can be distinguished from other phyllostomid bats occurring in the U.S. by its relatively shorter ears, longer and narrower rostrum, and the presence of a tail. This species typically roosts in twilight areas near the entrances of caves, mines, rock crevices, and abandoned buildings. Roosting groups are usually comprised of < 15 individuals, but some colonies may reach 40-50 individuals. During the spring and summer, they rarely cluster and typically roost 1-2 inches apart. In the autumn when temperatures drop below 70oF, they have been observed to cluster in groups of 5-6. These bats are wary of intrusion and tend to fly out of the roost when disturbed. However, multiple roost sites are usually located within close proximity of each other and bats often return to roosts shortly after a disturbance stops. Choeronycteris mexicana forages primarily on nectar and pollen of night-blooming flowers such as species of Agave and columnar cacti. It also may eat the fruit of columnar cacti, along with incidental insects found on the fruit or flowers. Hummingbird feeders may help sustain individuals that arrive in Arizona early in the year, or remain into winter when natural food sources are not available. However, sugar water lacks essential nutrients (e.g., protein, vitamins) required for long-term survival. There is also evidence that they will forage on ornamental vegetation, such as Mexican bird-of-paradise. Very little is known about the migratory movements of this species. Over the past few years, these bats have arrived in Arizona as early as May. Apparently only females come north into the United States to birth and raise their young. The young are typically born in late June to early July, but reports of early-spring and late-autumn births indicate variation in parturition time. The young can fly within 2-3 weeks of birth. In October and November, they depart their maternity roosts for Mexico and Central America, where they remain active during the winter. Evidence suggests that some individuals may over-winter in warmer areas of Arizona and autumn and/or winter records exist for southern California and Texas.
Possible threats to this species include recreational caving; natural or intentional mine closures, renewed mining, mine reclamation, and loss of food resources. Long-term sustainability of food plants may be extremely important to this species. Anthropogenic activities such as development, prescribed fire, or grazing could potentially have negative impacts on food plants. In addition, direct disturbance and loss of riparian habitat brought about by such activities may also adversely affect this species in the southern United States. In general, the long term persistence of North American bat species is threatened by the loss of clean, open water; modification or destruction of roosting and foraging habitat; and, for hibernating species, disturbance or destruction of hibernacula. Chemicals in the environment that affect bats or their prey are also a threat. Because of low fecundity and long generational turnover, many bat populations may be vulnerable to human-induced pressures.
Morphologically distinct. Roosts are difficult to find, but bats are easy to detect in roost. Effectiveness of netting depends on habitat type. This species is difficult to detect acoustically and is indistinguishable from Leptonycteris species in flight, except at very close range (e.g. hummingbird feeders).
More information is needed to delineate the distribution of this species and better understand its seasonal movement patterns throughout its range. Studies are needed to clarify roosting and foraging requirements. This species may be amenable to mark-recapture methods for assessing population trends.
Arizona Game and Fish Department. In Prep. Wildlife of special concern in Arizona. Nongame and Endangered Wildlife Program. Arizona Game and Fish Department, Phoenix, Arizona.
Arizona Game and Fish Department. 1994. Choeronycteris mexicana. Unpublished abstract compiled and edited by the Heritage Data Management System, Arizona Game and Fish Department, Phoenix, Arizona.
Arroyo-Cabrales, J., R. R. Hollander and J. K. Jones, Jr. 1987. Choeronycteris mexicana. American Society of Mammalogists, Mammalian Species, 291:1-5.
Castner, Shawn V. 1995. “Mexican long-tongued bat.” Arizona Wildlife Views. June.
Constantine, D. G. 1987. Long-tongued bat and spotted bat at Las Vegas, Nevada. Southwestern Naturalist, 32(3):392.
Cryan, P. M. and M. A. Bogan. 2003. Recurrence of Mexican long-tongued bats (Choeronycteris mexicana) at historical sites in Arizona and New Mexico. Western North American Naturalist, 63:314-319.
Fleming, T. H., Tibbitts, T., Petryszyn, Y. and V. Dalton. 2003. Current status of pollinating bats in southwestern North America. Pp. 63-68 In Monitoring trends in bat populations of the United States and territories: problems and prospects (T.J. O’Shea and M.A. Bogan, eds.). U.S. Geological Survey, Biological Resources Discipline, Information and Technology Report, USGS/BRD/ITR–2003-0003. 274 pp.
Hoffmeister, D. R. 1986. Mammals of Arizona. University of Arizona Press, Tucson. 602 pp.
Schmidly, D. J. 1991. The bats of Texas. University of Texas Press, Austin, TX. 189 pp.
Original account by Debra Noel
2005 update by Paul Cryan
Leptonycteris curasoae, a member of the Family Phyllostomidae (New World leaf-nosed bats), is recorded in southern Arizona from the Agua Dulce Mountains in the west, north to Phoenix and east to southwestern New Mexico, south through Mexico to El Salvador. This species inhabits of the Sonoran desert scrub, semi-desert grasslands and lower oak woodlands in the United S. In Mexico, the lesser long-nosed bat occurs in coastal desert-scrub, thorn-scrub, thorn forest, pine-oak woodlands, and ponderosa pine habitat.
Global Rank: G4; State Ranks: AZ – S2, NM – S1; Other Ranks: IUCN – VU; Mexico – Threatened; AGFD – Wildlife of Special Concern; USFS – Sensitive; Federally listed as endangered in 1988 due to long term population declines, reports of absence from historic roosts, decline in agave pollination, and concern for death of an ecosystem. Population decline information has been questioned due to improperly timed surveys and overestimates of historic populations. A 5-year review is underway in 2005 to ensure that the endangered classification is accurate.
The lesser long-nosed bat is a medium-sized bat with relatively large eyes and a forearm of 51-56 mm. It has reddish-brown fur and an elongated snout and nose leaf, no tail, and the interfemoral membrane is reduced to a narrow band along each hind leg. This species does not hibernate, and is one of few bat species that undergo long distance migrations. They migrate south in the fall to Mexico, where they breed and spend the winter. Migration corridors are not known exactly, but data have shown use of two corridors during spring migration, one coastal and the other inland. Lesser long-nosed bats may follow the sequential blooming of agave, saguaro, ocotillo, palo verde, prickly pear and organ pipe cactus during their migrations, feeding on nectar and pollen. The tongue is long and tipped with brush-like papillae to lap up nectar. Some authors suggest pollination success of Agave palmeri is dependent upon this and other nectar-feeding bats. This bat roosts in caves and mine tunnels. Males form separate, smaller colonies from females. Females may arrive in southwestern Arizona as early as the second week in April and form maternity colonies from early May to late June/early July. Maternity colonies number in the hundreds to thousands and in a few places in the tens of thousands. Females give birth to one young per year, which are volant by the end of June. In Arizona, following break up of maternity colonies by the end of July, some bats move east to transient roosts at the higher elevations of southern Arizona and southwestern New Mexico. Others found at these eastern roosts beginning in mid-July might come directly from Mexico. Efforts to conserve and learn more about the life history of this species include: annual surveys of important roosts in Arizona, New Mexico, and Mexico, including simultaneous efforts; surveys for new roost locations, migration corridor studies, foraging studies, public education and information efforts, improved population census techniques, roost characteristics study, and roost protection at some sites.
Threats to the lesser long-nosed bat includes loss of foraging habitat by fire; roost site disturbance from recreational caving, illegal immigrant/smuggler activities near maternity roosts near the Arizona-Mexico border; destruction of forage plants by development, grazing, and human exploitation of agaves for food and alcohol production; possible reduction in numbers of forage plants resulting from depressed pollination; and direct mortality by humans.
Netting/capture effectiveness depends on habitat type. Identification: Morphologically distinct. Roost Location: Roosts in mines and caves, and is highly colonial. Identification at Roost: Easy to detect and identify in roost except in areas of overlap with Leptonycteris nivalis. Passive acoustic detection: Difficult to detect acoustically where range overlaps with Choeronycteris mexicana. Active acoustic detection: Indistinguishable in flight from Leptonycteris nivalis and Choeronycteris mexicana, except possibly at very close range (e.g. hummingbird feeders).
Continue gathering information on population size and trends; information regarding the timing of seasonal movements, migration routes used, and plant species and phenology along such routes; genetics of sub-populations; interdependence of the species with individual plant species and communities; location of important roosting areas; characteristics of ideal roosts.
Cockrum, E. L. 1991. Seasonal distribution of northwestern populations of the long-nosed bats, Leptonycteris sanborni, family Phyllostomidae. Anales Inst. Biol. Univ. Nac. Auton. Mexico, Ser. Zool., 62(2):181-202.
Cockrum, E. L., and Y. Petryszyn. 1991. The long-nosed bat, Leptonycteris: an endangered species in the Southwest? Occ. Pap. Mus. Texas Tech Univ., 142:1-32.
Cockrum, E. L., B. Musgrove, and Y. Petryszyn. 1996. Bats of Mohave County, Arizona: Populations and Movements. Occ. Papers Mus. Texas Tech Univ., 157:1-71.
Fleming, T. H. 1991. Following the nectar trail. Bats, 9(4):4-7.
Fleming, T. H. 1993. Plant-visiting bats. American Scientist, 81(5):460-467.
Fleming, T. H., R. A. Nunez and L. D. S. L. Sternberg. 1993. Seasonal changes in the diets of migrant and non-migrant nectarivorous bats as revealed by carbon stable isotope analysis. Oecologia (Heidelb), 94(1):72-75.
Hoyt, R. A., J. S. Altenbach, and D. J. Hafner. 1994. Observations on long-nosed bats (Leptonycteris) in New Mexico. Southwestern Naturalist, 39:175-179.
Sahley, C. T., M. A. Horner, and T. H. Fleming. 1993. Flight speeds and mechanical power outputs of the nectar-feeding bat, Leptonycteris curasoae (Phyllostomidae: Glossophaginae). Journal of Mammalogy, 594-600.
U.S. Fish and Wildlife Service. 1995. Lesser Long-nosed Bat Recovery Plan. U.S. Fish and Wildlife Service, Albuquerque , New Mexico. 45 pp.
Wilkinson, G. S., and T. H. Fleming. 1996. Migration and evolution of lesser long-nosed bats Leptonycteris curasoae, inferred from mitochondrial DNA. Molecular Ecology, 5(3):329-339.
Original account by Michael Herder
2005 update by Angela McIntire
Leptonycteris nivalis, a member of the Family Phyllostomidae (leaf-nosed bats), is found in the southern Trans-Pecos in Texas and the southwestern corner of New Mexico, southward through central and eastern Mexico, mostly east of the 102 meridian and south at least to Guerrero and Guatemala. High-elevation pine-oak woodlands (5,000 ft. to snow line) and at lower elevations (1860 ft.) In agave and desert-scrub woodlands.
Global Rank – G3. State Ranks: NM – S1; TX – S1. Federally listed as endangered in 1988 due to long-term population declines, apparent abandonment of historic roosts, and decline in agave pollination.
An agile flyer capable of quick maneuvering and high speed flight. Roosts colonially in caves, deep caverns, mines, culverts, hollow trees, and unused buildings. Known to share roosts with Corynorhinus townsendii, and may use the same roost as Myotis thysanodes and M. volans, but at different times. Breeding season in Texas reportedly April, May and June, with lactating females found in June and July and volant young in late June. Adult males segregate geographically in summer and do not occupy the northern part of the range. Produces one young per year. Feeds on nectar, pollen, insects (accidental), and probably soft succulent cactus fruits during the non-flowering season. Feeds from flowers of various agaves (Agave scabra, A. chisosensis, A. lechguilla, and A. schotti), mescal (A. spp.), jimson weed (Datura stramonium) and wax mallow (Malvaviscus spp.). Feeds by thrusting its snout into the flower and licking the nectar with its long tongue. Emerges with its head covered with pollen. This species is an effective pollinator of many cacti, agave, and other species on which it feeds.
Loss of foraging habitat by fire; destruction of forage plants (human exploitation of agaves for food and alcohol production); reduction in numbers of forage plants resulting from depressed pollination success caused by Leptonycteris population declines; roost site disturbance (recreational caving), and direct mortality by humans.
Netting/capture effectiveness depends on habitat type. Identification: Morphologically distinct. Roost Location: Roosts in mines and caves, and is highly colonial. Identification at Roost: Easy to detect and identify in roost except in areas of overlap with Leptonycteris nivalis. Passive acoustic detection: Difficult to detect acoustically where range overlaps with Choeronycteris mexicana. Active acoustic detection: Indistinguishable in flight from Leptonycteris nivalis and Choeronycteris mexicana, except possibly at very close range (e.g. hummingbird feeders).
Information is needed on population size and trends; the timing and destination of seasonal movements; interdependence of the species with individual plant species and communities; location of important roosting areas; characteristics of ideal roosts.
Hensley, A. P., and K. T. Wilkins 1988. Leptonycteris nivalis. American Society of Mammalogists, Mammalian Species, 307:1-4.
Hoyt, R. A., J. S. Altenbach, and D. J. Hafner. 1994. Observations on long-nosed bats (Leptonycteris) in New Mexico. Southwestern Naturalist, 39:175-179.
Schmidly, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, TX. 188 pp.
Account by Michael Herder
Macrotus californicus is the most northerly representative of the Phyllostomidae (a predominantly Neotropical family). It occurs in the Lower Sonoran life zone in the deserts of California, southern Nevada, Arizona and south into Baja California and Sonora, Mexico.
Global Rank – G4. State Ranks: AZ – S3S4; CA – S2S3; NV – S?; UT – SP. It is is included in Arizona Game and Fish Department’s Wildlife of Special Concern in Arizona, and listed as a Mammal of Special Concern in California. It is a former Category 2 (C2) candidate.
Human entry into mine or cave roosts and closure of mines for hazard abatement and renewed mining are the primary threats to Macrotus. Loss of desert riparian habitat (as in the development of golf courses and housing areas in the Coachella Valley) are also responsible for population declines.
Identifying mines used as roosts (maternity, winter and courtship) within the range of Macrotus, establishing the effectiveness of different bat gate designs, and determining the distance at which exploratory drilling and blasting in renewed mining activities causes impacts to roosting bats.
Anderson, S. 1969. Macrotus waterhousii. American Society of Mammalogists, Mammalian Species, 1:1-4.
Barbour, R. W. & Davis, W. H. 1969. Bats of America. Lexington, Ky: University of Kentucky Press.
Bell, G. P. 1985. The sensory basis of prey location by the California leaf-nosed bat Macrotus californicus (Chiroptera: Phyllostomidae). Behavioral Ecology and Sociobiology 16: 343-347.
Bell, G. P., G.A. Bartholomew, and K.A. Nagy. 1986. The roles of energetics, water economy, foraging behavior, and geothermal refugia in the distribution of the bat, Macrotus californicus. Journal of Comparative Physiology B 156: 441-450.
Berry, R.D. and P.E. Brown. 1995. [ABS]. Natural history and reproductive behavior of the California leaf- nosed bat (Macrotus californicus). Bat Research News 36(4): 49-50.
Brown, P. E., R. D. Berry, and C. Brown. 1993. [ABS].Foraging behavior of the California leaf-nosed bat, Macrotus californicus as determined by radiotelemetry. Bat Research News 34(4):104.
Brown, P. E., Berry, R. D. & Brown, C. 1995. The California leaf-nosed bat (Macrotus californicus) and American Girl Mining joint venture – impacts and solutions. Pp. 54-56 in Proceedings VI:Issues and technology in the management of impacted wildlife. Thorne Ecological Institute, Boulder, CO.
Hoffmeister, D. F. 1986. The mammals of Arizona. University of Arizona Press, Tucson, AZ. 602 pp.
Account by Patricia E. Brown
vesper bats
Vespertilionidae /
Vespertilionidae, the taxonomic family of “evening bats,” “vesper bats,” or “common bats” compose the largest family within the order Chiroptera, containing approximately 529 species of 60 genera. As the second largest mammalian family, vespertilionids occur on every continent except Antarctica. The majority of these species possess a simple face and relatively small eyes, are insectivores and rely primarily on echolocation.
Antrozous pallidus (Vespertilionidae) ranges throughout western North America, from British Columbia ‘s southern interior, south to Queretaro and Jalisco, and east to Texas (Figure 1). An isolated population, A. p. koopmani, is endemic to Cuba . A. pallidus inhabits low elevation (< 1,830 m / 6,000 feet) rocky arid deserts and canyonlands, shrub-steppe grasslands, karst formations, and higher elevation coniferous forests (> 2,100 m / 7,000 feet). It is most abundant in xeric ecosystems, including the Great Basin, Mojave, and Sonoran Deserts .
Global Rank – G5. State Ranks: AZ – S4/S5; CA – S3; CO – S4; ID – S1; KS – S1; MT – S1; NM – S5; NN – S5; NV – S3B; OK – S3; OR – S3; TX – S5; UT – S4; WA – S3; WY – S1; BC – S1. USFS – None; BLM – Special Status/Sensitive; USFWS – Sensitive. California Species of Special Concern. Mexico – Not a species of concern. IUCN Red List Category – LR.
Pallid bats’ tendency to roost gregariously and their relative sensitivity to disturbance makes them vulnerable to mass displacement. Roosts and hibernacula can be damaged or destroyed by vandalism, mine closures and reclamation, recreational activities such as rock climbing, forestry practices such as timber harvest, and, where man-made structures are occupied, demolition, modification, chemical treatments, or intentional eradication and exclusion. Maternity colonies and hibernating bats are especially susceptible to disturbance. Loss or modification of foraging habitat due to prescribed fire, urban development, agricultural expansion, and/or pesticide use pose potential threats. This is especially true in coastal California , where urbanization has reduced roosting and foraging habitat, and in British Columbia , Canada where agricultural expansion may compromise prey availability and quality.
There are scant records of seasonal movements, locations of hibernacula and winter roosts, and mating behavior. There is a paucity of information quantifying tolerance to habitat modification (i.e., conversion of native habitat for agriculture and forced roost relocation) and impacts of threats such as roost disturbance and pesticide or heavy metal contamination. Data are also lacking for population trends, roosting and habitat requirements, and limiting factors, especially for peripheral populations. There have been few studies of this species in Mexico and Cuba.
Brown, P.E. and R.D. Berry. 1997. Surveys for bat species of special concern. Unpub. report prepared for California Department of Fish and Game, Wildlife Management Division. Sacramento, CA. Contract FG5124WM. 6 pp.
Chapman, K., K. McGuiness, and R.M. Brigham. 1994. Status of the pallid bat in British Columbia. B.C. Environment. Victoria, B.C. Wildlife Working Report No. WR-61. 32 pp.
COSEWIC. 2002. Canadian Species at Risk, May 2002. Committee on the Status of Endangered Wildlife in Canada. 39 pp.
Fuzessary, Z.M., P. Buttenhoff, B. Andrews and J.M. Kennedy. 1993. Passive sound localization of prey by the pallid bat (Antrozous pallidus). Journal of Comparative Physiology A. 171: 767-777.
Hermanson, J.W., and T.J. O’Shea. 1983. Antrozous pallidus. American Society of Mammalogists. Mammalian Species. No. 213: 1-8.
Herrera, M.L.G., T.H. Fleming and J.S. Findley 1993. Geographic variation in carbon composition of the pallid bat, Antrozous pallidus, and its dietary implications. Journal of Mammalogy. 74(3): 601-606.
Johnston, D.S. 2002. [ABS]. Prey discrimination by olfactory cues in the pallid bat (Antrozous pallidus). Bat Research News. 42(4): 162.
Johnston, D.S. 2004. [ABS]. Winter roosting ecology of pallid bats (Antrozous pallidus) in a central California woodland forest. 2nd Bats and Forest Conference. Hot Springs, AR.
Johnston , D.S. and M.B. Fenton. 2001. Individual and population-level variability in diets of pallid bats (Antrozous pallidus). Journal of Mammalogy. 82(2): 362-373.
Jones, C. 1965. Ecological distribution and activity periods of bats of the Mogollon Mountains area of New Mexico and adjacent Arizona. Tulane Studies in Zoology. 12: 93-100.
Lewis, S.E. 1993. Effect of climatic variation on reproduction by pallid bats (Antrozous pallidus). Canadian Journal of Zoology. 71: 1429-1433.
Lewis, S.E. 1994. Night roosting ecology of pallid bats (Antrozous pallidus) in Oregon . American Midland Naturalist. 132(2): 19-226.
Lewis, S.E. 1996. Low roost-site fidelity in pallid bats: associated factors and effect on group stability. Behavioral Ecology and Sociobiology. 39(5): 335-344.
Pierson, E.D., W.E. Rainey, and R.M. Miller. 1996. Night roost sampling: a window on the forest bat community in northern California. Pp. 151-163. In Bats and Forests Symposium. October 19-21, 1995. Victoria, British Columbia, Canada. Research Branch, Ministry of Forests. Victoria, B.C. Working Paper 23/1996.
Rambaldini, D.A. 2006. Behavioural ecology of pallid bats (Chiroptera: Antrozous pallidus) in British Columbia. Unpublished report prepared for Environment Canada, Canadian Wildlife Service, BC Ministry of Environment, Osoyoos (Nk’Mip) Indian Band, and World Wildlife Fund of Canada. 82 pp.
Rambaldini, D.A. and R.M. Brigham. 2004. Habitat use and roost selection by pallid bats (Antrozous pallidus) in the Okanagan Valley, British Columbia. Unpublished report prepared for Canadian Wildlife Service, BC Ministry of Land, Water and Air Protection, Osoyoos (Nk’Mip) Indian Band, and World Wildlife Fund of Canada. 65 pp.
Rodhouse, T.J. and R.G. Wright. 2004. Study of bat roosts in John Day Fossil Beds National Monument. Unpublished report prepared for the University of Idaho and National Park Service, Upper Columbia Basin Network. Department of Fish and Wildlife Resources. Moscow, ID. 43 pp.
Tatarian, G. 2001. Successful pallid bat house design in California. BATS Magazine. Fall Issue. 9(2): 2-4.
Original account by Rick Sherwin
2005 update by Daniela A. Rambaldini
Corynorhinus townsendii occurs throughout the west and is distributed from the southern portion of British Columbia south along the Pacific coast to central Mexico and east into the Great Plains, with isolated populations occurring in the central and eastern United States (Figure 1). It has been reported in a wide variety of habitat types ranging from sea level to 3,300 meters. Habitat associations include: coniferous forests, mixed meso-phytic forests, deserts, native prairies, riparian communities, active agricultural areas, and coastal habitat types.
Global Rank – G4T4 (This may need to be reviewed and revised along with state rankings). This species has been listed as vulnerable to extinction (VU) by the World Conservation Union’s 2004 IUCN Red List of threatened species (www.redlist.org). Federally in the United States, the western subspecies, C. t. townsendii and C. t. pallescens were listed as former USFWS category 2 candidate for listing (USFWS 1989; USFWS 1994) under the Endangered Species Act (ESA). The two isolated subspecies in the central and eastern United States, C. t. ingens and C. t. virginianus, respectively are listed as endangered species (authorized under the ESA) and managed as such by the USFWS (USFWS 1979). In the western United States the only current federal protection for this species is as a sensitive species by management agencies on their lands. The USFS lists this bat as a sensitive species in Region 2, Region 3, and Region 4. However, recently this sensitive species status has been removed from C. townsendii in USFS Region 6. C. townsendii is a BLM sensitive species in California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and Wyoming. State Status Ranks are as follows: AZ – S3; CA – S3S4; CO – S2; ID – S2; KS-S2; KY-S2; MT – S2S3; ND – ?; NE – S1; NM – S3; NV – S3; OK – S3; OR – S2;SD-S2S3;TX-S4;UT-S4;WA-S2;WV-S2;WY-S2;BC-S2S3. Finally,thisbatislistedas state Species of Special Concern by the following states: Arizona, California, Idaho, Montana, Oregon, Texas, and Utah.
C. townsendii is quite effective at avoiding mist-nets. Morphologically these bats are similar to the Allen’s Big-eared bat (Idionycteris phyllotis). Roost locations are most effectively found by searching for colonial roosts in mines and caves. However, roosts can be found in buildings in the coastal and northern portions of range. In some portions of its range, particularly Canada and some desert areas, roosts can be very difficult to locate. Because these bats hang pendulum-like they can be easy to locate and identify in a roost. These bats are difficult to detect with passive acoustic detection because they utilize low intensity calls (“whispering bat”), however they are acoustically (passively and through recording devices) and visually distinctive in most settings.
Brown, P. E., R. Berry, and C. Brown. 1994. Foraging behavior of Townsend’s big-eared bats (Plecotus townsendii) on Santa Cruz Island. Fourth California islands Symposium: Update on the status of resources, 367-369.
Clark, B. K., and B. S. Clark. 1997. Seasonal variation in use of caves by the endangered Ozark big-eared bat (Corynorhinus townsendii ingens) in Oklahoma. American Midland Naturalist, 137: 388-392.
Handley, C. O. 1959. A revision of the American bats of the genera Euderma and Plecotus. Proceedings of the U.S. National Museum, 110: 95-246.
Humphrey, S.R., and T. H. Kunz. 1976. Ecology of a Pleistocene relict, the western big-eared bat (Plecotus townsendii) in the southern Great Plains. Journal of Mammalogy, 57: 470-494.
Idaho State Conservation Effort. 1995. Habitat conservation assessment and conservation strategy for the Townsend’s big-eared bat. Draft unpubl. rep. no. 1. Boise, ID, 62 pp.
Kunz, T. H., and R. A. Martin. 1982. Plecotus townsendii. American Society of Mammalogists, Mammalian Species, 175: 1-6.
Navo, K. W., and Krabacher, P. 2005. The use of bat gates at abandoned mines in Colorado. Bat Research News.
Pearson, O. P., M. R. Koford, and A. K. Pearson. 1952. Reproduction of the lump-nosed bat (Corynorhinus rafinesquei) in California. Journal of Mammalogy, 33: 273-320.
Piaggio, A. J., and S. L. Perkins. In review. Molecular phylogeny of North American big-eared bats (Vespertilionidae: Corynorhinus): inter- and intraspecific relationships inferred from mitochondrial and nuclear DNA sequences. Molecular Phylogenetics and Evolution.
Pierson, E. D., and W. E. Rainey. 1996. The distribution, status and management of Townsend’s big-eared bat (Corynorhinus townsendii) in California. Calif. Dept. of Fish and Game, Bird and Mammal Conservation Program Rep. 96-7. 49 pp.
Sherwin, R. E., D. Stricklan, and D. S. Rogers. 2000a. Roosting affinities of Townsend’s big-eared bat (Corynorhinus townsendii) in northern Utah. Journal of Mammalogy, 81: 939–947.
Sherwin, R. E., W. L. Gannon, and J. S. Altenbach. 2003. Managing complex systems simply: understanding inherent variation in the use of roosts by Townsend’s big-eared bat. Wildlife Society Bulletin, 3: 62–72.
Sherwin, R. E., W. L. Gannon, J. S. Altenbach, and D. Stricklan. 2000b. Roost fidelity of Townsend’s big- eared bat in Utah and Nevada. Transactions of the Western Section of the Wildlife Society, 36: 15–20.
United States Fish and Wildlife Service. 1979. Endangered and threatened wildlife and plants; listing of the Virginia and Ozark Big-Eared Bats as endangered species, and critical habitat determination. Federal Register, 44: 69206-69208.
United States Fish and Wildlife Service. 1985. Endangered and Threatened Wildlife and Plants; Animal Candidate Review for Listing as Endangered or Threatened Species. Federal Register, 50: 37965.
United States Fish and Wildlife Service. 1994. Endangered and Threatened Wildlife and Plants; Animal Candidate Review for Listing as Endangered or Threatened Species. Federal Register, 59: 58988.
Original account by Rick Sherwin
2005 update by Antoinette Piaggio
Eptesicus fuscus, a member of the Family Vespertilionidae, has an extremely broad distribution reaching from Alaska and northern Alberta to northern South America. It occurs in all western States and Provinces associated with the Western Bat Working Group. Two subspecies are recognized in the western U.S. : E. f. bernardinus and E. f. pallidus E. fuscus occurs in a wide variety of habitats from desert scrub and moist coastal forests to high elevation conifer forests, and is one of the few species that persists in relatively urbanized environments.
Global Rank – G5. State Ranks: AZ – S4; CA – S5; CO – S5; ID – S5; MT – S4; NM – S5; NV – S?; OR – S4; TX – S5; UT – S4; WA – S?; WY – S5; AL – S4S5; BC – S4S5. Not listed by any State or Province. Perceived as relatively common in many localities. It is the second most common bat found in urban areas in Washington and Oregon.
E. fuscus is a medium to large sized North American vespertilionid. It can be distinguished from all other large vespertilionids by the combination of relatively dark color, a keeled calcar, and a blunt tragus. The tip of its tail usually extends 3 mm beyond the uropatagium. E. fuscus is a colonial species, with the size of maternity colonies varying from about a dozen to several hundred. This species is well known for its propensity to roost in anthropomorphic structures, including buildings, mines, and bridges, but it has also been found in caves, crevices in cliff faces, and a hole in a giant saguaro. More recently extensive tree roosting (particularly in large diameter snags) has been documented in forested, preferably uncluttered, landscapes. Bridges are commonly used as night roosts by males and pre-parturition and post-lactating females. In the west, E. fuscus is known to hibernate in relatively small numbers per site in caves, buildings and mines. E. fuscus forages within a few kilometers of its roost, generally pursuing prey in tree canopies, over meadows, or along water courses. It feeds primarily on heavy-bodied insects, and is an important predator on certain agricultural pests (e.g, Diabrotica, the spotted cucumber beetle). Although primarily beetle (coleopteran) specialists, their diet also includes hemipterans, dipterans, lepidopterans, trichopterans and hymenopterans. E. fuscus mate in the fall and winter, but ovulation does not occur until the spring. Each female produces producing one young (the eastern subspecies produce twins) in early summer, after a gestation of about 60 days. The young are volant in three to four weeks. E. fuscus appears to be a relatively sedentary species and is not known to migrate large distances (although males may migrate elevationally in the Cascade Mountains). Females roost separately from males in the spring and summer, and roost with males at hibernating sites. This species hibernates for most of the winter in the northern portion of its range, but is active on warm nights in the winter in the southwest.
More information is needed on roosting requirements, particularly in forested landscapes. The effects of timber harvest need to be investigated. Studies are needed to further investigate the role of this species in controlling insect pests. Information is generally lacking on seasonal movements, and hibernation sites.
Betts, B. 1995. Roosting behavior of silver-haired and big brown bats in Northeast Oregon. Pp. 55-61, in Bats and Forests Symposium, October 19-21, 1995, Victoria, British Columbia, Canada. Research Branch, Ministry of Forests, Victoria, British Columbia, Working Paper 23/1996.
Brigham, R. M. 1991. Flexibility in foraging and roosting behaviour by the big brown bat (Eptesicus fuscus). Canadian Journal of Zoology, 69(1): 117-121.
Kurta, A. and R. H. Baker. 1990. Eptesicus fuscus. American Society of Mammalogists, Mammalian Species, 356: 1-10.
Kalcounis, M. 1994. [ABS]. Selection of tree roost sites by big brown (Eptesicus fuscus), little brown (Myotis lucifugus) and hoary (Lasiurus cinereus) bats in Cypress Hills, Saskatchewan. Bat Research News, 35(4): 103.
Perkins, J. M. 1996. Bat distribution within a managed forest. Bats and Forests Symposium, Victoria, B. C. Canada. Brigham and Barclay, eds. Pp. 164-174, in Bats and Forests Symposium, October 19-21, 1995, Victoria, British Columbia, Canada. Research Branch, Ministry of Forests, Victoria, British Columbia, Working Paper 23/1996.
Vonhof, M. 1995. Roosting ecology and roost-site preferences of reproductive Eptesicus fuscus and Lasionycteris noctivagans in the Pend D’Oreille Valley in southern British Columbia. Pp. 62-80, in Bats and Forests Symposium, October 19-21, 1995, Victoria, British Columbia, Canada. Research Branch, Ministry of Forests, Victoria, British Columbia, Working Paper 23/1996.
Whitaker, J. O., Jr. 1995. Food of the big brown bat Eptesicus fuscus from maternity colonies in Indiana and Illinois. American Midland Naturalist, 134(2): 346-360.
Account by Mark Perkins
Euderma maculatum, a member of the Family Vespertilionidae, occurs throughout western North America, from British Columbia as far south as Jalisco, Mexico. In the United Sates, it is known from all the states west of and including Montana, Wyoming, Colorado, New Mexico and Texas. Although broadly distributed, this species is rarely common, but may be locally abundant in southern British Columbia, northern Arizona, Arizona/Utah border, and west Texas. Spotted bats have been found from below sea level to 2700 m elevation, occurring from arid, low desert habitats to high elevation conifer forests. Prominent rock features appear to be a necessary feature for roosting. Winter range and hibernacula are unknown for most its range, though the species has been captured year-round in the southern part of its range and is may be year-round in central Oregon with the exception of December and January.
Global Rank: G4. IUCN Red List Category: LR – Lower risk. Natural Heritage State Ranks: AZ – S1S2; CA – S2S3; CO – S2; ID – S2; MT – S1; NM – S3; NV – S1S2; OR – S1; TX – S2; UT – S2S3; WA – S3; WY – S3. Canada Ranks: BC – S3S4. USFWS: No status. BLM and FS: Sensitive species in several states and regions. The spotted bat has been listed as a species of concern because of limited information available, and uncertainty as to life history and population trends. States with specific ranking include: AZ – Wildlife of Special Concern Candidate; CA – Species of Special Concern; ID – Species of Concern; MT – S2; NM – Threatened; NV – Threatened; TX – State Threatened Species; UT – Wildlife Species of Concern; WA – State Monitor Species; WY – NSS2. Canada Ranks: BC – Special Concern Species.
Netting can be effective where water is a limiting factor in xeric conditions, although netting is not effective in many portions of range. This species is easy to detect acoustically (with microphones sensitive to audible frequencies). Calls are audible to many people. Identification in hand is easy as the species is morphologically distinct. Euderma maculatum is difficult to distinguish in flight from I. phyllotis; but is otherwise distinctive. Cliff roosts are very difficult to locate and are generally inaccessible.
More information is needed on life history, ecology, reproduction, habitat use, patterns of movement, distribution and abundance.
Berna, H. J. 1990. Seven bat species from the Kaibab Plateau, Arizona with a new record of Euderma maculatum. Southwestern Naturalist, 35(3): 354-356.
Fenton, M. B., D. C. Tennant, and J. Wyszecki. 1987. Using echolocation calls to measure the distribution of bats: the case of Euderma maculatum. Journal of Mammalogy, 68(1): 142-144.
Fullard, J. H., and J. W. Dawson. 1997. The echolocation calls of the spotted bat Euderma maculatum are relatively inaudible to moths. Journal of Experimental Biology, 200(1): 129-137.
Geluso, K. 2000. Distribution of the spotted bat (Euderma maculatum) in Nevada, including notes on reproduction. Southwestern Naturalist 45(3): 347-352.
Gitzen, R. A., S. D. West, and J. A. Baumgardt. 2001. A record of the spotted bat (Euderma maculatum) from Crescent Bar, Washington. Northwestern Naturalist, 82(1): 28-30.
Hoffmeister, D. F. 1986. The mammals of Arizona. University of Arizona Press, Tucson, AZ 602 pp.
Leonard, M. L., and M. B. Fenton. 1983. Habitat use by spotted bats (Euderma maculatum, Chiroptera: Vespertilionidae): roosting and foraging behavior. Canadian Journal of Zoology, 61(7): 1487-1491.
Luce, R.J. and D. Keinath. 2005. Spotted Bat (Euderma maculatum): A Technical Conservation Assessment. USDA Forest Service, Rocky Mountain Region Species Conservation Project. 78pp. In review.
Navo, K. W., J. A. Gore, and G. T. Skiba. 1992. Observations on the spotted bat, Euderma maculatum, in northwestern Colorado. Journal of Mammalogy, 73(3): 547-551.
O’Farrell, M. J. 1981. Status report: Euderma maculatum (J.S. Allen). U.S. Fish and Wildlife Service, Office of Endangered Species. 29pp.
Pierson, E. D., and W. E. Rainey. 1998. Distribution of the spotted bat, Euderma maculatum, in California. Journal of Mammalogy, 79(4): 1296-1305.
Poche, R. M. 1981. Ecology of the spotted bat (Euderma maculatum) in southwest Utah. Utah Division of Wildlife Resources, Salt Lake City, Utah. Publ. No. 81-1. 63pp.
Poche, R. M., and G. A. Ruffner. 1975. Roosting behavior of male Euderma maculatum from Utah. Great Basin Naturalist, 35(1): 121-122.
Poche, R. M., and G. L. Bailie. 1974. Notes on the spotted bat (Euderma maculatum) from southwest Utah. Great Basin Naturalist, 34(4): 254-256.
Priday, J., and B. Luce. 1999. New distributional records for spotted bat (Euderma maculatum) in Wyoming. Great Basin Naturalist, 59(1): 97-101.
Rabe, M. J., M. S. Siders, C. R. Miller, and T. K. Snow. 1998. Long foraging distance for a spotted bat (Euderma maculatum) in northern Arizona. The Southwestern Naturalist, 43(2): 266-269.
Rodhouse, T. J., M. F. McCaffrey, and R. G. Wright. Distribution, foraging behavior, and capture results of the spotted bat (Euderma maculatum) in central Oregon. Western North American Naturalist, 65(2): In press.
Ruffner, G. A., R. M. Poche, M. M. Meierkord, and J. A. Neal. 1979. Winter bat activity over a desert wash in southwestern Utah. The Southwestern Naturalist, 24(3): 447-453.
Schmidly, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, TX. 188 pp.
Snow, T. K., S. V. Castner, S. R. MacVean, C. R. Miller, and D. C. Noel. 1996. Spotted bat survey of the North Kaibab Ranger District (Coconino County, Arizona). Nongame and Endangered Wildlife Program Technical Report 102. Arizona Game and Fish Department. Phoenix, Arizona. 26pp.
Storz, J. F. 1995. Local distribution and foraging behavior of the spotted bat (Euderma maculatum) in northwestern Colorado and adjacent Utah. Great Basin Naturalist, 55(1): 78-83.
Wai-Ping, V., and M. B. Fenton. 1989. Ecology of spotted bat (Euderma maculatum) roosting and foraging behavior. Journal of Mammology 70(3): 617-622.
Watkins, L. C. 1977. Euderma maculatum. American Society of Mammalogists, Mammalian Species, 77: 1-4.
Woodsworth, G. C., G. P. Bell, and M. B. Fenton. 1981. Observations of the echolocation, feeding behavior, and habitat use of Euderma maculatum (Chiroptera: Vespertilionidae) in Southcentral British Columbia. Canadian Journal of Zoology, 59(6): 1099-1102.
Original account by Bob Luce
2005 update by Carol Chambers and Michael Herder
Allen’s lappet-browed bat (Idionycteris phyllotis) is one of the rarest bats in North America, occurring from central Mexico north through the southwestern United States, including Arizona , New Mexico , southern Nevada and southern Utah (Figure 1). It is also known as Allen’s big-eared bat, Allen’s lappet-eared bat, or Mexican big-eared bat. Although it ranges close to the California and Colorado borders, it is not yet verified from those states. Recorded locations range from Mojave Desert scrub to fir forest at elevations ranging from 403-3225 meters (m) (1320 to 9800 feet (ft)), although most captures are from elevations between 1,100-2,500 m (3,500-7,500 ft) in oak-juniper woodland and ponderosa pine forest.
Global Rank – G4. State Ranks: Arizona – S2, California –no ranking; Colorado – no ranking; Nevada – S1; New Mexico – S2; and Utah – S1. Lappet-browed bat is a former U.S. Fish and Wildlife Service Category 2 Candidate for listing under the Endangered Species Act and is now a Species of Concern for U.S. Fish and Wildlife Service, a Candidate for listing by Arizona Game and Fish Department, a Species of Special concern in Utah , and a Bureau of Land Management Sensitive Species.
The lappet-browed bat can be distinguished from all other species by the presence of a pair of lappets projecting over the forehead from the median bases of the large ears, hence the common name of lappet-browed or lappet-eared bat. Based on 138 cranial characters, Tumlison (1993) split Idionycteris phyllotis into two subspecies that appear to have different habitat requirements. The preponderance of captures is in scrub woodland and forest, often associated with cliffs and rocky slopes, suggesting a roosting relationship with caverns and rock fissures. Maternity colonies have been found within passages in a large boulder pile (Commissaris 1961), in a sandstone crevice in a natural bridge in Canyon lands (M. Bogan pers. comm.) and a cliff in Grand Escalante (M. Siders, pers. comm.), under exfoliating bark on ponderosa pine snags (Rabe et al. 1998; Morrell et al. 1999) and in abandoned mines (Cockrum and Musgrove 1964, Brown and Berry 2001). In Arizona , the only known permanent maternity roosts of lappet-browed bats are in three mines in the vicinity of Union Pass in the Black Mountains, Mojave County . Pregnant individuals have been found in June, parturition occurs in mid- to late June, and lactation extends through July and early August. A single young is produced annually. Lactating females have been captured entering a mine after dark in Utah , possibly to catch moths inside the entrance and to night roost (M. Perkins, pers. comm.). R. Sherwin (pers. comm.) has also seen night-roosting bats and individual males in abandoned uranium mines in Utah . Individuals may move from higher elevation summer ranges to low elevation winter habitats (O’Farrell, unpublished data). Foraging lappet-browed bats emit loud human-audible echolocation calls, similar to those of spotted bats (Euderma maculatum). Lappet-browed bats eat primarily small moths (6-12 millimeters) that possess simple “ears” tuned to ultrasonic frequencies, which may explain the use of lower frequency echolocation signals below the range of the moths’ hearing (Simmons and O’ Farrell 1977). The bats also emit human- audible communication signals, especially near roosts. An August 2004 telemetry study of 12 post-lactating females from a mine in the Black Mountains demonstrated high roost fidelity when the bats traveled between 70-100 km (43-62 mi) roundtrip nightly to forage in the next mountain range to the east, despite the fact that there were many abandoned mines in the foraging area (Brown and Berry, 2004). Mesquite grassland, scrub oak and pinyon/juniper woodland were present in the higher elevation areas (1500-2000 m; 4921-6562 ft) where the bats were foraging. The elevation of the roost mine is 1000 m (3280 ft) in creosote bush scrub.
Idionycteris is captured relatively infrequently in mist nets. They may be difficult to locate during initial surveys. Finding roosts may be difficult, especially in trees and rock crevices, unless radio-telemetry is used. In mines, they are easy to detect since they roost in clusters on an open surface (e.g., domes of mines). However, without disturbing the cluster they can be mistaken for Corynorhinus townsendii. The easiest method of detection is acoustic (with a low frequency microphone). Most sequences are diagnostic, except they may be difficult to distinguish from Euderma maculatum, with which they geographically overlap throughout much of their range. A very distinctive social call is used, especially near roosts.
Relatively little is known of maternity roost requirements or the range of roost types used, especially during the winter. Foraging behavior and seasonal requirements in different habitats needs further research. Reproductive biology and population dynamics are poorly understood. It will be necessary to gather these data to properly evaluate potential threats and provide adequate management protocols. The current lack of knowledge of lappet-browed bats suggests the need for focused surveys throughout their geographic range.
Brown, P. E., and R. D. Berry. 2001. Identification and protection of roosts of lappet-browed bats, Idionycteris phyllotis. Report submitted to BCI for NABCP 1999 project.
Brown, P. E., and R. D. Berry. 2004. Foraging habitat and home range of Allen’s big-eared bat (Idionycteris phyllotis) in the Arizona Desert as determined by radio-telemetry. Bat Research News, 45: 207-208.
Cockrum, E. L., and B. G. Musgrove. 1964. Additional records of the Mexican big-eared bat, Plecotus phyllotis (Allen), from Arizona. Journal of Mammalogy, 45: 472-74.
Cockrum, E. L., B. Musgrove, and Y. Petryszyn. 1996. Bats of Mohave County, Arizona: populations and movements. Occasional Papers. The Museum, Texas Tech University, 157: 1-71.
Commissaris, L.R. 1961. The Mexican big-eared bat in Arizona. Journal of Mammalogy, 42: 61-65.
Czaplewski, N. J. 1983. Idionycteris phyllotis. Mammalian Species, 208: 1-4.
Hinman, K. E., and T. K. Snow, eds. 2003. Arizona Bat Conservation Strategic Plan. Nongame and Endangered Wildlife Program Technical Report 213. Arizona Game and Fish Department, Phoenix, Arizona.
Hoffmeister, D. F. 1986. Mammals of Arizona . University of Arizona , Tucson . 602 pp.
Morrell, T. E., M. J. Rabe, J. C. DeVos, Fr., H. Green, and C. R. Miller. 1999. Bats captured in two ponderosa pine habitats in north-central Arizona. Southwestern Naturalist, 44: 501-506.
O’Farrell, M. J., and W. G. Bradley. 1969. A new bat record, Plecotus phyllotis, from Nevada. Journal of Mammalogy, 50:128.
Rabe, M. J., T. E. Morrell, H. Green, J. C. DeVos, Jr., and C. R. Miller. 1998. Characteristics of ponderosa pine snag roosts used by reproductive bats in northern Arizona. Journal of Wildlife Management, 62: 612-621.
Simmons, J. A., and M. J. O’Farrell. 1977. Echolocation by the long-eared bat, Plecotus phyllotis. Journal of Comparative Physiology, 122: 201-214.
Tumlison, R. 1993. Geographic variation in the Lappet-eared bat, Idionycteris phyllotis, with descriptions of subspecies. Journal of Mammalogy, 74(2): 412-421.
Tumlison, R., and M. Douglas. 1992. Parsimony analysis and phylogeny of the plecotine bats (Chiroptera: Vespertilionidae). Journal of Mammalogy, 73: 276-285.
Original account by Michael J. O’Farrell
2005 update by Patricia Brown and Lyle Lewis
Lasionycteris noctivagans, a member of the Family Vespertilionidae, is found from southern Alaska, throughout southern Canada, and most of the United States into the San Carlos Mountains of northeastern Mexico. L. noctivagans is primarily a forest bat, associated primarily with north temperate zone conifer and mixed conifer/hardwood forests. It has been found in winter and during seasonal migrations in low elevation, more xeric habitats.
Global Rank – G5. State Ranks: AZ – S3; CA – Sx; CO – S4B; ID – S5; MT – S4; NM – S5; NV – S?; OR – S4?; TX – S4; UT – S3S4; WA – S?; WY – S4; AL – S3; BC – S4.
L. noctivagans is a medium sized vespertilionid with black or dark brown hairs which are silver-tipped. The interfemoral membrane is partially furred. Its ears are short and rounded, with a blunt tragus. Females form small nursery colonies of up to 70 individuals. Maternity roosts appear to be almost exclusively in trees — inside natural hollows and bird excavated cavities or under loose bark of large diameter snags. Roosting sites are generally at least 15 m above the ground. Both males and females change roosts frequently, and use multiple roosts within a limited area throughout the summer, indicating that clusters of large trees are necessary. Some records exist for roosts in other structures. Based on recent radio telemetry, these appear to be largely anomalies. This species has been found hibernating in hollow trees, under sloughing bark, in rock crevices, and occasionally under wood piles, in leaf litter, under foundations, and in buildings, mines and caves. L. noctivagans forages above the canopy, over open meadows, and in the riparian zone along water courses. Radiotracking has shown that it travels considerable distances from roost sites to foraging areas. Although the species is known to take a wide variety of insects, including chironomids, moths appear to be a major portion of dietary prey. This species appears to have gestation of 50-60 days, and give birth to twins in mid to late June. The young require >36 days to become volant. Seasonal records suggest considerable north south migration, with animals moving to warmer, more southern climates in the winter. The few overwitnering L. noctivagans that have bee found in Oregon and Washington were juveniles from the previous summer. In some there appears to be summer segregation of the sexes ( e.g., whereas both adult males and females are captured during the summer reproductive season in parts of northern California, males and females are geographically separated in most of Oregon).
More information is needed distribution of breeding populations, on regional differences in roosting requirements, the timing and patterns of migration for each sex throughout the west, and the location of possibly important mating and migratory stopover sites. Information is also needed on what factors (e.g., temperature, local food availability) determine year to year variation in local distribution and abundance.
Barclay, R. M. R. Long-versus short-range foraging strategies of hoary (Lasiurus cinereus) and silver- haired (Lasionycteris noctivagans) bats and the consequences for prey selection. Canadian Journal of Zoology, 63: 2507-2515.
Betts, B. J. 1996. Roosting behaviour of silver-haired bats (Lasionycteris noctivagans) and big brown bats (Eptesicus fuscus) in northeast Oregon. Pp. 55-61, in R. M. R. Barclay and M. R. Brigham, ed. Bats and Forest Symposium, October 19-21,1995, Victoria, British Columbia, Canada, Research Branch, B.C. Ministry of Forests, Victoria, British Columbia.
Campbell, L. A., J. G. Hallett, and M. A. O’Connell. 1996. Conservation of bats in managed forests: use of roosts by Lasionycteris noctivagans. Journal of Mammalogy, 77: 976-984.
Cross, S. P., Editor. 1976. A survey of bat populations and their habitat preferences in Southern Oregon. An SOSC of the NSF Unpub. Rept. 89 pp.
Kunz, T. H. Lasionycteris noctivagans. 1982. American Society of Mammalogists, Mammalian Species, 172: 1-5.
Mattson, T. A., S. W. Buskirk, and N. L. Stanton. 1996. Roost sites of the silver-haired bat (Lasionycteris noctivagans) in the Black Hills, South Dakota. The Great Basin Naturalist, 56: 247-253.
Perkins, J. M. and S. P. Cross. 1988. Differential use of some coniferous forest habitats by hoary and silver- haired bats in Oregon. Murrelet, 69: 21-24.
Perkins, J. M. and S. P. Cross. 1982. Sexual differentiation in migratory patterns of Lasionycteris noctivagans in Oregon and Washington. Paper presented to the 22nd annual North American Symposium on bat research, Austin, TX.
Vonhof, M. J. 1996. Roost-site preference of big brown bats (Eptesicus fuscus) and silver-haired bats (Lasionycteris noctivagans) in the Pend d’Oreille Valley in southern British Columbia. Pp. 62-80, in R. M. R. Barclay and M. R. Brigham, edS. Bats and Forest Symposium, October 19-21,1995, Victoria, British Columbia, Canada, Research Branch, B.C. Ministry of Forests, Victoria, British Columbia.
Vonhof, M. J. & Barclay, R. M. R. 1996. Roost-site selection and roosting ecology of forest-dwelling bats in southern British Columbia. Canadian Journal of Zoology, 74:1797-1805.
Account by Mark Perkins
Lasiurus blossevillii, a member of the Family Vespertilionidae, has a broad distribution reaching from southern British Columbia in Canada, through much of the western United States, through Mexico and Central America, to Argentina and Chile in South America.
Global Rank – G5. State Ranks: AZ- S2; CA – S?; NM – S?; NV – S?; OR – S?; TX – S2; UT – S1; WA – S3; BC – S1?. L. blossevillii is proposed as a Mammal of Special Concern in California, is included in Arizona Game and Fish Department’s Wildlife of Special Concern in Arizona, and is considered a Species of Special Concern due to declining populations and limited distribution in Utah.
L. blossevillii can be distinguished from all other western bat species except Lasiurus borealis (the eastern red bat) by its distinctive red coloration, and can be distinguished from L. borealis by its slightly smaller size and lack of frosted appearance.The only area where these two species are known to overlap is western Texas. L. blossevillii is typically solitary, roosting primarily in the foliage of trees or shrubs. Day roosts are commonly in edge habitats adjacent to streams or open fields, in orchards, and sometimes in urban areas. There may be an association with intact riparian habitat (particularly willows, cottonwoods, and sycamores). Roost sites are generally hidden from view from all directions except below; lack obstruction beneath, allowing the bat to drop downward for flight; lack lower perches that would allow visibility by predators; have dark ground cover to minimize solar reflection; have nearby vegetation to reduce wind and dust; and are generally located on the south or southwest side of a tree. L. blossevillii may also occasionally use caves, as both dead and live red bats, including a pregnant female, have been collected from Carlsbad Caverns in New Mexico. Red bats generally begin to forage one to two hours after sunset. Although some may forage all night, most typically have an initial foraging period corresponding to the early period of nocturnal insect activity, and a minor secondary activity period corresponding to insects that become active several hours before sunrise. Red bats have been observed feeding around street lights and flood lights. Reported prey items include homopterans, coleopterans, hymenopterans, dipterans, and lepidopterans. Red bats mate in late summer or early fall. Females become pregnant in spring and have a pregnancy of 80-90 days. Females may have litters of up to five pups per year. This species is considered to be highly migratory. Although generally solitary, red bats appear to migrate in groups and forage in close association with one another in summer. The timing of migration and the summer ranges of males and females seem to be different. Winter behavior of this species is poorly understood. The eastern red bat has been found hibernating in leaf-litter. Arousal from hibernation on warm days to feed has been reported, as has periodic foraging during the winter in the San Francisco Bay area. Predators reported for L. blossevillii include birds (e.g., scrub jays, falcons, accipters, owls, roadrunners), opossums, and domestic cats.
Loss of riparian zones, primarily due to agricultural conversion and creation of water storage reservoirs has reduced both roosting and foraging habitat of red bats. The intensive use of pesticides in fruit orchards may constitute a threat to roosting bats and may significantly reduce the amount of insect prey available. Controlled burns may be another significant mortality factor for red bats that roosting in leaf litter during cool temperatures.
The following areas need more investigation to accurately determine the status of and conserve the red bat in the western U.S.: habitat requirements (esp. roost sites and foraging habitat), altitudinal distribution, migration patterns, effects of controlled burns, and effects of pesticide use in orchards.
Baker, R. J., J. C. Patton, H. H. Genoways, and J. W. Bickham. 1988. Genic studies of Lasiurus (Chiroptera: Vespertilionidae). Occas. Pap. Mus. Tex. Tech Univ., 117(00): 1-15.
Hoffmeister, D. F. 1986. The mammals of Arizona. University of Arizona Press, Tucson, AZ. 602 pp.
Morales, J. C., and J. W. Bickham 1995. Molecular systematics of the genus Lasiurus (Chiroptera: Vespertilionidae) based on restriction-site maps of the mitochondrial ribosomal genes. Journal of Mammalogy, 76(3): 730-749.
Schmidly, D. J. 1991. The bats of Texas. Vol. University of Texas Press, Austin. 189 pp.
Shump, K. A. , Jr., and A. U. Shump. 1982. Lasiurus borealis. American Society of Mammalogists, Mammalian Species, 183: 1-6.
Account by Betsy C. Bolster
Lasiurus cinereus, a member of the Family Vespertilionidae, is the most widespread of all North American bats. This species ranges from near the limit of trees in Canada, southward at least to Guatemala, and from Brazil to Argentina and Chile in South America. L. cinereus is also found in Hawaii and the Galapagos Islands. Hoary bats are uncommon throughout most of the eastern U.S. and in the northern Rocky Mountains, but are more common in the prairie states and Pacific Northwest. They are highly associated with forested habitats in the west.
Global Rank – G5. State Ranks: AZ – S3; CA – S5; CO – S5B; ID – S5; MT – S4; NM – S5; NV – S?; OR – S4?; TX – S4; UT – S3; WA – S?; WY – S4; AL – S2?; BC – S4.
L. cinereus can be distinguished from all other species by a combination of its large size (forearm of 46-58 mm), frosted fur, golden coloration around the face, rounded ears, blunt tragus and furred uropatagium. Hoary bats are solitary and roost primarily in foliage of both coniferous and deciduous trees, near the ends of branches, 3-12 m above the ground. Roosts are usually at the edge of a clearing. Some unusual roosting situations have been reported in caves, beneath a rock ledge, in a woodpecker hole, in a grey squirrel nest, under a driftwood plank, and clinging to the side of a building. Although thought to be highly migratory, wintering sites have not been well documented, and no specific migration routes have been discerned. Hoary bats are often found flying in waves of large groups during autumn migration, whereas spring migration is apparently less organized. This species tolerates a wide range of temperatures as illustrated by captures at air temperatures between 0 and 22oC. The ambient temperature at which individuals employ torpor also appears to be variable, as entry into torpor was observed in one study to vary from 5oC to 13oC. Hoary bats probably mate in the fall, followed by delayed implantation and birth in the following May through July. Females have from one to four pups annually, with two being the norm. Hoary bats usually emerge late in the evening to forage, although they occasionally have been observed flying during late winter afternoons or just before sunset. Evening emergence and capture times range from just over one hour after sunset to after midnight.The swift, direct flight of this species makes it identifiable on the wing from all other U.S. bats except molossids. Hoary bats reportedly have a strong preference for moths, but are also known to eat beetles, flies, grasshoppers, termites, dragonflies, and wasps. Reported predators include jays, kestrels and snakes, and likely include hawks and owls as well.
Loss of roosting habitat due to timber harvest is likely the biggest threat to this species. Use of pesticides on public forest lands may also be a potential source of mortality to roosting bats and their insect prey. In suburban settings, where jays thrive in association with humans, this bird may pose a major threat to sleeping or hibernating hoary bats.
The habitat use and relationships of L. cinereus, especially regarding wintering sites, needs to be investigated more thoroughly. The impact of current timber harvest practices on roosting and foraging also should be examined.
Barclay, R. M. R. 1985. Long- versus short-range foraging strategies of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats and the consequences for prey selection. Can. J. Zool. 63: 2507-2515.
Barclay, R. M. R. 1985 -1986. Foraging strategies of silver haired (Lasionycteris noctivagans) and hoary (Lasiurus cinereus) bats. Myotis 23-24: 161-166.
Hickey, C. B. 1990. Use of torpor by free-living Lasiurus cinereus. Bat Research News, 30(4): 67.
Perkins, J. M., and S. P. Cross. 1988. Differential use of some coniferous forest habitats by hoary and silver-haired bats in Oregon. Murrelet 69: 21-24.
Shump, K. A., Jr., and A. U. Shump. 1982. Lasiurus cinereus. American Society of Mammalogists, Mammalian Species, 185: 1-5.
Account by Betsy C. Bolster
Formerly considered conspecific with the southern yellow bat, but currently considered a distinct species, Lasiurus xanthinus occurs in northern Mexico, western Arizona, southern California, southern Nevada, and southwestern New Mexico. Western yellow bats are associated with dry, thorny vegetation on the Mexican Plateau, and are found in desert regions of the southwestern United States, where they show a particular association with palms and other desert riparian habitats. They are known to occur in a number of palm oases, but are also believed to be expanding their range with the increased usage of ornamental palms in landscaping. L. xanthinus occurs up to ca. 2,000 m. in the mountains in Arizona.
Global Rank – G5. National Rank – N2. State Ranks: AZ – S1; CA – SNR; NV – S1; NM – S1; TX – S1. L. xanthinus is included in Arizona Game and Fish Department’s Wildlife of Special Concern.
Western yellow bats can be distinguished from other bat species by the combination of yellow coloration, size (forearm = 42-50 mm), and short ears. Yellow bats are suspected to be non-colonial. Individuals usually roost in trees, hanging from the underside of a leaf. They are commonly found in the southwestern U.S. roosting in the skirt of dead fronds in both native and non-native palm trees, and have also been documented roosting in cottonwood trees. At least some individuals or populations may be migratory, although some individuals appear to be present year-round, even in the northernmost portion of their range. Yellow bats probably do not hibernate; activity has been observed year-round in both the southern and northern portions of their range. Sexual dimorphism in size exists, with females averaging 2mm longer in forearm length then males. Yellow bats are insectivorous. Analysis of fecal samples of western yellow bats indicate their diet includes Coleoptera, Diptera, Hemiptera, Homoptera, Lepidoptera, and Orthoptera. Capture sites are often associated with natural and non-natural water features in open grassy areas and scrub, as well as canyon and riparian situations. Captures are also reported over swimming pools, lawns in residential areas, and orchards. In northern areas, seasonal segregation between sexes during parturition may occur, as males are scarce from April through June. In the U.S., pregnant females are known from late April through June, with lactation occurring during June and July. The number of embryos carried by pregnant females varies from one to four, with no known geographic trend. Reported predators include barn owls, domestic dogs and domestic cats.
Few threats to the survival of yellow bats have been reported. Probably one of the primary threats in the U.S., however, is the cosmetic trimming of palm fronds. The use of pesticides in date-palm and other orchards may also constitute a threat to both roosting bats and the insects upon which they forage. Domestic cats, whether pets or feral, may be a substantial source of predation, as they are for many lizards, songbirds, and rodents. In general, the long term persistence of North American bat species is threatened by the loss of clean, open water; modification or destruction of roosting and foraging habitat; and, for hibernating species, disturbance or destruction of hibernacula. Chemicals in the environment that affect bats or their prey are also a threat. Because of low fecundity, high juvenile mortality, and long generational turnover, many bat populations may be vulnerable to human-induced pressures.
Morphologically distinct. It is difficult to locate tree roosts, but can sometimes Lasiurus xanthinus can be located by monitoring palm trees at emergence time. This species is difficult to observe in the roost, but is easy to identify during emergence from roost. In some habitats, it is readily captured using nets, but apparently difficult to capture in others. Not enough known about appropriate habitats. Easy to detect acoustically; most sequences diagnostic, but some acoustic overlap with L. borealis and E. fuscus. Lasiurus xanthinus is reasonably distinctive in flight.
The following areas need more investigation to accurately determine the status of and to conserve the yellow bat in the U.S.: distribution, migration, habitat requirements, activity patterns (both daily and seasonally), and threats including palm frond trimming and pesticide use in orchards.
Baker, R. J., J. C. Patton, H. H. Genoways, and J. W. Bickham. 1988. Genetic studies of Lasiurus (Chiroptera: Vespertilionidae). Occasional Papers. The Museum, Texas Technical University, 117: 1-15.
Brown, P. E. 1996. Bat Survey of the Bill Williams River. AGFD Heritage Fund Project I93073, Administered by Lake Havasu BLM.
Constantine, D. G. 1998. Range extensions of ten species of bats in California. Bulletin of the Southern California Academy of Science, 97: 49-75.
Higginbotham, J. L., L. K. Ammerman, and M. T. Dixon. 1999. First record of Lasiurus xanthinus (Chiroptera: Vespertilionidae) in Texas. Southwestern Naturalist, 44: 343-347.
Higginbotham, J. L., M. T. Dixon, and L. K. Ammerman. 2000. Yucca provides roost for Lasiurus xanthinus (Chiroptera: Vespertilionidae) in Texas. Southwestern Naturalist, 45: 338-340.
Kurta, A., and G. C. Lehr. 1995. Lasiurus ega. Mammalian Species, 515: 1-7.
Mirowsky, K. 1997. Bats in palms: precarious habitat. Bats, 15: 1-6.
Morales, J. C., and J. W. Bickham. 1995. Molecular systematics of the genus Lasiurus (Chiroptera: Vespertilionidae) based on restriction-site maps of the mitochondrial ribosomal genes. Journal of Mammalogy, 76: 730-749.
O’Farrell, M. J., J. A. Williams, and B. Lund. 2004. Western yellow bat (Lasiurus xanthinus) in southern Nevada. The Southwestern Naturalist, 49: 514-518.
Williams, J. A. 2001. Community structure and habitat use by bats in the upper Moapa Valley, Clark County, Nevada. Unpublished M.A.S. Thesis. University of Nevada, Las Vegas. 39pp. + Appendices.
Original account by Betsy C. Bolster
2005 update by Jason A. Williams
Myotis auriculus, a member of the Family Vespertilionidae, ranges from central Arizona and New Mexico to southern Mexico. Its distribution in the United States is quite limited. Myotis auriculus occurs in southwestern forests that include oak, cottonwood, and mixed conifer, but it is primarily a resident of ponderosa pine forests.
Global Rank – G5. State Ranks: AZ – S3; NM – S4.Take is regulated by permit in New Mexico and Arizona.
Myotis auriculus is a member of the long-eared group of Myotis that includes M. evotis, M. keenii, M. septentrionalis, and M. thysanodes. M. auriculus does not occur within the range of M. keenii or M. septentrionalis and barely overlaps with M. evotis. Myotis auriculus has shorter (18-20 mm), brown, not glossy black, ears compared to M. evotis and does not have a distinct uropatagial fringe like M. thysanodes. It has been observed to glean insects off tree trunks and buildings. When in sympatry with M. evotis, M. auriculus preys upon moths and some beetles, whereas M. evotis feeds primarily on beetles. In allopatry, both species have similar food habits, but exhibit differences in food preference between sexes (e.g., male M. auriculus eat more moths). M. auriculus is most active from 0.5 to 2 h after sunset and in New Mexico is seasonally active from April to September. Some evidence for seasonal migrations exists in Arizona. The species is known to roost in caves, mines, and buildings. Females are pregnant in early to mid-June and give birth to a single young in late June and early July. One banded individual lived a minimum of 3 years, 2 months. The early literature refers to this species as M. evotis or M. keenii.
May be affected by recreational caving, closure of abandoned mines without surveys, and certain forest-management practices.
No information known about population trends, roost requirements, and use and acceptance of bat gates. Also more information is needed on foraging requirements.
Gannon, W.L. 1997. Assessing ecological interactions between bat species using morphological and acoustical techniques. Unpubl. Ph.D. dissertation, University of New Mexico, Albuquerque, 109 pp.
Hoffmeister, D.F. 1986. Mammals of Arizona. The University of Arizona Press and The Arizona Game and Fish Department, Tucson, Arizona, 602pp.
Husar, S.L. 1976. Behavioral character displacement: Evidence of food partitioning in insectivorous bats. Journal of Mammalogy, 57: 331-338.
Warner, R.M. 1982. Myotis auriculus. American Society of Mammalogists, Mammalian Species, 191: 1-3.
Account by M. A. Bogan, E. W. Valdez, and K.W. Navo
Myotis californicus, a member of the Family Vespertilionidae, ranges across much of western North America from southeastern Alaska and southwestern British Columbia, through most of the United States west of the Rocky mountains, and south to Baja California and much of mainland Mexico, and into Guatemala. This species occurs in a wide variety of habitats. While typical of deserts and interior basins in the western U. S., it also occurs in forested and montane regions.
Global Rank – G5. State Ranks: AZ – S4S5; CA – S5; CO – S3S4; ID – S3; MT – S4; NM – S5; NV – S?; OR – S4; TX – S4; UT – S3S4; WA – S?; WY – S4; BC – S4S5. Take usually regulated by permit procedures in individual states.
Myotis californicus is a small bat with dark brown to black ears and wing membranes, a distinctly keeled calcar, and pelage that varies from dark brown to pale reddish-yellow to blond. It is an acrobatic flyer and uses small waterholes to obtain needed moisture; its kidneys are adapted for arid environments. Myotis californicus differs from M. ciliolabrum, which is sympatric and similar in appearance, by having a more globose skull, narrower rostrum, overall more delicate appearance, and no black mask. These two species are often difficult to distinguish in the field. Individuals are most active soon after sunset and periodically rest at a night roost. They typically feed on moths and flies, but have been known to eat other insects. Myotis californicus mates during autumn, perhaps in the spring in California. In spring or early summer, females form maternity colonies where they give birth to one pup per year. Individuals have been known to live up to 15 years. During summer, M. californicus roost alone or in small groups in caves, mines, rocky hillsides, under tree bark, and in buildings. Recent studies in Canada have documented maternity colonies of up to 52 individuals roosting under sloughing bark, and in cracks and hollows of large diameter, intermediate stage snags (preferably ponderosa pine). In winter, solitary individuals and small groups have been found in caves, mines, and buildings. Individuals are known to be active periodicially in the winter, even at temperatures below freezing.
May be affected by closure of abandoned mines without adequate surveys and by recreational caving. This species may be affected by some timber harvest practices, particularly the removal of large diameter snags. Like all bats it also could be subject to contaminant poisoning.
No information known on population trends and use and acceptance of bat gates. More information is needed on roosting and foraging requirements.
Bogan, M. A. 1974. Identification of Myotis californicus and M. leibii in southwestern North America. Proceedings Biological Society Washington, 87: 49-56.
Bogan, M. A. 1975. Geographic variation in Myotis californicus in the southwestern United States and Mexico. U.S. Fish and Wildlife Service, Wildlife Research Report 3: 1-31.
Bogan, M. A. In Press. Myotis californicus. In: Book of North American Mammals, D. E. Wilson, ed. Smithsonian Press, Washington, D.C.
Brigham, R. M., M. J. Vonhof, R. M. R. Barclay, and J. C. Gwilliam. 1997. Roosting behavior and roost- site preferences of forest-dwelling California bats (Myotis californicus). Journal of Mammalogy, 78(4): 1231-1239.
Simpson, M. R. 1993. Myotis californicus. American Society of Mammalogists, Mammalian Species, 428: 1-4.
Account by M. A. Bogan, E. W. Valdez, and K.W. Navo
Myotis ciliolabrum, a member of the Family Vespertilionidae, ranges across the western half of North America from British Columbia, Alberta, and Saskatchewan in Canada, throughout most of the United States west of the 100th Meridian, and into central Mexico.
Global Rank – G5. State Ranks: AZ – S3; CA – S?; CO – S4; ID – S4; MT – S4; NM – S5; NV – S3; OR – S3; TX – S3; UT – S3S4; WA – S3; WY – S4; AL – S2; BC – S2S3. Former category 2 candidate species. U.S. Forest Service and Bureau of Land Management list as special status; generally regulated by state permit procedures.
M. ciliolabrum is a small bat with a keeled calcar, small foot, black ears, and a black mask across the eyes and nose. Pelage varies from brown to pale yellow. Myotis ciliolabrum differs from M. californicus, which is sympatric and similar in appearance, by having a longer, broader, and flatter skull with a gradual slope from cranium to rostrum; overall it is a more robust bat. However, these two species are often difficult to distinguish in the field. M. ciliolabrum occurs in deserts, chaparral, riparian zones, and western coniferous forest; it is most common above piñon-juniper forest. Individuals are known to roost singly or in small groups in cliff and rock crevices, buildings, concrete overpasses, caves, and mines. They forage early in the evening, feeding on various small insects. Copulation takes place in the fall, with sperm being stored in females until spring when ovulation occurs. M. ciliolabrum produces one young per year in late spring or early summer. Individuals have been known to live up to 12 years. Older literature refers to this species as M. subulatus and M. leibii.
May be affected by closure of abandoned mines without adequate surveys and by recreational caving. Contaminant poisoning is a possibility.
No information known on population trends, and use and acceptance of bat gates. More information is needed on roosting and foraging requirements.
Bogan, M. A. 1974. Identification of Myotis californicus and M. leibii in southwestern North America. Proceedings Biological Society Washington, 87: 49-56.
Bogan, M. A. In Press. Myotis ciliolabrum. In: Mammals of North of America, D. E. Wilson, ed. Smithsonian Press, Washington, D.C.
van Zyll de Jong, C.G. 1984. Taxonomic relationships of Nearctic small-footed bats of the Myotis leibii group (Chiroptera:Vespertilionidae). Canadian Journal Zoology 62: 2519-2526.
van Zyll de Jong, C.G. 1985. Handbook of Canadian mammals; 2, bats. National Museum of Natural Sciences, Ottawa, 212 pp.
Account by M. A. Bogan, E. W. Valdez, and K.W. Navo
Myotis evotis, a member of the Family Vespertilionidae, ranges across western North America from southwestern Canada (British Columbia, Alberta and Saskatchewan) to Baja California and eastward in the United States to the western Great Plains.
Global Rank – G5. State Ranks: AZ – S3; CA – S3S4; CO – S4; ID – S4; MT – S4; NM – S4; NV – S?; OR – S3; TX – SX; UT – S3S4; WA – S3; WY – S4; AL – S2; BC – S4S5. Former category 2 candidate species. Some federal agencies list the species as being of concern; take usually regulated by state permit.
M. evotis has pale brownish to straw- colored pelage. It is distinguished from M. auriculus and M. thysanodes by having long (19 to 25 mm), glossy black ears and no distinct fringe of hairs along the edge of the uropatagium. M. evotis eats moths and small beetles, as well as flies, lacewings, wasps, and true bugs. In areas where M. evotis and M. auriculus are sympatric, M. evotis tends to eat more beetles. This species is a slow flier and is often described as a hovering gleaner that feeds by eating prey off foliage, tree trunks, rocks, and from the ground. It generally leaves its roost for foragingafter dark, but individuals have been caught as early as 0.5 h after sunset. M. evotis occurs in semiarid shrublands, sage, chaparral, and agricultural areas, but is usually associated with coniferous forests. Individuals roost under exfoliating tree bark, and in hollow trees, caves, mines, cliff crevices, sinkholes, and rocky outcrops on the ground. They also sometimes roost in buildings and under bridges. During the summer, females form small maternity colonies, whereas males and non-reproductive females roost alone or in small groups nearby. Females give birth to one young in late spring to early summer. Individuals have lived up to 22 years. Presumably, most individuals hibernate during the winter.
May be affected by closure of abandoned mines without surveys, recreational caving, some forest-management practices, and activities (such as highway construction, water impoundments, blasting of cliffs for avalanche control) that impact cliff faces or rock outcrops.
Little or no information known on population trends, winter roosting requirements, winter range, importance of snags as summer roosts, and use and acceptance of bat gates. Also more information is needed on foraging requirements.
Bogan, M.A. In Press. Myotis evotis. In: Mammals of North America, D.E. Wilson, ed. Smithsonian Press, Washington, D.C.
Faure, P.A. and R.M.R. Barclay. 1994. Substrate-gleaning versus aerial-hawking: plasticity in the foraging and echolocation behaviour of the long-eared bat, Myotis evotis. Journal Comparative Physiology 174: 651-660.
Manning, R.W. 1993. Systematics and evolutionary relationships of the long-eared myotis, Myotis evotis (Chiroptera:Vespertilionidae). Special Publications, The Museum, Texas Tech University No. 37, 1-58pp.
Manning, R.W. and J.K. Jones, Jr. 1989. Myotis evotis. American Society of Mammalogists, Mammalian Species, 329: 1-5.
Vonhof, M. J. & Barclay, R. M. R. 1996. Roost-site selection and roosting ecology of forest-dwelling bats in southern British Columbia. Canadian Journal of Zoology, 74: 1797-1805.
Vonhof, M. J. and R. M. Barclay 1997. Use of tree stumps as roosts by the western long-eared bat. Journal of Wildlife Management, 61: 674-684.
Account by M. A. Bogan, E. W. Valdez, and K.W. Navo
Myotis keenii, a member of the Family Vespertilionidae, has a very limited distribution, reaching from southeastern Alaska south along the coast and coastal islands of British Columbia to the area of Puget Sound in Washington. The winter range is unknown.
Global Rank – G2G3. State Ranks: WA – SH; BC – S2?.
M. keenii is an inhabitant of dense, mature forests. The only known maternity colony of 70 animals roosts under rocks heated by a natural hot spring. Other llikely roost sites are hollow trees, rock crevices and small caves. This species has been observed foraging over hot spring pools, over shrubs, and possibly in the forest canopy, along the forest edge, and over ponds and clearings. Juveniles and lactating females have been observed in late July, suggesting young are born in late June or early July. This species has recently been discovered hibernating in a cave in British Columbia.
Habitat (roosting as well as foraging) loss through logging and forest fires seem to be the main limiting factors for Keen’s long-eared bats. Old growth forests and riparian areas appear to be essential for continued viability of this species.
Information is needed on M. keenii regarding the status of the species, size of population, biology, and ecology. There is little information on this species due to difficulties in field identification. M. keenii is virtually identical to Myotis evotis which has longer ears (3 mm longer) and very similar to Myotis thysanodes which has a fringe of hairs on the edge of the tail membrane and shorter ears.
Chatwin, T.A., M. Davis, and D. Nagorsen. 1997. [ABS]. Bat usage of the Weymer Creek cave system on northern Vancouver Island, Canada. Bat Research News 38(3). In Press.
Nagorsen, D. W. and R. M. Brigham 1993. Bats of British Columbia. Vol. University of British Columbia Press, Vancouver, BC. 164 pp.
Parker, D.I., J.A. Cooko,. and S.W. Lewis. 1996. Effects of timber harvest on bat activity in southeasetern Alaska’s temperate rainforests. Pp. 277-292 in R. M. R. Barclay and M. R. Brigham, eds. Bats and Forests Symposium, October 19-21, 1995, Victoria, British Columbia, Canada. Research Branch, Ministry of Forests, Victoria, British Columbia, Working Paper 23/1996.
van Zyll de Jong, C. G. 1985. Handbook of Canadian mammals. Vol. 2: Bats. National Museum of Natural Sciences, Ottawa, Ontario. 212 pp.
Account by J. Wenger
Myotis lucifugus is among the most widespread and common bats in mesic, typically forested, areas of temperate North America. Overall distribution extends from near the treeline in Canada and Alaska to the southern tier of the United States. There is a distributional gap extending south from the largely treeless Great Plains through Texas. In the western U.S., this species is typically absent from hot, arid lowlands, but extends south (at increasing elevation) along forested mountain ranges into southern California, Nevada, Utah, and Colorado.
Global Rank – G5. State Ranks: AZ – S3; CA – S4; CO – S5?; ID – S5; MT – S5; NM – S5; NV – S?; OR – S4; TX – SA; UT – S4; WA – S?; WY – S5; AL – S5; BC – S4S5.
M. lucifugus is a medium size Myotis which lacks a calcar and has moderate length pointed ears with a blunt tragus. Pelage color is highly variable, but fur is typically longer, darker, and more glossy than similar co-occuring species. In the Northwest, external morphology and skull characters are insufficient to reliably assign a small percentage of individuals to M. lucifugus or the similar M. yumanensis, but intermediate individuals in southwest British Columbia were identifiable to species on biochemical characters. A few individuals in southern Colorado and northern New Mexico are intermediate in skull characters between M. lucifugus and M. occultus (which are sometimes synonomized). Body size (and time to maturity) increases with latitude. Among woodland/forest bats, M. lucifugus, is an ecological generalist exploiting a wide variety of natural and man-made roost sites and a taxonomically wide spectrum of flying insect prey, including emerging adults of aquatic species. Summer maternity colony sites (consisting largely of reproductive females and dependent young) include tree cavities, caves and human-occupied structures. Fidelity to physically stable day and night roost sites is strong and individuals return for many years. Active season roosting by males and non-reproductive females is little studied, but male aggregations are known. Daily foraging movements are likely in the 1-10 km range, seasonal aggregation at mass hibernation sites may involve larger distances Hibernation sites (typically caves and abandoned mines) and seasonality have been studied in eastern and mid-continent populations, but are poorly known in the west.
The primary threats are common themes for forest bats — alterations in snag density and recruitment by timber harvest, liability reduction, agricultural or residential habitat conversion or riparian forest alteration for flood control. This species often occupies structures and is vulnerable to pest control operations. Highly aggregated hibernation in abandoned mines in eastern and central North America suggests closure of cold mines without adequate survey could have major population impact. Populations in montane forest islands, especially near the southern range limit, are at greater risk because population sizes and available habitat are small and development pressures (e.g., forest recreation) can be high.
Lack of knowledge of hibernation sites (and the degree of population aggregation at these sites) is a key point of vulnerability for this species. Inadequate systematic resolution may affect management decisions (e.g., the status of M. occultus). Isolated populations in montane forest islands may be sufficiently differentiated to deserve taxonomic recognition. The status of these should be carefully evaluated as their habitats and population sizes may be small and subject to strong development pressure.
Adams, R. A. 1990. Biogeography of bats in Colorado – ecological implications of species tolerances. Bat Research News 31: 17-21.
Fenton, M. B. and R. M. R. Barclay 1980. Myotis lucifugus. Mammal. Species 142: 1-8.
Herd, R. M. and M. B. Fenton 1983. An electrophoretic, morphological, and ecological investigation of a putative hybrid zone between Myotis lucifugus and Myotis yumanensis (Chiroptera: Vespertilionidae). Can. J. Zool. 61: 2029-2050.
Nagorsen, D. W. and R. M. Brigham 1993. Bats of British Columbia. University of British Columbia Press, Vancouver.
Jones, J. K., D. M. Armstrong, R. S. Hoffmann ,and C. Jones. 1982. Mammals of the Northern Great Plains. University of Nebraska Press, Lincoln. 379 pp.
Thomas, D. W. and S. D. West. 1991. Forest age associations of bats in the southern Washington Cascade and Oregon coast ranges. U.S. Forest Service. General Technical Reports PNW 295-303.
Schmidly, D. J. 1991. The bats of Texas. University of Texas Press, Austin. 189 pp.
van Zyll de Jong, C. G. 1985. Handbook of Canadian mammals. Vol. 2: Bats. National Museum of Natural Sciences, Ottawa. 212 pp.
Account by William E. Rainey
Myotis occultus, a member of the Family Vespertilionidae, has been found from southeastern California through Arizona, New Mexico, and south into Chihauhau, Mexico. There is a single record from western Texas. It occurs south into Chihauhau, Mexico. The Western Bat Species Global and State Ranks also lists this species as occurring in Nevada.
Global Rank – G5T3T4. State Ranks: AZ – S3; CA – S?; NM – S3; NV – S1; TX – SA. It is considered a Species of Special Concern in California, and was formerly a category 2 candidate (as a subspecies of Myotis lucifugus).
M. occultus is a medium sized Myotis (forearm 36-41 mm) that lacks a keeled calcar, and could most easily be confused with M. yumanensis (forearm 33-36 mm) or M. lucifugus with which it overlaps in size. Although origianlly described as a separate species, it was for many years considered a subspecies of M. lucifugus. While some investigators still treat it as a subspecies of M. lucifugus, Hoffmeister (1986) argued, based on a principal components analysis of 25 cranial measurements, that M. occultus should be considered a separate species. M. occultus is most commonly found in conifer forests in the 6,000 – 9,000 foot elevation range, although nursery colonies were known from much lower elevations (e.g., along the Colorado River in California). In the 1960’s, it was reported to be one of the most common Myotis species at higher elevations in New Mexico. This species has been found using bridges and attics as maternity roosts, with colony size up to 800. A recent radiotracking study in Arizona identified three maternity roosts, one in a building and two in large ponderosa pine snags. Limited information suggests that females give birth to a single young, generally in June, at lower elevations they are known to forage in association with orchards, permanent water, and riparian vegetation, and at higher elevations over ponds in in forest clearings. No information is available on its diet. No information is available on winter habits.
The main threat to these animals appears to be lack of enough knowledge about them to develop any kind of conservation strategy. Recent discovery of tree roosting suggests timber harvest practices could affect status.
More systematic investigations, including molecular comparisons, are needed to evaluate the status of this speices. More information is needed on roosting requirements (particularly in natural roosts), seasonal patterns, foraging requirements, and status of populations.
Barbour, R.W. and W.H. Davis. 1969. Bats of America. University of Kentucky Publ., 286 pp.
Castner, S. V., T. K. Snow, and D. C. Noel. 1994. Bat Inventory and Monitoring in Arizona 1992-1994. Arizona Game and Fish Department. Nongame and Endangered Wildlife Program. Technical Report 54. 1-32.
Cockrum, E. L., B. Musgrove, and Y. Petryszyn. 1996. Bats of Mohave County, Arizona: Populations and Movements. Occasional Papers, the Museum, Texas Tech University, 157: 1-71.
Findley, J. S., and C. Jones. 1967. Taxonomic relationships of the bats of the species Myotis fortidens, M. lucifugus, and M. occultus. Journal of Mammalogy, 48: 429-444.
Hoffmeister, D. F. 1986. The mammals of Arizona. University of Arizona Press, Tucson, AZ, 602 pp.
Lutch, D., and W. H. Miller. 1996. [ABS]. Roost site charcteristics for Antrozous pallidus, Eptesicus fuscus, and Myotis occultus in a central Arizona ponderosa pine forest. Abstracts. Four Corners Regional Bat Conference. Durango, CO.
Schmidly, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, TX. 188 pp.
Account by Susan Murdock
Myotis septentrionalis, a member of the Family Vespertilionidae, ranges from British Columbia and Alberta, Canada, eastward to the Atlantic Ocean and southward to Arkansas and Florida. It is primarily an eastern species, but does occur in North Dakota, South Dakota, eastern Wyoming, eastern Nebraska, Kansas, and eastern Oklahoma.
Global Rank – G4. State Ranks: MT – S2; TX – SA; AL – S3; BC – S1S3. Take regulated by permit in some states.
Myotis septentrionalis is a medium- sized bat that has dull, yellowish-brown pelage with pale, grey ventral pelage. This species is similar to M. lucifugus, from which it can be distinguished by having ears that extend beyond the tip of the nose when laid forward (ear length: 17-19 mm) and a long, pointed tragus. The calcar often has a slight keel. This species forages at dusk or shortly after sunset with intermittent periods of night roosting and then a second peak of activity just before dawn. It roosts singly or as small groups in buildings, under shingles of buildings, under exfoliating tree bark, and in caves and mines. Occasionally, these bats day roost with other bat species such as M. lucifugus, Eptesicus fuscus, and Pipistrellus subflavus. During autumn, M. septentrionalis congregate into groups of a few hundred individuals, and often copulate before they go into torpor. Pregnant females have been recorded in late spring and lactating females were captured as late as mid-August in the Black Hills. Females give birth to one young per year. Individuals have been known to live up to 18.5 years. This species was formerly considered an eastern subspecies of M. keenii (M. keenii septentrionalis).
May be affected by recreational caving, closure of abandoned mines without surveys, pest control activities in human structures, and some forest-management practices.
No information known about population trends, reproduction, and use and acceptance of bat gates. More information is needed on roosting and foraging requirements.
Cryan, P.M. 1997. Distribution and roosting habits of bats in the southern Black Hills, South Dakota. Unpubl. M. S. Thesis, University of New Mexico, 98 pp.
Jones, J. K. Jr., D.M. Armstrong, R.S. Hoffman, and C. Jones. 1983. Mammals of the Northern Great Plains. University of Nebraska Press, Lincoln, 379pp.
Sasse, D.B. and P. J. Pekins. 1996. Summer roosting ecology of northern long-eared bats (Myotis septentrionalis) in the White Mountain National Forest. Pp. 91-101 in Bats and forests symposium, R.M. R. Barclay and R.M. Brigham, eds. B.C. Ministry of Forests, Research Branch, Victoria, B.C., Working Paper 23/1996
van Zyll de Jong, C.G. 1979. Distribution and systematic relationships of long-eared Myotis in western Canada. Canadian Journal Zoology 57: 987-994.
Account by M. A. Bogan, E. W. Valdez, and K.W. Navo
Myotis thysanodes ranges through much of western North America from southern British Columbia, Canada, south to Chiapas, Mexico and from Santa Cruz Island in California, east to the Black Hills of South Dakota (Figure 1). M. thysanodes occurs from sea-level to 2850 m but is most common at middle elevations 1200 Ð 2100 m. Distribution is patchy. It appears to be most common in drier woodlands (oak, pinyon-juniper, ponderosa pine) but is found in a wide variety of habitats including desert scrub, mesic coniferous forest, grassland, and sage-grass steppe. Three subspecies have been recognized: M. t. thysanodes in the main portion of its range, M. t. pahasapensis from the Black Hills of South Dakota, Wyoming and Nebraska, and M. t. aztecus from Oaxaca, Mexico. A fourth subspecies, M. t. vespetinus has been suggested to occur west of the Cascade mountains in southern Washington, Oregon, and northern California. Recent molecular work has found great genetic variation within long-eared Myotis species in western North America. For instance, within species sequence divergence has so far appeared greater across the range of M. thysanodes than from M. evotis in close geographic proximity. Further, genetic variability has not been consistent with recognized subspecies boundaries.
Global Rank Ð G4. State Ranks: AZ – S3S4; CA – S4; CO – S3; ID Ð S2; MT -S3; NM – S5; NV Ð S2B; OR Ð S2S3; SD Ð S2; TX – S3; UT – S3B; WA – S3; WY Ð S2; BC – S2S3. M. thysanodes is widespread in western North America but distribution is patchy in most portions of its range. It is a Species of Special Concern in California, Idaho, Oregon, Utah, and Wyoming.
Threats identified to date for M. thysanodes largely focus on loss or modification of roosting habitat. Specifically M. thysanodes may be threatened by: closure or renewed activity at abandoned mines, recreational caving and mine exploration loss of current and future large, decadent trees and replacement of buildings and bridges with non- bat friendly structures. Removal of large blocks of forest or woodland habitat may also threaten the species due to its apparent propensity for foraging in and around trees. In general, the long term persistence of North American bat species is threatened by the loss of clean, open water; modification or destruction of roosting and foraging habitat; and, for hibernating species, disturbance or destruction of hibernacula. Chemicals in the environment that affect bats or their prey are also a threat. Because of low fecundity, high juvenile mortality, and long generational turnover, many bat populations may be vulnerable to human-induced pressures.
Capture is the most reliable method to identify M. thysanodes because of its low-intensity echolocation call and habit of roosting in crevices. Once captured, identification is generally easy, but it may be morphologically similar to M. evotis in some regions. Low-intensity makes echolocation calls difficult to detect but, relative to other Myotis, are more readily identified. Identification using echolocation requires experience and humility. Not all calls will be identifiable and confirming species presence with capture is preferable. As M. thysanodes is a crevice roosting species it is difficult to detect particularly at natural roosts (e.g., trees and rock crevices). It can sometimes be detected in man- made roosts, but requires capture to confirm species identification.
Knowledge of the following is lacking: 1. Hibernation roosts and winter behavior; 2. migration behavior; 3. range or region-wide population status; 4. foraging habitat selection; 5. adult male life history; 6. breeding locations and behavior; 7. reason that distribution appears patchy.
Cryan, P. M., M. A. Bogan, and J. S. Altenbach. 2000. Effect of elevation on distribution of female bats in the Black Hills of South Dakota. Journal of Mammalogy, 81: 719-725.
Cryan, P.M., M. A. Bogan, and G. M. Yanega. 2001. Roosting habits of four bat species in the Black Hills of South Dakota. Acta Chiropterologica, 3: 43-52.
Mannings, R. W., and J. K. Jones. 1988. A new subspecies of fringed Myotis, Myotis thysanodes, from the northwestern coast of the United States. Occasional Papers. The Museum, Texas Technical University, 123: 1-6.
O’Farrell, M. J., and E. H. Studier. 1980. Myotis thysanodes. American Society of Mammalogists, Mammalian Species, 137: 1-5.
Rabe, M. J., T. E. Morrell, H. Green, J. C. DeVos, Jr., and C. R. Miller. 1998. Characteristics of ponderosa pine snag roosts used by reproductive bats in northern Arizona. Journal of Wildlife Management, 62: 612-621.
Weller, T. J., and C. J. Zabel. 2001. Characteristics of fringed myotis day roosts in northern California. Journal of Wildlife Management, 65: 489-497.
Original account by Pete Bradley and Mark Ports
2005 update by Theodore J. Weller
Myotis velifer, a member of the Family Vespertilionidae, occurs from Kansas, Oklahoma and western Texas, to southern Nevada, and southeastern California (along the Colorado River only), south through Mexico to Honduras. At least some populations are migratory. Hibernacula have been discovered in Mexico, Arizona, and Kansas. Within the U.S. it is most widely distributed in Arizona. This species is found primarily at lower elevations (the Sonoran and Transition life zones) of the arid southwest, in areas dominated by creosote bush, palo verde, brittlebush, and cactus.
Global Rank – G5. State Ranks: AZ – S3S4; CA – S1S2; CO – S?; NM – S4; NV – S?; TX – S4. Hayward (1961) claimed that M. velifer was very common in southern Arizona, with at least 500,000 individuals during the summer months. Current status is not well known. The BRD Bat Population Database has about 50 observation records of colonies from 13 literature citations from peer-reviewed journals, but current status of these colonies is unknown. Very severe declines have been documented along the Colorado River in California.
M. velifer is a large Myotis, with a forearm of 37-47 mm. It can be distinguished from other large Myotis by the presence of a conspicuous bare patch on the back between the scapulae, and the absence of either a keel on the calcar or fringe on the interfemoral membrane. As implied by the vernacular name, caves are the main roosts for this southwestern species, although it also uses mines, and occasionally buildings and bridges. It is primarily a “crevice dweller,” preferring “crevices, pockets, and holes in the ceilings of its underground retreats” (Stager 1939). This species is also known to roost in barn swallow nests. Colonies of 2,000 to more than 10,000 individuals have been reported. This bat is reported to fly less erratically and more strongly than other species of Myotis. It has been reported foraging over dense riparian vegetation and in drier desert washes. Dietary studies in Arizona, Kansas, and Mexico indicate that lepidopterans and coleopterans are typical prey. Known predators include rat snakes, hawks, barn owls, and raccoons. In southern Arizona this species has been found in the winter occupying wet mine tunnels above 6,000 feet, where roost temperatures are 8o to 11o C.
Potential threats include recreational caving, mine closures and subsequent roost destruction, and loss of foraging habitat in riparian zones.
We need information regarding status of historically identified colonies, trends in population numbers, more information on roosting and foraging requirements, basic life history information.
Arita, H.T. 1993. Conservation biology of the cave bats of Mexico. Journal of Mammalogy, 74: 693-702.
Fitch, J.H., K.A. Shump, J.R., and A.U. Shump. 1981. Myotis velifer. American Society of Mammalogists, Mammalian Species, 149: 1-5.
Hayward, B.J. 1961. The natural history of the cave bat, Myotis velifer. Unpublished dissertation, University of Arizona.
Hoffmeister, D. F. 1986. The mammals of Arizona. Vol. University of Arizona Press, Tucson. 602 pp.
Jackson, J. , B.J. Scharden, C. D. Cooley, and B.E. Rowe. 1982. Cave myotis roosting in barn swallow nests. Journal of Mammalogy, 27: 463-464.
Kunz, T. H. 1974. Feeding ecology of a temperate insectivorous bat (Myotis velifer). Ecology, 55(4): 693- 711.
Pitts, R.M., and J.J. Scharninghausen. 1986. Use of cliff swallow and barn swallow nests by the cave bat, Myotis velifer, and the free-tailed bat, Tadarida brasiliensis. The Texas Journal of Science, 38: 265-266.
Schmidly, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, TX. 188 pp.
Stager, K. 1939. Status of Myotis velifer in California, with notes on its life history. Journal of Mammalogy, 20: 225-228.
Account by Kathy Peckham
Myotis volans, a member of the Family Vespertilionidae, ranges across western North America from southeastern Alaska, British Columbia and Alberta in Canada to Baja California and central Mexico. It occurs throughout the western United States from the Pacific coast to the Great Plains and central Texas.
Global Rank – G5. State Ranks: AZ – S3; CA – S5; CO – S5; ID – S3; MT – S4; NM – S5; NV – S?; OR – S3; TX – S4; UT – S3S4; WA – S3; WY – S4; AL – S2; BC – S4S5. Former category 2 candidate species. Take regulated by permit in various states. Proposed as a Species of Special Concern in California.
Myotis volans is recognized by its short rounded ears, small hindfeet, long tibia, distinctly keeled calcar, and long, dense fur on the underside of the wing membrane that extends from the body to a line joining the elbow and the knees. Although some variation in color exists, it is typically dark brown. It is a bat primarily of coniferous forests, but also occurs seasonally in riparian and desert habitats. It is a relatively poor urine concentrator. M. volans uses abandoned buildings, cracks in the ground, cliff crevices, exfoliating tree bark, and hollows within snags as summer day roosts; caves and mine tunnels as hibernacula. It is active throughout the night, but peak activity is 3-4 hours after sunset. It is a rapid, direct flier, often traveling some distance while foraging, and feeds in and around the forest canopy, primarily on moths and other soft-bodied insects. Individuals copulate in autumn, with females storing the sperm overwinter, ovulating in the spring, and giving birth from May through August. Individuals have lived a minimum of 21 years.
May be affected by closure of abandoned mines without adequate surveys and certain forest-management practices. Residues of DDT and its metabolites have been found in this species in Oregon.
No information known on population trends and use and acceptance of bat gates. More information is needed on roosting and foraging requirements.
Bogan, M.A. et al. 1997. A study of bat populations at Los Alamos National Laboratory and Bandelier National Monument, Jemez Mountains, New Mexico. Unpubl. report to Cooperators, U.S. Geological Survey, Biological Resources Division, Albuquerque, NM. 76 pp. + appendices.
Ormsbee, P.C. 1996. Characteristics, use, and distribution of day roosts selected by female Myotis volans (long-legged myotis) in forested habitat of the central Oregon Cascades. Pp. 124-131 in Bats and forests symposium, R.M.R. Barclay and R.M. Brigham, eds. B.C. Ministry of Forests, Research Branch, Victoria, B.C., Working Paper 23/1996.
Parker, D.I., J.A. Cook, and S.W. Lewis. 1996. Effects of timber harvest on bat activity in southeastern Alaska’s temperate rainforests. Pp. 277-292 in Bats and forests symposium, R.M.R. Barclay and R.M. Brigham, eds. B.C. Ministry of Forests, Research Branch, Victoria, B.C., Working Paper 23/1996.
Warner, R.M. and N.J. Czaplewski. 1984. Myotis volans. American Society of Mammalogists, Mammalian Species, 224: 1-4.
Account by M. A. Bogan, E. W. Valdez, and K.W. Navo
Myotis yumanensis, a member of the Family Vespertilionidae, ranges across the western third of North America from British Columbia, Canada, to Baja California and southern Mexico. In the United States, it occurs in all the Pacific coastal states, as far east as western Montana in the north, and as far east as western Oklahoma in the south.
Global Rank – G5. State Ranks: AZ – S3S4; CA – S5; CO – S3; ID – S3; MT – S3; NM – S5; NV – S?; OR – S3; TX – S4; UT – S3; WA – S?; WY – S2?; BC – S4S5. Former category 2 candidate species. Take regulated by permit in some states.
Myotis yumanensis is a small bat that is usually gray or brown to pale tan dorsally with a paler venter of tan or gray; ears and membranes are frequently pale brown to gray. In some areas M. yumanensis is difficult to distinguish from M. lucifugus and caution is required. Both species are usually associated with permanent sources of water, typically rivers and streams, but Yuma myotis also use tinajas in the arid West. It occurs in a variety of habitats including riparian, arid scrublands and deserts, and forests. The species roosts in bridges, buildings, cliff crevices, caves, mines, and trees. Individuals become active and forage just after sunset, feeding primarily on aquatic emergent insects. Their diet is known to include caddis flies, flies, midges, small moths and small beetles. After feeding, they periodically rest at night roosts where the food is digested. Mating is typically in the fall and females give birth to one young from mid-spring to mid-summer in maternity colonies that may range in size up to several thousand; males tend to roost singly in the summer.
May be affected by closure of abandoned mines without adequate surveys, some forest management practices, and disturbance of maternity roosts in caves and buildings. Since this species frequently occurs in anthropogenic structures, it is vulnerable to destructuve pest control activities. Some riparian-management practices may be detrimental.
No information known on use and acceptance of bat gates, impacts of grazing and riparian habitat management, winter range, and winter roost requirements. Information is needed on geographic variation in roosting and foraging requirements.
Barbour, R.W., and W.H. Davis. 1969. Bats of America. The University Press of Kentucky, 286pp.
Betts, B. J. 1997. Microclimate in Hell’s Canyon mines used by maternity colonies of Myotis yumanensis. Journal of Mammalolgy, 78: 1240-1250.
Brigham, R. M., H. D. J. N. Aldridge, and R. L. Mackey. 1992. Variation in habitat use and prey selection by yuma bats, Myotis yumanensis. Journal of Mammalogy, 73(3): 640-645.
Harris, A.H. 1974. Myotis yumanensis in interior southwestern North America, with comments on Myotis lucifugus. Journal Mammalogy 55: 589-607.
Hoffmeister, D.F. 1986. Mammals of Arizona. University of Arizona Press and Arizona Game and Fish Department, Tucson, 602 pp.
Pierson, E.D., W.E. Rainey, and R.M. Miller. 1996. Night roost sampling: a window on the forest bat community in northern California. Pp. 151-163 in R. M. R. Barclay and M. R. Brigham, eds. Bats and Forests Symposium, October 19-21, 1995, Victoria, British Columbia, Canada. Research Branch, Ministry of Forests, Victoria, British Columbia, Working Paper 23/1996.
Account by M. A. Bogan, E. W. Valdez, and K.W. Navo
Parastrellus hesperus, a member of the Family Vespertilionidae, occurs from the desert lowlands of the southwestern United States, with its range extending into southern Washington. In Mexico, it ranges throughout Baja California and on the mainland to Michoacan and Hildago. While most commonly associated with arid, desert landscapes, it also occurs in association with significant rock features in lower elevation mixed conifer forest in mountain ranges in California and up to fir-spruce forest in Arizona.
Global Rank – G5. State Ranks: AZ – S5; CA – S5; CO – S4; ID – S3; NM – S5; NV – S?; OR – S4; TX – S5; UT – S4; WA – S4?.
P. hesperus is the smallest of all North American bats, and can be distinguished from the small Myotis species (californicus or ciliolabrum) by the club-shaped tragus compared to the pointed tragus of Myotis. All three of these small bats have a keeled calcar. In Texas, there is a slight overlap in range with the eastern pipistrelle (P. subflavus) which is larger, with an unkeeled calcar and tricolored fur. Western pipistrelles are also commonly known as canyon bats due to their association with rocky canyons and outcrops (usually at elevations below 2,000 meters), where they roost in small crevices. Occupied crevices may also be in mines and caves. They have been observed at dusk flying over creosote bush scrub several miles from rocky areas, and it is postulated that they may roost under rocks or in rodent burrows. They emerge early in the evening, often before sunset, and may be active after sunrise. Near rocky canyons, their small fluttery forms can fill the sky in the fading desert light. They are often the first bats captured in an evening in mist nets set over isolated desert water holes or across mine entrances as they enter to night roost. Stomach content analysis suggest they feed on small swarming insects such as flying ants, mosquitoes, fruit flies, leafhoppers and ants. During cooler winter months, pipistrelles hibernate in rock crevices (sometimes in mines), although on warm winter days, they may emerge to forage during the day. It is reported that females give birth to twins in late May through June, and mothers with their young may roost alone or in groups of less than 20 individuals. The young are volant within a month.
Destruction of rocky areas due to renewed mining or other development activities (road construction, housing developments, water impoundments) can kill roosting bats and remove roosting habitat.
Since this bat is too tiny to carry a transmitter, no data exists on individual foraging areas or range. Although P. hesperus is a ubiquitous bat throughout the arid southwest, limited information is available on social structure, microhabitat roost requirements, roost fidelity, or longevity. Without more knowledge of natural history, it is difficult to assess potential threats to this species.
Barbour, R. W., and W. H. Davis. 1969. Bats of America. University of Kentucky Press, Lexington, KY, 286 pp.
Bradley, W. G., and M. J. O’Farrell. 1969. Temperature relationships of the western pipistrelle (Pipistrellus hesperus). Pp. 85-96, in C. C. Hoff and M. L. Riedesel, eds. Physiological systems in semiarid environments, Univ. New Mexico Press, Albuquerque, NM.
Hayward, B. J., and S. P. Cross. 1979. The natural history of Pipistrellus hesperus (Chiroptera: Vespertilionidae). Western New Mexico Univiersity. Office of Research, 3: 1-36.
Hoffmeister, D. F. 1986. The mammals of Arizona. University of Arizona Press, Tucson, AZ, 602 pp.
Schmidly, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, TX, 188 pp.
Account by Patricia E. Brown