BATSL i v i n g w i t h W i l d l i f e

Oregon Department of Fish and Wildlife3406 Cherry Ave NESalem, OR 97303www.dfw.state.or.us

O R E G O N D E P A R T M E N T O F F I S H A N D W I L D L I F E

ODFW: 12/00

BAT FACTSBats are the only flying mammals, they use sound to

locate their prey, and they live a very long time for such small animals. Oregondoes not have spectacular congregations of thousands of bats like those found inTexas caves. The species found here are varied and interesting, but either solitaryor found in small colonies.

While bats in otherparts of the world feed onfruit, fish, nectar, or evenblood, all Oregon batsdine on insects. They con-sume pests such as sprucebudworm moths, tussockmoths, mosquitoes, pinebark beetle moths andgypsy moths. A bat cancatch up to 600 insects inan hour.

People who mean noharm to bats often do notunderstand how vulner-able bats are to disturbance of their roosting sites. Thus these beneficial and harm-less animals have been killed or have been unable to reproduce enough to maintaintheir numbers. While accurate counts of these small, nocturnal, and widely distrib-uted animals are very difficult, there is evidence that some species are declining.

Bats are members of the orderChiroptera, meaning “hand-wing.” Likeall mammals, bats have warm blood andhair. They bear live young and nursethem with milk. Their wings are sup-ported by long finger bones coveredwith two thin layers of skin, like thewebbing between your thumb and firstfinger. This skin covering extends to thelegs and, in some species, between thelegs to the tail. Bats can use the wingand tail membranes to scoop insects.Bats have small, movable thumbs on thetop of their wings for grasping andclimbing. Their back feet are usedfor hanging.

Wings make bats look bigger thanthey really are. The biggest bat in Or-egon is the Hoary bat, which weighsabout an ounce, or about the same asfive quarters.

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What Bat is That?Bats are easy to distinguish from

other mammals simply because theyhave wings. In the field, their twistingflight pattern and nocturnal activityseparate them from birds, althoughmany people confuse bats with swifts.About 1,000 species are found through-out the world, 15 of them in Oregon.

Big brown bat (Eptesicus fuscus).This is a relatively large bat, with awingspan of 13 to 14 inches. The largesize, dark color and slow flight helpidentify it. It is more likely to be activein cold weather than other bats. Ears arerelatively short and black. It is commonthroughout the state and prefers humanstructures for roosting, so this bat is seenfairly often. It usually lives in colonies,often with other kinds of bats.

Myotis bat (Myotis spp.). Sevenspecies of the genus Myotis live in Or-egon, all of them small brown bats withwingspans of 10 inches or less. Manyare difficult to identify; most live in for-ests. The little brown bat is the mostcommon and is frequently found inbuildings. The fringed myotis and thewestern small-footed myotis are theleast common. Myotis bats dwell inrock crevices, trees and human struc-tures. As a group, myotis bats are themost abundant in Oregon, but severalspecies are declining and/or are speciesof interest by the U.S. Fish and Wild-life Service.

Hoary bat (Lasiurus cinereus). Thisis one of the most colorful bats in Or-egon. It is also the biggest bat in Or-egon, with a wingspan of nearly 16inches. The body has dark fur tippedwith white. The face has a dark mask,with a yellow-orange throat. The nearlyround ears are edged in black. It is dis-tinguished from the similar silver-hairedbat by these markings and by patchesof stiff, light tan hairs on its wrists. Thisimpressive solitary bat roosts among thebranches of both deciduous and conif-erous trees throughout the state andlikes to feed around permanent outdoorlights. They do not roost in buildings.This fast-flying bat migrates to south-ern California or perhaps beyond, re-turning to Oregon in the spring. It oftenbears twins.

Silver-haired bat (Lasionycterisnoctivagans). This solitary bat found inold growth forests has a wingspan ofabout 10 inches. The fur is glossy black,tipped with white. This bat looks some-what similar to the hoary bat, but issmaller and lacks colorful markings. Itis found throughout Oregon. This isusually the first bat out in the evening,emerging about 30 minutes after sun-set. It often forages over woodlandponds, streams, meadows and roads,often flying very low. Like the hoarybat, it usually bears twins. It often roostsbehind loose tree bark.

Pallid bat (Antrozous pallidus).This is a large, pale bat with huge ears,large eyes and a dog-like face. Its wing

beat is slower than most bats. It emergeslate at night to feed primarily on theground, eating large beetles, crickets andscorpions. It produces a musky odorwhen disturbed. The pallid bat is uncom-mon and is found mostly in arid regionsin canyons.

Townsend’s big-eared bat (Plecotustownsendii). This is a medium-sized batwith enormous inch-plus long ears. It isgray, brown, or black and has a largelump on each side of its nose. It is gener-ally active only after full darkness andsometimes collects insects from the air,as well as on plants. This is the bat mostoften found in caves; it usually hibernatesinstead of migrating. This species is veryvulnerable to human disturbance and itsnumbers are declining sharply across itsentire range, which includes most of thewestern United States. In Oregon, it isclassified as a sensitive species in the“critical” category.

Western pipistrelle (Pipistrellushesperus). The smallest bat in the UnitedStates, this species weighs less than one-quarter ounce (5 grams). The fur is paleyellow or brownish gray. The ears arerelatively short and it has a dark facemask. This bat is common only in theOwyhee uplands in extreme southeasternOregon. It flies early in the evening, wellbefore dusk, and has a characteristic flut-tering flight.

Spotted bat (Euderma maculatum).Spotted bats are rare in Oregon and seenonly on the east side of the state. This isa medium-large bat with ears longer thanthose of any other bat in the U.S. It hasdark fur with three large white spots—two on the shoulders and one onthe rump.

Brazilian (Mexican) Free-tailed bat(Tadarida brasiliensis). Roseburg, Or-egon may be the most northern part ofthis bat’s wide range. This is a fast-fly-ing, medium-small bat with long narrowwings and a tail that extends beyond themembranes. This is the bat found in hugecolonies in Texas. It appears to survivethe cold winters in Oregon by staying inheated buildings instead of hibernatingor migrating, often sharing these quar-ters with other bat species.

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3Getting Alongwith Bats

Here are some tips for peaceful co-existence with your bat neighbors.

♦ In winter, avoid places where batshibernate, because awakening a batdepletes energy reserves. A bat canlose 10 to 30 days worth of fat re-serves from being awakened andthen is at risk of starvation beforespring arrives. Support protectingcaves from human use when batsare present.

♦ In summer, avoid disturbing nurs-ery caves or roosts. Frightenedmother bats may drop or abandontheir babies.

♦ Bats need open water. Support ef-forts to preserve, create and enhancemarshes and wetlands.

♦ Never touch or pick up a bat. It maybite in self-defense like any otherwild animal. A bat you or your petcan catch outside is probably sickand should be left alone. Do nothandle dead bats.

RabiesLess than 1/10 of 1 percent of all

bats are believed to carry rabies.Infected bats are rarely aggressive andsoon die of the disease. Nonetheless,always avoid contact with any bat. Ifyou are bitten or scratched by a bat, orany other wild animal, or have anycontact with the animal’s saliva,report it to your doctor and localhealth authority immediately. Capturethe bat, if possible.

More InformationGeneral:America’s Neighborhood Bats byMerlin D. Tuttle

Web sites:http://www.torstar.com/romTour a bat cave in Jamaica.

http://www.batcon.orgVisit Bat Conservation International.See their Bat Links page for manyother sites.

Keeping Our Bat Populations HealthyBats have lost many of their natural roosting sites in old trees, snags and caves

as a result of human activity. Some species can roost in man-made structures. Con-servation includes protecting natural sites and encouraging bats to use bridges, cul-

verts and mineswhere their activitydoes not interferewith human use ofthese structures.

The OregonDepartment ofFish and Wildlifeis protecting oldmines used by batsfrom human dis-turbance, advising

people who have bats in their buildings, working with consultants on designingbridges so that bats can use them as roosts, and surveying the state’s population ofTownsend’s big-eared bats. Many of these activities are in cooperation with theU.S. Forest Service, Bureau of Land Management, Bat Conservation International,The Forest Industry, U.S. Fish and Wildlife Service, Oregon Department of Trans-portation, Oregon Department of Forestry, other agencies and private landowners.

♦ If a bat flies into your house, removepets and children and close the roomand closet doors. Open the windowsand quietly watch the bat until itleaves. The bat is most likely lost,young and eager to leave. Watch itto be sure it leaves.

♦ If bats are roosting in your attic, youmay want to evict them. Keep inmind that a small colony may havelived peacefully with you for yearsbefore you noticed them—it’s notan emergency. Watch the buildingat dusk to see where the animals areleaving. Then during the day, iden-tify all possible entrances, includ-ing any more than 1/4 inch by 3/4inch. Do not close up entrances insummer when baby bats are present,or the babies will die without theirmothers. Wait until all bats have left,then cover holes with netting, placea one way valve to ensure bats canexit but not return, or fill all holesand cracks. Bats will not gnaw atbarriers you install. You can alsospray the roost (not the bats) withdog or cat repellant. Poisons are notrecommended; they are a serioushealth hazard to humans living in

the house. For more informationabout ways you can exclude batsfrom your home, contact your localODFW office.

♦ Good roosts are hard to find. Con-sider providing a bat house. Instruc-tions are available from Oregon De-partment of Fish and Wildlife, orhouses can be purchased at naturestores.

♦ Keep your cat inside your house.Domestic cats eat thousands ofbirds and other wildlife annually.

♦ Do not use pesticides near bat roostsor open water.

♦ If you own or manage forestedproperty, preserve snags and cavitynesting trees for birds, bats andmammals that call these trees home.

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