Indiana bats can become a nuisance in some places where their summer roots have been destroyed due to increasing human populations. Bats will then find their way into homes and attics to roost. Like most mammals in the United States, Indiana bats also may be carriers of rabies. However, documented incidence of rabies infection in Indiana bats is low. It is also very unlikely that humans will come into close contact with Indiana bats for the disease to be transmitted.
Negative Impacts: injures humans (carries human disease)
Indiana bats may impact humans by helping to control pest insect populations.
Positive Impacts: controls pest population
Indiana bats help control insect populations and are prey for bat predators. They are hosts for species of mites (Steatonyssus occidentalis and Macronyssus crosbyi) but there have been no documented intestinal parasites. Indiana bats have a direct impact on their cave environment by adding nutrients to the cave with their guano and decomposing bodies.
Commensal/Parasitic Species:
Indiana bats consume a diet of insects. A study found that Indiana bats eat insects from five main taxa: Coleoptera (beetles), Diptera (flies), Hymenoptera (bees, wasps), Lepidoptera (butterflies and moths), and Trichoptera (caddisflies). There are also differences in what females eat based on whether they are pregnant or lactating or neither. Lactating females eat greater amounts of coleopterans and trichoperans compared to non-lactating female bats. There are slight differences in diet based on location; southern colonies feed more on terrestrial insect species, whereas more northern bats fed on insects around wetlands.
Animal Foods: insects
Primary Diet: carnivore (Insectivore )
Myotis sodalis, also known as the Indiana bat, is found only in North America. Their range spans from Iowa, Missouri, and northern Arkansas east to western Virginia and North Carolina, and north into New York, Vermont, New Hampshire, and Massachusetts. These areas include both their winter hibernation sites and summer ranges. Indiana bats hibernate in the northern reaches of their range in caves during the winter. In the summer and autumn months Myotis sodalis migrate to summer roosting sites.
Biogeographic Regions: nearctic (Native )
Indiana bats hibernate predominantly in limestone caves, though some hibernate under the bark of dead trees. Cave temperatures range from 3.0 to 7.2 degrees Celsius; warmer temperatures are at the start of the hibernating season in October to November and cooler temperatures during March to April. They roost at elevations from 0 to 1,746 m above sea level (average 1047 m). During the summer, Indiana bats roost under the bark of large trees, under bridges, and sometimes in buildings. Trees in which Indiana bats are known to roost include bitternut hickory (Carya cordiformis), oaks (Quercus), elms (Ulmus), pines (Pinus), American sycamore (Platanus occidentalis), and eastern cottonwood (Populus deltoides).
Range elevation: 0 to 1,746 m.
Average elevation: 1,047 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest ; mountains
Other Habitat Features: caves
Indiana bats have lived as long as 20 years in the wild. Their expected lifespan in the wild is 15 years.
Range lifespan
Status: wild: 20 (high) years.
Typical lifespan
Status: wild: 15 (high) years.
Indiana bats are small, weighing approximately 7 g with a forearm range of 35 to 41 mm. They are dark grey or brown in color and their fur is considered soft. They are distinguished from other, similar, co-occuring members of M. myotis by their distinctly keeled calcar, a small cartilage projection from the foot, giving added stability to the wing. Indiana bat fur is soft in comparison to that of the very similar and closely-related little brown bat, Myotis lucifugus, which has fur that tends to be more shiny. Male and female Indiana bats are very similar with the female tending to be a little larger than the male.
Range mass: 5 to 11 g.
Range length: 70.8 to 90.6 mm.
Average length: 81.7 mm.
Range wingspan: 240 to 267 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Predators of Indiana bats include carnivorous animals such as snakes, owls, raccoons (Procyon lotor), and other medium-sized mammals. The main adaptations Indiana bats have against predation is that they roost in caves and inaccessible tree crevices, putting them out of reach of many predators. They are also active at night and agile in flight. Myotis sodalis individuals hibernate in large clusters which help ensure survival (and warmth) between October and April. Their cryptic coloration also helps to protect them from predation.
Humans have been known to kill these bats, although they are not eaten. For example, at Carter Caves State park in Kentucky, two men clubbed 105 Indiana bats to death. Humans also unintentionally kill bats by destroying or cutting down summer roost trees or disturbing hibernation sites.
Known Predators:
Anti-predator Adaptations: cryptic
Indiana bats are a federally endangered species and are endangered on the IUCN Red List. They are mostly threatened by habitat loss, and their numbers are monitored. For example, any organization intending to change a habitat where they live must first check for roosting locations, and accommodate the bats if they find them. Humans also disturb Indiana bats through recreational caving, so many of their hibernation areas are now closed off to humans.
Temperate North American bats, including Indiana bats, are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%. Currently, there is no known cure for white nose syndrome.
US Federal List: endangered
CITES: no special status
State of Michigan List: endangered
IUCN Red List of Threatened Species: endangered
Indiana bats, like other insectivorous bat species, use echolocation to maneuver through their various habitat types. They have well-developed eyesight which they use to aid with their travels from their winter hibernacula to their summer roosting sites. We can assume that Myotis sodalis individuals do communicate with each other using sound, but there have been no studies to further investigate this. Like other mammals, it is likely that these bats use chemical cues to communicate reproductive state.
Communication Channels: visual ; acoustic ; chemical
Perception Channels: visual ; tactile ; echolocation ; chemical
Indiana bats are polygynous, with one male mating with multiple females. Males wait at the entrance to winter hibernacula for the opportunity to copulate with un-mated females. This occurs during the "fall swarming" period in October or November. There have been some accounts of Indiana bats copulating in late winter or early spring but this is rare.
Mating System: polygynous
Myotis sodalis copulate in the fall, generally in late October. This is the time right before they enter into hibernation. Pregnancy does not begin at this time, as the females can store sperm over winter. This delayed fertilization allows the young to be born in summer (up to 68 days post fertilization). Females give birth to only one pup (on rare occasions twins) per year. Most pups are born between late June and early July with weaning at about 31 days (range 25 to 37 days). The first born of the season may be volant as early as mid-July.
Breeding interval: Indiana bats breed once yearly.
Breeding season: Copulation generally occurs in October, before hibernation.
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Range gestation period: 68 (high) days.
Range weaning age: 25 to 37 days.
Range time to independence: 2 to 3 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; induced ovulation ; fertilization ; viviparous ; delayed fertilization
Average number of offspring: 1.
Females provide care for pups after birth at summer roosting sites. Often maternity colonies are formed and male presence is rare. Females are responsible for providing nourishment for their pups through lactation. Time to weaning is about 31 days and pups are fully independent from their mothers in 2 to 3 months.
Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
Common dominant trees utilized by Indiana bat throughout its range include oaks (Quercus spp.), hickories (Carya spp.), ashes (Fraxinus spp.), elms (Ulmus spp.), eastern cottonwoods (Populus deltoides), locusts (Robinia spp.), and maples (Acer spp.). The understory may include hawthorns (Crataegus spp.), dogwoods (Cornus spp.), fragrant sumac (Rhus aromatica), giant ragweed (Ambrosia trifida), sedges (Carex spp.), Virginia creeper (Parthenocissus quinquefolia), wood nettle (Laportea canadensis), goldenrod (Solidago spp.), poison-ivy (Toxicodendron radicans), and wild grape (Vitis spp.) [35].
Indiana bats were found in a variety of plant associations in a southern Iowa study. Riparian areas were dominated by eastern cottonwood, hackberry (Celtis occidentalis), and silver maple (Acer saccharinum). In the forested floodplains, the dominant plants included black walnut (Juglans nigra), silver maple, American elm (Ulmus americana), and eastern cottonwood. In undisturbed upland forest, the most common plants were black oak (Quercus velutina), bur oak (Q. macrocarpa), shagbark hickory (Carya ovata), and bitternut hickory (C. cordiformis). Black walnut, American basswood, American elm, and bur oak dominated other upland Indiana bat sites [23].
Studies have identified at least 29 tree species that Indiana bats use during the summer. The greatest number of utilized tree species are found in the central portion of Indiana bats's range (primarily Missouri, southern Illinois, southern Indiana, and Kentucky), but this is likely because the majority of research conducted on the species has occurred in this region. Roost trees from these central states, which are mainly in the oak-hickory cover type, include silver maple, red maple (Acer rubrum), sugar maple (A. saccharum), white oak (Q. alba), red oak (Q. rubra), pin oak (Q. palustris), scarlet oak (Q. coccinea), post oak (Q. stellata), shingle oak (Q. imbricaria), eastern cottonwood, shagbark hickory, bitternut hickory, mockernut hickory (C. alba), pignut hickory (C. glabra), American elm, slippery elm (Ulmus rubra), honey locust (Gleditsia triacanthos), sourwood (Oxydendrum arboreum), green ash (Fraxinus pennsylvanica), white ash (F. americana), Virginia pine (Pinus virginiana), American sycamore (Platanus occidentalis), and sassafras (Sassafras albidum) [17,18,20,35,36,38,44,47,50,59,89]. In southern Michigan and northern Indiana, which are mainly in the oak-hickory and elm-ash-cottonwood cover types, trees utilized as roosts include green, white, and black ash (Fraxinus nigra), silver maple, shagbark hickory, and American elm [22,46,51,56]. And finally, in the southern areas of the Indiana bat's range (primarily Tennessee, Arkansas, and northern Alabama), which include the oak-hickory and oak-pine cover types, Indiana bats utilize shagbark hickory, white oak, red oak, pitch pine (P. rigida), shortleaf pine (P. echinata), loblolly pine (P. taeda), sweet birch (Betula lenta), and eastern hemlock (Tsuga canadensis) [14,85]. Virtually no information exists for Indiana bats roosting in the Northeast (such as Pennsylvania, New York, and Vermont) or for the eastern sections of the range (including Virginia, West Virginia, and Maryland). In these areas, Indiana bats likely utilize the some of the same species listed here and also take advantage of other tree species that are available.Primary roosts used by Indiana bats are typically snags in canopy gaps and forest edges that receive direct sunlight throughout the day [17]. Alternate roosts live or dead trees, generally located in the forest interior, that usually receive little or no direct sunlight [17,44]. Weather, such as very warm temperatures and precipitation, appears to influence the use of interior alternate roost trees over primary roosts, as alternate roosts generally offer more shade and protection during inclement weather and extreme heat [17,44,64]. However, this preference may fluctuate from season to season. Indiana bats moved to the alternate roost during periods of heavy rain and colder ambient temperatures during fall in Missouri, but chose to roost in the primary snag during inclement weather in the spring. These differences may be attributed to variation in the heat retention capabilities of the trees at different times of the year [44]. Gumbert and others [38] discovered bats from a maternity colony switched roosts more frequently in summer and autumn than they did in spring in an oak-pine forest in Kentucky. Indiana bats exhibit strong fidelity to individual roost trees from year to year if they are still suitable roost sites [26,38,44,52,56]. Many trees are no longer usable after just a few years [17,26,35,44,51,56,93], while others may last as long as 20 years [81].
Another important factor relating to roost suitability is tree condition. Indiana bats prefer dead or dying trees with exfoliating bark [51]. The amount of exfoliating bark present on a tree seems to be insignificant [47]. Indiana bats show an affinity for very large trees that receive lots of sunlight [54]. Typically, Indiana bats roost in snags, but a few species of live trees are also utilized. Live roost trees are usually shagbark hickory, silver maple, and white oak [17,35,89]. Shagbark hickories make excellent alternate roosts throughout the Indiana bats's range due to their naturally exfoliating bark [93]. Although Indiana bats primarily roost under loose bark, a small fraction roost in tree cavities [14,35,50,51,53,89].
Primary roosts are generally larger than alternate roosts [14], but both show a lot of variability. Females typically use large roost trees averaging 10.8 inches (27.4 cm) to 25.7 inches (65.3 cm) as maternity roosts [17,35,41,47,50,51,56,83,85]. Males are more flexible, roosting in trees as small as 3 inches (8 cm) dbh [35,41,47,59]. In a review, Romme and others [78] determined that Indiana bats required tree roosts greater than 8 inches (22 cm) dbh, while Clawson [26] suggested that roosts of 12 inches (30 cm) dbh or larger were preferred. The heights of roost trees vary, but they tend to be tall, with average heights ranging from 62.7 feet (19.1 m) to 100 feet (30 m). The heights of the actual roosting sites are variable as well, ranging from 4.6 feet (1.4 m) to 59 feet (18 m) [41,51,56,85]. There is evidence that roost height is influenced by the extent of canopy closure. Specifically, more open canopies tend to be correlated with into lower roost heights [35]. However, this rule does not appear to hold true in all localities [51,85].
In addition to day roosts, Indiana bats use temporary roosts throughout the night to rest between foraging bouts. Limited research has examined the use of night roosts by Indiana bats, and thus their use and importance are poorly understood. Males, lactating and postlactating females, and juveniles have been found roosting under bridges at night [48,65]. Some Indiana bats were tracked to 3 different night roosts within the same night [67]. Night roosts are often found within the bats's foraging area. Indiana bats using night roosts are thought to roost alone and only and for short periods, typically 10 minutes or less. Lactating bats may return to the day roost several times each night, presumably to nurse their young. Pregnant bats have not been tracked back to the day roost during the night except during heavy rain. Because Indiana bats are difficult to track during their nightly movements and usually rest for such short periods of time, the specific requirements that Indiana bats need in a night roost, and reasons why night roosts are needed, are still unknown.
During spring and fall, Indiana bats migrate between hibernacula and summer roosting sites. In New York and Vermont, bats traveled up to 25 miles (40 km) between hibernacula and summer roosting sites in spring [15]. This is a considerably shorter distance than what is seen in the Midwest, where bats may travel up to 300 miles (500 km) [52]. Many males remain close to hibernacula during the spring and summer [2,102] rather than migrating long distances like females. Occasionally, they even roost within hibernacula during the summer [102]. Males also roost in caves and trees during fall swarming [26,102]. Few data exist for the roosting requirements of Indiana bats during spring and fall migrations; data indicate that requirements during these times are similar to summer needs in that the bats chose large trees with direct sunlight and exfoliating bark [15,41].
The ability for Indiana bats to find suitable hibernating conditions is critical for their survival. A hibernaculum that remained too warm during one winter caused a 45% mortality rate in hibernating Indiana bats [77]. Bats generally hibernate in warmer portions of the hibernacula in fall, then move to cooler areas as winter progresses. During October and November, temperatures at roosting sites within major hibernacula in 6 states averaged 43.5 °F to 53.2 °F (6.4-11.8 °C). Roost temperatures at the same hibernacula ranged from 34.5 °F to 48.6 °F (1.4-9.2 °C) from December to February. Temperatures in March and April were slightly lower than in autumn at 39.6 °F to 51.3 °F (4.2-10.7 °C) [90]. The Indiana Bat Recovery Team [93] discovered that Indiana bat populations increased over time in hibernacula that had stable mid-winter temperatures averaging 37.4 °F to 45.0 °F (3.0-7.2 °C), and declined in hibernacula with temperatures outside this range [90,93]. Temperatures slightly above freezing during hibernation allow Indiana bats to slow their metabolic rates as much as possible without the risk of freezing to death or using up fat too quickly [42,77]. Hibernating Indiana bats may also survive low temperatures by sharing body heat within the tight clusters they typically form [28]. Bats awaken periodically throughout the hibernation period, presumably to eliminate waste or to move to more appropriate microclimates [39,40]. This periodic waking does not seem to affect the survival of Indiana bats, but waking caused by disturbance can cause Indiana bats to use up large amounts of energy, which can cause them to run out of fat reserves before the end of winter, possibly leading to death [86].
One way in which caves retain low temperatures is through a constant input of cold air from outside the cave circulating in. Typically, the caves supporting the largest Indiana bat populations have multiple entrances that allow cool air from outside the cave to come in, creating a circulation of fresh cooled air [91]. Gates that are meant to keep vandals out of caves have altered the temperature and airflow of hibernacula, resulting in population declines of Indiana bats at many major hibernacula throughout their range. Removing or modifying gates at some of these have given these populations a chance to rebound [30]. Also, the bats seem to prefer a relative humidity of 74% to 100%, although it is uncommon for the air to be saturated [2,26,28,39,42]. Relative humidities of only 50.4% have also been recorded [76]. More research is needed to identify other specific environmental conditions that bats require at hibernacula.
Indiana bats feed exclusively on terrestrial and aquatic flying insects [69]. The most common prey items taken by Indiana bats are moths (Lepidoptera), beetles (Coleoptera), and mosquitoes and midges (Diptera) [10,58]. Selection of prey depends largely on availability in the foraging habitat with diet varying seasonally, by reproductive status of females, and from night to night. In southern Michigan, Indiana bats primarily ate caddisflies (Trichoptera) and bees, wasps, and ants (Hymenoptera), in addition to the more common prey previously listed [55,68,69]. In the Ozarks of southern Missouri, the bats also primarily ate bees, wasps, ants, moths, and beetles as well as leafhoppers (Homoptera), although diet did vary throughout the summer [10]. Bats in Indiana were found to prefer beetles, moths, mosquitoes, midges, leafhoppers, and wasps [100,101]. Other arthropod groups which are consumed by Indiana bats in very limited quantities are lacewings (Neuroptera), spiders (Araneae), stoneflies (Plecoptera), mayflies (Ephemeroptera), mites and ticks (Acari), and lice (Phthiraptera) [10,47,55,69].
In addition to differences in diet, variation in Foraging behaviors have been documented. For instance, the distance that an individual Indiana bat travels between a day roost and a nightly foraging range can vary. Garner and Gardner [36] discovered that Indiana bats traveled up to 1.6 miles (2.6 km) from their day roosts to their foraging sites in Illinois. Similarly, bats traveled up to 1.5 miles (2.4 km) to forage in Kentucky [47]. In Michigan, female bats traveled as far as 2.6 miles (4.2 km) to reach foraging areas with an average of 1.5 miles (2.4 km) [67].
Several studies have documented similarities in how foraging habitats are actually utilized by Indiana bats. Humphrey and others [44] found Indiana bats in Indiana were foraging around the canopy, which was 7 to 98 feet (2-30 m) above ground. LaVal and others [57], whose study was also conducted in Missouri, found that a female bat foraged 7 to 33 feet (2-10 m) above a river. In the same study, a male Indiana bat was observed flying in an elliptical pattern among trees at 10 to 33 feet (3-10 m) above the ground under the canopy of dense forests [57]. In addition, bats were observed foraging at canopy height in Virginia [41], which would likely provide foraging conditions similar to the studies previously mentioned.
Differences in the extent of foraging ranges have also been noted. Bats from the same colony foraged in different areas at least some of the time [67]. Humphrey and others [44] reported that the average foraging area for female bats in Indiana was 843 acres (341 ha), but the foraging area for males averaged 6,837 acres (2,767 ha). Hobson and Holland reported a male bat utilizing a foraging area of 1,544 acres (625 ha) in Virginia [41]. In Illinois, however, the foraging ranges were much smaller at an average of 625 acres (253 ha) for adult females, 141 acres (57 ha) for adult males, 91 acres (37 ha) for juvenile females, and only 69 acres (28 ha) for juvenile males [35,36,47]. Humphrey and others [44] found that foraging areas utilized by Indiana bats in Indiana increased throughout the summer season, but only averaged 11.2 acres (4.54 ha) in mid-summer.
Fire could have mixed effects on Indiana bat habitat. On one hand, fire could burn down a suitable roost tree [81] or weaken it to such an extent that it would fall shortly after. Also, a fire could burn off bark peeling from a roost, taking away preferred roosting locations on the tree. This would also make a roost tree suddenly become unsuitable for Indiana bats. On the other hand, fire could kill some trees, creating new roosting habitat. Overall, fire may result in both the loss and the production of snags [97]. Carter and others [19] suggested that fire in any season that results in tree mortality may provide more benefit to southeastern bats through snag creation than any negative impacts that may occur. A crown fire in an occupied forest stand would likely increase the amount of solar radiation reaching a roost, which would be preferable to a completely closed canopy (see Preferred Habitat). In addition, opening the canopy via a crown fire, or causing tree fall, could improve foraging habitat. In the long term, fire may benefit Indiana bat habitat by reducing the threat of future severe fires. Removing fuel biomass will decrease the risk of major fire events within a stand, which would ensure the continued presence of suitable roosts and foraging habitat for the Indiana bat. In addition, the growth of remaining trees after prescribed fire may be promoted due to decreased competition with other vegetation [74]. Since Indiana bats evolved in habitats that were affected by fire in the past, fire is unlikely to have a strong, long-term negative impact on bat populations [4].
MacGregor and others [59] discovered Indiana bats utilizing roosts located within prescribed fire areas twice as much as expected during 1 year based on the amount of area available. Indiana bat utilization was equal to expected during the 2nd year of the Kentucky study [59]. Some individuals were discovered roosting in a partially burned post oak (Quercus stellata) in Illinois [35]. These studies show that fire-affected landscapes remain suitable for Indiana bat use over time.
A mathematical model suggested that closely related bat species in California would be affected differently by high-severity fires. The fringed myotis (Myotis thysanodes) and the Yuma myotis (M. yumanensis) were both predicted to be adversely affected by postwildfire conditions due to a perceived decrease in habitat suitability. In contrast, the model suggested that the long-eared myotis (M. evotis) would benefit from a high severity wildfire through the production of more suitable habitat [7]. Based on the results of this model, it is unclear how a high severity fire may affect Indiana bat habitat.
The following table provides fire return intervals for plant communities and ecosystems where the Indiana bat is important. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Community or Ecosystem Dominant Species Fire Return Interval Range (years)maple-beech-birch Acer-Fagus-Betula spp. >1,000 silver maple-American elm Acer saccharinum-Ulmus americana <5 to 200 sugar maple A. saccharum >1,000 sugar maple-basswood A. saccharum-Tilia americana >1,000 sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica <35 to 200 beech-sugar maple Fagus spp.-Acer saccharum >1,000 black ash Fraxinus nigra <35 to 200 yellow-poplar Liriodendron tulipifera <35 shortleaf pine-oak Pinus echinata-Quercus spp. <10 slash pine-hardwood P. elliottii-variable <35 longleaf pine-scrub oak P. palustris-Quercus spp. 6-10 Table Mountain pine P. pungens <35 to 200 eastern white pine P. strobus 35-200eastern white pine-eastern hemlock Pinus strobus-Tsuga canadensis 35-200 Virginia pine-oak P. virginiana-Quercus spp. 10 to <35 sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-Ulmus americana <35 to 200 black cherry-sugar maple Prunus serotina-Acer saccharum >1,000 oak-hickory Quercus-Carya spp. <35 [98]oak-gum-cypress Quercus-Nyssa-spp.-Taxodium distichum 35 to >200 [70]southeastern oak-pine Quercus-Pinus spp. <10 white oak-black oak-northern red oak Quercus alba-Q. velutina-Q. rubra <35 northern pin oak Q. ellipsoidalis <35 bear oak Q. ilicifolia <35 bur oak Q. macrocarpa <10 chestnut oak Q. prinus 3-8 northern red oak Q. rubra 10 to <35post oak-blackjack oak Q. stellata-Q. marilandica <10 black oak Q. velutina <35 eastern hemlock-yellow birch Tsuga canadensis-Betula alleghaniensis >200 [98]elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. <35 to 200 [31,98]Indiana bats may respond positively to some forest disturbance [93], but direct and indirect effects of land management on the Indiana bat are still unknown. Direct mortality, injury, or harassment of Indiana bats is possible from felling trees, especially if snags are felled [84]. Belwood [5] noted that a maple snag felled in a new residential area had been a maternity roost. A dead female and 33 nonvolant juveniles were found near the tree after felling. The juveniles were retrieved by their mothers shortly after being placed in a bat house for protection [5]. All juveniles appear to have survived the destruction of the tree, but it is unclear whether the female died as a result of tree felling or from other causes.
Harvesting trees within stands where Indiana bats are known to roost during the summer could result in the mortality or displacement of individual bats or possibly entire colonies [84]. Harvests would probably be safer in these areas during the hibernation period when the trees are not being utilized. However, felling trees at any time may result in the loss of unknown maternity roosts [8]. Cutting down a tree with roosting Indiana bats is assumed to be unlikely in most cases because of the rarity of the species, because many stands with suitable habitat have more potential roost trees than are likely utilized by Indiana bats, and because most maternity colonies are far apart across their range [103].
Since roost trees tend to be ephemeral, lasting for just a couple of seasons because of tree fall or loss of exfoliating bark from the bole, it may be more beneficial for Indiana bat conservation to protect and manage stands rather than individual trees. Others go a step further by recommending that existing snags should be retained and new snags should be recruited [3]. This may be especially true for lands intensively managed for wood harvest where forests are not allowed to reach old age classes and very few snags are typically created [97]. Since Indiana bats need a variety of roosts to suit their roosting needs, trees of various species, size, and condition should be maintained to provide the maximum probability that the needs of the bats will be met [62] and to provide a continuous supply of roosts for when old roosts become unsuitable [26].
When harvesting trees in either green or salvage units, the U.S. Fish and Wildlife Service in Pennsylvania [94] recommends that all shagbark and shellbark hickories, living or dead, be retained in any area where Indiana bats could potentially occur. More than 16 live trees of at least 9 inches (23 cm) dbh should be left per acre in partial harvest units. Three of these live trees should be at least 20 inches (51 cm) dbh. For final harvest units and clearcuts, 8 to 15 live trees at least 9 inches (23 cm) dbh should be retained per acre with 1 tree being at least 20 inches dbh per acre. For partial to intermediate harvests in green stands, canopy cover should be reduced to 54%. Live residual trees surrounding approximately 1/3rd of the large (>12 inches (30 cm) dbh) snags with exfoliating bark should be saved in order to provide partial shade of the snags throughout the summer [94]. These live trees could potentially become suitable roosts in the future. Live hickories, oaks, elms, ashes, cottonwoods, and maples should be retained when possible since they are the types primarily used as roosts [78,94]. In partial and final harvests in salvage units as well as in clearcuts, 5 to 10 snags of at least 9 inches (23 cm) in diameter should be retained per acre. At least 1 snag 16 inches (41 cm) dbh should remain per 2 acres (0.8 ha). All known Indiana bat roosts should be protected until they are no longer suitable for use as roosts [94]. In other reports, even more harvest guidelines were presented. For instance, for every 5 acres (2 ha) harvested, a clump of trees 0.25 acre ( 0.1 ha) in size should be left and contain "den trees," snags, oaks and hickories, conifers, less common species, and/or mast species in a variety of sizes [81]. Additionally, large snags in open canopy should be preserved [26]. Due to the bats' preference for large snags, removal of any snag with exfoliating bark within Indiana bat habitat would potentially cause habitat degradation by the removal of current or potential roost sites.
Several studies document stand use by Indiana bats after tree harvest. Bats completely avoided sites in the study area that had been recently clearcut in Kentucky [59]. However, unmanaged forest stands received 1.5 to 2 times as much activity as expected based on habitat availability. Recent two-aged shelterwood harvests experienced 4 to 7 times the amount of activity expected. These two-aged shelterwood harvests followed guidelines that called for the retention of 40 live trees/ha as well as all snags, shagbark hickories, hollow trees, and trees with large dead limbs. More roosts and more bats utilizing those roosts were found within these harvested areas than in a similar Kentucky study where 40 live trees and just 5 snags/ha were retained [59]. In Illinois, a maternity colony remained in a selectively harvested area and utilized the same roosts that were previously occupied [35]. Indiana bats were occasionally observed foraging under intact canopies and forests with gaps that were created by diameter-limit harvests in West Virginia. Indiana bat activity was not recorded in clearcut areas or under complex canopies [72].
A project in eastern Texas proposed that thinning in pine forests will create more suitable habitats for the southeastern myotis (Myotis austroriparius) and Rafinesque's big-eared bat (Corynorhinus rafinsquii) by promoting the growth of remaining pine trees to old-growth age class [74]. This condition is reportedly similar to what is preferred by the Indiana bat [85]. Thus, thinning understory may help to improve Indiana bat summer habitat. (See Site Characteristics for discussion on the preferred stand structure of Indiana bats.)
Further recommendations for improving and maintaining the landscape for the Indiana bat have been proposed by biologists in Missouri, Pennsylvania, and Ohio. Riparian corridors should be forested for 100 feet (30 m) or more on either side of a stream. In areas lacking wide forest corridors, reforestation should be a priority [26]. Reducing forest canopies from 100% cover to roughly 30% to 80% cover and clearing some understory is also recommended [8,26]. However, reducing canopy cover even more could be detrimental to the bats by causing the loss of current and future roosts as well as by altering the landscape and microhabitats. Creating new water sources, especially in upland habitats, may improve habitats in which other water sources are not readily available [26]. Sedimentation of stream corridors following logging could potentially affect the insect prey assemblage in a foraging area [8].
Greater threats to the survival of Indiana bats may exist during hibernation. Hibernating bats that are disturbed by human activity have faster weight loss than those not visited by people. Bats located in hibernacula that are visited by people during the hibernation period are more likely to die before spring [45]. The biggest threats to Indiana bat hibernacula are human disturbance, including researchers and spelunkers, and vandalism, poorly designed gates that disrupt airflow, natural hazards such as flooding or mine collapse, and microclimate changes [39,93]. Although gating cave and mine entrances can deter humans from entering hibernacula and disturbing hibernating bats, gates can severely change temperature and airflow within the cave causing it to fall below optimal conditions [42,77]. Management recommendations include protecting hibernacula with bat-friendly gates [30] and restoring abandoned hibernacula if possible [26,103]. Hibernacula should also be closed to visitation from September 1 to April 30 toward the southern extent of the species's range, and from September 1 to May 31 in the north. To minimize disturbance to hibernating populations, censuses of Indiana bats should only occur biennially [26]. Clawson [26] also recommended that a 0.25-mile (0.4 ha) buffer zone be established around hibernacula, in which no development, agricultural activities, logging, or mining should occur. Kiser and Elliott [47] suggested that any snags located within 1.4 miles (2.4 km) of a hibernaculum should be retained, and recruitment of new snags in the same area should also be a priority to ensure that a continuous supply of new roost trees will be available. In addition, any areas that have been altered through agricultural, mining, logging, and other activities should be reforested with trees that are commonly used by Indiana bats for roosting [47].
Pesticides commonly used in agriculture in the past and present, such as organochlorines, organophosphates, carbamates, and pyrethroids, have all been found in the feces and tissues of bats. Since the ban on organochlorines, pyrethroids may be the biggest threat to bat health because they are likely to persist in the environment [71]. Pesticides inhibit cholinesterase and may cause cancer, birth defects, and death in bats. These conclusions are based on preliminary results and thus are largely speculative [80]. Organochlorines, especially DDE, a long-lived product of DDT, build up in bat tissues but are not always found at lethal levels [24]. Products of DDT are highly soluble in fat, so when bats build up fat for hibernation, they run the risk of taking so much that it can be fatal. Pesticide residues concentrate in the brain as other fat in the body is metabolized [24]. There is evidence of Indiana bat mortality due to organochlorines found in the Indiana bat [25,71]. Organochlorine residues still exist in the environment even though their use has been banned for decades. Pesticide residues originate in the bats' prey and build up in tissues, including brain tissues, over time [71]. Pesticide toxicity may have contributed to many mass die-offs that have occurred in the Indiana bat as well as other species around the world [24]. Restricting pesticide use, especially within the vicinity of hibernacula, may help reduce the negative impacts that they can have on Indiana bats and other bat species.
In the northern regions of its range, Indiana bat populations have remained stable or increased slightly since surveys were first conducted in 1960, especially in Indiana, New York, Ohio, and West Virginia. However, Indiana bat populations have decreased drastically in the southern portion of its range, especially in Kentucky, Missouri, Tennessee, and Arkansas [27,93]. What we have learned about their year-round habitat needs can give us direction on how land should be managed to ensure the survival of the Indiana bat.During hibernation, predators of Indiana bats may include black rat snakes (Elaphe obsoleta) [21,99] and northern raccoons (Procyon lotor) [66,83,99]. During other times of the year northern raccoons have been observed trying to grab bats from the air when they attempt to fly away [83]. Skunks (Mephitidae), Virginia opossums (Didelphis virginiana), and feral cats (Felis catus) may pose a similar threat [4,99]. If Indiana bats fly from their day roosts during the day, they may be susceptible to predation by hawks (Accipitridae) [83,99]. Indiana bats foraging at night may also be susceptible to predation by owls (Strigidae) [44,99]. While not a predator, woodpeckers (Picidae) may disturb roosting bats through their foraging activities by peeling away sections of bark being utilized by Indian bats, causing Indiana bats to fly from the roost during the day and making the tree unsuitable for future habitation [51,83]. It is possible that this disturbance could cause some indirect mortality of Indiana bats by destroying habitat and by causing nonvolant juveniles to fall to the ground or become exposed to predators.
The impact of natural predators on Indiana bats is minimal compared to the damage to habitat and mortality caused by humans, especially during hibernation. The presence of people in caves can cause Indiana bats to come out of hibernation, leading to a large increase in the energy used by the bats. By causing Indiana bats to wake up and use greater amounts of energy stores, humans can cause high mortality in a cave population of hibernating Indiana bats [86]. Human disturbance and the degradation of habitat are the primary causes for the decline of the Indiana bat [13].
Landscape: Habitat requirements for the Indiana bat are not completely understood. Bottomland and floodplain forests were once thought to be the most important habitats during the summer, but subsequent study has shown that upland forest habitats may be equally important, especially in the southern portions of the species's range [17,23,35]. Indiana bats are found in hardwood forests throughout most of their range [35,44,56] and mixed hardwood-pine forests in the southeastern United States [14,59]. Stone and Battle [85] found a significantly greater proportion (p<0.05) of old-growth forest (greater than 100 years), more hardwoods, and fewer conifers in stands occupied by Indiana bats than in random stands in Alabama.
In an Illinois study by Gardner and others [35], the study area where Indiana bats were found was estimated as approximately 67% agricultural land including cropland and old fields; 30% was upland forest; while 2.2% was floodplain forest. Finally, only 0.1% of the area was covered with water. Kurta and others [53] found that in southern Michigan, the general landscape occupied by Indiana bats consisted of open fields and agricultural lands (55%), wetlands and lowland forest (19%), other forested habitats (17%), developed areas (6%), and perennial water sources such as ponds and streams (3%). In southern Illinois, Carter and others [18] reported that all roosts were located in bottomland, swamp, and floodplain areas. Miller and others [64] determined the predominant habitat types near areas where Indiana bats were captured in Missouri were forest, crop fields, and grasslands. Indiana bats did not show any preference for early successional habitats, such as old fields, shrublands, and early successional forests, showing 71% to 75% of activity occurring in other habitats [34]. Although much of the landscape throughout the distributional range of the Indiana bat is dominated by agricultural lands and other open areas, these areas are typically not utilized by Indiana bats [44,67].
Indiana bats typically spend the winter months in caves or mines. However, a few bats have been found hibernating on a dam in northern Michigan [88]. Indiana bats need very specific conditions in order to survive the winter hibernation period, which lasts approximately 6 months. As the microclimate in a hibernaculum fluctuates throughout the winter, Indiana bats sometimes fly to different areas within the hibernaculum to find optimal conditions [28,40], but this does not appear necessary for every hibernaculum [39]. Indiana bats may even switch between nearby hibernacula in search of the most appropriate hibernating conditions [58]. Indiana bats are generally loyal to specific hibernacula or to the general area near hibernacula that they have occupied previously [58]. Critical winter habitats of Indiana bats have been designated by the U.S. Fish and Wildlife Service and include 13 hibernacula distributed across Illinois, Indiana, Kentucky, Missouri, Tennessee, and West Virginia [92].
Three types of hibernacula have been designated depending on the amount of use each receives from year to year. Priority One hibernacula are those that consistently have greater than 30,000 Indiana bats hibernating inside each winter. Priority Two hibernacula contain 500 to 30,000 bats, and Priority 3 hibernacula are any with fewer than 500 bats. At least 50% of Indiana bats are thought to hibernate in the 8 Priority One hibernacula, which can be found in Indiana (3 hibernacula), Missouri (3), and Kentucky (2). Estimates of hibernating populations in 2001 suggest that Priority One hibernacula have experienced a 48% decline since 1983. Overall, populations have fallen approximately 57% since 1960 across all hibernacula. Evidence suggests that Priority Two hibernacula are becoming more important to Indiana bat survival [27].
Site Characteristics: Studies have identified at least 29 tree species (see Plant Communities) used by Indiana bats during the summer and during spring and fall migrations. Since so many tree species are utilized as roosts, tree species is likely not a limiting habitat requirement. In addition to trees, Indiana bats have used a Pennsylvania church attic [16], a utility pole [85], and bat boxes [79] as roosts. However, use of man-made structures appears to be rare. Roost selection by females may be related to environmental factors, especially weather. Cool temperatures can slow fetal development [44,75], so choosing roosts with appropriate conditions is essential for reproductive success [93] and probably influences roost choice.
Two types of day roosts utilized by Indiana bats have been identified as primary and alternate roosts. Primary roosts typically support more than 30 bats at a time [64] and are used most often by a maternity colony. Trees that support smaller numbers of Indiana bats from the same maternity colony are designated as alternate roosts. In cases where smaller maternity colonies are present in an area, primary roosts may be defined as those used for more than 2 days at a time by each bat, while alternate roosts are generally used less than 2 consecutive days [14]. Maternity colonies may use up to 3 primary roosts and up to 33 alternate roosts [36,64] in a single season. Reproductively active females frequently switch roosts to find optimal roosting conditions. When switching between day roosts, Indiana bats may travel as little as 23 feet (7 m) or as far as 3.6 miles (5.8 km) [53,54,56]. In general, moves are relatively short and typically less than 0.6 mile (1 km) [102].
Primary roosts are most often found at forest edges or in canopy gaps [17,64]. Alternate roosts are generally located in a shaded portion of the interior forest and occasionally at the forest edge [17]. Most roost trees in a Kentucky study occurred in canopy gaps in oak, oak-hickory, oak-pine, and oak-poplar community types [47]. Roosts found by Kurta and others [53] in a elm-ash-maple forest in Michigan were in a woodland/marsh edge, a lowland hardwood forest, small wetlands, a shrub wetland/cornfield edge, and a small woodlot. Around hibernacula in autumn, Indiana bats tended to choose roost trees on upper slopes and ridges that were exposed to direct sunlight throughout the day [47].
The preferred amount of canopy cover at the roost is unclear. Many studies have reported the need for low cover, while others have documented use of trees with moderate to high canopy cover, occasionally up to complete canopy closure. Canopy cover ranges from 0% at the forest edge to 100% in the interior of the stand [17,35,59]. A general trend is that primary roosts are found in low cover, while alternate roosts tend to be more shaded. Few data directly compare the differences between roost types. In Alabama, canopy cover at the roost tended to be low at an average of 35.5%, but at the stand level, canopy cover was higher with a mean of 65.8% [85]. In a habitat suitability model, Romme and others [78] recommended the ideal canopy cover for roosting Indiana bats as 60% to 80%. Actual roost sites in eastern Tennessee were very high in the tree, and Indiana bats were able to exit the roost above the surrounding canopy. Thus, canopy cover measurements taken from the bases of roost trees may overestimate the actual amount of cover required by roosting Indiana bats [14].
A great deal of difference exists between stands occupied by Indiana bats. A Virginia pine roost was in a stand with a density of only 367 trees/ha [41] while in Kentucky, a shagbark hickory roost was in a closed canopy stand with 1,210 trees/ha [47]. Overall tree density in Great Smoky Mountain National Park was higher around primary roosts than at alternate roosts [14]. At the landscape level, the basal area for stands with roosts was 30% lower than basal area of random stands in Alabama [85]. Tree density in southern Iowa varied between different habitats. In a forested floodplain, tree density was lowest at 229 trees/ha, while a riparian strip had the highest tree density at 493 trees/ha [23].
The number of roosts used and home range occupied by a maternity colony can vary widely. In Missouri, Callahan and others [17] found that the highest density of roosts being used in a oak-hickory stand was 0.25 tree/ha. In Michigan, the number of trees utilized by a colony was 4.6 trees/ha, with as many as 13.2 potential roosts/ha in the green ash-silver maple stand [56]. Clark and others [23] estimated that the density of potential roosts in southern Iowa in areas where Indiana bats were caught was 10 to 26/ha in riparian, floodplain, and upland areas dominated by eastern cottonwood-silver maple, oak-hickory, and black walnut-silver maple-American elm, respectively. In Illinois, the suggested optimal number of potential roost trees in an upland oak-hickory habitat was 64/ha; the optimal number for riparian and floodplain forest, dominated by silver maple and eastern cottonwood, was proposed to be 41/ha [35]. Salyers and others [79] suggested a potential roost density of 15 trees/ha was needed, or 30 roosts/ha if artificial roost boxes are erected in a stand with American elm and shagbark hickory. The roosting home range used by any single Indiana bat was as large as 568 hectares in a oak-pine community in Kentucky [59]. Roosts of 2 maternity colonies in southern Illinois were located in roosting areas estimated at 11.72 hectares and 146.5 hectares and included green ash, American elm, silver maple, pin oak, and shagbark hickory [18]. The extent of the maternity home range may depend on the availability of suitable roosts in the area [94].
Most habitat attributes measured for the Indiana bat were insignificant as well as inconsistent from one location to another. In Missouri, oak-hickory stands with maternity colonies had significantly (p=0.01) more medium trees (12-22 inches (30-57 cm) dbh) and significantly (p=0.01) more large sized trees (>22 inches (57 cm) dbh) than areas where Indiana bats were not found. No other major landscape differences were detected [64].
Distances seen between roosts and other habitat features may be influenced by the age, sex, and reproductive condition of the Indiana bats. Distances between roosts and paved roads is greater than the distances between roosts and unpaved roads in some locales, although overlap between the two situations has been documented. In Illinois, most roosts used by adult females and juveniles were about 2,300 feet (700 m) or more from a paved highway, while adult males roosted less than 790 feet (240 m) from the road [35,36]. In Michigan, roosts were only slightly closer to paved roads: 2,000 feet (600 m) on average for all roosts located [51]. In general, roosts were located 1,600 feet (500 m) to 2,600 feet (800 m) from unpaved roads in Illinois and Michigan [36,51]. Roost trees used during autumn in Kentucky were very close to unpaved roads at an average of 160 feet (50 m) [47].
Roost proximity to water is highly variable and therefore probably not as important as once thought. In Indiana, roost trees were discovered less than 660 feet (200 m) from a creek [44], while roosts in another part of Indiana were 1.2 miles (2 km) from the nearest permanent water source [36,51]. To the other extreme, roosts of a maternity colony from Michigan were all found in a 12-acre (5 ha) wetland that was inundated for most of the year [51]. In Virginia, foraging areas near a stream were utilized [41]. Intermittent streams may be located closer to roosts than more permanent sources of water [35,51]. Ponds, streams, and road ruts appear to be important water sources, especially in upland habitats [60].
Foraging habitat: Studies on the foraging needs for Indiana bats are inconclusive. Callahan and others [17] reported that bats foraged in a landscape composed of pasture, corn fields, woodlots, and a strip of riparian woodland, although Indiana bat activity was not necessarily recorded in all these habitat types. Murray and Kurta [67] made some qualitative assessments of Indiana bat foraging habitat in Michigan: the majority of bats were found foraging in forested wetlands and other woodlands, while 1 bat foraged in an area around a small lake and another in an area with 50% woodland and 50% open fields. Another Indiana bat foraged over a river, while 10 others foraged in areas greater than 0.6 mile (1 km) from the same river [67]. Bat activity was centered around small canopy gaps or closed forest canopy along small 2nd-order streams in West Virginia [33]. Indiana bats foraged under the dense oak-hickory forest canopy along ridges and hillsides in eastern Missouri, but rarely over streams [57]. Indiana bats have been detected foraging in upland forest [11,23,47,93] in addition to riparian areas such as floodplain forest edges [11,23,44,55,69,72,93]. Romme and others [78] also suggested that foraging habitat would ideally have 50% to 70% canopy closure. Indiana bats rarely utilize open agricultural fields and pastures, upland hedgerows, open water, and deforested creeks for traveling or foraging [36,44,67]. Boyles and others [9] concluded that most activity occurred under the canopy as opposed to above the canopy.
Hibernacula: During hibernation, Indiana bats occupy open areas of hibernacula ceilings and generally avoid crevices and other enclosed areas [76]. Indiana bats were associated with hibernacula that were long (x=2,817 feet (858 m)), had high ceilings (x=15 feet (4.5 m)), and had large entrances (x=104.4 feet² (9.7 m²)). The preferred hibernacula often had multiple entrances promoting airflow. Hibernacula choice may be influenced by the ability of the outside landscape to provide adequate forage upon arrival at the hibernacula as well as the specific microclimate inside. Having forested areas around the hibernacula entrance and low amounts of open farmland may be important factors influencing the suitability of hibernacula [76]. This is the only comprehensive habitat assessment of Indiana bat hibernacula known to date (2005).
Indiana bats begin to arrive at hibernacula (caves and mines in which they spend the winter) from their summer roosting sites in late August, with most returning in September [2]. Females enter hibernation shortly after arriving at hibernacula, but males remain active until late autumn to breed with females arriving late. Most Indiana bats hibernate from October through April, but many at the northern extent of their range hibernate from September to May. Occasionally, Indiana bats are found hibernating singly, but almost all are found hibernating in dense clusters of 3,230 bats/m² to 5,215 bats/m² [93].
Spring migration can begin as early as late March, but most Indiana bats do not leave their winter hibernacula until late April to early May [2]. Females emerge from hibernacula first, usually between late March and early May. Most males do not begin to emerge until mid- to late April [58,93]. Females arrive at summer locations beginning in mid-April. Females form summer nursery colonies of up to 100 adult females during summer [47,93]. Males typically roost alone or in small bachelor groups during the summer. Many males spend the summer near their winter hibernacula, while others migrate to other areas, similar to areas used by females [93].
Females can mate during their 1st fall, but some do not breed until their 2nd year [81,93]. Males become reproductively active during their 2nd year [93]. Breeding occurs in and around hibernacula in fall [29,93]. During the breeding season, Indiana bats undergo a phenomenon known as swarming. During this activity, large numbers of bats fly in and out of caves from sunset to sunrise [93]. Swarming mainly occurs during August to September [29] and is thought to be an integral part of mating [93]. Bats have been observed copulating in caves until early October [2]. During the swarming/breeding period, very few bats are found roosting within the hibernacula during the day [29]. Limited mating may also occur at the end of hibernation [93].
Fertilization does not occur until the end of hibernation [81,87,93], and gestation takes approximately 60 days [4]. Parturition occurs in late May to early July [81,93]. Female Indiana bats typically give birth to 1 pup [81,87,93]. Juveniles are weaned after 25 to 37 days [44] and become volant (able to fly) at about the same time [93]. Most young can fly by early to late July [44,62], but sometimes do not fly until early August [81]. Humphrey and others [44] reported an 8% mortality rate by the time young were weaned. However, they assumed that all females mate in the autumn [81], which is not the case, so not all the females would give birth. Thus, mortality of young may be even lower than 8%.
Indiana bats are relatively long lived. One Indiana bat was captured 20 years after being banded as an adult [58]. Data from other recaptured individuals show that females live at least 14 years 9 months [43], while males may live for at least 13 years 10 months [73].
Endangered [96]
The Indiana bat was one of the 1st species in the United States that was listed as endangered and has been protected by law since March 11, 1967 [96].
El ratpenat d'Indiana (Myotis sodalis) és una espècie de mamífer pertanyent a la família dels vespertiliònids.[2] Es troba a Nord-amèrica: des de l'est d'Oklahoma[3] i Iowa[4] fins a Michigan,[5][6][7] Nova York, Nova Anglaterra, el nord de Nova Jersey, el nord d'Alabama i Arkansas. Antigament, també n'hi havia una població al nord-oest de Florida.[8]
Fa 41-49 mm de llargària total. Té una envergadura de 240-267 mm, pesa 5-11 g. Té el pelatge fi i esponjós de color gris castany, amb una porció basal negra al dors i menys brillant que el d'altres ratpenats similars (com ara, Myotis lucifugus). Les parts inferiors són de color canyella. El nas és rosa clar. Té les Potes petites amb pèls curts i escassos que no s'estenen més enllà dels dits dels peus. Les orelles i les membranes alars tenen una aparença opaca. No presenta dimorfisme sexual.[9][10][11]
Empra l'ecolocalització i la vista per orientar-se mentre vola. A més, té una oïda excel·lent i es comuniquen entre ells utilitzen el so.[12]
Menja coleòpters, papallones nocturnes i d'altres insectes voladors.[11] Pot consumir fins a la meitat del seu pes corporal en insectes cada nit i, per tant, el seu paper en el control de les poblacions d'insectes és molt significativa. A més, té un paper essencial en els ecosistemes de les coves, ja que hi porta nutrients en forma de guano que altres formes de vida aprofiten.[13][14] Per a hibernar, prefereix coves de pedra calcària amb temperatures estables. A l'estiu, els boscos de ribera són els seus indrets preferits per a alimentar-se i dormir.[11][15] S'aparella a la tardor i les femelles emmagatzemen l'esperma durant tota la hibernació per esdevindre prenyades a finals del març o principis de l'abril. La gestació dura de 60 dies i té una sola cria a finals del juny o principis del juliol, la qual serà capaç de volar al cap d'un mes.[11][16] Les poblacions septentrionals migren cap a Alabama, Tennessee, Kentucky, Indiana, Missouri i Virgínia Occidental quan arriba l'hivern. Hom creu que la meitat de la població total d'aquesta espècie hiberna al sud d'Indiana.[8] A l'estiu, la femella ocupa un territori de, si fa no fa, 52 hectàrees. Una vegada ha tingut la seva cria, l'amplia fins a les 232.[17] Pot arribar a viure fins als 14 anys en estat salvatge.[18] Igual que tots els ratpenats, es considera un reservori potencial de malalties com la ràbia i la histoplasmosi.[12]
Ha desaparegut de la major part de la seva distribució històrica del nord-est dels Estats Units per diversos factors: l'activitat humana (incloent-hi el turisme i les estructures construïdes a les entrades de les coves per restringir-hi l'accés humà, ja que obstaculitzen el moviment dels ratpenats i els fluxos d'aire, les temperatures i els nivells d'humitat de l'interior), els desastres naturals, la caça furtiva, la pèrdua del seu hàbitat forestal i els plaguicides.[19][11]
El ratpenat d'Indiana (Myotis sodalis) és una espècie de mamífer pertanyent a la família dels vespertiliònids. Es troba a Nord-amèrica: des de l'est d'Oklahoma i Iowa fins a Michigan, Nova York, Nova Anglaterra, el nord de Nova Jersey, el nord d'Alabama i Arkansas. Antigament, també n'hi havia una població al nord-oest de Florida.
Das Indiana-Mausohr (Myotis sodalis) oder auch Indiana-Fledermaus ist eine Fledermausart aus der Familie der Glattnasen (Vespertilionidae), welche in Nordamerika beheimatet ist. Sie ist nach ihrem Hauptverbreitungsgebiet benannt. Der Artname sodalis ist lateinisch und bedeutet „kameradschaftlich“, was sich auf die großen Gruppengrößen bezieht, in welchen die Tiere anzutreffen sind.
Das Indiana-Mausohr ist eine kleine Fledermaus mit einer Unterarmlänge von 36 bis 40,6 mm und einer Flügelspannweite von 240 bis 267 mm. Die Weibchen sind mit einem Gewicht von 7,5 g etwas größer als die Männchen mit 7,1 g (Sexualdimorphismus). Der kurze stumpfe Tragus reicht nicht ganz bis zur Mitte der Ohrmuschel. Die Schwanzflughaut ist bist zu den Knien behaart. Der Calcar ist lang und geschwungen, die Füße sind etwas mehr als halb so lang wie die Tibia. Das Fell ist flauschig und von einem stumpfen grau-braun.
Das Indiana-Mausohr wird häufig mit der Kleinen Braunen Fledermaus (Myotis lucifugus) verwechselt, unterscheidet sich von dieser aber durch die borstenähnlichen Haare an den Zehen, dem geschwungenen Calcar und dem kleineren Fuß (9 statt 10 mm).
Das Indiana-Mausohr ist wie die meisten Fledermäuse nachtaktiv und ernährt sich von Insekten, wobei Nachtfalter und andere Insekten mit weichen Körpern bevorzugt werden. Auf Futtersuchflügen erreichen sie eine Fluggeschwindigkeit von über 20 km/h. Die dabei ausgestoßenen Echoortungsrufe bewegen sich zwischen 96 und 40 kHz und sind somit für das menschliche Ohr nicht wahrnehmbar. Das Indiana-Mausohr ist eine der am häufigsten im Zusammenhang mit Winterschlaf studierten Fledermausarten. Während des Winterschlafs werden in der Milz rote Blutzellen gespeichert, welches zu einer 5-fachen Vergrößerung des Organs und einer 41%igen Abnahme von roten Blutzellen im Blut führt. Während des Erwachens werden die Blutzellen von der Milz abgegeben, was wahrscheinlich dazu dient, mehr Sauerstoff während der Aufwachphase zu transportieren, und das Aufwachen somit zu beschleunigen. Im September, kurz vor dem Winterschlaf, nehmen die Tiere zu 50 % an Körper- und Fettmasse zu, welche kontinuierlich während des Winterschlafs abgebaut wird.
Die Körpertemperatur des Indiana-Mausohrs liegt immer 1–1,5 °C über der Umgebungstemperatur. Fällt die Umgebungstemperatur außerhalb der Winterschlafphase auf unter null Grad, so geht die Fledermaus in Torpor und hält eine Körpertemperatur über dem Gefrierpunkt durch zittern der Muskeln aufrecht. Temperaturen über 35 °C werden nur schlecht toleriert und können für die Tiere tödlich enden. Den Schlafplatz teilt sich das Indiana-Mausohr mit anderen Fledermausarten wie der Kleinen (M. lucifugus) und Großen Braunen Fledermaus (Eptesicus fuscus), M. septentrionalis, M. grisens, M. austrioriparius und Pipistrellus subflavus.
Während des Winterschlafs werden Höhlen aus Sandstein mit Teichen bevorzugt. Das Indiana-Mausohr bildet Gruppen, die an den glatten Decken oder Wänden der Höhle hängen. Dabei bevorzugt Myotis sodalis eine Umgebungstemperatur von 2 bis 5 °C, einer relativen Luftfeuchtigkeit von durchschnittlich 87 % und gelegentlich guter Belüftung. Alle 8–10 Tage wachen die Tiere auf, so dass es in der Gruppe immer Tiere gibt, die gerade nicht schlafen. Die Winterschlafhöhle wird im April oder frühen Juni verlassen, wobei die Weibchen früher abziehen als die Männchen. Danach wandern die Tiere bis zu 480 km weit in ihre Sommergebiete. Somit gehört das Indiana-Mausohr zu jenen Fledermäusen, die migrieren.
Die älteste je gefundene Fledermaus dieser Art war über 20 Jahre alt. Zu den bekannten Fressfeinden gehört der Mink, Schlangen wie die Erdnatter und Eulen wie die Ost-Kreischeule.
Die Paarung des Indiana-Mausohrs findet zwischen September und Oktober statt. Die Weibchen lagern die Spermien durch den Winter hindurch ein; der Eisprung und die anschließende Befruchtung der Eizelle erfolgt nach dem Winterschlaf im Frühling. Im Sommer trennen sich die Weibchen von den Männchen und bilden Mutterkolonien von selten mehr als 100 Tieren, in denen sie ihre Jungen gebären und säugen, bis diese nach 25–37 Tagen selbständig sind. Die Weibchen gebären dabei pro Jahr jeweils ein einziges Jungtier. Mutterkolonien findet man meist unter loser Baumrinde und in hohlen Baumstämmen, jedoch nicht in Höhlen. Nachdem die Jungen selbständig fliegen können, begleiten sie ihre Mutter in Tandems auf Futtersuchflügen.
Der Bestand des Indiana-Mausohrs wird von der IUCN wegen ihres kleinen Verbreitungsgebiets als stark gefährdet („endangered“) eingestuft[1]. Grund dafür ist ein Rückgang der Population um 50 % innerhalb der letzten 10 Jahre. Bereits nach dem Endangered Species Act des US-Kongresses 1973 wurden zahlreiche Maßnahmen ergriffen, um die Art zu schützen. Zuvor gingen die Populationen aufgrund von Naturkatastrophen, Störungen durch den Menschen und verändertes Klima in den Höhlen zurück. So nahm die Anzahl an Tieren innerhalb von 15 Jahren um 28 % ab. 1978 überwinterten 87 % der Gesamtpopulation in der Höhle der Bat Cave and Cascade Caverns State Nature Preserves im Carter County (Kentucky), in einer einzigen Höhle in Indiana. Diese und andere wichtige Überwinterungshöhlen stehen unter Schutz. Nebst der Gefährdung der Winterschlafplätze ist der Schutz von des Indiana-Mausohrs schwierig, da kaum bekannt ist, wo die Tiere den Sommer verbringen. Weibchen findet man meist in Mutterkolonien unter loser Baumrinde, jedoch ist über die Ökologie der Männchen praktisch nichts bekannt.
Zu den wichtigsten Gefährdungen gehört die Störung durch den Menschen. Wenn Fledermäuse ungewollt aus dem Winterschlaf aufwachen, verbrauchen sie kostbare Energiereserven. Dies ist vor allem in kommerziell genutzten Höhlen ein Problem. Hinzu kommt die absichtliche Tötung der Tiere durch private Höhlenbesitzer, die Veränderung des Klimas im Innern der Höhle durch das Öffnen zusätzlicher Eingänge, und die unsachgemäße Versperrung der Höhleneingänge. Weiterhin gehört Myotis sodalis zu jenen Fledermausarten, die durch das White-Nose-Syndrom stark gefährdet sind.
Das Indiana-Mausohr kommt in den Vereinigten Staaten in Westen von Kansas bis an die Ostküste, sowie im Norden von Michigan bis im Süden nach Alabama vor.
Das Indiana-Mausohr (Myotis sodalis) oder auch Indiana-Fledermaus ist eine Fledermausart aus der Familie der Glattnasen (Vespertilionidae), welche in Nordamerika beheimatet ist. Sie ist nach ihrem Hauptverbreitungsgebiet benannt. Der Artname sodalis ist lateinisch und bedeutet „kameradschaftlich“, was sich auf die großen Gruppengrößen bezieht, in welchen die Tiere anzutreffen sind.
The Indiana bat (Myotis sodalis) is a medium-sized mouse-eared bat native to North America. It lives primarily in Southern and Midwestern U.S. states and is listed as an endangered species. The Indiana bat is grey, black, or chestnut in color and is 1.2–2.0 in long and weighs 4.5–9.5 g (0.16–0.34 oz). It is similar in appearance to the more common little brown bat, but is distinguished by its feet size, toe hair length, pink lips, and a keel on the calcar.
Indiana bats live in hardwood and hardwood-pine forests. It is common in old-growth forest and in agricultural land, mainly in forest, crop fields, and grasslands. As an insectivore, the bat eats both terrestrial and aquatic flying insects, such as moths, beetles, mosquitoes, and midges.
The Indiana bat is listed as an endangered species by the U.S. Fish and Wildlife Service.[2][3] It has had serious population decline, estimated to be more than 50% over the past 10 years, based on direct observation and a decline on its extent of occurrence.[1]
The length of the Indiana bat's head to the body is from 4.1 to 4.9 cm. The animal weighs about 8 g (.25 ounce). These bats are very difficult to distinguish from other species, especially the more common little brown bat (Myotis lucifugus), unless examined closely. The size of the feet, the length of the toe hairs, and the presence of a keel on the calcar are characteristics used to differentiate the Indiana bat from other bats. Indiana bats typically live 5 to 9 years, but some have reached 12 years of age. They can have fur from black to chestnut with a light gray to cinnamon belly. Unlike other common bats with brown hair and black lips, Indiana bats have brown hair and pink lips, which is helpful for identification.
Indiana bats spend the summer living throughout the eastern United States. During winter, however, they cluster together and hibernate in only a few caves. Since about 1975, their population has declined by about 50%. Based on a 1985 census of hibernating bats, the Indiana bat population is estimated around 244,000. About 23% of these bats hibernate in caves in Indiana. The Indiana bat lives in caves only in winter; but, there are few caves that provide the conditions necessary for hibernation. Stable, low temperatures are required to allow the bats to reduce their metabolic rates and conserve fat reserves. These bats hibernate in large, tight clusters which may contain thousands of individuals. Indiana bats feed entirely on night flying insects, and a colony of bats can consume millions of insects each night. The range of the Indiana bat overlaps with that of the more narrowly distributed gray bat (Myotis grisescens), also listed as endangered.
The Indiana bat was listed as federally endangered under the Endangered Species Preservation Act, on 11 March 1967, due to the dramatic decline of populations throughout their range. Reasons for the bat's decline include disturbance of colonies by human beings, pesticide use and loss of summer habitat resulting from the clearing of forest cover. As of 1973, the Indiana bat has been listed as endangered under the Endangered Species Act (as amended), and additionally protected by the Federal Cave Resources Protection Act of 1988, to protect hibernacula on federal lands. In 2013, Bat Conservation International listed this species as one of the 35 species of its worldwide priority list of conservation.[4]
Indiana bat populations in the northeastern United States are crashing with the rapid spread of white-nose syndrome, the most devastating wildlife disease in recent history. By the end of 2011, this unprecedented threat had killed 5.7 to 6.7 million bats in the United States since its discovery in 2007 based on photographs taken in 2006.[5] Among these, at least 15,662 Indiana bats died from WNS in 2008 alone (3.3% of the 2007 range wide population), and an estimated 95% of Pennsylvania's entire cave bat population has died.[6][7]
Although becoming less common, direct and intentional killings by humans have occurred. On 23 October 2007, Lonnie W. Skaggs of Olive Hill, Kentucky, and Kaleb Dee Carpenter, of Grayson, Kentucky, entered Laurel Cave in Carter Caves State Park, Kentucky, and killed 23 Indiana bats. Skaggs re-entered the cave three days later and killed another 82 endangered Indiana bats. An investigation began when Carter Caves State Park employees discovered at least 105 dead Indiana bats. The two men admitted to knowingly slaughtering an endangered species, using flashlights and rocks to knock hibernating bats off their roosts, and smashing their bodies with rocks. Bats that attempted to escape by flying away were knocked down from the air. The men stomped bats to death, bludgeoned them with flashlights, and crushed their bodies with rocks in several areas of the hibernaculum. BCI worked with the Kentucky Department of Fish & Wildlife Resources to establish a reward fund and provided the initial contribution. The reward quickly grew to $5,000 with support from the Southeastern Bat Diversity Network and Defenders of Wildlife and was widely reported, and the two men were caught following an anonymous tip. This incident was called a "senseless killing" by James Gale, Special Agent-in-Charge for the USFWS Southeast Region, and resulted in conviction. They pleaded guilty to violating the federal Endangered Species Act. U.S. Magistrate Judge Edward Atkins sentenced Skaggs to eight months in federal prison, and placed Carpenter on three years' probation. The case marks the first time nationwide that individuals were sentenced for killing endangered Indiana bats. BCI thanked members and donors for allowing them to help protect these bats and work toward a time when such killings finally cease.[8][9]
Additionally, Indiana bat mortality due to wind turbines has been confirmed, even resulting in a December 2009 injunction against a West Virginia wind farm.[10] As of 2013, only five Indiana bat mortalities have been documented; two females at Fowler Ridge in Indiana in September 2009 and 2010, one female at the North Allegheny Wind Energy Facility, Pennsylvania, in September 2011,[11] one male at the Laurel Mountain Wind Power facility, West Virginia in July 2012, and one female at the Blue Creek Wind Farm, Ohio in October 2012.[12] Fatality rates of up to 63.9 bats per turbine, per year have been estimated.[13] Mortality is caused both by direct impact with rotors and by barotrauma.[14]
Other anthropogenic effects have contributed to the loss of Indiana bat populations, including pesticide use, human disturbance of hibernacula, improper application of cave gates, climate change, and agricultural development. As a result, the Indiana bat experienced a nationwide 57% population decline from 1960 to 2001.[15]
Common dominant trees used by Indiana bats throughout their range include oaks (Quercus spp.), hickories (Carya spp.), ashes (Fraxinus spp.), elms (Ulmus spp.), eastern cottonwoods (Populus deltoides), locusts (Robinia spp.), and maples (Acer spp.). The understory may include hawthorns (Crataegus spp.), dogwoods (Cornus spp.), fragrant sumac (Rhus aromatica), giant ragweed (Ambrosia trifida), sedges (Carex spp.), Virginia creeper (Parthenocissus quinquefolia), wood nettle (Laportea canadensis), goldenrod (Solidago spp.), poison ivy (Toxicodendron radicans), and wild grape (Vitis spp.).[16]
Indiana bats were found in a variety of plant associations in a southern Iowa study. Riparian areas were dominated by eastern cottonwood, hackberry (Celtis occidentalis), and silver maple (Acer saccharinum). In the forested floodplains, the dominant plants included black walnut (Juglans nigra), silver maple, American elm (Ulmus americana), and eastern cottonwood. In undisturbed upland forest, the most common plants were black oak (Quercus velutina), bur oak (Q. macrocarpa), shagbark hickory (Carya ovata), and bitternut hickory (C. cordiformis). Black walnut, American basswood, American elm, and bur oak dominated other upland Indiana bat sites.[17]
Indiana bats use at least 29 tree species during the summer. The greatest numbers of tree species are found in the central portion of Indiana bats' range (primarily Missouri, southern Illinois, southern Indiana, and Kentucky), but this is likely because the majority of research conducted on the species has occurred in this region. Roost trees from these central states, which are mainly in the oak-hickory cover type, include silver maple, red maple (Acer rubrum), sugar maple (A. saccharum), white oak (Q. alba), red oak (Q. rubra), pin oak (Q. palustris), scarlet oak (Q. coccinea), post oak (Q. stellata), shingle oak (Q. imbricaria), eastern cottonwood, shagbark hickory, bitternut hickory, mockernut hickory (C. alba), pignut hickory (C. glabra), American elm, slippery elm (Ulmus rubra), honey locust (Gleditsia triacanthos), sourwood (Oxydendrum arboreum), green ash (Fraxinus pennsylvanica), white ash (F. americana), Virginia pine (Pinus virginiana), American sycamore (Platanus occidentalis), and sassafras (Sassafras albidum).[16][18][19][20][21][22][23][24]
In southern Michigan and northern Indiana, which are mainly in the oak-hickory and elm-ash-cottonwood cover types, trees used as roosts include green, white, and black ash (Fraxinus nigra), silver maple, shagbark hickory, and American elm.[25] And finally, in the southern areas of the Indiana bat's range (primarily Tennessee, Arkansas, and northern Alabama), which include the oak-hickory and oak-pine cover types, Indiana bats use shagbark hickory, white oak, red oak, pitch pine (P. rigida), shortleaf pine (P. echinata), loblolly pine (P. taeda), sweet birch (Betula lenta), and eastern hemlock (Tsuga canadensis).[26][27]
Indiana bats begin to arrive at hibernacula (caves and mines in which they spend the winter) from their summer roosting sites in late August, with most returning in September. Females enter hibernation shortly after arriving at hibernacula, but males remain active until late autumn to breed with females arriving late. Most Indiana bats hibernate from October through April, but many at the northern extent of their range hibernate from September to May. Occasionally, Indiana bats are found hibernating singly, but almost all are found hibernating in dense clusters of 3,230 to 5,215 bats/m2.[28]
Spring migration can begin as early as late March, but most Indiana bats do not leave their winter hibernacula until late April to early May. Females emerge from hibernacula first, usually between late March and early May. Most males do not begin to emerge until mid- to late April.[28][29] Females arrive at summer locations beginning in mid-April. Females form summer nursery colonies of up to 100 adult females during summer.[23][28] Males typically roost alone or in small bachelor groups during the summer. Many males spend the summer near their winter hibernacula, while others migrate to other areas, similar to areas used by females.[28]
Females can mate during their first fall, but some do not breed until their second year.[28][30] Males become reproductively active during their second year.[28] Breeding occurs in and around hibernacula in fall.[28] During the breeding season, Indiana bats undergo a phenomenon known as swarming. During this activity, large numbers of bats fly in and out of caves from sunset to sunrise.[28] Swarming mainly occurs during August to September and is thought to be an integral part of mating.[28] Bats have been observed copulating in caves until early October. During the swarming/breeding period, very few bats are found roosting within the hibernacula during the day. Limited mating may also occur at the end of hibernation.[28]
Fertilization does not occur until the end of hibernation,[28][30] and gestation takes about 60 days. Parturition occurs in late May to early July.[28][30] Female Indiana bats typically give birth to one pup.[28][30] Juveniles are weaned after 25 to 37 days [22] and are able to fly around the same time.[28] Most young can fly by early to late July,[22] but sometimes do not fly until early August.[30] Humphrey and others [22] reported an 8% mortality rate by the time young were weaned. However, they assumed that all females mate in the autumn,[30] which is not the case, so not all the females would give birth. Thus, mortality of young may be even lower than 8%.
Indiana bats are relatively long lived. One Indiana bat was captured 20 years after being banded as an adult.[29] Data from other recaptured individuals show that females live at least 14 years 9 months, while males may live for at least 13 years 10 months.[31]
Habitat requirements for the Indiana bat are not completely understood. Bottomland and floodplain forests were once thought to be the most important habitats during the summer, but subsequent study has shown that upland forest habitats may be equally important, especially in the southern portions of the species's range.[16][17][18] Indiana bats are found in hardwood forests throughout most of their range [16][22] and mixed hardwood-pine forests in the southeastern United States.[24][26] Stone and Battle [27] found a significantly greater proportion (p<0.05) of old-growth forest (greater than 100 years), more hardwoods, and fewer conifers in stands occupied by Indiana bats than in random stands in Alabama.
In an Illinois study by Gardner and others,[16] the study area where Indiana bats were found was estimated as roughly 67% agricultural land including cropland and old fields; 30% was upland forest; while 2.2% was floodplain forest. Finally, only 0.1% of the area was covered with water. Kurta and others [32] found that in southern Michigan, the general landscape occupied by Indiana bats consisted of open fields and agricultural lands (55%), wetlands and lowland forest (19%), other forested habitats (17%), developed areas (6%), and perennial water sources such as ponds and streams (3%).
In southern Illinois, Carter and others [19] reported that all roosts were located in bottomland, swamp, and floodplain areas. Miller and others [33] determined the predominant habitat types near areas where Indiana bats were captured in Missouri were forest, crop fields, and grasslands. Indiana bats did not show any preference for early successional habitats, such as old fields, shrublands, and early successional forests, showing 71% to 75% of activity occurring in other habitats. Although much of the landscape throughout the distributional range of the Indiana bat is dominated by agricultural lands and other open areas, these areas are typically not used by Indiana bats.[22][34]
Indiana bats typically spend the winter in caves or mines. However, a few bats have been found hibernating on a dam in northern Michigan. They need very specific conditions to survive the winter hibernation period, which lasts about 6 months. As the microclimate in a hibernaculum fluctuates throughout the winter, Indiana bats sometimes fly to different areas within the hibernaculum to find optimal conditions,[35] but this does not appear necessary for every hibernaculum. Indiana bats may even switch between nearby hibernacula in search of the most appropriate hibernating conditions.[29] Indiana bats are generally loyal to specific hibernacula or to the general area near hibernacula that they have occupied previously.[29] Critical winter habitats of Indiana bats have been designated by the U.S. Fish and Wildlife Service and include 13 hibernacula distributed across Illinois, Indiana, Kentucky, Missouri, Tennessee, and West Virginia.[36]
Three types of hibernacula have been designated depending on the amount of use each receives from year to year. Priority one hibernacula are those that consistently have greater than 30,000 Indiana bats hibernating inside each winter. Priority two hibernacula contain 500 to 30,000 bats, and priority three hibernacula are any with fewer than 500 bats. At least 50% of Indiana bats are thought to hibernate in the eight priority one hibernacula, which can be found in Indiana (three), Missouri (three), and Kentucky (two). Estimates of hibernating populations in 2001 suggest that priority one hibernacula have experienced a 48% decline since 1983. Overall, populations have fallen around 57% since 1960 across all hibernacula.[15]
Studies have identified at least 29 tree species used by Indiana bats during the summer and during spring and fall migrations. Since so many tree species are used as roosts, tree species is likely not a limiting habitat requirement. In addition to trees, Indiana bats have used a Pennsylvania church attic, a utility pole,[27] and bat boxes [37] as roosts. However, use of man-made structures appears to be rare. Roost selection by females may be related to environmental factors, especially weather. Cool temperatures can slow fetal development,[22] so choosing roosts with appropriate conditions is essential for reproductive success [28] and probably influences roost choice.
Two types of day roosts used by Indiana bats have been identified as primary and alternate roosts. Primary roosts typically support more than 30 bats at a time[33] and are used most often by a maternity colony. Trees that support smaller numbers of Indiana bats from the same maternity colony are designated as alternate roosts. In cases where smaller maternity colonies are present in an area, primary roosts may be defined as those used for more than 2 days at a time by each bat, while alternate roosts are generally used 1 day.[26] Maternity colonies may use up to three primary roosts and up to 33 alternate roosts [20][33] in a single season. Reproductively active females frequently switch roosts to find optimal roosting conditions. When switching between day roosts, Indiana bats may travel as little as 23 feet (7.0 m) or as far as 3.6 miles (5.8 km).[32] In general, moves are relatively short and typically less than 0.6 miles (0.97 km).[38]
Primary roosts are most often found at forest edges or in canopy gaps.[18][33] Alternate roosts are generally located in a shaded portion of the interior forest and occasionally at the forest edge.[18] Most roost trees in a Kentucky study occurred in canopy gaps in oak, oak-hickory, oak-pine, and oak-poplar community types.[23] Roosts found by Kurta and others [32] in an elm-ash-maple forest in Michigan were in a woodland/marsh edge, a lowland hardwood forest, small wetlands, a shrub wetland/cornfield edge, and a small woodlot. Around hibernacula in autumn, Indiana bats tended to choose roost trees on upper slopes and ridges that were exposed to direct sunlight throughout the day.[23]
The preferred amount of canopy cover at the roost is unclear. Many studies have reported the need for low cover, while others have documented use of trees with moderate to high canopy cover, occasionally up to complete canopy closure. Canopy cover ranges from 0% at the forest edge to 100% in the interior of the stand.[16][18][24] A general trend is that primary roosts are found in low cover, while alternate roosts tend to be more shaded. Few data directly compare the differences between roost types. In Alabama, canopy cover at the roost tended to be low at an average of 35.5%, but at the stand level, canopy cover was higher with a mean of 65.8%.[27] In a habitat suitability model, Romme and others [39] recommended the ideal canopy cover for roosting Indiana bats as 60% to 80%. Actual roost sites in eastern Tennessee were very high in the tree, and Indiana bats were able to exit the roost above the surrounding canopy. Thus, canopy cover measurements taken from the bases of roost trees may overestimate the actual amount of cover required by roosting Indiana bats.[26]
Stands occupied by this species can vary greatly. A Virginia pine roost was in a stand with a density of only 367 trees/ha,[40] while in Kentucky, a shagbark hickory roost was in a closed-canopy stand with 1,210 trees/ha.[23] Overall tree density in Great Smoky Mountain National Park was higher around primary roosts than at alternate roosts.[26] At the landscape level, the basal area for stands with roosts was 30% lower than basal area of random stands in Alabama.[27] Tree density in southern Iowa varied between different habitats. In a forested floodplain, tree density was lowest at 229 trees/ha, while a riparian strip had the highest tree density at 493 trees/ha.[17]
The number of roosts used and home range occupied by a maternity colony can vary widely. In Missouri,[18] the highest density of roosts being used in an oak-hickory stand was 0.25 tree/ha. In Michigan, the number of trees used by a colony was 4.6 trees/ha, with as many as 13.2 potential roosts/ha in the green ash-silver maple stand. Clark and others [17] estimated that the density of potential roosts in southern Iowa in areas where Indiana bats were caught was 10 to 26/ha in riparian, floodplain, and upland areas dominated by eastern cottonwood-silver maple, oak-hickory, and black walnut-silver maple-American elm, respectively. In Illinois, the suggested optimal number of potential roost trees in an upland oak-hickory habitat was 64/ha; the optimal number for riparian and floodplain forest, dominated by silver maple and eastern cottonwood, was proposed to be 41/ha.[16]
Salyers and others [37] suggested a potential roost density of 15 trees/ha was needed, or 30 roosts/ha if artificial roost boxes are erected in a stand with American elm and shagbark hickory. The roosting home range used by any single Indiana bat was as large as 568 hectares in an oak-pine community in Kentucky.[24] Roosts of two maternity colonies in southern Illinois were located in roosting areas estimated at 11.72 hectares and 146.5 hectares, and included green ash, American elm, silver maple, pin oak, and shagbark hickory.[19] The extent of the maternity home range may depend on the availability of suitable roosts in the area.[41]
Most habitat attributes measured for the Indiana bat were insignificant and inconsistent from one location to another. In Missouri, oak-hickory stands with maternity colonies had significantly more medium trees (12–22 in or 30–57 cm dbh) and significantly more large-sized trees (>22 inches or 57 cm dbh) than areas where Indiana bats were not found. No other major landscape differences were detected.[33]
Distances seen between roosts and other habitat features may be influenced by the age, sex, and reproductive condition of these bats. Distances between roosts and paved roads is greater than the distances between roosts and unpaved roads in some locales, although overlap between the two situations has been documented. In Illinois, most roosts used by adult females and juveniles were about 2,300 feet (700 m) or more from a paved highway, while adult males roosted less than 790 feet (240 m) from the road.[16][20] In Michigan, roosts were only slightly closer to paved roads: 2,000 feet (610 m) on average for all roosts located.[25] In general, roosts were located 1,600 to 2,600 feet (490 to 790 m) from unpaved roads in Illinois and Michigan.[20][25] Roost trees used during autumn in Kentucky were very close to unpaved roads at an average of 160 feet (49 m).[23]
Roost proximity to water is highly variable, so probably not as important as once thought. In Indiana, roost trees were discovered less than 660 feet (200 m) from a creek,[22] while roosts in another part of Indiana were 1.2 miles (1.9 km) from the nearest permanent water source.[20][25] To the other extreme, roosts of a maternity colony from Michigan were all found in a 12-acre (5 ha) wetland that was inundated for most of the year.[25] In Virginia, foraging areas near a stream were used.[40] Intermittent streams may be located closer to roosts than more permanent sources of water.[16][25] Ponds, streams, and road ruts appear to be important water sources, especially in upland habitats.[42]
Studies on the foraging needs for Indiana bats are inconclusive. Bats forage[18] in a landscape composed of pasture, corn fields, woodlots, and a strip of riparian woodland, although Indiana bat activity was not necessarily recorded in all these habitat types. Murray and Kurta[34] made some qualitative assessments of Indiana bat foraging habitat in Michigan; the majority of bats was found foraging in forested wetlands and other woodlands, while one bat foraged in an area around a small lake and another in an area with 50% woodland and 50% open fields. Another Indiana bat foraged over a river, while 10 others foraged in areas greater than 0.6 miles (0.97 km) from the same river.[34]
Bat activity was centered around small canopy gaps or closed forest canopy along small second-order streams in West Virginia. Indiana bats foraged under the dense oak-hickory forest canopy along ridges and hillsides in eastern Missouri, but rarely over streams.[43] Indiana bats have been detected foraging in upland forest [17][23][28] in addition to riparian areas such as floodplain forest edges.[17][22][28][44] Romme and others [39] also suggested that foraging habitat would ideally have 50% to 70% canopy closure. Indiana bats rarely use open agricultural fields and pastures, upland hedgerows, open water, and deforested creeks for traveling or foraging.[20][22][34]
During hibernation, Indiana bats occupy open areas of hibernacula ceilings and generally avoid crevices and other enclosed areas.[45] They were associated with hibernacula that were long (µ=2,817 feet or 858 m), had high ceilings (µ=15 feet or 4.5 m), and had large entrances (µ=104.4 feet² or 9.7 m2). The preferred hibernacula often had multiple entrances promoting airflow. Hibernacula choice may be influenced by the ability of the outside landscape to provide adequate forage upon arrival at the hibernacula, as well as the specific microclimate inside. Having forested areas around the hibernacula entrance and low amounts of open farmland may be important factors influencing the suitability of hibernacula.[45]
Primary roosts used by Indiana bats are typically snags in canopy gaps and forest edges that receive direct sunlight throughout the day.[18] Alternate roosts are live or dead trees, generally located in the forest interior, that usually receive little or no direct sunlight.[18][22] Weather, such as very warm temperatures and precipitation, appears to influence the use of interior alternate roost trees over primary roosts, as alternate roosts generally offer more shade and protection during inclement weather and extreme heat.[18][22][33] However, this preference may fluctuate from season to season. Indiana bats moved to the alternate roost during periods of heavy rain and colder ambient temperatures during fall in Missouri, but chose to roost in the primary snag during inclement weather in the spring. These differences may be attributed to variation in the heat-retention capabilities of the trees at different times of the year.[22] Bats from a maternity colony switched roosts more frequently in summer and autumn than they did in spring in an oak-pine forest in Kentucky.[21] They exhibit strong fidelity to individual roost trees from year to year if they are still suitable roost sites.[21][22][46] Many trees are no longer usable after just a few years,[16][18][22][25][28][46] while others may last as long as 20 years.[30]
Another important factor relating to roost suitability is tree condition. Indiana bats prefer dead or dying trees with exfoliating bark.[25] The amount of exfoliating bark present on a tree seems to be insignificant.[23] Indiana bats show an affinity for very large trees that receive plentiful sunlight. Typically, Indiana bats roost in snags, but a few species of live trees are also used. Live roost trees are usually shagbark hickory, silver maple, and white oak.[16][18] Shagbark hickories make excellent alternate roosts throughout the Indiana bats' range due to their naturally exfoliating bark.[28] Although Indiana bats primarily roost under loose bark, a small fraction roosts in tree cavities.[16][25][26][32]
Primary roosts are generally larger than alternate roosts,[26] but both show variability. Females typically use large roost trees averaging 10.8 to 25.7 inches (27 to 65 centimetres) as maternity roosts.[16][18][23][25][27][40][47] Males are more flexible, roosting in trees as small as 3 inches (7.6 cm) dbh.[16][23][24][40] In a review, Indiana bats required tree roosts greater than 8 inches (20 cm) dbh,[39] while roosts of 12 inches (30 cm) dbh or larger were preferred.[46] The heights of roost trees vary, but they tend to be tall, with average heights ranging from 62.7 to 100 feet (19.1 to 30.5 m). The heights of the actual roosting sites are variable, as well, ranging from 4.6 to 59 feet (1.4 to 18.0 m).[25][27][40]
In addition to day roosts, Indiana bats use temporary roosts throughout the night to rest between foraging bouts. Limited research has examined the use of night roosts by Indiana bats, thus their use and importance are poorly understood. Males, lactating and postlactating females, and juveniles have been found roosting under bridges at night. Some Indiana bats were tracked to three different night roosts within the same night.[34] Night roosts are often found within the bats' foraging area. Indiana bats using night roosts are thought to roost alone and only and for short periods, typically 10 minutes or less. Lactating bats may return to the day roost several times each night, presumably to nurse their young. Pregnant bats have not been tracked back to the day roost during the night except during heavy rain. Because Indiana bats are difficult to track during their nightly movements and usually rest for such short periods of time, the specific requirements that Indiana bats need in a night roost, and reasons why night roosts are needed, are still unknown.
During spring and fall, Indiana bats migrate between hibernacula and summer roosting sites. In New York and Vermont, bats traveled up to 25 miles (40 km) between hibernacula and summer roosting sites in spring. This is a considerably shorter distance than what is seen in the Midwest, where bats may travel up to 300 miles (480 km). Many males remain close to hibernacula during the spring and summer[38] rather than migrating long distances like females. Occasionally, they even roost within hibernacula during the summer.[38] Males also roost in caves and trees during fall swarming.[38][46] Few data exist for the roosting requirements of Indiana bats during spring and fall migrations; data indicate that requirements during these times are similar to summer needs in that the bats chose large trees with direct sunlight and exfoliating bark.[40]
The ability for Indiana bats to find suitable hibernating conditions is critical for their survival. A hibernaculum that remained too warm during one winter caused a 45% mortality rate in hibernating bats.[48] They generally hibernate in warmer portions of the hibernacula in fall, then move to cooler areas as winter progresses. During October and November, temperatures at roosting sites within major hibernacula in six states averaged 43.5 to 53.2 °F (6.4 to 11.8 °C). Roost temperatures at the same hibernacula ranged from 34.5 to 48.6 °F (1.4 to 9.2 °C) from December to February. Temperatures in March and April were slightly lower than in autumn at 39.6 to 51.3 °F (4.2 to 10.7 °C). Indiana bat populations increased over time in hibernacula that had stable midwinter temperatures averaging 37.4 to 45.0 °F (3.0 to 7.2 °C), and declined in hibernacula with temperatures outside this range.[28]
Temperatures slightly above freezing during hibernation allow Indiana bats to slow their metabolic rates as much as possible without the risk of freezing to death or using up fat too quickly.[48] Hibernating bats may also survive low temperatures by sharing body heat within the tight clusters they typically form.[35] Bats awaken periodically throughout the hibernation period, presumably to eliminate waste or to move to more appropriate microclimates. This periodic waking does not seem to affect their survival, but waking caused by disturbance can cause Indiana bats to use up large amounts of energy, which can cause them to run out of fat reserves before the end of winter, possibly leading to death.[49]
One way in which caves retain low temperatures is through a constant input of cold air from outside the cave. Typically, the caves supporting the largest populations have multiple entrances that allow cool air from outside the cave to come in, creating a circulation of fresh, cooled air. Gates that are meant to keep vandals out of caves have altered the temperature and airflow of hibernacula, resulting in population declines of Indiana bats at many major hibernacula throughout their range. Removing or modifying gates at some of these have given these populations a chance to rebound. Also, the bats seem to prefer a relative humidity of 74 to 100%, although the air is not commonly saturated.[46] Relative humidities of only 50.4% have also been recorded.[45]
Indiana bats feed exclusively on terrestrial and aquatic flying insects.[44] The most common prey items taken are moths (Lepidoptera), beetles (Coleoptera), and mosquitoes and midges (Diptera).[29] Selection of prey depends largely on availability in the foraging habitat with diet varying seasonally, by reproductive status of females, and from night to night. In southern Michigan, Indiana bats primarily ate caddisflies (Trichoptera) and bees, wasps, and ants (Hymenoptera), in addition to the more common prey previously listed.[44] In the Ozarks of southern Missouri, the bats also primarily ate bees, wasps, ants, moths, and beetles, as well as leafhoppers (Homoptera), although diet did vary throughout the summer. Bats in Indiana were found to prefer beetles, moths, mosquitoes, midges, leafhoppers, and wasps.[50] Other arthropod groups which are consumed by Indiana bats in very limited quantities are lacewings (Neuroptera), spiders (Araneae), stoneflies (Plecoptera), mayflies (Ephemeroptera), mites and ticks (Acari), and lice (Phthiraptera).[23][44]
In addition to differences in diet, variation in foraging behaviors have been documented. For instance, the distance that an individual Indiana bat travels between a day roost and a nightly foraging range can vary. Indiana bats traveled up to 1.6 miles (2.6 km) from their day roosts to their foraging sites in Illinois.[20] Similarly, bats traveled up to 1.5 miles (2.4 km) to forage in Kentucky.[23] In Michigan, female bats traveled as far as 2.6 miles (4.2 km) to reach foraging areas with an average of 1.5 miles (2.4 km).[34]
Several studies have documented similarities in how foraging habitats are actually used by Indiana bats. Indiana bats in Indiana were foraging around the canopy, which was 7 to 98 feet (2.1 to 29.9 m) above ground.[22] In Missouri, a female bat foraged 7 to 33 feet (2.1 to 10.1 m) above a river.[43] A male Indiana bat was observed flying in an elliptical pattern among trees at 10 to 33 feet (3.0 to 10.1 m) above the ground under the canopy of dense forests.[43] In addition, bats were foraging at canopy height in Virginia.[40]
Differences in the extent of foraging ranges have also been noted. Bats from the same colony foraged in different areas at least some of the time.[34] The average foraging area for female bats in Indiana was 843 acres (341 hectares), but the foraging area for males averaged 6,837 acres (2,767 hectares).[22] A male bat used a foraging area of 1,544 acres (625 hectares) in Virginia.[40] In Illinois, however, the foraging ranges were much smaller at an average of 625 acres (253 hectares) for adult females, 141 acres (57 hectares) for adult males, 91 acres (37 hectares) for juvenile females, and only 69 acres (28 hectares) for juvenile males.[16][20][23] Foraging areas used by Indiana bats in Indiana increased throughout the summer season, but only averaged 11.2 acres (4.5 hectares) in midsummer.[22]
During hibernation, predators of Indiana bats may include black rat snakes (Pantherophis obsoletus) [51] and northern raccoons (Procyon lotor).[47][51] During other times of the year, northern raccoons have been observed trying to grab bats from the air when they attempt to fly away.[47] Skunks (Mephitidae), Virginia opossums (Didelphis virginiana), and feral cats (Felis catus) may pose a similar threat.[51] If Indiana bats fly from their day roosts during the day, they may be susceptible to predation by hawks (Accipitridae).[47][51] Indiana bats foraging at night may also be susceptible to predation by owls (Strigidae).[22][51] While not a predator, woodpeckers (Picidae) may disturb roosting bats through their foraging activities by peeling away sections of bark being used by Indiana bats, causing them to fly from the roost during the day and making the tree unsuitable for future habitation.[25][47]
The impact of natural predators on Indiana bats is minimal compared to the damage to habitat and mortality caused by humans, especially during hibernation. The presence of people in caves can cause Indiana bats to come out of hibernation, leading to a large increase in their energy use. By causing them to wake up and use greater amounts of energy stores, humans can cause high mortality in a cave population of hibernating Indiana bats.[49] Human disturbance and the degradation of habitat are the primary causes for their decline.[52]
In the year 2020, the American "field recorder" Stuart Hyatt released a music album which combines sounds made by the Indiana bat along with music from ambient and experimental artists. Hyatt recorded the ultrasonic echolocations of the Indiana bat and then modulated the sounds in order to make the sounds audible to humans. This "sound library" of the Indiana bat was sent to musicians who then combined the sounds from the Indiana bat along with original music. Hyatt was quoted as saying that "bat noises are like bird songs, just in a register no one can hear. I wanted to bring out the musicality of their voices." Hyatt's album is entitled Ultrasonic, and it features music from "Eluvium," "Machinefabriek," Ben Lukas Boysen and others.[53][54] The album also features a poem written and read by the poet Cecily Parks about the Indiana bat.[55][56]
This article incorporates public domain material from Myotis sodalis. United States Department of Agriculture.
The Indiana bat (Myotis sodalis) is a medium-sized mouse-eared bat native to North America. It lives primarily in Southern and Midwestern U.S. states and is listed as an endangered species. The Indiana bat is grey, black, or chestnut in color and is 1.2–2.0 in long and weighs 4.5–9.5 g (0.16–0.34 oz). It is similar in appearance to the more common little brown bat, but is distinguished by its feet size, toe hair length, pink lips, and a keel on the calcar.
Indiana bats live in hardwood and hardwood-pine forests. It is common in old-growth forest and in agricultural land, mainly in forest, crop fields, and grasslands. As an insectivore, the bat eats both terrestrial and aquatic flying insects, such as moths, beetles, mosquitoes, and midges.
The Indiana bat is listed as an endangered species by the U.S. Fish and Wildlife Service. It has had serious population decline, estimated to be more than 50% over the past 10 years, based on direct observation and a decline on its extent of occurrence.
El murciélago de Indiana (Myotis sodalis) es una especie de murciélago de la familia de los vespertiliónidos. Se encuentra en América del Norte: desde el este de Oklahoma e Iowa hasta Michigan, Nueva York, Nueva Inglaterra, el norte de Nueva Jersey, el norte de Alabama y Arkansas. Antiguamente, también había una población en el noroeste de Florida.
Hace entre 41 y 49 mm de longitud total. Tiene una envergadura de 240 a 267 mm, pesa 5-11 g. Tiene el pelaje fino y esponjoso de color gris castaño, con una porción basal negra en el dorso y menos brillante que el de otros murciélagos similares (como Myotis lucifugus). Las partes inferiores son de color canela. La nariz es rosa claro. Tiene las patas pequeñas con pelos cortos y escasos que no se extienden más allá de los dedos de los pies. Las orejas y las membranas alares tienen una apariencia opaca. No presenta dimorfismo sexual.
Emplea la ecolocalización y la vista para orientarse mientras vuela. Además, tiene un oído excelente y se comunican entre ellos utilizando el sonido.
Come coleópteros, polillas y otros insectos voladores. Puede consumir hasta la mitad de su peso corporal en insectos cada noche y, por lo tanto, su papel en el control de las poblaciones de insectos es muy significativo. Además, tiene un papel esencial en los ecosistemas de las cuevas, ya que lleva nutrientes en forma de guano que otras formas de vida aprovechan.
Para hibernar, prefiere cuevas de piedra caliza con temperaturas estables. En verano, los bosques de ribera son sus lugares preferidos para alimentarse y dormir.
Aparea en otoño y las hembras almacenan el esperma durante toda la hibernación para estar preñadas a finales de marzo o principios de abril. La gestación dura 60 días y tiene una sola cría a finales de junio o principios de julio, la cual será capaz de volar al cabo de un mes. Las poblaciones septentrionales migran hacia Alabama, Tennessee, Kentucky, Indiana, Missouri y Virginia Occidental cuando llega el invierno. Se cree que la mitad de la población total de esta especie hiberna en el sur de Indiana. En verano, la hembra ocupa un territorio de, más o menos, 52 hectáreas. Una vez ha tenido su cría, la amplía hasta las 232 hectáreas. Puede llegar a vivir hasta los 14 años en estado salvaje. Al igual que todos los murciélagos, se considera un reservorio potencial de enfermedades como la rabia y la histoplasmosis.
Ha desaparecido de la mayor parte de su distribución histórica del noreste de Estados Unidos por varios factores: la actividad humana (incluyendo el turismo y las estructuras construidas en las entradas de las cuevas para restringir el acceso humano, ya que obstaculizan el movimiento de los murciélagos y los flujos de aire, las temperaturas y los niveles de humedad del interior), los desastres naturales, la caza furtiva, la pérdida de su hábitat forestal y los plaguicidas.
El murciélago de Indiana (Myotis sodalis) es una especie de murciélago de la familia de los vespertiliónidos. Se encuentra en América del Norte: desde el este de Oklahoma e Iowa hasta Michigan, Nueva York, Nueva Inglaterra, el norte de Nueva Jersey, el norte de Alabama y Arkansas. Antiguamente, también había una población en el noroeste de Florida.
Myotis sodalis Myotis generoko animalia da. Chiropteraren barruko Myotinae azpifamilia eta Vespertilionidae familian sailkatuta dago
Myotis sodalis Myotis generoko animalia da. Chiropteraren barruko Myotinae azpifamilia eta Vespertilionidae familian sailkatuta dago
Chauve-souris de l'Indiana
Myotis sodalis, communément appelé la Chauve-souris de l'Indiana, est une espèce de chauves-souris de la famille des Vespertilionidae. Cette espèce, de taille moyenne et souvent de couleur grise ou marron, est souvent confondue avec la Petite chauve-souris brune. On la trouve principalement aux États-Unis dans les États de l'est, du Midwest et du sud.
La Chauve-souris de l'Indiana mesure de 4 à 5 cm et pèse moins de 10 g. Elle est difficilement reconnaissable par rapport à d'autres espèces notamment par rapport à la Petite chauve-souris brune (Myotis lucifugus). La taille de ses pattes et la longueur de ses poils permettent toutefois de différencier l'espèce des autres. L'espérance de vie est comprise entre 5 et 9 ans mais certaines ont atteint l'âge de 14 ans. La fourrure varie du noir au brun noisette avec quelques pointes de gris clair et ses lèvres sont roses. L'espèce se nourrit d'insectes durant la nuit. Chaque colonie abrite des milliers d'individus. Chaque colonie consomme ainsi des milliers d'insectes toutes les nuits.
L'espèce est présente dans l'Est des États-Unis durant l'été. Par contre en hiver, les individus se rassemblent dans un nombre limité de grottes alors qu'en été elles n'ont pas besoin de grottes. En hiver, elles ont en effet besoin d'une température basse et stable pour pouvoir hiberner.
Sa zone d'extension est en partie la même que celle de la Chauve-souris grise (Myotis grisescens) qui est également une espèce menacée.
La chauve-souris femelle donne naissance à une seule chauve-souris chaque été. Les jeunes commencent à voler un mois après la naissance. Ils passent la fin de l'été et l'automne à accumuler des graisses pour passer l'hiver. C'est également en automne que les chauves-souris se reproduisent mais le sperme du mâle est stocké dans la femelle jusqu'au printemps lorsque les chauves-souris arrêtent d'hiberner pour regagner leurs abris d'été et ce n'est qu'à ce moment que la gestation débute. En été, les colonies sont constituées d'une centaine d'individus.
Cette espèce a été décrite en 1928 par Gerrit Smith Miller, Jr et Glover Morrill Allen. L'épithète spécifique « sodalis » signifie camarade, compagnon, collègue, c'est-à-dire qui partage certaines occupations ou habitudes[1], notamment avec la Petite chauve-souris brune (Myotis lucifugus).
Elle est classée dans le genre Myotis, à « oreilles de souris », dans les Vespertilionidae[2], la seconde plus grande famille de mammifères après celle des Muridés.
C'est une espèce en danger selon l'UICN[3]. Elle fait partie de la liste des espèces menacées depuis le 11 mars 1967.
La population a chuté de 50 % depuis 1975. Selon un recensement datant de 1985, la population était estimée à 244 000. 23 % de cette population hibernait dans les grottes de l'Indiana. La menace provient des activités humaines, de l'utilisation de pesticides contre les insectes mais aussi de maladie, en particulier le syndrome du nez blanc[4].
Chauve-souris de l'Indiana
Myotis sodalis, communément appelé la Chauve-souris de l'Indiana, est une espèce de chauves-souris de la famille des Vespertilionidae. Cette espèce, de taille moyenne et souvent de couleur grise ou marron, est souvent confondue avec la Petite chauve-souris brune. On la trouve principalement aux États-Unis dans les États de l'est, du Midwest et du sud.
Myotis sodalis (Miller & Allen, 1928) è un pipistrello della famiglia dei Vespertilionidi endemico degli Stati Uniti d'America orientali.[1][2]
Pipistrello di piccole dimensioni, con la lunghezza della testa e del corpo tra 41,4 e 49 mm, la lunghezza dell'avambraccio tra 36 e 40,6 mm, la lunghezza della coda tra 27 e 43,8 mm, la lunghezza del piede tra 7 e 8,6 mm, la lunghezza delle orecchie tra 10,4 e 14,8 mm, un'apertura alare fino a 26,7 cm e un peso fino a 7,5 g.[3]
La pelliccia è fine. Le parti dorsali sono grigio-castane, con le punte dei peli grigiastre, che donano un effetto generale brizzolato, mentre le parti ventrali sono bianco-rosate, con la base dei peli grigio scure. Le orecchie sono bruno-nerastre, moderate, con il bordo anteriore convesso alla base e diritto all'estremità e con la punta arrotondata. Il trago è corto, smussato e leggermente curvato in avanti. Le membrane alari sono bruno-nerastre e attaccate posteriormente alla base delle dita dei piedi, i quali sono piccoli. L'estremità della lunga coda si estende leggermente oltre l'ampio uropatagio. Il calcar è lungo, sottile e distintamente carenato al centro. Il cariotipo è 2n=44 FNa=50.
Si rifugia in piccoli gruppi nelle cavità degli alberi e sotto le cortecce staccate. Durante l'inverno entra in ibernazione all'interno di grotte, individuate in non più di 15 in tutto il suo areale. Forma vivai di poche centinaia di femmine con i loro piccoli.
Si nutre di piccoli lepidotteri, ditteri, tricotteri, imenotteri, coleotteri, plecotteri, omotteri e neurotteri.
Gli accoppiamenti avvengono in autunno, con ovulazione, fertilizzazione ed impianto dell'embrione ritardati al termine dell'ibernazione. Danno alla luce un piccolo alla volta a fine giugno o nei primi giorni di luglio. Lo svezzamento avviene tra 25 e 37 giorni dalla nascita. L'aspettativa di vita è di 13-14 anni fino a un massimo di 20 anni.
Questa specie è endemica degli stati americani orientali dell'Iowa meridionale, Missouri, Arkansas settentrionale, Oklahoma orientale, Illinois, Indiana, Kentucky; Virginia e Carolina del Nord occidentali, Michigan meridionale, Ohio, Pennsylvania, New York, Massachusetts occidentale, Vermont e New Hampshire meridionali; Virginia Occidentale, Tennessee; Alabama, Georgia e Carolina del Sud settentrionali.
La IUCN Red List, considerato che è stato osservato un drastico declino nella popolazione di circa il 50% negli ultimi 10 anni, classifica M.sodalis come specie in pericolo (EN).[1]
Myotis sodalis (Miller & Allen, 1928) è un pipistrello della famiglia dei Vespertilionidi endemico degli Stati Uniti d'America orientali.
Myotis sodalis is een zoogdier uit de familie van de gladneuzen (Vespertilionidae). De wetenschappelijke naam van de soort werd voor het eerst geldig gepubliceerd door Miller & Allen in 1928.
De soort komt voor in de Verenigde Staten.
Bronnen, noten en/of referentiesMyotis sodalis is een zoogdier uit de familie van de gladneuzen (Vespertilionidae). De wetenschappelijke naam van de soort werd voor het eerst geldig gepubliceerd door Miller & Allen in 1928.
Myotis sodalis[2][3][4][5][6][7] är en fladdermusart som beskrevs av Miller och Allen 1928. Myotis sodalis ingår i släktet Myotis och familjen läderlappar.[8][9] Inga underarter finns listade i Catalogue of Life.[8]
Denna fladdermus blir 41 till 49 mm lång (huvud och bål), har en 27 till 44 mm lång svans och väger 5 till 11 g. Artens vingspann är 240 till 267 mm. Den mjuka pälsen har på ovansidan en mörk gråbrun till svartbrun färg, vid buken är pälsen rosa till kanelbrun. I motsats till nära besläktade arter har Myotis sodalis en böjd sporre (calcar) vid bakfötterna.[10]
Arten förekommer i östra USA från Kansas och Oklahoma till Maine och södra Alabama.[1] Den lever i olika habitat. Jakten efter insekter sker ofta vid vattendrag eller vid insjöarnas strandlinjer. Myotis sodalis jagar även i skogar eller vid andra trädansamlingar.[10]
Denna fladdermus uppsöker före vintern större grottor. Arten ställer ganska höga krav på övervintringsplatsen. Myotis sodalis föredrar fuktiga kyliga grottor med en konstant temperatur på 2 till 7 °C. Mellan grottan och området där en viss population lever på sommaren kan ligga 575 km.[10] I grottan bildas stora kolonier med upp till 30 000 medlemmar.[1] Vanligen är kolonin uppdelad i grupper med cirka 5 000 individer som håller tät intill varandra vinterdvala.[10] Individernas kroppstemperatur kan variera mellan 5 och 35 °C och den ligger vanligen 1 till 1,5 °C över områdets temperatur.[11]
Under den varma årstiden används även andra viloplatser som trädens håligheter eller lösa barkskivor.[1]
På natten fångar arten olika insekter. Ibland äter denna fladdermus insekter med en vikt som motsvarar hälften av sin egen vikt.[10]
Parningen sker under hösten och sedan förvaras sädescellerna i honans könsdelar. Äggens befruktning äger under våren rum. Före ungens födelse bildar honor kolonier med cirka 100 medlemmar som är skilda från hanarna.[10] Ungen diar sin mor 25 till 37 dagar. Livslängden går vanligen upp till 14 år och sällan upp till 20 år.[11]
På grund av artens höga krav finns bara ett fåtal grottor där den kan gå i ide. När fladdermusen störs förbrukar den energi som behövs för att överleva. IUCN uppskattar att hela beståndet minskade med 50 procent under de senaste 10 åren och listar Myotis sodalis som starkt hotad (EN).[1]
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Wikimedia Commons har media som rör Myotis sodalis.
Wikispecies har information om Myotis sodalis.
Myotis sodalis är en fladdermusart som beskrevs av Miller och Allen 1928. Myotis sodalis ingår i släktet Myotis och familjen läderlappar. Inga underarter finns listade i Catalogue of Life.
'Myotis sodalis — вид рукокрилих роду Нічниця (Myotis).
Проводить літні місяці у всій східній частині США. Взимку, однак, вони групуються разом і зимують лише в кількох печерах. . Живуть в листяних лісах і листяно-соснових лісах, полях і луках. Комахоїдний, їсть як наземних, так і водних літаючих комах, таких як молі, жуки, комарі і мошки.
Вид середніх розмірів (4,5—9,5 г). Колір сірий, чорний або каштановий.
'Myotis sodalis — вид рукокрилих роду Нічниця (Myotis).
Myotis sodalis là một loài động vật có vú trong họ Dơi muỗi, bộ Dơi. Loài này được Miller & Allen mô tả năm 1928.[2]
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Phương tiện liên quan tới Myotis sodalis tại Wikimedia Commons
Bài viết họ Dơi muỗi này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Myotis sodalis là một loài động vật có vú trong họ Dơi muỗi, bộ Dơi. Loài này được Miller & Allen mô tả năm 1928.
Myotis sodalis (Miller & Allen, 1928)
Ареал
Индианская ночница[1] (лат. Myotis sodalis) — вид летучих мышей рода ночницы (Myotis) семейства гладконосые летучие мыши (Vespertilionidae), обитающий в Северной Америке.
Проводит летние месяцы во всей восточной части США. Зимой животные группируются и зимуют лишь в нескольких пещерах. Живут в лиственных лесах и лиственно-сосновых лесах, полях и лугах. Насекомоядный, ест как наземных, так и водных летающих насекомых, таких как моли, жуки, комары и мошки.
Самки весом 7,5 грамм крупнее самцов весом весом 7,1 грамм (половой диморфизм). Окраска меха серая, чёрная или каштановая.
Индианская ночница (лат. Myotis sodalis) — вид летучих мышей рода ночницы (Myotis) семейства гладконосые летучие мыши (Vespertilionidae), обитающий в Северной Америке.
Проводит летние месяцы во всей восточной части США. Зимой животные группируются и зимуют лишь в нескольких пещерах. Живут в лиственных лесах и лиственно-сосновых лесах, полях и лугах. Насекомоядный, ест как наземных, так и водных летающих насекомых, таких как моли, жуки, комары и мошки.
Самки весом 7,5 грамм крупнее самцов весом весом 7,1 грамм (половой диморфизм). Окраска меха серая, чёрная или каштановая.
인디애나박쥐(Myotis sodalis)는 애기박쥐과에 속하는 박쥐이다. 중간 크기의 윗수염박쥐로 북아메리카의 토착종이다. 미국 동부 지역에서 발견된다.[2] 멸종위기종으로 등록되어 있다. 털 색은 회색과 검은색 또는 밤색을 띠며, 몸길이는 3~5cm이고 몸무게는 4.5~9.5g이다. 좀더 흔한 작은갈색박쥐와 유사하지만 발 크기와 발가락 털 길이, 핑크색 입술, 용골 위의 돌기 등이 다르다. 인디애나박쥐는 활엽수림과 소나무 숲에서 서식한다. 농경지와 오래된 벌판같은 농경지 등의 노숙림에서 주로 발견된다. 보통 숲과 농경지, 초원에서 주로 서식한다. 식충성 동물로 나방과 딱정벌레, 모기, 각다귀 등의 육상성과 수상성의 날아다니는 곤충을 먹는다. 미국 어류 및 야생동물관리국의 멸종위기종에 등록되어 있다. 직접적인 관찰과 서식 범위 내의 감소 추세에 기초한 조사 결과, 지난 10년 동안 50% 이상으로 추산되는 심각한 개체수 감소 추세를 보이고 있다.[1]
다음은 윗수염박쥐속의 계통 분류이다.[3]
윗수염박쥐속구대륙 분류군
신대륙 분류군 신북구작은갈색박쥐, 술꼬리박쥐, 킨윗수염박쥐, 긴귀윗수염박쥐
구북구붉은윗수염박쥐, 벨벳윗수염박쥐, 물가윗수염박쥐, 엘리겐트윗수염박쥐
슈바르츠윗수염박쥐, 도미니카윗수염박쥐, 아타카마윗수염박쥐
은색작은박쥐, 산지윗수염박쥐, 검은윗수염박쥐, 노랑윗수염박쥐
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