Blackwell, B. B.

Conover, M. R.

Depaepe, V

Messmer, T. A.

English

Bats belong to the order Chiroptera which means  hand-wing.  They are the only mammal capable of true flight. There are approximately 950 species of bats in the world, making up over 20% of all mammals. Of the 44 species of bats found in the United States, 18 occur in Utah during some time of the year. The big brown bat (Eptesicus fuscus) is the most common bat in Utah, and is one of the most widely distributed species in North America (Figure 1)

Messmer, Terry A.

Conover, Michael R.

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1Wildlife DamageManagement SeriesFigure 1. Big Brown Bat.NR-WD-004February 1996 BATS  USU Extension in cooperation with: CNR—Wildlife Damage Management Program Utah Division of Wildlife Resources USDA/APHIS Animal Damage Control Utah Department of Agriculture The Berryman InstituteVeda DePaepe, Dr. Terry A. Messmer, Dr. Michael R. Conover Department of Fisheries and WildlifeUtah State University, Logan, Utahand Boyde BlackwellUtah Division of Wildlife ResourcesSalt Lake City, UtahBats belong to the order Chiroptera which means scorpions. Bats use echolocation and are a major predator of“hand-wing.” They are the only mammal capable of true night-flying beetles, moths, flies, ants, and other bugs, manyflight. There are approximately 950 species of bats in the of which are considered agricultural and timber pests. Thus,world, making up over 20% of all mammals. Of the 44 bats constitute an important component of Utah’sspecies of bats found in the United States, 18 occur in Utah ecosystems.during some time of the year. The big brown bat ( Eptesicus Human-bat conflicts most commonly result whenfuscus) is the most common bat in Utah, and is one of the bats use human dwellings as habitat. Bats rarely attackmost widely distributed species in North America (Figure 1). people, but can transmit two diseases, histoplasmosisBats are intelligent, shy creatures who benefit humans. Histoplasmosis, a fungal disease that can cause ahumans by eating from 30–100% of their body weight in flu-like illness, is common east of the Mississippi River butinsects each night. In Utah, bats eat only insects, with one rare in Utah’s dry soils. Rabies occurs in less than 1% ofspecies, the pallid bat, also consuming centipedes and bats, but if contracted and not treated, can be fatal. For that(Histoplasma capsulatum) and rabies (Lyssavirus spp.), toreason, any bat that behaves strangely (e.g., active duringthe day), or can be easily caught, must be suspected of beingrabid and should be avoided. LEGAL STATUSAll bat species are protected by Utah law. It isillegal to intentionally kill bats. Additional Federalprotection is extended to bat species on the EndangeredSpecies List.2BIOLOGY and BEHAVIORUtah’s bats are from two families, Vespertilionidae(plain-nosed bats, 16 species), and Molossidae (free-tailedbats, 2 species). The largest Utah bat, the adult big free-tailed, has a wing span of 17 in. (530 mm) but weighs lessthan 1 oz. (28 g). The smallest, the adult western pipistrelle,is the size of a hummingbird and weighs 1/10 oz. (3 g). Thefur color of each species is a mixture of tans, browns, rust,and black, sometimes accented in white.Utah bats live in and use a variety of habitats asroost sites. These roosts may include caves and mines, treefoliage, hollow trees, cracks in rock cliffs, and buildings.Most Utah bat species are year-round residents of the statewho hibernate during the winter. Some bat species migratesouth and remain active all year. Hibernation is a specialadaptation bats use to survive cold periods when insects arenot available. In late summer, bats prepare for hibernationby feeding heavily and accumulating extra body fat. Mostbats are able to store enough fat to last through thehibernation period, which can last 6 months. In the autumn,bats seek out cool environments where they are able to lowertheir body temperature, breathing, metabolism, and bloodcirculation to begin hibernation. If repeatedly disturbedduring hibernation, the bats may starve to death beforespring. Because good hibernation sites are becoming morescarce, thousands of bats, of several species, may gather in asingle cave or abandoned mine. In 1992, nearly one millionbats were discovered hibernating in a single abandoned ironmine in Northern Michigan. Bats that hibernate usually mate in the autumn. Batsthat migrate, mate in the spring. The gestation period formost bats begins in early spring and ranges from 50–90days, depending on the species. In the late spring, femalebats gather in large nursery colonies where young, calledpups, are born in May or June. Most species have only onepup per year; a few species have twins. Tree-roosting redbats (Lasiurus spp.) frequently have quadruplets. Pups areblind and helpless at birth, but grow rapidly and are able tofly in 3–6 weeks. The average life span for a bat is 10–20years. Natural enemies of bats include hawks, owls, cats,raccoons, snakes, bobcats, ringtails, and weasels.BAT PROBLEMSMany bats prefer open cavities such as house atticsfor nursery colony sites. These cavities protect the bats frompredators, and offer the warmth that allows the newbornbats to use their energy for rapid growth. Large colonies candeposit sizable piles of droppings (guano) which can cause astrong, musty odor and stain ceilings and walls. In addition,bats can be noisy because of scrambling and squeaking.Bats do not chew entrances but can get into buildingsthrough any existing openings 1/4 in. (5 mm) in diameter orlarger. Bats may also get into rooms through open doorsand windows, loose or torn screens, or gaps around atticdoors. These bats are often lost youngsters just developingtheir flying skills. A bat flying around in a room may appearto be diving at people. In fact, it is merely swoopingdownward to regain flight speed and control which were lostwhen it slowed to make the turn at the end of the room.Opening an outside door, or window and screen, will allowthe bat to exit. However, if it lands, a jar or other containercan be placed over the bat and a piece of heavy paper orcardboard slid under the mouth of the container, trapping thebat inside. The bat can then be released outside away fromchildren and pets. Never attempt to touch bats with yourbare hands.If a person is bitten by a bat, they should getmedical treatment immediately. The wound should bewashed with soap and water, and your doctor and the healthdepartment should be contacted. Every attempt should bemade to capture the bat alive using the technique describedabove. The captured bat should then be taken to the healthdepartment for rabies testing. Occasionally pets catch bats.For this reason, keeping pets vaccinated against rabiesreduces the risk to humans.CONTROL IDENTIFICATION OF DAMAGE The first step in controlling bat-human conflicts isto determine what animals are causing the problem.Scratching, squeaking noises in walls, attics or chimneys canbe caused by bats, birds, mice, squirrels, or raccoons. All ofthese animals may use human dwellings for refuge at sometime if the opportunity presents itself. About half of Utah’sbat species enter and use human dwellings. Bats may occupydwellings for an entire season, or briefly during spring orfall migrations.Evidence of bat activity may first appear as a brownstain on the ceiling or walls of a dwelling, and anaccompanying musty, urine-like odor. The homeowner mayalso want to check for leaks in the roof which can causesimilar stains. If the attic or crawl space can be examined,live bats may be observed flying or roosting on the walls orbeams. If no bats are present, the area should be examinedfor droppings. Roosting bats tend to gather in clusters near the roofpeaks causing their guano to collect in piles beneath thesehigh points. Guano may also be found clinging to the raftersand roof beams. Rodent droppings will not be in piles or onrafters, and will occur more commonly along the base ofwalls. In addition, bat droppings are solid brown and6663 Figure 2. Bird netting is placed over the hole, and stapled tight along the topedge and down both sides. The bottom is left open. When the bats leave theyhit the netting and crawl down the siding and out the open bottom. Whenthey return they are unable to fly back up under the netting, and cannotreturn to their roost.crumble easily because they contain insectfragments. Rodent droppings contain plantfiber and do not crush easily. Several types of small arthropodinsects are commonly found with largecolonies of bats in buildings. Some of theseinsects live on the bats themselves, whileothers feed on the guano. These batectoparasites rarely bite humans or pets, anddo not cause diseases. Without bats or guano,the insects simply die.To determine how and where bats maybe entering buildings, the outside of thebuilding should be examined for small gaps insiding, openings around chimneys, or wherewalls meet the roof. Bats prefer entrances 12ft. (3.6 m) up or higher, but will use any smallnatural gap they can fit through. When the batsemerge at dusk to feed, watch the building andnote where they are exiting. Smallaccumulations of guano on the ground mayprovide another clue to the whereabouts of adifficult to locate entrance.HABITAT MODIFICATIONThe best way to stop bats from roosting inside because bats do not always go out each night, especially ifdwellings is to locate and seal the cracks and holes the bats the weather is cool and rainy. When all the bats have exited,are using to enter the house or rooms. Entrance holes should remove the excluders and seal the holes using materialsnot be sealed when flightless young are present (late May described earlier. through July). Excluding the parents will starve the young, If the roosting area is to be cleaned of guanoand could create a subsequent odor problem. droppings, a mask should be worn to block dust particles asBecause most bats in Utah vacate their roosts in the small as 2 microns. If possible, the area should be moistenedfall, this is the best time to close the openings. A variety of as well as ventilated while working. Deodorizing chemicalsmaterials, such as caulk, self-expanding foam sealant, foam can be sprayed on urine soaked areas. In addition, arearubber, fiberglass, oakum, or steel wool can be used to close fumigation with a total release pyrethrum-based aerosol mayany openings. Metal screening, small mesh (<1/4 in. be an appropriate solution for arthropod knockdown withindiameter) wire hardware cloth, or tar paper can be tacked an enclosed space, but only after bats have departed. Forover larger holes. Corrugated steel or Spanish tile roofs can long-term arthropod control, lightly dust appropriatebe blocked at the edges with coarse steel wool or crumpled surfaces (affected attic beams, soffits) with boris acidballs of metal screening. Since steel and tile roofs can powder or diatomaceous earth. Carefully read all productaccumulate considerable heat they should not be sealed air- labels before using any pesticide.tight. To keep bats and birds out of chimneys, sparkarresters or bird screens may be installed.When eviction cannot wait for the fall season, an Unfortunately, no ultrasonic or chemical repellentsalternative exclusion technique can be used. Heavy plastic appear to be even moderately effective in permanentlysheeting or quarter-inch or smaller polypropylene fruit-tree eliminating bats from their roosts in buildings. Thebird netting (purchased at garden shops or hardware stores) Environmental Protection Agency (EPA), which regulates allcan be hung, using duct tape or staples, several inches chemicals used on wildlife, permits only one chemical,directly above the exit holes. The netting should extend at naphthalene (crystals or flakes) as a bat repellent for indoorleast 1 ft. (350 mm) to each side and below the exit hole use. Naphthalene, applied at the rate of 5 lb. (2.3 kg) per(Figure 2). The sides may be attached to the buildings, but 2000 ft  (60 m ) of attic space, will create a strongthe bottom must hang free permitting the bats passage to the disagreeable odor for a short period of time. This may helpoutside. They will have no trouble dropping down to leave, encourage the bats to leave. However, caution should bebut will be unable to reenter the building through thecovered hole. Leave the netting in place for at least 4–5 daysREPELLENTS3 3The BerrymanInstitutetaken because such concentrations of fumes can affecthumans. All exit holes should be sealed as soon as the batsleave or they will return when the naphthalene fumesevaporateAerosol dog and cat repellent may discourage batsfrom using a particular outdoor roosting spot for up toseveral months. The spray may be applied to the roost whenthe bats are away, but never on the bats themselves.POPULATION MEASURESThere are no chemicals or toxicants registered forlethal control of bats. In the past, the EnvironmentalProtection Agency permitted the use of chemicals such asDDT and RoZol (chlorophacinone) to kill unwanted batpopulations. All such registrations have been withdrawn.BEHAVIORAL APPROACHESProviding bats with alternative roosts can encouragethem to remain in the area and reduce their mortality whenthey are excluded. Potential roost sites may include hollowtrees, unused barns or out-buildings, providing the roofs areintact and large openings are closed to provide additionalprotection from inclement weather. In addition, bat housescan be constructed and placed around the property. Ideally,alternative roosts should be prepared before the bats areexcluded from the original site. Plans for bat houses areavailable from bat books, through your local Utah Divisionof Wildlife Resources, or local Utah State University CountyExtension Service Office. ADDITIONAL SOURCES OFINFORMATION AND ASSISTANCEFor further information, contact:Utah Division of Wildlife Resources, 1596 West NorthTemple, Salt Lake City, UT 84116-3159. Phone(801) 538-4700.USDA/APHIS Animal Damage Control, P.O. Box 26976,Salt Lake City, UT 84126 . Phone (801) 975-3315.Extension Fisheries and Wildlife Specialist, Department ofFisheries and Wildlife, Utah State University,Logan, UT 84322-5210. Phone (801) 797-3975.Utah Department of Agriculture, 350 North Redwood Road,Salt Lake City. UT 84116. Phone (801) 538-4171.Berryman Institute, Utah State University, Logan, UT84322-5210. Phone (801)797-2436.References and books on bats:Fenton, M. B. 1983.  Just Bats. University of Toronto Press.Toronto, Can.Fenton, M. B. 1992 . Bats. Facts on File, Inc. New York,NY.Graham, G. L. 1994 . Bats of The World.  Golden Guide.Golden Press. New York, NY.Greenhall, A. M. 1982. House Bat Management.  UnitedStates Department of the Interior. ResourcePublication 143. U. S. Government Printing Office.Washington, DC. Tuttle, M. D. 1989. America’s Neighborhood Bats .University of Texas Press. Austin, TX.Bat Education Organizations: Bat Conservation International. P.O. Box 162603. Austin,TX. Phone (512) 327-9721. Utah State University Extension, an equal opportunity employer, provides programs and services to all personsregardless of race, color, national origin, gender, age, religion, or disability.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S.Department of Agriculture, Robert L. Gilliland, Vice President and Director, Cooperative Extension Service, Utah StateUniversity. (EP/04-96/DF)

Bats: Wildlife Damage Management Series

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Bats: Wildlife Damage Management Series

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