often include bats as part of the Halloween Treat: motif. Is there a biological basis for these myths? Is it possible to sepa- Bat Facts and Folklore rate fact from fable? The follow- ing brief account provides a Thomas H. Kunz glimpse of what we presently know about these fascinating, nocturnal, flying mammals. For Bats do not get into your hair, more extensive treatments, the they are not flying mice, they reader is referred to recent books don't come "out of hell," they by Kunz (1982) and Fenton are not blind, and only three out (1983). The former book is a of approximately 850 different scholarly treatment of bat species actually make a regular written by specialists in their re- spective fields, although most of diet of blood. The news media, Downloaded from http://online.ucpress.edu/abt/article-pdf/46/7/394/41557/4447878.pdf by guest on 27 September 2021 movies, television, and comic it can be easily understood by the books commonly perpetuate such nonspecialist. The latter book is a myths, misunderstandings, "old- less technical presentation written wives-tales", and legends about with the lay audience in mind. bats to which many of us have become indoctrinated. These and Diversity and Distribution other myths and misconceptions Bats belong to the mammalian about bats have been and remain Order Chiroptera, meaning an integral part of many human "hand-wing." Members of this cultures. The ancient Egyptians group of flying mammals have believed that bats could prevent existed (in their present form) for or cure such "diseases" as poor at least 50 million years. Approx- eyesight, toothache, fever, and Fig. 1. The greater short-nosed fruit bat imately 850 different species are baldness. A bat hung over the (Cynopterus sphinx) pollinating a wild ba- known worldwide (Fig. 1). Bats doorway of a home was thought nana flower in Thailand. Members of this are second only to the rodents in to prevent the entry of demons species are known to construct "tents" by chewing the veins on palm fronds, caus- number of species and they prob- which might carry these "dis- ing the leaf to collapse and form a tent ably outnumber all other mam- eases." Bat gods were important roost. Photo courtesy of Merlin D. Tuttle. mals in overall abundance. Dis- to many pre-Colombian civiliza- Since the time of Cortez and his tributed on every continent tions in central America. Bats bats are conquistadors, peoples of western except Antarctica, have long been used in voodoo known from oceanic is- civilization have linked vampire many worship in parts of Africa as well lands. The bats with the legendary "human" overwhelming as in some parts of the Caribbean number of bat live in vampires of Transylvania. Even species even today. The association of dif- the writings of Shakespeare, Ste- tropical regions. Thirty-nine bats with the legend of human ferent are known venson, and others have contrib- species from vampires has an uncertain origin. the continental United uted to legends that cast a veil of States. fear on people, when they associ- Thomas Kunz is an associate professor of Characteristics Biology, and director of the Graduate ate bats with graveyards, death, Program in Ecology, Behavior, and Evo- ghosts, and goblins. Adult bats range in size from lution at Boston University, Boston, MA 02215, where he has taught since 1971. To the Chinese, however, bats the smallest mammal, weighing He received his B.S. degree from Central are symbols of happiness and approximately two grams (0.07 State University, his M.A. degree good fortune (health, wealth, se- ounces) with a wing span of from Drake University, and his Ph.D. de- gree from the University of . His re- renity, virtue, and long life). At about 10 centimeters (four search interests on the ecology and behav- one time Chinese mothers sewed inches), to those weighing over ior of bats have taken him throughout small jade buttons in the shape of one kilogram (2.2 pounds) and much of North America, as well as to the Caribbean islands of Cuba, Puerto Rico, a bat on the caps of their babies, having a wing span of nearly 1.5 and Trinidad. He is the author of numer- a custom believed to impart long meters (six feet). The skeletal fea- ous publications on bats and he has re- life. Ancient and modern-day art tures of bats are comparable to cently contributed to and edited a book entitled Ecology of Bats, Plenum Press, objects, tapestries, imperial robes, those of humans and most other New York (1982). home furnishings, and the like, mammals. Unlike most birds,

394 THE AMERICAN BIOLOGY TEACHER, VOLUME 46, NO. 7, OCTOBER 1984 which have hollow bones, the such as avocados, figs, mangos, bones of bats are typically small breadfruit, and guava. Others and delicate. The bones of the pollinate economically important hands are lengthened to provide trees such as balsa, kapoc (silk-cot- support for the wings (Fig. 2). A ton), and chicle (an ingredient of highly resilient double membrane chewing gum). Vampire bats stretches between the elongated feed exclusively on the blood of fingers, attaches to the side of the birds and mammals. They do so body, and extends to the ankle. by licking blood from small cuts they make in the skin of their prey with razor sharp teeth. The flow of blood is facilitated by a special anticoagulant in the bat's saliva which prevents the blood from clotting. These small (35- 45 g) bats are known only from the New World tropics, and Downloaded from http://online.ucpress.edu/abt/article-pdf/46/7/394/41557/4447878.pdf by guest on 27 September 2021 range from central Mexico, Fig. 3. Pallid bat (Antrozous pallidus) perched on a shrub near Carlsbad Cav- southward to central Argentina, erns, New Mexico. This bat is known to Chile, Bolivia, and Brazil. feed almost exclusively on insects and other arthropods that frequent the ground. Photo courtesy of Merlin D. Tut- Activity tle. Bats typically seek shelter in ing mosquitoes, biting midges, roosts during the daytime and are beetles, and moths. (Bats do not active on the wing at night. eat blackflies or gypsy moths be- They depart from their day roosts cause adult (flying) forms of these shortly after sunset and return be- Fig. 2. Little brown bat (Myotis lucifugus) in flight. The wings are in the up-stroke insects are active only in the fore sunrise. The timing of night- position and the mouth is open while the daytime.) ly departure and return is closely bat is echolocating. Photo courtesy of All bats are important members synchronized with light levels Merlin D. Tuttle. of food webs; some serve as val- and is associated with seasonal ued pollinators and seed dispersers changes in day length. One or Food Habits (Fig. 4), while others become the more feeding periods may occur prey or predator to other ani- Bats exhibit a diversity of food on a given night, depending on mals. Many tropical feed habits unparalleled among living species food availability and the tem- on economically fruits mammals. Diets of many species important perature of the night air. Feed- include insects, others eat nectar ing activity is often interrupted and pollen, fruit, leaves, or by periods of night roosting, blood, and some eat small verte- where individuals seek temporary brates, including fish, frogs, liz- shelter alone or in small groups in ards, birds, and small mammals. trees, in open buildings, on the In temperate North America bats rafters of porches, carports, feed almost exclusively on insects breezeways, etc. Moonlight may (Fig. 3). In the warm months of influence the nightly activity of the year, individuals may eat up some species, directly as an avoid- to one-half of their body weight ance response to bright moonlight on a given night. If this level of (which may decrease their suscep- consumption is extrapolated to a tibility to predators), or indirectly population of 50,000 bats (a con- through its inhibitory effect on servative estimate for the number the activity of their prey. of bats living in a 100-square-mile Fig. 4. The dwarf epauletted bat (Microp- Roosting and Social Habits area in New England), this terous pusillus) is one of several African would amount to over 13 tons of fruit-eating species that plays a crucial role Most bats are highly gregarious insects eaten in one summer. in the maintenance of forest diversity and D. Tuttle. animals that seek daytime shelter Many bats are also important in caves, caverns, rock crevices, predators of insect pests, includ- hollow trees, foliage (Fig. 5), and

BAT FACTS AND FOLKLORE 395 in a variety of man-made struc- Movements, Echolocation, tures. Social groups are com- and Navigation monly formed during migration, in hibernation, during courtship, Some bats in temperate regions and when rearing young. In migrate several hundred kilo- temperate regions females form meters between their summer large aggregations known as ma- and winter quarters. Tropical spe- ternity colonies, where young cies generally are more sedentary, bats are born and reared. Such although many engage in local groups range in size from a few movements in response to seasonal individuals to several million at a variation in the distribution and single roost. Bats do not build abundance of food. Although nests; instead, when at rest most bats do have eyes, most cannot species cling to the substrate using see as well as other mammals. In their hind feet with their wings some species (the flying foxes), folded next to the body. Bats eyes are essential to navigation Downloaded from http://online.ucpress.edu/abt/article-pdf/46/7/394/41557/4447878.pdf by guest on 27 September 2021 that roost in small crevices com- since they lack the highly spe- monly assume a horizontal pos- cialized sonar system (called echo- Fig. 5. Hoary bat (Lasiurus cinereus) roost- location) that other bats exhibit. ture. ing in the foliage of a spruce tree. This bat commonly roosts alone (except for Echolocation allows most bats to Reproduction mothers and offspring) and it migrates navigate in total darkness, avoid- northward over much of North America ing trees, cave walls, and each Bats also exhibit a variety of re- in spring and southward during autumn. Photo courtesy of Merlin D. Tuttle. other; it also allows them to de- productive patterns and mating tect and capture food on the systems. Most species are polygy- Individual babies may weigh up wing. Even in species that have nous (a single male mates with to 30% of their mother's postbirth well developed echolocation, vi- several females), some are promis- weight. (This is comparable to a sion plays an important role in cuous, and only a few species are 100-pound human female giving synchronizing activity rhythms monogamous. The reproductive birth to a 30-pound baby.) and in navigation. pattern typical of bats in temper- Female bats suckle their young Many bats have specialized fa- ate North America involves au- with milk, and weaning usually cial ornaments and ear structures tumn mating and delayed ovula- occurs at the age of four to six that serve important roles in tion; mating usually occurs before weeks. Most bats grow rapidly sound production and hearing bats enter hibernation, the female and reach 90% of adult size by (Fig. 7). Echolocation typically stores sperm in her uterus during the time they are weaned. consists of pulsed emissions of high the winter and ovulation and fertilization follow in spring upon arousal from hibernation. De- pending on spring temperatures, gestation proceeds uninterrupted and may last from 60 to 100 days.

Number of Young and Size at Birth Most female bats give birth during a two-to-three-week peri- A - ~ ~ A~ od in early summer. The timing of parturition varies considerably among species, but most give birth at times of maximum food abundance. In temperate regions, bats that feed on insects usually give birth to a single annual litter of one or two offspring. A few species have litters of three or four young. Most baby bats are Fig. 6. Maternity cluster of newborn Myotis velifer on the rafter of a barn. Photograph unusually large at birth (Fig. 6). was taken at night when the mothers were out feeding. Photo by Thomas H. Kunz.

396 THE AMERICAN BIOLOGY TEACHER, VOLUME 46, NO. 7, OCTOBER 1984 frequency sounds and the detec- tion of echoes returning from ei- ther moving or stationary objects. Most bats produce high intensity (loud) sounds while others (called whispering bats) produce low in- tensity sounds. Humans usually cannot hear echolocation sounds produced by bats since they are produced at frequencies beyond our hearing sensitivity (>20 kHz). If we could hear them it would be comparable to placing your ear next to an activated smoke alarm. Some species produce sounds having a constant frequen- cy (CF bats), whereas others pro- Downloaded from http://online.ucpress.edu/abt/article-pdf/46/7/394/41557/4447878.pdf by guest on 27 September 2021 duce what are called frequency modulated (FM) sounds. As a bat Fig. 8. A small group of cave bats (Myotisvelifer) hibernating in a Kansas cave. Hiber- detects an insect with echoloca- nating bats are especially prone to human disburbance;frequent arousals can deplete tion, the rate of sound produc- valuable stores of body fat. Photo by Thomas H. Kunz. tion increases from five to 20 pulses per second up to 200 per Hibernation cies are able to minimize their second immediately before cap- energy expenditure during hiber- ture. Some insects have evolved Following the mating season in nation. Arousals caused from re- tactics to avoid being eaten by temperate regions, some species peated human disturbance in bats. For example, some moths of migrate to warmer climates. Most caves where bats hibernate may the families Sphingidae and Noc- bats, however, seek shelter in unnecessarily cause the depletion tuidae take evasive action in re- caves and other places (sometimes of fat reserves and this can be sponse to the sonar cries of ap- in houses) that are protected from one factor that increases winter proaching bats. Some sounds that freezing temperatures. During hi- mortality. are made by roosting bats are au- bernation the body temperature dible to the human ear, but these of bats becomes reduced to with- sounds are usually made in a so- in a few degrees of ambient tem- Mortality and Longevity cial context instead of being used perature (Fig. 8). If the roost Bat mortality can result from in echolocation. temperature is 6?C, the tem- predation, disease, starvation, and perature of the bat will be near accidents. Predators include owls, 70 or 8?C. At this low body tem- snakes, skunks, weasels, racoons, perature the bats' heart and house cats, other bats, and some- breathing rates are greatly re- times people. In some parts of the N duced from normal, active levels. world bats are hunted and eaten I-~~~~~~~~~~~~~~~~~~~~. During hibernation the heart rate by the native people. For their may be as little as 20 times per size bats are relatively long-lived, minute. This contrasts with a rate some may live up to 30 years al- of 600 beats per minute in an though most only live for four or aroused but resting state and 1300 five years. This contrasts with the beats per minute during flight. survivorship of other small mam- Most bats endure hibernation by mals, such as rodents and shrews, S_* slowly metabolizing the fat re- that seldom live beyond one serves which are deposited in late year. summer and early fall. Bats may arouse periodically from the hi- Public Health, Parasites, and bernating state during the Diseases Fig. 7. Eastern big-eared bat (Plecotus winter. This often happens dur- rafinesquii) in a Tennessee cave. This spe- ing unseasonably warm periods. As with any wild animal, bats cies is now rare due to human disturbance of cave roost sites. Photo courtesy of Mer- The formation of dense clusters in may attempt to bite if handled. lin D. Tuttle. winter is one way that some spe- Caution, however, should be

BAT FACTS AND FOLKLORE 397 taken to avoid physical contact presence in an enclosed area of a ing(s) should be sealed so that bats with bats. A bat should not be building having deposits of bat cannot reenter. It may be neces- handled unless the person is guano may increase the risk of sary to repeat this procedure sev- trained to do so or unless the in- exposure in certain geographic eral times until all openings have dividual is wearing heavy gloves. areas (central and southeastern been closed. The best time to seal Rabies is a disease that can be U.S.). such openings is in the early transmittedto humans from bites Many bats harbor ectoparasites spring or in autumn. One should of carnivorous mammals. Al- (ticks, bat bugs, fleas, etc.) but as avoid sealing them from late May though the incidence of rabies in with most parasites, they are host to mid-July since young bats too most populations of bats is very specific and do not survive long young to fly may be trapped in- low, caution should be taken to away from their natural hosts. No side. Chemical repellents (e.g. avoid being bitten by any bat. In serious health risks are associated moth balls, sulfur candles, am- temperate regions of North with the ectoparasitesof bats. monia) are generally ineffective America the incidence of rabies in getting rid of bats. Bats may in most colonial species is less than be temporarily evicted by using one half of one percent. The in- Bat Management these repellents but they are like-

cidence is somewhat higher (four Bats sometimes take up residen- ly to return after the chemical Downloaded from http://online.ucpress.edu/abt/article-pdf/46/7/394/41557/4447878.pdf by guest on 27 September 2021 to 10%)in sick and moribund in- cy in, or accidently enter houses has dissipated. Pesticides (e.g. dividuals. In some solitary species and other man-made structures. Rozal, chlorodane, lindane, etc.) the incidence of rabies may ex- Under most circumstances these often sicken bats before killing ceed 10 percent but most people situations pose no serious prob- them, and seldom are they com- rarely encounter these bats. If a lems. The benefits of having bats pletely effective. When these poi- person is bitten by a bat, an usually outweigh the disadvan- sons are used, bats can become effort should be made to capture tages created by their presence. sick and fall to the ground, it and have it tested for rabies. If If, however, it is deemed neces- which increases the risk of expos- bitten, the wound should be sary to evict a colony of bats ing children and pets to sick bats washed thoroughly with soap from a house, the only environ- which may bite if handled. Ap- and water and a physician or mentally sound and effective plication of poisons to the interior public health department should method is to close the openings of a house for controlling bats be notified immediately. Postex- that bats use for their exit and may impose adverse health risks posure antirabiestreatment is rec- entry. Bats usually enter buildings to the human occupants, conse- ommended. Persons with high through small openings along the quently this practice should be risks of exposure to bats (e.g. sci- edge of the roof, through crev- avoided. Devices that produce entists studying bats, public health ices where the masonry has sounds at ultrasonic frequencies personnel, veterinarians, etc.) pulled away from the clapboard, (sonar type) are ineffective in rid- usually take a preexposure vac- or through unscreened air vents. ding bats from buildings. Use of cine for protection. To determine where bats are en- lights in roosting areas may re- Histoplasmosis is the only other tering or exiting a building two duce the number of bats present disease that can result (indirectly) or more people should position under some circumstances. Al- from contact with bats. Histo- themselves outside the house though the safest and soundest plasmosis is a disease of the lungs shortly after sunset (in the warm approach for eliminating bats that is caused by a fungus that months). Bats can best be ob- from buildings is to physically grows in the moist droppings served by silhouetting them close the openings that they are (guano) of bats and many birds. against a clear view of the twi- using for exit and entry portals, The symptoms are caused in re- light sky. It may take up to one this may be difficult to accom- sponse to the inhalation of spores hour for all bats to depart on a plish if the building has holes and from the fungus. In many regions given evening. Usually they will crevices too numerous to effec- of the world (including parts of not fly out on cold, rainy nights. tively seal. the United States) this fungus oc- (If you see something flying into If a single bat gets into a house curs naturally in the soil and your chimney at dusk, you prob- accidently (a common occurrence many residents of these areas ably don't have bats. Instead, you in late summer when young bats have developed a natural immu- likely have swallows or chimney are learning how to fly), the nity. Histoplasmosis is not consid- swifts.) lights should be turned on, doors ered a serious health problem for After you have located places or windows should be opened, most people. Cave explorers are that bats are using as exit and en- and soon the bat will leave on its subject to the greatest level of ex- try holes, and all the bats have own. Unless the bat is sick or in- posure although a prolonged left to feed at night, the open- jured it will invariably leave,

398 THE AMERICAN BIOLOGY TEACHER, VOLUME 46, NO. 7, OCTOBER 1984 probably not to be seen again. If (deforestation, cave flooding, efforts, the readers should contact a bat is discovered in living quar- vandalism, commercialization of "Bat Conservation International", ters during the day, efforts to en- caves, etc.), unintentional disturb- % Milwaukee Public Museum, courage it to leave will be most ance to bats caused during cave Milwaukee, WI 53233. successful if done at night. exploration,and use of pesticides. In some cases bats are destroyed as Referencesand Books for perceived pests. Because of their FurtherReading Conservation importance in controlling insects, Barbour, R.W., and W.H. Davis. (1969). In recent years the numbers of dispersing seeds, and pollinating Bats of America.Lexington, KY:Univer- bats have declined dramatically flowers, bats should be protected sity Press of Kentucky. the world. as important members of natural Fenton, M.B. (1983). Just bats. Toronto, in some regions of Canada:University of TorontoPress. These declines have resulted from communities. For further infor- Kunz, T.H. (ed.). (1982). Ecologyof bats. the destruction of native habitat mation about bat conservation New York:Plenum Press. Downloaded from http://online.ucpress.edu/abt/article-pdf/46/7/394/41557/4447878.pdf by guest on 27 September 2021 Just PJublished! COMING SOON! Human Ecology: Plants in the Laboratory A Perspective for Biology Education Monograph Series I Monograph Series 11 This monograph takes you from Twelve classroom experiments to use with your students theory to practice with human in the first of a series of monographs from the National As- ecology in the biology classroom. sociation of Biology Teachers. It includes: Plants in the Laboratoryis a compilation of practical labo- Ideas ratory projects published previously in the AmericanBiology Current Data Teacher,written by distinguished biologists as "How-to-do- ClassroomActivities A Comprehensive Curriculum It" articles. Some of the titles: A Miniaturized Plant Press Review and Herbarium; Demonstrating the Photoreversion of Seed; Simple Separation of Plant Pigments; Easy-to-make PrepublicationPrice-$10 Casts and Slides. Send to: Human Ecology Mono- Prepress orders exceeded expectations, so order your graph, NABT, 11250 Roger Bacon copy of Plants in the Laboratorynow. It will be a useful ad- Dr., #19, Reston, VA 22090, with dition to your professional library. the following coupon. Plants in the Laboratory.Members - $5.00 Nonmembers - $7.00 Reserve copies of Human Fill in the coupon below and send to: Plants in the Lab- Ecology at $10 each. oratory, NABT, 11250 Roger Bacon Dr., #19, Reston, VA I enclose $ 22090. Name: Send me copy(ies) of Plants in the Laboratory My address: (name) Address:

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