Habitat Bats can be found in many terrestrial habitats below the polar regions. Typical habitats include temperate and tropical forests, deserts, open fields, agricultural areas, and in suburban and urban environments. Many bats forage near freshwater streams, lakes and ponds, preying on insects as they emerge from the water. Generally, if a terrestrial habitat provides access to sufficient roost sites and appropriate food, one or more species will be found there. Bats generally have very specific roosting requirements, which differ among species. They may roost in caves, crevices, trees, under logs, and even in human dwellings. Bats may also use different types of roosts at different times. For example, a species that hibernates in a cave during the winter may use crevices in tree holes as roosts during warmer months. Habitat Regions

temperate

tropical

terrestrial Terrestrial Biomes

desert or dune

savanna or grassland

chaparral

forest

rainforest

scrub forest

mountains Wetlands

marsh

swamp

bog Other Habitat Features

urban

suburban

agricultural

riparian

estuarine

Lifespan/Longevity Bats live surprisingly long lives. Typically, mammalian lifespans roughly correlate with their body size: smaller mammals live short lives, whereas larger mammals live longer lives. Bats are the only group of mammals that does not conform to this relationship. Despite the fact that bats are generally small mammals, many bats can live over 30 years in the wild. Where data on longevity is available, lifespans in the wild are often recorded from 10 to 25 years. Typically, a given species will live at least 3.5 times longer than other mammals of similar size. (Wilkinson and South, 2002) There are several viable hypotheses to explain longevity in bats. Hibernation and daily torpor may restrict lifetime energy expenditure in individuals, allowing them to live longer. Lack of predation pressure on adults may also allow bats to live long lives. For their size, bats have low reproductive rates in a given breeding season. Typically, females give birth to only one or two young per year, but reproduce many times over a long life. By evolving a reproductive strategy that is more typical of large mammals, perhaps lifespans have evolved to match those of large mammals as well. (Wilkinson and South, 2002) The longest-lived bat on record is a little brown bat (Myotis lucifigus). One banded individual was recaptured 33 years after it was originally tagged. These bats weigh only 7 grams as adults, roughly 1/3 the size of a house mouse. Myotis lucifugus is one of the most widely studied species worldwide; thus, it would not be surprising if other, less well-known species live even longer. (Kurta, 1995)

Behavior The behavior that unifies all of Chiroptera is flight. Bats are the only group of mammals to have evolved powered flight (although many species glide), and only the third vertebrate group to do so. Depending upon the size and shape of their wings relative to their body mass, different species of bats may have different flight styles. Many species have large, broad wings and relatively small bodies, which allows them to fly slowly but with high maneuverability. This flight behavior is useful for chasing evasive insect prey and maneuvering within a dense forest at night. Some species with large, broad wings can even hover. This behavior is especially useful for bats that eat nectar or pollen from stationary flowers. Other species have long, narrow wings, which are useful for acheiving high speeds, but which restricts maneuverability. Many of these species forage in open spaces and may be able to fly long distances. These two wing morphologies represent the ends of a continuum, most species have wing morphologies that fall between these extremes. (Hill and Smith, 1984; Nowak, 1991; Vaughan, et al., 2000) Many bats live in groups, while some species are solitary. Often, bats roost in colonies for some portion of the year. Living in a colony can serve many functions. For bats, one of the main purposes of group living is to collectively conserve heat. Bats are small and have high metabolic rates, so heat conservation is vital. Many bats hibernate during the winter and undergo daily torpor to conserve energy. Clustering together while roosting can further reduce heat loss. Some bats that roost together do so in groups of several individuals. Some groups (e.g. Tadarida) roost in caves in groups of thousands, or even millions. Some bat species migrate to hibernation sites or to follow a food source (flowering cacti, for example). Most bat species are not known to defend foraging areas, but this behavior is known from some tropical species. Territorial defense of roosting sites is also known in some species. (Hill and Smith, 1984; Vaughan, et al., 2000) Key Behaviors

flies

nocturnal

crepuscular

parasite

motile

migratory

sedentary

hibernation

daily torpor

solitary

territorial

social

colonial

Predation Few studies have directly examined the effects of predators on bat populations. Most of this type of information comes from anecdotal observation of predation events or evidence of bats in the scat of predators. Groups that are known to eat bats are owls and other birds of prey, many carnivores, other bats, and snakes. Bats are probably most vulnerable to predators as they roost during the day or emerge in large groups in the early evening. Predators like snakes or hawks often wait near the entrances of caves at dusk, attacking bats as they leave the roost. Juvenile bats that cannot yet fly are also at risk of predation if they fall to the ground. Individual bats flying in the dark of night are probably difficult to catch, even for owls, which can fly and locate prey well in the dark. Several species of bat have become specialized for preying on other bats, these include the New World species Vampyrum spectrum and Chrotopterus auritus, and two Old World species in the genus Megaderma. (Hill and Smith, 1984) Bats generally avoid predation by staying in protected roosts during the day and through agile flight at night. Most bats are also cryptically colored. Anti-predator Adaptations

cryptic Known Predators owls hawks bats Mammalian carnivores snakes



Economic Importance for Humans: Positive Although many people consider bats to be harmful pests, bats play pivotal roles in ecological communities and benefit humans in numerous ways. Many species of insectivorous bats prey heavily on insects that transmit diseases or are crop pests. In addition, bat guano (feces) is often used to fertilize crops. Many tons of guano are mined each year from caves where bats aggregate in large numbers. In other words, some species eat crop pests and excrete crop fertilizer! Evidence continues to accumulate in support of the immense economic benefit of insectivorous bats for the agricultural industries worldwide. Frugivorous bats are important seed dispersers, helping promote the diversity of fruiting trees in the tropics. Bats that eat pollen and nectar are important pollinators, and some plants they pollinate are economically important to humans, such as Agave and bananas (Musa). Larger bats, such as pteropodids are sometimes eaten by humans. (Hill and Smith, 1984; Nowak, 1991) Recently, common vampire bats have become an important focus of medical research. Vampire bats are generally considered a significant threat to human interests because they regularly transmit rabies to cattle (and sometimes to people). However, the anticoagulant protein in their saliva ("Desmoteplase") is being studied in an effort to help prevent blood clots in humans, such as those being treated for stroke. (Reddrop, et al., 2005) The increasing popularity of bats has led to a booming ecotourism industry, often surrounding large roost emergences, such as those of Mexican free-tailed bats. ("Bat Conservation International", 2004) Positive Impacts

food

ecotourism

source of medicine or drug

research and education

produces fertilizer

pollinates crops

controls pest population

Economic Importance for Humans: Negative Although bats are often perceived as much more of a threat to human interests than they actually are, bats may negatively impact humans in at least two ways. Some species roost in human dwellings and can become a nuisance. This is particularly true if a large colony takes up residence in a home, producing a great deal of guano and an unpleasant odor. Bats also carry and transmit rabies. In general, bats rarely transmit rabies to other species, including humans and domestic animals. Vampire bats, on the other hand, regularly transmit the disease to domestic cattle, representing a large financial burden for the cattle industry in the New World tropics. Rabies is transmitted through saliva and other body fluids and vampire bats exhibit several behaviors which make them especially effective vectors of the disease (e.g., social grooming and food sharing). Their feeding habits result in their saliva contacting the blood of other animals, which is an ideal situation for rabies transmission. (Hill and Smith, 1984; Vaughan, et al., 2000) Negative Impacts

injures humans carries human disease

causes or carries domestic animal disease

household pest

Conservation Status Approximately 25% of all species within Chiroptera (nearly 240 species) are considered threatened by the International Union for the Conservation of Nature (IUCN). At least twelve species have gone extinct in recent times. Megachiropterans tend to be more at risk than microchiropterans (34% and 22% of species, respectively), but both groups are facing substantial threats from habitat loss and fragmentation. Destruction of, or disturbances to, roost sites is particularly problematic for bats. Pesticide use also indirectly harms bats that eat insects or plant products that have been chemically treated. Species with relatively small geographic ranges and/or that are ecologically specialized tend to be at greatest risk. (Jones, et al., 2003) In recent years, the general public has become increasingly aware of the beneficial roles that bats play in ecosystems and their unique and amazing life histories. A wealth of research now demonstrates that bats are a vital component of many ecosystems and an important resource for humans. Efforts to protect bats have increased. For example, many caves that serve as large hibernacula are fixed with gates that allow access by bats, but not by humans. Rather than trying to eradicate bats from homes and neighborhoods, many people are placing bat houses in their yards to give bats appropriate roosting habitat. In the United Kingdom, all bats and bat roosts are protected by law. Several large roost emergences, including evening emergences from a roost under the Congress Avenue Bridge in Austin, Texas, draw millions of tourists each year. Conservation organizations like Bat Conservation International (www.batcon.org) have growing memberships among the general public and run many successful bat conservation projects, including projects in the developing world designed to increase awareness and appreciation. ("Bat Conservation International", 2004; Fenton, 1997) IUCN Red List [Link] Not Evaluated

The name "Chiroptera" is derived from Greek and literally means "hand wing" ("chiro" + "ptera"). Bats are so named because evolution has shaped their wings through modifications to the ancestral tetrapod forelimb. These modifications are primarily the result of an elongation of the digits, or fingers. Thus, the majority of a bat's wing is actually its hand. The earliest fossil bat is a remarkably well preserved animal from early Eocene rocks in the Green River formation of Wyoming. Given the name Icaronycteris, it comes from a species that is clearly microchiropteran. This implies that the split between the two groups occurred quite early, and the fossil sheds no light on the question of whether bats are monophyletic. (Vaughan, et al., 2000)

Contributors Tanya Dewey (editor), Animal Diversity Web. Matthew Wund (author), University of Michigan-Ann Arbor, Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary Australian Living in Australia, New Zealand, Tasmania, New Guinea and associated islands. Ethiopian living in sub-Saharan Africa (south of 30 degrees north) and Madagascar. Nearctic living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico. Neotropical living in the southern part of the New World. In other words, Central and South America. Palearctic living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa. acoustic uses sound to communicate agricultural living in landscapes dominated by human agriculture. altricial young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching. bilateral symmetry having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria. bog a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum. carnivore an animal that mainly eats meat causes or carries domestic animal disease either directly causes, or indirectly transmits, a disease to a domestic animal chaparral Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo. chemical uses smells or other chemicals to communicate colonial used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms. cosmopolitan having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific. crepuscular active at dawn and dusk cryptic having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect. delayed fertilization a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage. delayed implantation in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months. desert or dunes in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots. drug a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease echolocation The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves. ecotourism humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals. embryonic diapause At about the time a female gives birth (e.g. in most kangaroo species), she also becomes receptive and mates. Embryos produced at this mating develop only as far as a hollow ball of cells (the blastocyst) and then become quiescent, entering a state of suspended animation or embryonic diapause. The hormonal signal (prolactin) which blocks further development of the blastocyst is produced in response to the sucking stimulus from the young in the pouch. When sucking decreases as the young begins to eat other food and to leave the pouch, or if the young is lost from the pouch, the quiescent blastocyst resumes development, the embryo is born, and the cycle begins again. (Macdonald 1984) endothermic animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds. estuarine an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity. food A substance that provides both nutrients and energy to a living thing. forest forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality. frugivore an animal that mainly eats fruit herbivore An animal that eats mainly plants or parts of plants. heterothermic having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature. hibernation the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals. insectivore An animal that eats mainly insects or spiders. island endemic animals that live only on an island or set of islands. iteroparous offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes). keystone species a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter). marsh marshes are wetland areas often dominated by grasses and reeds. migratory makes seasonal movements between breeding and wintering grounds monogamous Having one mate at a time. motile having the capacity to move from one place to another. mountains This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation. native range the area in which the animal is naturally found, the region in which it is endemic. nectarivore an animal that mainly eats nectar from flowers nocturnal active during the night oceanic islands islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands. omnivore an animal that mainly eats all kinds of things, including plants and animals oriental found in the oriental region of the world. In other words, India and southeast Asia. parasite an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death pheromones chemicals released into air or water that are detected by and responded to by other animals of the same species piscivore an animal that mainly eats fish polygynandrous the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females. polygynous having more than one female as a mate at one time rainforest rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal. riparian Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream). sanguivore an animal that mainly eats blood scent marks communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them scrub forest scrub forests develop in areas that experience dry seasons. seasonal breeding breeding is confined to a particular season sedentary remains in the same area sexual reproduction that includes combining the genetic contribution of two individuals, a male and a female social associates with others of its species; forms social groups. solitary lives alone sperm-storing mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females. suburban living in residential areas on the outskirts of large cities or towns. swamp a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation. tactile uses touch to communicate temperate that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle). terrestrial Living on the ground. territorial defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement tropical the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south. tropical savanna and grassland A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia. savanna A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome. temperate grassland A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands. ultrasound uses sound above the range of human hearing for either navigation or communication or both urban living in cities and large towns, landscapes dominated by human structures and activity. visual uses sight to communicate viviparous reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female. year-round breeding breeding takes place throughout the year