BATS American Museum of Natural History New York, New York 10024

Home , Maternity colony

Arthur M. Greenhall Research Associate Department of Mammalogy BATS American Museum of Natural History New York, New York 10024

Stephen C. Frantz Vertebrate Vector Specialist Wadsworth Center for Laboratories and Research New York State Department of Health Albany, New York 12201-0509

Fig. 1. Little brown bat, Myotis lucifugus

Damage Prevention and Air drafts/ventilation. Important Note: This document is included for information it provides Control Methods Ultrasonic devices: not effective. pertinent to bat behavior, exclusion Sticky deterrents: limited efficacy. techniques, damage identification, Exclusion prevention and control measures. Toxicants Polypropylene netting checkvalves However, pages D14 - D18 contain simplify getting bats out. None are registered. information about rabies and removal of bats from homes that is incomplete Quality bat-proofing permanently Trapping with regard to current public health excludes bats. Available, but unnecessarily recommendations. For current information see Initiate control before young are born complicated compared to exclusion or after they are able to fly. and bat-proofing. Guidelines for Managing Bats and Risk of Repellents Other Methods Rabies Transmission at: Naphthalene: limited efficacy. Sanitation and cleanup. www.health.state.ny.us/nysdoh/zoonoses/batmanage.pdf Illumination. Artificial roosts.

PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994 Cooperative Extension Division Institute of Agriculture and Natural Resources University of Nebraska - Lincoln United States Department of Agriculture Animal and Plant Health Inspection Service Animal Damage Control D-5 Great Plains Agricultural Council Wildlife Committee Introduction

Conservation and Public Education Despite their ecological value, bats are relentlessly and unjustifiably perse- cuted. Bats are often killed because they live near people who needlessly fear them. These actions emphasize the need to educate the public on the rea- sons for bat conservation and why it is important to use safe, nondestructive methods to alleviate conflicts between people and bats. General sources of information on bats include states’ Cooperative Extension Services, uni- versities, government environmental conservation and health departments, and Bat Conservation International (Austin, Texas). Except where control is necessary, bats should be appreci- ated from a distance — and not disturbed. Identification and Range

Bats, the only mammals that truly fly, belong to the order Chiroptera. Their ability to fly, their secretiveness, and their nocturnal habits have contributed Fig. 2. Little brown bat, Myotis lucifugus to bat folklore, superstition, and fear. They are worldwide in distribution and include about 900 species, second in number only to Rodentia (the rodents) among the mammals. Among the 40 species of bats found north of Mexico, only a few cause problems for humans (note that vampire bats are not found in the United States and Canada). Bats congregating in groups are called colonial bats; those that live a lone existence are known as solitary bats. The colonial species most often encountered in and around human buildings in the United States are the little brown bat, (Myotis lucifugus, Fig. 2), the big brown bat (Eptesicus fuscus, Fig. 3), the Mexican free-tailed bat (Tadarida brasiliensis, Fig. 4), the pallid bat (Antrozous pallidus), the Yuma myotis (Myotis yumanensis), and the evening bat (Nycticeius humeralis). Fig. 3. Big brown bat, Eptesicus fuscus Solitary bats typically roost in tree foliage or under bark, but occasionally are found associated with buildings, some only as transients during migration.

D-6 Fig. 4. Mexican free-tailed bat, Tadarida brasiliensis

These include Keen’s bat (Myotis keenii), the red bat (Lasiurus borealis), the silver-haired bat (Lasionycteris noctivagans), and the hoary bat (Lasiurus cinereus). Excellent illustra- tions of all bats discussed herein can be found in Barbour and Davis (1979), Wrist Knee Tuttle (1988), Geluso et al. (1987), and Ear Harvey (1986). Tail membrane Several species of bats have been included here, with significant inter- specific differences that need to be clarified if well-planned, comprehen- Tragus sive management strategies are to be Upper arm developed. Any problems caused by Calcar bats are limited to species distribution; Forearm Foot thus animal damage control personnel Thumb need not be concerned with every spe- Wing membrane cies. Colonial and solitary bats have obvious differences that serve to separate Fifth finger Second finger the species into groups (refer to Fig. 5). Fourth finger Much of the descriptive material that Third follows is adapted from Barbour and finger Davis (1979).

Fig. 5. Anatomy of a typical bat

D-7 Colonial Bats ant of high temperatures; M. keenii E. fuscus frequently shares roosts may also share the same site. Sepa- with M. lucifugus in the East, and Little brown bat (Myotis lucifugus) rate groups of males tend to be with M. yumanensis, Taderida, and Recognition smaller and choose cooler roosts Antrozous in the West. Males typi- within attics, behind shutters, under cally roost in smaller groups or forearm — 1.34 to 1.61 inches (3.4 to tree bark, in rock crevices, and alone during the summer. 4.1 cm) within caves. wingspan — 9.02 to 10.59 inches (22.9 The big brown bat is one of the most to 26.9 cm) In the winter, little brown bats in the widely distributed of bats in the ears — 0.55 to 0.63 inches (1.4 to 1.6 eastern part of their range abandon United States and is probably famil- cm) buildings to hibernate in caves and iar to more people than any other foot — approximately 0.39 inches (1.0 mines. Such hibernacula may be species. This is partially due to its cm); long hairs on toes extend be- near summer roosts or up to a few large, easy-to-observe size, but also yond claws. hundred miles (km) away. Little is to its ability to overwinter in build- known of the winter habits of M. ings (attics, wall spaces, and base- Distribution (Fig. 6a) lucifugus in the western United ments). Its close proximity to Color States. humans, coupled with its tendency to move about when temperature The life span of little brown bats has Pale tan through reddish brown to shifts occur, often brings this bat been established to be as great as 31 dark brown, depending on geo- into human living quarters and years. The average life expectancy, graphic location. The species is a basements in summer and winter. however, is probably limited to only rich dark brown in the eastern Big browns also hibernate in caves, a few years. United States and most of the west mines, storm sewers, burial vaults, coast. Fur is glossy and sleek. Big brown bat (Eptesicus fuscus) and other underground harborage. Confusion may occur with a few other While E. fuscus will apparently “house” bat species. In the East, it Recognition travel as far as 150 miles (241 km) to hibernacula, the winter quarters of may be confused with Keen’s bat forearm — 1.65 to 2.01 inches (4.2 to the bulk of this species are largely (M. keenii), which has longer ears 5.1 cm) unknown. [0.69 to 0.75 inches (1.7 to 1.9 cm)] wingspan — 12.80 to 13.78 inches (32.5 and a longer, more pointed tragus to 35.0 cm) Big brown bats may live as long as 18 (the appendage at the base of the ears — with rounded tragus years. ear). In the West, it resembles the Distribution (Fig. 6b) Yuma myotis (M. yumanensis), Mexican free-tailed bat (Tadarida which has dull fur and is usually Color brasiliensis) smaller. However, the Yuma myotis and little brown may be indistin- From reddish brown, copper colored, Recognition to a dark brown depending on geo- guishable in some parts of the forearm — 1.42 to 1.81 inches (3.6 to graphic location. This is a large bat northwestern United States where 4.6 cm) without distinctive markings. they may hybridize. wingspan — 11.42 to 12.80 inches (29.0 Habits Confusion may occur with the evening to 32.5 cm); long narrow wings bat (Nycticeius humeralis) though the tail (interfemoral) membrane — does This is one of the most common bats latter is much smaller. not enclose the lower one-third to found in and near buildings, often one-half of the tail, hence the name Habits located near a body of water where free-tailed they forage for insect prey. Summer This hardy, rather sedentary species foot — long, stiff hairs as long as the colonies are very gregarious, com- appears to favor buildings for roost- foot protrude from the toes. monly roosting in dark, hot attics ing. Summer maternity colonies Distribution (Fig. 6c) and associated roof spaces where may include a dozen or so and up maternity colonies may include to a few hundred individuals, roost- Color hundreds to a few thousand indi- ing behind chimneys, in enclosed Dark brown or dark gray. Fur of some viduals. Colonies may also form eaves, in hollow walls, attics, barns, individuals may have been beneath shingles and siding, in tree and behind shutters and unused bleached to a pale brown due to hollows, beneath bridges, and in sliding doors. They also form colo- ammonia fumes from urine and de- caves. Litter size is 1 in the North- nies in rock crevices, beneath composing guano. east; twins occasionally occur in bridges, in hollow trees, and under some other areas. The roost is often loose bark. Litter size is 2 in the East Confusion is not likely to occur with shared with the big brown bat (E. to the Great Plains; from the other species that commonly inhabit fuscus) though the latter is less toler- Rockies westward 1 young is born. human buildings.

D-8 Habits Habits M. yumanensis is more closely associated with water than is any other T. brasiliensis forms the largest colonies Maternity colony size ranges from North American bat species. Nearly of any warm-blooded animal, estab- about 12 to 100 individuals. Roost all roosts have open water nearby. lishing sizable colonies in buildings, sites include buildings, bridges, and This species is not as tolerant as M. particularly on the West Coast and rock crevices; less frequently, tree lucifugus of high roost temperatures in the Gulf states from Texas east. cavities, caves, and mines. Litter and will move to cooler niches Hundreds to thousands may be size is most commonly 2. The roost within a building when tempera- found in buildings or under is frequently shared with T. tures rise much above 100o F bridges. It is primarily a cave bat in brasiliensis and E. fuscus in the West. (37.8o C). Arizona, New Mexico, Oklahoma, While groups of males tend to seg- and Texas; buildings are used as regate during the nursery period M. yumanensis abandons maternity temporary roosts during migra- (sometimes in the same building), colonies in the fall, but its winter tions. Litter size is 1. other males are found within the habitat is not known. maternity colony. Taderida often share roosts with other Evening bat (Nycticeius humeralis) species. In the West, for example, An interesting feature of pallid bats is they may be found in buildings that they fly close to the ground, Recognition with A. pallidus, M. yumanensis, and may hover, and take most prey on forearm — 1.30 to 1.54 inches (3.3 to E. fuscus. Some males are always the ground, not in flight. Prey 3.9 cm) present in the large maternity colo- includes crickets, grasshoppers, wingspan — 10.24 to 11.02 inches (26.0 nies, but they tend to segregate in beetles, and scorpions. They will to 28.0 cm) separate caves. also forage among tree foliage. ears — with short, curved, and A few Taderida may overwinter in Pallid bats are not known to make long rounded tragus buildings as far north as South migrations, though little is known Confusion may occur with the big Carolina in the East and Oregon in of their winter habits. brown bat (E. fuscus), which can be the West. Most of this species readily distinguished by its larger migrate hundreds of miles to Yuma myotis (Myotis yumanensis) size. It bears some resemblance to warmer climes (largely to Mexico) Recognition the somewhat smaller little brown for the winter. forearm — 1.26 to 1.50 inches (3.2 to bat (M. lucifugus) but can be identified by its characteristic blunt Pallid bat (Antrozous pallidus) 3.8 cm) wingspan — about 9.25 inches (23.5 tragus. Recognition cm) Distribution (Fig. 6f) forearm — 1.89 to 2.36 inches (4.8 to ears — 0.55 to 0.59 inches (1.4 to 1.5 cm) Color 6.0 cm) foot — 0.39 inches (1.0 cm) wingspan — 14.17 to 15.35 inches (36.0 Distribution (Fig. 6e) Medium brown with some variation to to 39.0 cm) yellow-brown in subtropical ears — large; widely separated and Color Florida. No distinctive markings. more than half as broad as long. Light tan to dark brown; underside is Habits The ears are nearly half as long as whitish to buffy. the combined length of the bat’s Summer maternity colonies in build- head and body. Confusion may occur in the West with ings may consist of hundreds of eyes — large M. lucifugus, though the latter tends individuals. Litter size is usually 2. to have longer, glossier fur, and is Colonies also form in tree cavities Distribution (Fig. 6d) larger. In the Northwest, hybridiza- and under loose tree bark. In the Color tion occurs with M. lucifugus, mak- Southeast, T. brasiliensis commonly ing the species indistinguishable. inhabits the same building with N. pale, upper parts are light yellow, the humeralis. This is one of the most hairs tipped with brown or gray. Habits common bats in towns throughout Underparts are pale creamy, almost Maternity colonies, up to several the southern coastal states. Very white. This large, light-colored bat thousand individuals, form in the little is known about this species, is relatively easy to recognize. summer in attics, belfries, under and virtually nothing is known of Confusion with other species that com- bridges, and in caves and mines. its winter habitat except that it monly inhabit human buildings is Litter size is 1. Males typically almost never enters caves. not likely to occur. segregate during the nursery period and roost as solitary individuals in buildings and other suitable harborage.

D-9 Solitary Bats Habits may roost in and on buildings. The litter size is 2. The sexes segregate Keen’s bat (Myotis keenii) Red bats live solitary lives, coming together only to mate and migrate. through much of the summer range. Recognition Few people are familiar with this spe- L. noctivagans hibernates in tree crevices, forearm — 1.26 to 1.54 inches (3.2 to cies. They typically spend summer under loose bark, in buildings 3.9 cm) days hidden in the foliage of decidu- (including churches, sky scrapers, and wingspan — 8.98 to 10.16 inches (22.8 ous trees. The number of young ranges wharf houses), hulls of ships, rock to 25.8 cm) from 1 to 4, averaging 2.3. crevices, silica mines, and non- ears — 0.67 to 0.75 inches (1.7 to 1.9 cm); These bats often chase insects that are limestone caves. It also may migrate, with a long, narrow, pointed tragus attracted to lights, such as street during which time it is encountered in buildings (they favor open sheds, Distribution (Fig. 6g) lamps. It is this behavior that most likely brings them in close proxim- garages, and outbuildings rather than Color ity to people. enclosed attics), in lumber piles, and on ships at sea. Brown, but not glossy; somewhat paler L. borealis is well-adapted for surviving Hoary bat (Lasiurus cinereus) in the East. drastic temperature fluctuations; it Confusion may occur with M. does not hibernate in caves, but Recognition lucifugus, which has glossy fur, apparently in trees. Some migrate shorter ears, and does not have the long distances. During migration, forearm — 1.81 to 2.28 inches (4.6 to 5.8 cm) long, pointed tragus. red bats have been known to land wingspan — 14.96 to 16.14 inches (38.0 on high-rise buildings and on Habits to 41.0 cm) ships at sea. ears — relatively short, rounded, Excluding small maternity colonies (up Silver-haired bat (Lasionycteris edged with black, and with fur to 30 individuals are on record), M. noctivagans) tail membrane — completely furred on keenii are generally found singly in the upper surface East. Roosting sites include: behind Recognition Distribution (Fig. 6j) shutters, under wooden shingles, shel- forearm — 1.46 to 1.73 inches (3.7 to tered entryways of buildings, in roof 4.4 cm) Color spaces, in barns, and beneath tree wingspan — 10.63 to 12.20 inches (27.0 Dark, but many hairs are tipped in bark. In the West, this bat is known as to 31.0 cm) white, giving it a frosted appear- a solitary species, roosting in tree cavi- ears — short, rounded, hairless ance. This bat also has a yellowish ties and cliff crevices. Litter size is tail membrane — upper surface is or orangish throat “collar.” probably 1. The roost is sometimes sparsely furred on the anterior one- shared with M. lucifugus. The sexes half. Confusion may sometimes occur with probably segregate during the nurs- the much smaller silver-haired bat Distribution (Fig. 6i) ery period. In winter, these bats hiber- (Lasionycteris noctivagans), which nate in caves and mines. Color lacks the fur patches and markings on the ears, markings on the throat, Red Bat (Lasiurus borealis) Usually black with silver-tipped fur; and has a tail membrane that is only some individuals with dark brown, Recognition lightly furred on the upper surface. yellowish-tipped fur. forearm — 1.38 to 1.77 inches (3.5 to Habits 4.5 cm) Confusion sometimes occurs with the wingspan — 11.42 to 13.07 inches (29.0 larger hoary bat (Lasiurus cinereus), Hoary bats generally spend summer to 33.2 cm); long, pointed wings which has patches of hair on the ears days concealed in tree foliage (often ears — short rounded and wings, heavy fur on the entire in evergreens), rarely enter houses, tail membrane — heavily furred on upper surface of the tail membrane, and are not commonly encountered upper surface, with a distinctive and has a distinctive throat “collar.” by people. L. cinereus at their day long tail. Habits roosts are usually solitary except Distribution (Fig. 6h) when with young. The litter size is The silver-haired bat roosts in a wide 2. The sexes segregate through most Color variety of harborages. A typical of the summer range. roost might be behind loose tree Bright orange to yellow-brown; usu- bark; other sites include tree hol- This is one of the largest bats in North ally with a distinctive white mark lows and bird nests. This species is America, a powerful flier, and an on the shoulders. solitary except when with young. accomplished migrant. Records Confusion may occur with the hoary Additionally, there are unconfirmed indicate that some L. cinereus may bat (L. cinereus), which is frosted- reports that it is sometimes colonial hibernate in northern parts of their gray in appearance and larger. (Dalquest and Walton 1970) and range.

D-10 abc

def

g hi

Figure 6. Distributions of selected bat species in North America: (a) little brown bat, (b) big brown bat, (c) Mexican free-tailed bat, (d) pallid bat, (e) Yuma myotis, (f) evening bat, (g) Keen’s bat, (h) red bat, (i) silver-haired bat, (j) hoary bat.

D-11 Food Habits migrate relatively short distances, Modification and destruction of roost whereas certain populations of the sites has also decreased bat numbers. Bats in North America are virtually all Mexican free-tailed bat may migrate Sealing and flooding of mineshafts and insectivorous, feeding on a variety of up to 1,000 miles (1,600 km). Bats in caves and general quarrying opera- flying insects (exceptions among house the northern United States and Canada tions may inadvertently ruin bat har- bats were noted previously). Many of may hibernate from September borages. Forestry practices have the insects are harmful to humans. through May. Hibernation for the reduced the number of hollow trees While there must be some limitations same species in the southern part of available. Some of the elimination of based on such factors as bats’ body their range may be shorter or even natural bat habitat may contribute to size, flight capabilities, and jaw open- sporadic. Some may fly during warm bats roosting in buildings. ing, insectivorous bats apparently con- winter spells (as big brown bats may in sume a wide range of prey (Barbour the northeastern part of the United Damage and Damage and Davis 1979). The little brown bat’s States). Bats often live more than 10 Identification diet includes mayflies, midges, mos- years. quitoes, caddis flies, moths, and In response to a variety of human Bat Presence beetles. It can consume insects equal to activities, direct and indirect, several Bats often fly about swimming pools, one-third of its body weight in 1/2 bat species in the United States have from which they drink or catch insects. hour of foraging. The big brown bat declined in number during the past White light (with an ultraviolet com- may fill its stomach in about 1 hour few decades. Chemical pesticides (par- ponent), commonly used for porch (roughly 0.1 ounce per hour [2.7 g/hr]) ticularly the use of persistent and lights, building illumination, street and with prey including beetles, moths, fly- bioaccumulating organic pesticides) parking-lot lights, may attract flying ing ants, true bugs, mayflies, caddis have decreased the insect supply, and insects, which in turn attract bats. flies, and other insects. The nightly contaminated insects ingested by bats Unfortunately, the mere presence of a consumption of insects by a colony of have reduced bat populations. Many bat outdoors is sometimes beyond the bats can be extremely large. bats die when people disturb summer tolerance of some uninformed people. maternity roosts and winter hiber- Information is a good remedy for such nacula. Vandals and other irrespon- situations. General Biology, sible individuals may deliberately kill Reproduction, and bats in caves and other roosts. Even Bats commonly enter buildings through openings associated with the Behavior the activities of speleologists or biologists may unintentionally disturb roof edge and valleys, eaves, apex of hibernating bats, which depletes fat the gable, chimney, attic or roof vent, Most North American bats emit high reserves needed for hibernation. dormers, and siding (see Fig. 7). Other frequency sounds (ultrasound) inau- dible to humans and similar to sonar, in order to avoid obstacles, locate and capture insect prey, and to communi- cate. Bats also emit audible sounds Under roofing Ridge cap Chimney flue that may be used for communication Fascia boards Under siding between them. Between house & chimney Drip edge Bats generally mate in the fall and win- Flashing ter, but the female retains the sperm in Rafters the uterus until spring, when ovulation Vent Soffits Hollow walls and fertilization take place. Pregnant Under females may congregate in maternity porch colonies in buildings, behind chim- roof neys, beneath bridges, in tree hollows, caves, mines, or other dark retreats. No nests are built. Births typically occur from May through July. Young bats grow rapidly and are able to fly within 3 weeks. Weaning occurs in July and August, after which the nursery colonies disperse. Bats prepare for winter around the time of the first frost. Some species Fig. 7. Common points of entry and roosting sites of house bats.

D-12 openings may be found under loose- semi-enclosed (loading docks, entrance be segmented, elongated, and friable. fitting doors, around windows, gaps foyers), partially sheltered (porches, When crushed, they become powdery around various conduits (wiring, carports, pavilions, highway under- and reveal shiny bits of undigested plumbing, air conditioning) that pass passes, bridges), and open structural insect remains. In contrast, mice and through walls, and through utility areas (window shutters, signs). Once rat droppings tend to taper, are vents. there, active bats in and on buildings unsegmented, are harder and more can have several economic and aes- fibrous, and do not become powdery Bats are able to squeeze through nar- thetic effects, often intertwined with when crushed (unless extremely aged). row slits and cracks. For purposes of public health issues (Frantz, 1988). bat management, one should pay The droppings of some birds and liz- Unusual roosting areas include wells, attention to any gap of approximately ards may occasionally be found along sewers, and graveyard crypts. Before 1/4 x 1 1/2 inches (0.6 x 3.8 cm) or a with those of bats. However, bat drop- considering control measures, verify hole 5/8 x 7/8 inch (1.6 x 2.2 cm). Such pings never contain the white chalky that bats are actually the cause of the openings must be considered potential material characteristic of the feces of problem. entries for at least the smaller species, these other animals. such as the little brown bat. The Rub Marks Bat excrement produces an unpleasant smaller species require an opening no odor as it decomposes in attics, wall Surface areas on walls, under loose wider than 3/8 inch (0.95 cm), that is, a spaces, and other voids. The pungent, woodwork, between bricks and hole the diameter of a US 10-cent coin musty, acrid odor can often be around other bat entryways often have (Greenhall 1982). Openings of these detected from outside a building con- a smooth, polished appearance. The dimensions are not uncommon in taining a large or long-term colony. stained area is slightly sticky, may con- older wood frame structures where Similar odor problems occur when ani- tain a few bat hairs, and is yellow- boards have shrunk, warped, or other- mals die in inaccessible locations. The brown to blackish brown in color. The wise become loosened. odor also attracts arthropods which smooth gloss of these rub marks is due may later invade other areas of a The discovery of one or two bats in a to oils from fur and other bodily secre- building. house is a frequent problem. In the tions mixed with dust, deposited there Northeast, big brown bats probably as many animals pass repeatedly for a Bat guano may provide a growth account for most sudden appearances long period over the same surface. medium for microorganisms, some of (see Figs. 3 and 8). Common in urban Openings marked in this way have which are pathogenic (histoplasmosis, areas, they often enter homes through been used heavily by bats. for example) to humans. Guano accu- open windows or unscreened fire- mulations may fill spaces between places. If unused chimneys are selected Noise walls, floors, and ceilings. It may cre- for summer roosts, bats may fall or ate a safety hazard on floors, steps, Disturbing sounds may be heard from crawl through the open damper into and ladders, and may even collapse vocalizations and grooming, scratch- the house. Sometimes bats may appear ceilings. Accumulations also result in ing, crawling, or climbing in attics, in a room, then disappear by crawling the staining of ceilings, soffits, and sid- under eaves, behind walls, and under a door to another room, hall- ing, producing unsightly and between floors. Bats become particu- way, or closet. They may also disap- unsanitary conditions. pear behind curtains, wall hangings, larly noisy on hot days in attics, before bookcases, under beds, into waste bas- leaving the roost at dusk, and upon Bats also urinate and defecate in flight, kets, and so forth. Locating and returning at dawn. Note that rustling causing multiple spotting and staining removing individual bats from living sounds in chimneys may be caused by on sides of buildings, windows, patio quarters can be laborious but is birds or raccoons and scratching and furniture, automobiles, and other important. If all else fails, wait until thumping sounds in attics and behind objects at and near entry/exit holes or dusk when the bat may appear once walls may indicate rats, mice, or beneath roosts. Bat excrement may again as it attempts to find an exit. squirrels. also contaminate stored food, commer- Since big brown bats may hibernate in cial products, and work surfaces. Guano and Urine the cooler recesses of heated buildings, Bat urine readily crystallizes at room they may suddenly appear (flying Fecal pellets indicate the presence of temperature. In warm conditions un- indoors or outdoors) in midwinter animals and are found on attic floors, der roofs exposed to sun and on chim- during a warm spell or a cold snap as in wall recesses, and outside the house ney walls, the urine evaporates so they move about to adjust to the tem- at its base. Fecal pellets along and quickly that it crystallizes in great perature shift. inside walls may indicate the presence accumulations. Boards and beams of mice, rats, or even roaches. Since saturated with urine acquire a whitish Roosting Sites most house bats north of Mexico are powderlike coating. With large num- Bats use roosting niches that are insectivorous, their droppings are bers of bats, thick and hard stalactites indoors (human dwellings, outbuild- easily distinguished from those of and stalagmites of crystallized bat ings, livestock quarters, warehouses), small rodents. Bat droppings tend to urine are occasionally formed.

D-13 Although the fresh urine of a single bat priate surfaces (affected attic beams, result of accidental or careless han- is relatively odorless, that of any mod- soffits) with boric acid powder or dia- dling of grounded bats. Even less fre- erate-sized colony is obvious, and the tomaceous earth; carefully read all quently, bats in this stage of illness odor increases during damp weather. product labels before using any pesti- may be involved in unprovoked Over a long period of time urine may cide. Note that neither rabies nor attacks on people or pets (Brass, pers. cause mild wood deterioration (Frantz Lyme disease is transmitted by any commun.; Trimarchi et al. 1979). It is and Trimarchi 1984). As the urine satu- arthropods associated with bats. during this stage that the rabid bat is rates the surfaces of dry wood beams capable of transmitting the disease by and crystallizes, the wood fibers Public Health Issues biting another mammal. As the disease expand and separate. These fibers then Rabies—General Epidemiology. progresses the bat becomes increas- are torn loose by the bats crawling Bats are distinct from most vertebrate ingly paralyzed and dies as a result of over such surfaces, resulting in wood pests that inhabit human dwellings be- the infection. The virus in the carcass is fibers being mixed with guano accu- cause of the potential for transmitting reported to remain infectious until mulations underneath. rabies — a viral infection of mammals decomposition is well advanced. The close proximity of bat roosts to that is usually transmitted via the bite Significance. Rabies is the most human living quarters can result in of an infected animal. Rabies does not important public health hazard associ- excreta, animal dander, fragments of respond to antibiotic therapy and is ated with bats. Infection with rabies arthropods, and various microorgan- nearly always fatal once symptoms has been confirmed in all 40 North isms entering air ducts as well as fall- occur. However, because of the long American species of bats that have ing onto the unfortunate residents incubation period (from 2 weeks to been adequately sampled in all of the below. Such contaminants can result in many months), prompt vaccination contiguous United States and in most airborne particles of public health sig- following exposure can prevent the provinces of Canada. Figure 8 shows nificance (Frantz 1988). disease in humans. Dogs, cats, and the frequency of bat species submitted livestock also can be protected by for rabies testing in New York State Ectoparasites and other periodic vaccinations. over the last 12 years. While not a Arthropods Bats are not asymptomatic carriers of nationwide measure of human Several arthropods (fungivores, detri- rabies. After an incubation period of 2 encounters with bats, Figure 8 illus- tivores, predators, and bat ectopara- weeks to 6 months, they become ill trates that bat species are not encoun- sites) are often associated with colonies with the disease for as long as 10 days. tered equally. Note that bats submitted of bats in buildings. Their diversity de- During this latter period, a rabid bat’s for testing are often ill and/or easily pends on the number of bats, age and behavior is generally not normal—it captured. The numbers and species quantity of excreta deposits, and sea- may be found active during the day- encountered will vary with the region son. Arthropods such as dermestid time or on the ground incapable of fly- of the country; data are generally beetles (Attagenus megatoma) contribute ing. Most human exposures are the available from local and state health to the decomposition of guano and in- authorities. sect remnants, but may also become a pest of stored goods and/or a nuisance within the living quarters. Cock- roaches (for example, Blatta orientalis) Big Brown (R = 6.0%) attracted to guano may invade other parts of a building. Bat bugs (Cimex Little Brown (R = 1.0%) spp.) are sometimes found crawling on the surface of beams or around holes Keen’s (R = 1.8%) leading to secluded recesses used by bats. Bat ectoparasites (ticks, mites, Red (R = 5.7%) fleas, and bugs) rarely attack humans or pets and quickly die in the absence Hoary (R = 16.3%) of bats. Ectoparasites may become a nuisance, however, following exclu- Silver-haired (R = 8.9%) sion of large numbers of bats from a well-established roost site. Area fumi- Other and Unknown (R = 2.5%) gation with a total release pyrethrum- based aerosol may be an appropriate solution for arthropod knockdown 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 within an enclosed space, but only af- Number of Bats ter bats have departed. For long-term arthropod control, lightly dust appro- Fig. 8. Profile of bat species submitted to the New York State Rabies Laboratory, 1981-1992.

D-14 Random sampling of bats (healthy and Numerous wild and domestic animals lesions on routine radiographs. Other ill) indicates an overall infection rate of are susceptible to histoplasmosis, but individuals may have chronic or pro- less than 1%. Finding a rabid bat in a bats (and perhaps the armadillo) are gressive lung disease requiring treat- colony does not imply that the remain- the only important animal vectors. ment. Less severe forms of these ing animals are rabid. In fact, the prob- Unlike bats, birds do not appear to infections may be accompanied by ability of immediately finding more become infected with the fungus. Both fever, cough, and generalized symp- than one additional infected bat in that the presence of guano and particular toms similar to a prolonged influenza. colony is small. environmental conditions are neces- Resolution of the disease confers a sary for H. capsulatum to proliferate. In degree of immunity to reinfection. In Bats rank third (behind raccoons and avian habitats, the organism appar- addition, resolution confers varying skunks) in incidence of wildlife rabies ently grows best where the guano is in degrees of hypersensitivity to H. in the United States (Krebs et al. 1992). large deposits, rotting and mixed with capsulatum; as a consequence, massive In the last 20 years, however, there soil rather than in nests or in fresh reinfection in highly sensitized lungs have been more human rabies cases of deposits. Specific requirements regard- may result in a fatal acute allergic bat origin in the United States than of ing bats have not been described, reaction. any other wildlife group. Furthermore, though bat roosts with long-term the disease in bats is more widely dis- In a small percentage of chronic infestation are often mentioned in the tributed (in all 48 contiguous states in histoplasmosis cases, the fungus dis- literature. 1989) than in any other species. In seminates to involve multiple organ Canada, bats also rank third (behind While histoplasmosis in the United systems and may be fatal. This form is foxes and skunks) in the incidence of States is particularly endemic to the usually seen in young children (1 year wildlife rabies. Therefore, every bat Ohio-Mississippi Valley region (which or older) and in immunocompromised bite or contact must be considered a is also an area with the greatest star- adults. In recent years, systemic infec- potential exposure to rabies. While ling concentration) and areas along the tions have been increasing in fre- aerosol transmission of the rabies virus Appalachian Mountains, it is also quency globally as an opportunistic from bats in caves to humans and found in the lake and river valleys of infection of AIDS patients. some other mammals has been other states. Outside areas with reported, this is not a likely route of “appropriate” environmental condi- Legal Status infection for humans entering bat tions, there also occur scattered foci roosts in buildings in temperate North with high infection rates usually The lethal control of bats, even when America. Note that vampire bats are associated with caves inhabited by there is a proven potential danger to not a threat north of Mexico. bats or birds. humans, often is subjected to careful scrutiny and interagency coordination. Significance. When soil or guano Histoplasmosis—General Epidemi- A survey of federal legislative actions, containing H. capsulatum is physically ology. Histoplasmosis is a very com- court decisions, and agency interpreta- disturbed, the spores become airborne. mon lung disease of worldwide tions concerning bats can be found in Persons at particular risk of histoplas- distribution caused by a microscopic Bat Management in the United States mosis of bat origin include spelunkers, fungus, Histoplasma capsulatum. (Lera and Fortune 1979). bat biologists, pest control technicians, Histoplasma exists in nature as a sapro- people who clean out or work in areas phytic mold that grows in soil with Some states have laws that specifically where bats have habitually roosted, high nitrogen content, generally associ- mention bats, either providing or and people in contact with guano- ated with the guano and debris of denying protection. Others have legis- enriched soil — such as around the birds (particularly starlings, Sturnus lation that applies to bats only by foundation of a building where guano vulgaris, and chickens) and bats. Wind interpretation, since bats may be con- has sifted down through the walls. is probably the main agent of dis- sidered nongame wildlife or indig- enous state mammals. Some bats have persal, but the fungus can survive and Infection occurs upon inhalation of protection as either federal or state- be transmitted from one site to another spores and can result in a variety of listed endangered species, but the in the intestinal contents of bats, and clinical manifestations; severity par- same state may not protect other spe- also in the dermal appendages of both tially depends on the quantity of cies of bats. Enforcement and public bats and birds. The disease can be spores inhaled. The infection may education must accompany legislation acquired by the casual inhalation of remain localized in the lungs where it to accomplish the intended goal of windblown spores, but infections are may resolve uneventfully; this is the protecting the public and saving more likely to result from visits to case for about 95% of the 500,000 infec- endangered bats. Familiarity with the point sources of growth of the fungus. tions occurring annually in the United appropriate federal and state laws Relative to bats, such sources include States. Such infections are identified should precede any nuisance manage- bat roosts in caves, barns, attics, and only by the presence of a positive ment activities. belfries, and soil enriched with bat histoplasmin skin test and/or calcified guano.

D-15 Damage Prevention and Locating the Roost(s). It is not America. Treatments might otherwise Control Methods always possible or convenient to con- result in the unnecessary death of ani- duct a bat watch. Thus, a detailed in- mals (especially young unable to fly) spection inside the building for bats or trapped inside, offensive odors, and Premanagement Considerations bat sign may be necessary to find attraction of arthropod scavengers. Bat Watch for Infestation Confir- specific roosts. Daytime is best, espe- Disease Considerations mation. To confirm that bats are actu- cially during the warmer part of the ally roosting in or on a building, look day. Bats roost in the most varied Rabies — Preventive Measures. It for bats flying in and out of a site and/ kinds of buildings and in every part should be noted that newspapers, tele- or for signs of infestation. A bat watch from cellar to attic. Some types of vision, and other mass media some- can be conducted by two people (more buildings appear preferable (older times misrepresent the role of rabid may be necessary to observe large or houses, churches, barns, proximity to bats as a risk to humans. However, the complex sites) posted at opposite cor- water) as do certain roost locations unfortunate recent (1983 to 1993) ners of a structure. An evening watch therein, especially areas with little dis- deaths of a 22-year-old man in Texas, a begins about 30 minutes before dark turbance, low illumination, little air cir- 30-year-old bat scientist in Finland, a and a morning watch begins about 1 culation, and high temperatures. Often university student in British Columbia, hour before dawn. Observations it is easy to locate bats, especially in a 5-year-old girl in Michigan, a man in should continue for approximately 1 warm weather in attics or lofts, where Arkansas, an 11-year-old girl in New hour. they may hang in clusters or side-by- York, and a woman in Georgia amply side from the sloping roof lath, beams, underscore the need to pay prompt Such observations can indicate exit/ and so forth. However, bats have the attention to bat bites and other entry points and the number of bats. ability to find crevices and cavities, exposures. With practice, distinguishing some bat and if disturbed may rapidly disap- species may also be possible. For Many rabies exposures could be pear into the angles between converg- example, compared to the big brown avoided if people simply refrained ing beams, behind such beams or bat, the little brown bat is noticeably from handling bats. Adults and chil- wallboards, into mortise holes on the smaller in size, and its flight has more dren should be strongly cautioned underside of beams, and into the mul- rapid wing beats, and more rapid never to touch bats with bare hands. tilayered wall and roof fabrications. If turning and darting. All necessary measures should be bats cannot be openly observed, usu- taken to ensure that bats cannot enter It may be necessary to watch for more ally there are various interior and exte- living quarters in houses and apart- than one night to compensate for rior signs of their presence. Often there ments. Pet cats and dogs should be weather conditions, bats’ sensitivity to are multiple roost sites within or on a kept up-to-date in rabies vaccinations. observers, noisy or inexperienced ob- single building. This is also true for pets confined servers, and improper use of light. Ob- Problem Assessment. Once it has indoors, because contact with bats fre- servations can be enhanced with a been confirmed that bats are present, quently occurs indoors. Valuable live- standard flashlight, but be certain to one must determine if there is damage, stock also should be vaccinated if kept keep the bright part of the beam as far if there is a health risk, and if some in buildings harboring bats or if in a as possible away from the exit hole be- intervention is warranted. There are rabies outbreak area (NASPHV 1993). ing observed. Bright light will increase circumstances in which “no action” is While transmission of rabies from bats bats’ reluctance to exit and may result the correct action because of the bene- to terrestrial mammals apparently is in an incomplete exit of the colony. A ficial role of bats. In cases where there not common, such incidents have been valuable observation aid is a powerful, is risk of contact, damage from excreta reported (Reid-Sanden et al. 1990, rechargeable flashlight equipped with accumulations, stains, and so on, inter- Trimarchi 1987). Dogs, cats, and live- a plastic, red pop-off filter (similar to vention may be necessary. stock that have been exposed to a the Kodak Wratten 89B). Also, an elec- rabid or suspected-rabid animal, but tric headlamp, supplied with recharge- Timing. With the exception of disease are not currently vaccinated, must be able batteries and fitted to a climbing treatment and removal of the occa- either quarantined or destroyed. or spelunking helmet, allows hands-off sional bat intruder, timing becomes an illumination outdoors as well as in- important planning consideration. Lastly, pest control technicians, nui- doors when exploring roost locations. Management procedures must not sance wildlife control personnel, wild- Bats are sensitive to light intensity and complicate an already existing prob- life biologists, and other individuals at can visually discriminate shapes and lem and should emphasize bat conser- particular risk of contact with rabid patterns in extremely low light situa- vation. Therefore, all interventions bats (or other wildlife) should receive a tions. They can only see in black and should be initiated before the young rabies pre-exposure vaccination. This white; hence, the low-contrast illumi- are born or after they are weaned and effective prophylaxis involves only nation and soft shadows produced by able to fly. Thus, the annual opportu- three injections of rabies vaccine, red light has little effect on bats. nity extends from about mid-August which are administered in the arm to mid-May for much of North during a month’s time.

D-16 Rabies — Treatment for Expo- nated, wear protective clothing and Removal of Occasional Bat sure. If a person is bitten or scratched gloves that can be removed at the site Intruders by a bat, or there is any suspicion that and placed in a plastic bag for later de- A bat that has blundered into the liv- bat saliva or nervous tissue has con- contamination via formalin and wash- ing quarters of a house will usually taminated an open wound or mucous ing. Also, clean footwear before find its way out by detecting air move- membrane, wash the affected area leaving the site to prevent spore dis- ment. When no bite or contact with thoroughly with soap and water, cap- semination in cars, the office, at home, people or pets has occurred, the sim- ture the bat without damaging the and elsewhere. plest solution for “removing” the bat is head, and seek immediate medical Guano deposits and guano-enriched to try to confine it to one room, then attention. The incident should be soils should not be unnecessarily dis- open windows and doors leading out- reported promptly to local health turbed. Dampening with water or doors and allow it to escape. If the bat authorities in order to arrange rabies scheduling outdoor work at a time is present at night, the lights should be testing of the bat. when the ground is relatively wet will dimmed to allow the animal to find If the bat is captured and immediate minimize airborne dust. Chemically open doors and windows; some light transportation to the testing laboratory decontaminate known infective foci is necessary if an observer is to insure is possible, and if immediate testing with a spray of 3% formalin (see CDC that the bat finds its way out. If bright can be arranged, postexposure treat- 1977). To protect the environment, lights are kept on, the bat may become ment may be delayed several hours decontamination must be conducted confused and may seek refuge behind until the test results are known. in accordance with state and local shelving, curtains, hanging pictures, or Postexposure prophylaxis must be regulations. Chemical decontamina- under furniture. administered immediately, however, if tion of an “active” bat roost should be Healthy bats normally will not attack the bat cannot be captured, if prompt conducted only after the bats have people even when chased. Chasing a transportation to the laboratory is not been excluded or after bats have flying bat with a folded newspaper, possible, if the specimen is not suitable departed for hibernation. tennis racket, or stick will cause the bat for reliable diagnosis, or if the test Histoplasmosis — Treatment. to take evasive action, and a bat’s results prove positive for rabies. Most infections in normally healthy flight reversal to avoid a wall is often The prophylaxis has little resemblance individuals are benign and self-limit- misinterpreted as an attack. These to that of many years ago. Today, it ing and do not require specific therapy flailings, often futile, will cause a bat to consists of one dose of rabies immune (George and Penn 1986; Rippon 1988). seek safety wherever possible, making globulin (human origin) and one dose Treatment with an antifungal agent escape more difficult for the bat and of rabies vaccine (human diploid cell) may be prescribed in more severe more frustrating for the human. administered preferably on the day of cases; amphotericin B and/or oral If the bat has difficulty escaping, it can exposure, followed by additional imidazole ketoconazole are typically be captured in a hand net (for exam- single doses of rabies vaccine on days recommended depending on the spe- ple, an insect net [Fig. 9]). Otherwise, 3, 7, 14, and 28 following the initial cific nature of the infection. injection. This treatment is normally safe, relatively painless, and very effective. Histoplasmosis — Preventive Measures. Histoplasmosis can most easily be prevented by avoiding areas that harbor H. capsulatum. Since this is not practical for individuals who must work in and around active/inactive bat roosting sites, other measures can be recommended to reduce the risk of infection during cleaning, field study, demolition, construction, and other activities. Persons working in areas known or suspected to be contaminated with H. capsulatum should always wear protective masks capable of filtering out particles as small as 2 microns in diameter or use a self-contained breathing appa- ratus. In areas known to be contami- Fig. 9. Using an insect net to remove a bat from a building.

D-17 wait for it to come to rest, quickly sue or plastic will wave and flutter cover it with a coffee can or similar from air movements (Fig. 10). Indoor container, and slide a piece of card- air leaks can be found easily by the use board or magazine under the can to of an air flow indicator (Fig. 11). Small- trap the bat inside (NYSDH 1990). volume smoke generators can be used Take the captured bat outdoors and to locate openings in the floor, ceiling, release it away from populated areas, attic, and basement. Obscure openings preferably after dark. Note that also may be located from outside the reasonably thick work gloves should house by activating smoke candles or be worn at all times when trying to smoke bombs (as within an attic), capture a bat. Also, if a bite or physical which will produce easily observed contact occurs, capture the bat without dense smoke. Be careful of any fire damaging its head and immediately hazards. contact a physician (see previous The easiest time to seal bats out of section regarding rabies treatment). buildings in northern latitudes is dur- Management of problems involving ing the cooler part of the year when bat colonies require more complicated colonies are not resident. During this procedures and a greater time commit- period, many homeowners need to be ment. reminded that bats, and bat problems, Exclusion return each summer. Basic carpentry, masonry, and tinsmith skills are valu- Fig. 10. Using a clothes hanger/plastic film com- Preventive Aspects. The most satis- able in bat exclusion and other bination to detect air leaks. factory and permanent method of pestproofing interventions. managing nuisance bats is to exclude Devices and Methods. Exclusion The traditional way to exclude bats them from buildings. Locate bats and becomes “denial of reentry” once the from an occupied roost involves five their points of exit/entry through bat bats have returned to establish mater- basic steps: (1) identify and close all in- watches or other inspection methods. nity colonies (and before the young are door openings through which bats This is a tedious process to locate all born), usually from April through might gain access to human living openings in use, and bats may switch mid-May in the Northeast. Denial of quarters; (2) close most confirmed and to alternate ones when normal routes reentry is also appropriate anytime all unused potential exterior exits, become unavailable. Thus, consider after mid-August when young are leaving only a few major openings (it’s “potential” as well as “active” points capable of flying, as long as bats con- best to complete this within 1 to 2 of access. tinue to utilize the roost. days); (3) at night shortly after the bats Often it is apparent where bats might gain entrance even when such openings are not directly observable. By standing in various locations of a dark- ened attic during daylight hours, one often can find leaks of light at the extreme parts of eaves, in layers of subroofing, and below chimney flashings. Seal all gaps of 1/4 x 1 1/2 inches (0.6 x 3.8 cm) and openings 5/8 x 7/8 inch (1.6 x 2.2 cm) or greater. Bats will also use some of the same obscure holes in buildings through which heat (or cooled air) is lost; thus, bat-proofing often conserves energy. Simple, homemade devices can be used to locate air leaks. Bathroom tissue or very thin plastic film bags can be taped to a clothes hanger. When placed in front of an area with an air leak (for example, around window frames and sashes where caulking or weatherstripping are needed), the tis- Fig. 11. Smoke from the Sensidyne Air Indicator makes it possible to visually determine the direc- tional pattern of air currents.

D-18 have departed to feed, temporarily close the few remaining, major exits; (4) check the roost for presence of bats and, if any remain, unplug the temporarily closed exits early the next evening to allow the bats to escape, then temporarily replug the exits (it may be necessary to repeat this step more than once); and (5) when the bats are all out, permanently seal the holes (Frantz and Trimarchi 1984, Greenhall 1982). Patience and timing are very important in this process. Much of this work can be done during daylight hours except steps 3 and 4, which require climbing on ladders and roofs at night, Fig. 12. Bat on birdnetting showing size relationships. sometimes with bats flying nearby. The danger of such work is obvious To overcome difficulties with exclus- exit point — a single hole, a series of and discouraging. ion devices, Frantz’ checkvalve was holes, or a long slitlike opening (Fig. developed using netting made of Some of these difficulties have been 13). Designs must be open enough not durable black polypropylene resin overcome by use of the Constantine to impede the exiting bats. The top can (Frantz 1984, 1986). Quality of product one-way valvelike device which is be much larger than the bottom. It is is important since the netting should installed in the last exit(s) during the probably best to restrict the bottom not fray or become misshapen under day, and permits bats to leave after opening to no larger than about 1.6 x hot summer conditions. Use only dark but prevents their reentry (Con- 1.6 feet (0.5 x 0.5 m). The length of a structural grade material that has stantine 1982). Eventually the valve checkvalve, that is, the distance from openings no larger than 1/2 x 1/2 inch should be removed and the hole(s) the lowest enclosed point of egress to (1.3 x 1.3 cm), weighs about 1.3 ounces sealed. Another device, the EX-100 the bottom of the netting, should be per square yard (44 g/m2) and is flex- Hanks Bat Excluder, consists of a piece about 3.3 feet (1 m). ible yet stiff enough to maintain the of nylon window screening, a wooden The above specifications usually are shape of the checkvalve fabricated plate with a hole in the middle to sufficient to abort bats’ reentry at- (Fig. 12). Waterproof duct tape, com- which is attached a one-way plastic tempts. If netting is applied while mon staples, and/or wooden lath flappervalve, and a rigid plastic mesh young are still in the roost, the strips are used to attach the netting to cone (Anon. 1983). The screening, to “evicted” mothers may be motivated metal, slate, brick, wood, asphalt which the wooden plate is attached, is to chew holes in the netting to reenter shingle, or other surfaces. Note that used to cover an opening that bats use the roost. Applied at the correct time duct tape may stain or discolor to exit a building. Both devices are of year, however, netting will allow all painted/enameled surfaces if kept in designed to be used on the last few bats to exit at dusk and thereafter deny contact for long periods of time. exit points. Installation instructions are them reentry. available, and properly applied they Application of checkvalves follows the Checkvalves should be kept in place will undoubtedly exclude bats from same two initial steps as traditional bat for 3 to 5 days. It is best to verify (con- relatively small, discrete openings. exclusion. Close interior openings, duct a bat watch) that bats no longer then close exterior openings except a The devices of Constantine and Hanks exit at dusk before the checkvalves are few major exits. These latter openings involve a one-way, self-closing valve dismantled and the holes are sealed will have been confirmed as important feature and can be readily installed permanently. As in any exclusion via bat watches, and it is here that during daylight hours. Such devices intervention, the excluded animals will checkvalves will be fitted during the are not readily adaptable to situations go elsewhere. This shift may be to an daylight. with large, diffuse and/or widely dis- alternative roost already in use such as tributed entryways. Also, bats can be The basic design is to attach the netting a night roost, or one used in previous inadvertently trapped inside if an around an exit hole except at the bot- years. important exit hole is mistakenly iden- tom where the bats will escape (see tified as a minor one and is sealed in Frantz 1986, for details). The width Supplemental Materials and an attempt to limit the number of holes and shape of checkvalves is highly Methods. While specifications for requiring an exclusion device. variable so as to embrace the necessary Frantz’ checkvalve have been

D-19 expanding polyurethane foam applied from pressurized containers can be used for openings larger than 3 inches (>7.5 cm). It must be applied with Open-bottomed box designs for bat-proofing caution so as to not lift clapboards, roof apex, roof corner, and soffit/wall interface. shingles, and other surfaces. Exposed surfaces should be sealed with epoxy paint to prevent insect infestation and ultraviolet degradation. Conventional draft sweeps (metal, rubber) and other weatherstripping supplies (felt, vinyl, metal) will seal the space between a door bottom and the threshold or around windows (Fig. 14). Remember to treat attic and basement doors whenever the gap exceeds 1/4 inch (0.6 cm). Flashing may be used to close gaps wherever joints Sleeve design for bat-proofing fascia board/clapboard inter- occur; for example, where the roof face (without roof overhang). meets a chimney. Materials commonly used include galvanized metal, copper, aluminum, and stainless steel. Self- adhesive stainless steel “tape” is also available. Insulation will provide some degree of barrier to bat movements. It is available in a number of forms and types including fiberglass, rock wool, Skirt design for bat- urethane, vermiculite, polystyrene, proofing ridge cap of tin or tile roof. and extruded polystyrene foam. Inor- ganic materials are fire and moisture resistant; the safest appear to be fiberglass and rock wool. The mesh size of screening must be small enough to prevent access of bats and other species, where desired. Hardware cloth with 1/4-inch (0.6-cm) mesh will exclude bats and mice; screening with 16 meshes per inch (2.5 Fig. 13. Sample configurations for Frantz’ checkvalve (Key: = birdnetting; ...... = attaching to cm) will exclude most insects. Soffits structure; • = exit/entry holes of bats). (underside of overhanging eaves) usually have ventilators of various shapes and sizes. Regardless of type, the slots provided, additional caulking, crevices that develop in a house as it should not exceed 1/4 x 1 inch (0.6 cm flashing, screening, and insulation ages, and are best applied during dry x 2.5 cm) and should be covered inside materials often are needed. The periods when wood cracks are widest. with insect mesh. To prevent bats from combination of materials used will Caulks that may be applied with a entering chimney flues, completely depend on the location, size, and caulking gun (in gaps up to about 0.4 enclose the flue discharge area with number of openings, and the need for inch [1 cm] wide) include latex, butyl, rust-resistant spark arresters or pest ventilation. Greenhall (1982) provides and acrylic, which last about 5 years. screens, secured to the top of the many details of bat-proofing methods Elastomeric caulks, such as silicone chimney. These should not be perma- and materials and is a practical guide. rubber, will last indefinitely, expand nently attached (for example, with Weatherstripping, knitted wire mesh and contract, do not dry or crack, and screws) in case they must be rapidly (Guard-All®, Stuf-fit®), waterproof tolerate temperature extremes. Oakum removed in the event of a chimney duct tape, stainless steel wool, and packs easily and firmly into small fire. Review fire codes before installing wood lath may be used to block long, cracks. Other fillers include sponge flue covers. Dampers should be kept narrow openings. Caulk-ing rubber, glass fiber, knitted wire mesh, closed except in the heating season. compounds will seal cracks and and quick-setting putty. Self-

D-20 Roof Problems. Rolled vinyl Adhesive-backed foam rubber Bats, particularly the Mexican free-tailed bat, often roost under Spanish or concrete tile roofing by entering the open ends at the lower- most row or where the tiles overlap (Fig. 15). Tight-fitting plugs are difficult to make due to the variation in opening sizes and thermal expansion and contraction. A solution was found Outside Inside Ouside Inside by Constantine (1979) in which a layer of coarse fiberglass batting was laid Window sash Window sash under the tiles so that bats entering holes would contact the fiberglass and Windowsill Windowsill be repelled. A layer of knitted wire mesh would undoubtedly work well for this purpose (and would not hold moisture). Bats also may be excluded Inside Inside from the tiles if rain gutters are Doorjamb Doorjamb installed directly under the open ends. Door Door Gaps under corrugated and galvanized roofing may be closed with knitted wire mesh, self-expanding foam (avoid causing roofing to lift), or with Outside Outside fiberglass batting (may retain moisture). Door sweep Rubber or fitted to bottom plastic gasket Wall Problems. Fiberglass or rock of door fitted to wool insulation blown into wall spaces bottom of door that are used by bats may be a deter- Inside rent, especially when it forms a physi- Outside cal barrier to passage. Such work must be done when bats are absent to avoid Rubber or plastic Interlocking their entrapment. gasket fitted to metal doorsill Temporary Roosts. Bats will some- metal doorsill and door shoe times temporarily roost on porches and patios, in garages, and behind Inside Inside shutters, shingles, and roof gutters. Roosting behind shutters may also be long-term in duration. Actual control measures may not be necessary unless Fig. 14. Weatherstripping and door sweeps are very useful bat-proofing measures. bat droppings become a problem or the risk of human contact is significant. Coarse fiberglass batting tacked to the surfaces where bats prefer to hang sometimes discourages them. A poten- tially useful intervention for the wall- ceiling interface is the application of a wide 45o molding strip to eliminate the 90o angle corner and force the bats to roost in a more exposed area.

Repellents While many chemical aromatics and irritants have been proposed and tested for bat repellency, efficacy has been very limited thus far.

Fig. 15. Open ends of tile roofs may allow bat entry and provide roosting sites.

D-21 Naphthalene crystals and flakes are they fly toward an entrance hole Section 24(c) of the Federal Insecticide, the only repellents registered by the (Frantz, unpublished data). The results Fungicide, and Rodenticide Act D-18 US Environmental Protection Agency have not been promising. Numerous (FIFRA). Lipha Tech, Inc. (the manu- (EPA) for indoor bat control and are to ultrasonic devices have been removed facturer of RoZol ) has voluntarily can- be applied in attics or between walls. from clients’ homes because the bats celled its registration for “RoZol Sometimes the chemical may be placed remained in the roost after the devices Tracking Powder for Control of Nui- in loose-mesh cloth bags and sus- were activated. Hurley and Fenton sance Bats” — effective December 16, pended from the rafters. About 2.5 (1980) exposed little brown bats to ul- 1991 (Fed. Reg., 1991). pounds per 1,000 cubic feet (1.2 kg/30 trasound in seminatural roosts with m3) is recommended to chronically re- virtually no effect. Largely because of Trapping pel bats as the chemical vaporizes. this lack of known scientific efficacy Kunz and Kurta (1988) reviewed an Dosages of 5 pounds per 1,000 cubic for ultrasonic devices, the New York extensive variety of efficient methods feet (2.4 kg/30 m3) may dislodge bats State Consumer Protection Board has for trapping bats from buildings and in broad daylight. Bats will return, cautioned against the use of such other roosting sites or foraging areas. however, when the odor dissipates. devices (NYSCPB 1988). Part of the For purposes of wildlife damage The prolonged inhalation of naphtha- concern is that such devices will pro- control, however, exclusion is less lene vapors may be hazardous to vide consumers with a false sense of complicated to carry out, less time- human health. security and, thus, may prevent them consuming, more effective, and from taking effective preventive Illumination has been reported to be requires no handling of bats. actions. an effective repellent. Floodlights strung through an attic to illuminate Distress cries of bats recorded on tape Other Methods all roosting sites may cause bats to and rebroadcast can be used to attract Sanitation and Cleanup. Once bats leave. Large attics may require many other bats to nets or traps, but they do have been excluded, repelled, or have 100-watt bulbs or 150-watt spotlights not serve as an effective repellent. departed at the end of the summer, to be effective. Fluorescent bulbs may Little brown and big brown bats measures must be completed to make also be used. In some situations such respond to their own distress cries but reinfestation less likely, and to lighting is difficult, costly, and may not to the cries of other species. eliminate odor and problematic result in an electrical hazard. Where Contact repellents, such as sticky-type bioaerosols. As a prelude to such possible, the addition of windows to bird repellents and rodent glues, have work, it is sometimes useful to apply a brighten an attic will help to reduce been used successfully in situations pyrethrum-based, total-release aerosol the desirability of the roost site and is where roost surfaces and bat accesses insecticide to eliminate unwanted not likely to introduce additional may be coated. Apply masking tape to arthropods. problems. the surface first if you desire to remove The safe handling and removal of bat Air drafts have successfully repelled the repellent after treatment is fin- guano has been discussed previously bats in areas where it is possible to ished. Replenish contact repellents (see the histoplasmosis section in this open doors, windows, or create strong occasionally, since dust accumulation chapter). In addition to the more bulky breezes by use of electric fans. Addi- causes them to lose their tackiness. accumulations of excreta, there are tion of wall and roof vents will Also, caution must be exercised so as often diffuse deposits of guano under/ enhance this effort, as well as lower to apply coatings that will be sticky, among insulation materials, caked roost temperature. These measures but will not entrap the bats. urine and guano on roof beams, and will increase the thermoregulatory splattered urine on windows. Such Toxicants (not recommended) burden on the bats, thus making the clean-up work during hot summer roost less desirable. In a similar fash- No toxicants are registered for control- weather may be the least desirable ion, colonies located in soffits, behind ling bats. In 1987 the Centers for activity of a management program, but cornices, and other closed-in areas can Disease Control, United States Depart- it is necessary. be discouraged by opening these areas ment of Health and Human Services, All caked, crystallized bat urine and to eliminate dark recesses. Discourage voluntarily withdrew the last registra- droppings should be scraped and bats from roosting behind shutters by tion for DDT use against bats in the wire-brushed, as necessary, from all removing the shutters completely or United States. Thus, DDT is no longer roof and attic beams. For this proce- by adding small blocks at the corners registered for any use in this country. to space them a few inches away from dure, workers should take the same the wall. Although federally registered for precautions as outlined for histoplas- rodents, chlorophacinone (RoZol ) mosis-related work. Accumulated Ultrasonic devices have been tested tracking powder, an anticoagulant, is excreta and contaminated insulation under natural conditions, both indoors not registered for bats. Furthermore, it should be sealed in plastic bags and and outdoors, to repel little brown and can no longer be registered by indi- removed for disposal. Remove all big brown bats either in the roost or as vidual states for restricted use under remaining droppings and debris with

D-22 No figures are available to determine the extent of damage caused by nuisance bats or the cost for their control. The problem is widespread in this and other countries. Costs for remedial services are highly variable, depending on the nature of the problem and who will do the work. For example, to fabricate a few Frantz’ checkvalves on the “average” two-story house would probably require two workers about one-half day, mostly on stepladders, and less than $50 in materials. Much more time would be required to seal up all the other active and potential bat exit/ entry holes. In addition, if a deterio- rated roof, eaves, or other woodwork Fig. 16. One of five bat houses constructed to provide an alternative roost for bats excluded from must be replaced, the costs can nearby structures. increase rapidly. a vacuum cleaner, preferably one that Development of an efficient method to It is often difficult or expensive for the has a water filter to reduce the amount relocate bats into alternative roosts public to obtain the services of reliable, of dust that escapes from the cleaner’s after they have been excluded from licensed pest control operators (PCOs). exhaust. buildings could be an important inter- Many PCOs have limited knowledge vention in comprehensive bat manage- of basic bat biology and are apprehen- Where possible, wash with soap and ment. Frantz (1989) found it helpful to sive to work with bats. They may want water all surfaces contaminated with “seed” newly constructed bat houses to avoid any liabilities should bat- urine and guano. Allow the surfaces to with several bats, a procedure that human contact occur. Select a qualified dry, then disinfect them by misting or later resulted in full-scale colonization professional service that concentrates swabbing on a solution of 1 part without further human interventions. on the exclusion of live bats from a household bleach and 20 parts tap Alternative roosts should be located structure rather than on use of lethal water. Ventilate the roost site to allow away from human high-use areas. chemicals. odors and moisture to escape. Installa- Thus, people can enjoy the benefits of tion of tight-fitting window screens, bats without sharing their dwellings Acknowledgments roof and/or wall ventilators in attics with them and with little risk of direct will enhance this process. Remember, contact with them. The authors wish to thank the many people who sanitation and cleanup accompanies have allowed them and other bat researchers to bat-proofing and exclusion measures, work in and about their homes, and have, thus, it does not replace them. contributed to this effort. We give special thanks Economics of Damage to Roger W. Barbour and Wayne H. Davis for and Control permission to reproduce figures from their Artificial Roosts. For more than 60 excellent book, Bats of America (University Press years, artificial bat roosts have been of Kentucky). Charles V. Trimarchi is Virtually all bats are of some economic used in Europe. Only recently have acknowledged for carefully reviewing this importance; those north of Mexico are chapter and providing many useful comments. they gained some popularity in the beneficial because of their insectivo- We thank Debra VonZwehl and Christine United States. Though the results are rous diet which eliminates many insect Borecki for processing the manuscript. variable, it appears that artificial pests of humans. The accumulated bat Figures 2 through 4 from Barbour and Davis roosts, if properly constructed and droppings, called guano, is rich in (1979). located, can attract bats that are dis- nitrogen and is a good organic fertil- Figure 5 adapted from Harvey (1986). placed or excluded from a structure. izer. At one time, bat guano was com- The Missouri Department of Conser- Figure 6 adapted from Tuttle (1988), except Yuma mercially mined in the Southwest; but vation described a successful “bat ref- myotis and Keen’s bat (from Barbour and Davis its importance has declined due to 1979). uge” that was quickly occupied by a reduced bat populations and the displaced colony of little brown bats Figure 7 adapted from Trimarchi and Frantz (1985). development of inorganic fertilizers. (LaVal and LaVal 1980). Bat houses of Figure 8 by R. Suss. Bat guano is still considered a valuable a similar design have been successfully fertilizer resource in some parts of the Figures 12, 15, and 16 by S. C. Frantz. used in Minnesota, New York, and world (such as Thailand and Mexico). elsewhere (see Fig. 16). Figures 9, 10, 11, and 14 from Greenhall (1982) Figure 13 by S. C. Frantz

D-23 For Additional Geluso, K. N., J. Scott Altenbach, and R. C. NYSDH. 1990. Bat rabies in New York State. Kerbo. 1987. Bats of Carlsbad Caverns Publ. No. 3003, New York State Dep. Health, Information National Park. Carlsbad Caverns Natural Albany. 12 pp. Hist. Assoc., Carlsbad, New Mexico. 34 pp. Reid-Sanden, F. L., J. G. Dobbins, J. S. Smith, and Anonymous. 1983. Wisconsin firm develops bat George, R. B., and R. L. Penn. 1986. D. B. Fishbein. 1990. Rabies surveillance in excluder. Pest. Control Technol. 11:74. Histoplasmosis. Pages 69-85 in G. A. Sarosi the United States during 1989. Spec. Rep., J. and S. F. Davies, eds. Fungal diseases of the Am. Vet. Med. Assoc. 197:1571-1583. Anonymous. 1986. States focus on bat lung. Grune and Stratton, Inc., New York. conservation. Bats. 3(3): 3-4. Rippon, J. W. 1988. Histoplasmosis Greenhall, A. M. 1982. House bat management. (Histoplasmosis capsulatum). Pages 381-423 in Barbour, R. W., and W. H. Davis. 1979. Bats of Resour. Publ. No. 143. US Dep. Inter., Fish J. W. Rippon, ed. Medical mycology. W. B. America. Univ. Kentucky Press, Lexington. Wildl. Serv., Washington, DC. 33 pp. Saunders Co., New York. 286 pp. Harvey, M. J. 1986. Arkansas bats: a valuable Stebbings, B., and S. Walsh. 1985. Bat boxes. Barclay, R. M. R., D. W. Thomas, and M. B. resource. Arkansas Game Fish Comm., Little Fauna and Floral Preserv. Soc., London. Fenton. 1980. Comparison of methods used Rock. 48 pp. 16 pp. for controlling bats in buildings. J. Wildl. Manage. 44: 501-506. Hill, J. E., and J. D. Smith. 1984. Bats: A natural Trimarchi, C. V. 1987. Rabies transmission from history. Univ. Texas Press, Austin. 243 pp. bats to terrestrial mammals: evidence of CDC. 1977. Histoplasmosis control. US Dep. frequency and significance. Bat Res. News. Health, Educ. and Welfare, Centers for Hurley, S., and M. B. Fenton. 1980. 28(3-4):38. Disease Control, Atlanta, Georgia. 10 pp. Ineffectiveness of fenthion, zinc phosphide, DDT and two ultrasonic rodent repellers for Trimarchi, C. V., M. K. Abelseth, and R. J. Rudd. Constantine, D. G. 1979. Bat rabies and bat control of populations of little brown bats 1979. Aggressive behavior in rabid big management. Bull. Soc. Vector Ecol. 4:1-9. (Myotis lucifugus). Bull. Environ. Contam. brown bats (Eptesicus fuscus). Pages 34-35 in Constantine, D. G. 1982. Bat-proofing of Toxicol. 25:503-507. Rabies Information Exchange, No. 1. US Dep. buildings by installation of valve-like Human Health Services, Centers for Disease Krebs, J. W., R. C. Holman, U. Hines, T. W. devices in entryways. J. Wildl. Manage. Control, Atlanta, Georgia. Strine, E. J. Mandel, and J. E. Childs. 1992. 46:507-513. Rabies surveillance in the United States Trimarchi, C. V., and S.C. Frantz. 1985. Bat Dalquest, W. W., and D. W. Walton. 1970. during 1991. Special Report, J. Am. Veterin. control. New York State Dep. Health Diurnal retreats of bats. Pages 162-187, in B. Med. Assoc. 201 (12):1836-1848. Pamphlet, Albany. 6 pp. H. Slaughter and D. W. Walton, eds. About Kunz, T. H. 1982. Roosting ecology of bats. Tuttle, M. D. 1988. America’s neighborhood bats. Southern Methodist Univ. Press, Dallas, Pages 1-55 in T. H. Kunz, ed. Ecology of bats. bats. Univ. Texas Press, Austin. 96 pp. Texas. Plenum Press, New York. Tuttle, M. D., and D. Stevenson. 1982. Growth Fed. Reg., 1991. Notices, Federal Register/ Kunz, T. H., and A. Kurta. 1988. Capture and survival of bats. Pages 105-150 in T.H. August 28, 1991. 56(167):42615, 42620, and methods and holding devices. Pages 1-29 in Kunz, ed. Ecology of bats. Plenum Press, 42621. T.H. Kunz, ed. Ecological and behavioral New York. Fenton, M. B. 1983. Just bats. Univ. Toronto methods for the study of bats. Smithsonian US EPA. 1980. Re. Bradley Exterminating Press, Toronto. 165 pp. Inst. Press, Washington, DC. Company, Richfield, MN, Dockett No. I. Frantz, S. C. 1984. Excluding housebats with Laidlaw, W. J., and M. B. Fenton. 1971. Control F&R. V-604-C, May 8, 1980. US Environ. birdnetting. Bat Res. News. 25(3/4):40-41. of nursery colony populations of bats by Protect. Agency, Kansas City, Missouri. artificial light. J. Ecol. Manage. 35:843-46. 50 pp. Frantz, S. C. 1986. Bat-proofing structures with birdnetting checkvalves. Proc. Vertebr. Pest LaVal, R. K., and M. L. LaVal. 1980. Ecological Wimsatt, W. A. 1970. Biology of bats. Vol. II. Conf. 12:260-268. studies and management of Missouri bats Academic Press, New York. 477 pp. with emphasis on cave-dwelling species. Frantz, S. C. 1987. Chlorophacinone, DDT and Missouri Dep. Conserv. Terr. Ser. 8. 53 pp. other pesticides for bat control: efforts to prohibit use in New York State. Bat Res. Lera, T. M., and S. Fortune. 1979. Bat News. 28(3-4): 34. management in the United States. Bull. Nat. Editors Speleol. Soc. 41:3-9. Frantz, S. C. 1988. Architecture and commensal Scott E. Hygnstrom vertebrate pest management. Pages 228-295 NASPHV. 1993. Compendium of animal rabies Robert M. Timm in R. B. Kundsin, ed. Architectural design control, 1993. Natl. Assoc. State Publ. Health Gary E. Larson and indoor microbial pollution. Oxford Vet., Inc. Texas Dep. Health, Austin. 4 pp. Univ. Press, New York. NPCA. 1991. Controlling bats. Technical Release Frantz, S. C. 1989. Bat houses in state parks: an ESPC 043233A, 11/13/91. Natl. Pest. experiment in New York. Bats. 7:14. Control. Assoc., Dunn Loring, Virginia. 4 pp. Frantz, S. C., and C. V. Trimarchi. 1984. Bats in NYSCPB. 1988. The quest for the pest. Consumer human dwellings: health concerns and News (July 4, 1988), pp. 29, 30. management. Proc. Eastern Wild. Damage Control Conf. 1:299-308.

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