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D a n i e l A . R . T a y l o r

More than 1,100 species of bats account for almost a quarterof all mammal species.

Bats are exceptionally vulnerable to extinction, in partbecause they are the slowest-reproducing mammals on Earthfor their size, most producing only one young annually.

Contrary to popular misconceptions, bats are not blind, donot become entangled in human hair and seldom transmitdisease to other animals or humans.

Bats are the only mammals capable of true flight. Most batspecies use an extremely sophisticated biological sonar calledecholocation to navigate and hunt for food. Some bats candetect an object as fine as a human hair in total darkness.

Worldwide, bats are primary predators of night-flyinginsects. A single little brown myotis, a common resident ofNorth American forests, can consume 1,000 mosquito-sizedinsects in just one hour.

All but four of the 47 species found in the United States andCanada feed solely on insects, including many destructiveagricultural pests. The remaining species feed on nectar,pollen and the fruit of cacti and agaves and play an impor-tant role in pollination and seed dispersal in southwesterndeserts.

The 20 million Mexican free-tailed bats at Bracken Cave,Texas, eat approximately 200 tons of insects nightly.

A colony of 150 big brown bats, which often roost in treecavities, can eat enough cucumber beetles each summer toeliminate up to 33 million of their rootworm larvae, a majoragricultural pest.

Desert ecosystems rely on nectar-feeding bats as primarypollinators of giant cacti, including the famous organ pipeand saguaro of Arizona.

Bat droppings in caves support whole ecosystems of unique organisms, including bacteria useful in detoxifying wastes,improving detergents and producing gasohol and antibiotics.

More than half of American bat species are in decline or already listed as endangered. Losses are occurring at alarmingrates worldwide.

During cold weather, many bats hibernate in caves, mines or other sites that provide stable, cool temperatures. Othersmigrate to warmer climates, sometimes traveling up to a thousand miles or more.

For their size, bats are among the world’s longest-lived mammals. The little brown myotis, a common forest bat, has adocumented life span of up to 34 years in the wild.

BAT BA S I C S

Because more than half of the non-industrial forest lands in the United States are privately

owned, forest landowners play a critical role in the stewardship of our wildlife resources.This

publication will introduce you to a group of wildlife that is particularly vital to forest ecosys-

tems, but also one of the least-studied and most-misunderstood:bats. It will demonstrate how

basic forest-management practices that improve forest health and productivity can also main-

tain and enhance habitat for these fascinating and beneficial animals.

As primary predators of night-flying insects, bats play an essential role in maintaining forest

health. Many bats can eat nearly their own body weight in insects each night.These include

moths, beetles and other destructive pests. Although long neglected in forest-management

planning, bats are essential to the health of forest ecosystems, fulfilling the same roles by night

that birds do by day. Helping bats is a wise investment in America’s forests.

© 2006, Bat Conservation International

A c k n o w l e d g e m e n t sThis publication was produced by Bat Conservation International, with the generous financial and editorial sup-port of the National Fish and Wildlife Foundation and USDA-Natural Resources Conservation Service. The textwas reviewed by T. Bently Wigley of the National Council for Air and Stream Improvement; Darren A. Miller ofWeyerhaeuser Company; Dennis L. Krusac of the USDA-Forest Service; Edward B. Arnett and Merlin D. Tuttleof Bat Conservation International; and Ed Hackett, USDA-Natural Resources Conservation Service’s WildlifeHabitat Management Institute. Valuable suggestions also were received from Charlie Rewa of the USDA-NaturalResources Conservation Service’s Wildlife Habitat Management Institute. The publication was designed by JasonHuerta of Bat Conservation International.

Daniel A. R. Taylor, a Bat Conservation International conservation biologist, is coordinator of the NorthAmerican Bat Conservation Partnership.

D a n i e l A . R . T a y l o r

TABLE OF CONTENTS

Habitat Needs of Bats . . . . . . . . . . . . . . . . . . . 3

Roosting Requirements . . . . . . . . . . . . . . . . . . 3

Dead Trees. . . . . . . . . . . . . . . . . . . . . . 3

Living Trees . . . . . . . . . . . . . . . . . . . . . 4

Forest Management and Bat Habitat . . . . . . . . . . . . 4

Roosting Trees . . . . . . . . . . . . . . . . . . . . 5

Foraging Habitat . . . . . . . . . . . . . . . . . . . . 6

Table: Forest Management Practices . . . . . . . . . . . . 7

Table: Timber & Wildlife Stand Improvements. . . . . . . . 8

Water Resources. . . . . . . . . . . . . . . . . . . . . 8

Other Resource Needs . . . . . . . . . . . . . . . . . . 1 0

Geologic Resources . . . . . . . . . . . . . . . . . . . 1 0

Artificial Roosts and Other Human Structures . . . . . . . . 1 0

A Sampling of Forest Bats . . . . . . . . . . . . . . . . . 1 1

Sources of Assistance . . . . . . . . . . . . . . . . . . . 1 4

Forest Management & Bats | 3

Habitats required by bats have three basic compo-nents: re s o u rces for roosting, foraging anddrinking. Almost all North American bats rely

on forests for survival.More than half roost in dead and dying trees (snags),

especially beneath loose bark, in tree cavities and hollowsor in crevices left by lightning strikes. Others roost exclu-sively in the foliage of living trees. In the western UnitedStates, the long-eared myotis (Myotis evotis) is known toroost under exfoliating bark on stumps and downed logs.These roosts are required for rearing young (maternityroosts), as migratory stopover sites and occasionally forhibernation. The remaining species use forests as foraginghabitat or movement corridors, while roosting in caves,old mines, cliff-face crevices, rock piles and human-madestructures such as old buildings, bridges and cisterns,

which are often located in forested envi-ronments. Bats also use many of thesefeatures as night roosts where they canrest and digest their food during nightlyforaging bouts.

Bats forage along forest edges, overriparian areas (land adjacent to andinfluenced by bodies of water), along for-est roads and trails and in natural forestgaps or harvest-created openings. Feed-ing strategies vary greatly among forest-dwelling species. Some forage aroundground-level shrubs, while others preferto forage under the tree canopy, in thecanopy or above it.

Bats need clean, pooled, open bodiesof fresh water that are large enough toenable drinking on the wing and withoutobstructions from vegetation, fencing orother objects.

Roosting Require m e n t sSome forest bats roost exclusively in the foliage of livingtrees; these are often referred to as “tree bats.” Otherspecies roost under loose, peeling bark or crevices of deadtrees. Others will also use cavities in healthy trees or inthose that are damaged or dying. Some bats, such as thebig brown bat (Eptesicus fuscus) and silver-haired bat(Lasionycteris noctivagans), seem to use cavities in eitherliving or dead trees.

Most forest-bat species move frequently betweenroost trees. This is especially true of maternity colonies,although bachelor (all-male) colonies also exhibit thisbehavior. This roost switching may be an effort to avoidpredators or parasites or to seek a warmer or cooler roost.For snag-roosting bats, switching could also be tied to thetemporary nature of dead and dying trees: If a roost treebecomes unstable or falls, the bats will already know of

an alternative roost. It is not uncommon for bats toreturn to the same roost tree or group of trees in the samepatch of forest in successive years.

Roost trees are often located along the edges of forestsor in open foreststands, where theygenerally re c e i vegreater solar heat-ing and have al e s s - o b s t r u c t e dflight appro a c h .In landscapeswith steeper topo-graphy and cold-air drainage, someevidence suggeststhat upland andridge-top tre e smay be used asroosts more fre-quently than those in valleys and canyon bottoms.

Dead TreesThe structural characteristics of a dead tree – height,diameter, stage of decay (“decay class”) – and its positionin the stand and on the landscape appear to be the most

HA B I TAT NE E D S O F BAT S

Snags retained in clear-cut harvestunits provide immediate and futureroosting habitat for bats.

A diversity of snag-decay classes and sizes should be main-tained across the landscape. Retaining snags in clumpsincreases their use by bats.

Hoary bats prefer tree roosts along theedges of forest stands.

© M E R L IN D . T U T T L E , B C I / 0 00 12 06

important factors in determining its suitability as a roostsite. These factors affect the roost’s temperature, an im-portant component in roost selection. The species of thetree is important only as it relates to these structuralattributes. Tree species that are more susceptible to fun-gal infestations attract cavity excavators such as wood-peckers. Also, those that retain bark for longer periods aremore likely to provide appropriate roosting spaces.

While the habitat needs of forest bats vary by species,geographic area and climate, bats that roost under thebark or in crevices and cavities of dead trees frequentlyselect the largest available snags, which often extendabove the forest canopy. This is especially true for roostsof maternity colonies, since larger snags better retain thesun’s warmth, which benefits the pups. Males often roostalone or in bachelor colonies and appear to use a widerrange of snag sizes. Maternity colonies of more than 500bats have been recorded emerging from cavities or underthe exfoliating bark of snags in both eastern and western

forests, demonstrating just how important a single deadtree can be to maintaining local bat populations. Themajority of snag-roosting bats prefer trees in the earlierstages of decay [Figure 1], with an ample amount ofloose, peeling bark.

Living TreesSome of the forest bats that roost under bark, in cavitiesor in lightning-strike crevices in dead trees also use thesesame features in healthy living trees or those that are dam-aged or dying. For example, the evening bat (Nyc t i c e i u sh u m e ra l i s) of the southeastern United States is oftenfound roosting in cavitiesin living fork - t o p p e dloblolly pine trees in bothmanaged and unmanagedf o rest stands. In bottom-land hardwood forests ofthe southeastern U.S., theR a f i n e s q u e’s big-eared bat(C o ry n o rhinus ra f i n e s q u i i)and southeastern myo t i s(Myotis austro r i p a r i u s)form maternity coloniesin the hollow trunks oflarge, living gum andbeech trees with basal cav-ities. In parts of theirrange, these bats have alsobeen found roosting un-der bridges and in old buildings and cisterns.

Foliage-roosting (or “tree”) bats roost exclusively inthe foliage of a wide variety of living trees, both evergreenand deciduous. They often choose dominant or co-dominant, large-crowned trees, roosting in locations thatoffer suitable temperatures, humidity and protectionfrom bad weather and predators. Tree bats often have twoto four pups and roost singly or in small groups. Tree batsfrom northern regions migrate south, where they oftenhibernate beneath leaf litter on forest floors in winter.Some tree bats, such as the Seminole bat (Lasiurus semi-nolus) and northern yellow bat (Lasiurus intermedius),often roost in clumps of Spanish moss, and northern andsouthern yellow bats (Lasiurus ega) will roost beneath thedead, hanging fronds of fan palms. The eastern red bat(Lasiurus borealis) roosts in a variety of tree species andforest habitats.

Forest Management and Bat HabitatFo rest-management practices such as logging or pre s c r i b e dburning can have positive or negative effects on bats byaltering the distribution and abundance of living and deadt rees used for roosting or the number of forest openingsand edge habitat used for foraging. With proper planning

4 | Forest Management & Bats

Forests can be successfully managed for both woodproducts and bat habitat, as long as adequate roosts,foraging habitat and water sources are provided acrossthe landscape.

A female eastern red bat with two pups. Red bats roost in thefoliage of a variety of trees and are known to hibernate inleaf litter on the forest floor.

and implementation, for-est health can be main-tained or improved whilep roviding a sustainablesupply of fiber for fore s tp roducts. Non-timber va l-ues can be protected, andb a t - roosting and -foraginghabitat and drinking re-s o u rces can be enhanced,g reatly benefiting bat pop-u l a t i o n s .

Roosting TreesRoosts are often consid-ered the most importanthabitat component, androost switching appears to

be essential for most species. The most important actionforest landowners can take to maintain bat populations isto provide a continuous supply of potential roost trees.

These include snags in various stagesof deterioration (especially those inearly stages of decay), hollow trees andthe green and dying trees that can pro-vide future snags. Dozens of otherwildlife species that depend on deadand dying trees for habitat will alsobenefit.

In addition to the following re c o m-mendations, most state fore s t ry agen-cies, county extension offices and stateor federal wildlife management agen-cies can provide guidelines and re c o m-mend practices for maintaining snags,g reen trees and other forest stru c t u re sthat are tailored to local conditions. Itis important to note that the U.S.Occupational Safety and Health Ad-ministration (OSHA) has strict guide-lines re g a rding where snags may beretained on intensively managed fore s t sdue to the inherent danger of operatingm a c h i n e ry around dead trees. T h e s eguidelines must be incorporated intoany snag maintenance and pro t e c t i o np ro g r a m .

How Many? The exact number of roost trees needed tomaintain forest-bat populations is unclear and likelyvaries by forest type and region. Bats that use live treescan find roosts in most forests, but managers need toensure that enough dead and dying trees are left for thespecies that depend on them. Bats need multiple roosts,

and because snags are a short-lived resource (especially inthe East), the availability of suitable roost trees for snag-roosting bats fluctuates over time. Federally managedforests and many state forestry regulations specify a min-imum number of trees to leave for wildlife, but forestowners should, whenever possible, leave as many dead,damaged, dying and cull (defective) live trees as possibleand as safety and silvicultural objectives permit.

Ol d e r, more mature forest stands produce more snags,so well-distributed, variably sized patches of mature ando l d - g rowth forest should be maintained where possible.Also, some stands could be managed through extendedh a rvest rotations. Careful management is re q u i red to pro-vide snags of sufficient numbers and size to ensure thelong-term we l f a reof bat populations. Although deve l o p e dfor the Pacific No rt h west, the DecAID De c a yed Wo o dAdvisor (see S o u rces of As s i s t a n c e)is one of the most thor-ough re s o u rces ava i l a b l efor snag and wildlifel e a ve - t ree planning inmanaged forests andcan be adapted to otherregions. Because ourk n owledge of howmany roost trees areneeded is limited formany species andregions of the country,these re c o m m e n d a t i o n sshould be taken as sug-gestions rather thanstrict guidelines.

Which ones? T h estructure of a snag ism o re important thanits species, althoughsome tree species makebetter snags than oth-ers. Emphasize larger-diameter snags becausethey generally re m a i nstanding and re t a i nb a rk longer and sup-port a greater variety ofbats and other wildlifethan smaller snags. Ingeneral, retain snags in the early stages of decay (Figure 1,Classes 1 and 2) rather than more-decayed ones, tall andlarge-diameter snags rather than smaller ones, and snagswith more bark cover than those with little cover. Inconifer-dominated and mixed-conifer stands, leave asmany hardwoods as possible that have natural or wood-pecker-excavated cavities.


Class 1 Class 2 Class 3

Large Class 2 snags locatedwithin a gap in the forest pro-vide ideal roost sites for manyspecies of forest-dwelling bats. Amaternity colony of long-leggedmyotis uses this snag.

A typical Class 3 snag retained in aclear-cut harvest unit. Such snags areshort-lived and normally offer less habi-tat value to bats than Class 1 or 2 snags.

Figure 1: Classes of snags

W h e re ? Snags should be well distributed across the land-scape, including along drainage bottoms, upland slopesand ridge tops. Pre f e rence should generally be given tomaintaining snags along forest-stand edges and other opena reas where they re c e i ve more sunlight. When practicinge ven-aged management, such as clearcuts, shelterw o o d sand seed-tree cuts, and where silvicultural and loggingsafety objectives are not compromised, consider leavingsnags either evenly distributed across harvest units or inpatches. Leaving snags in patches interspersed with gre e nt rees helps keep them from being blown over by highwinds, as will leaving them in locations with pro t e c t i o nf rom pre vailing winds. This also makes it easier to conductmanagement operations. In landscapes that are intensive-ly managed for timber, snags can be maintained primarilyin streamside management zones, forested corridors andother less-intensively managed habitats. In conifero u sf o rests, foliage-roosting bats that prefer broadleaf decidu-ous trees often are concentrated within riparian zo n e s ,since they usually contain more broadleaf ve g e t a t i o n .

Green tree retention: Natural fall rates will eventuallyreduce snag numbers unless new snags develop naturallyor are created. Leave as many large green or cull trees aspossible as “leave trees” to become future snags. Cull treesinclude those with broken tops, forked tops, woundedareas or other defects that reduce their commercial value.For example, recent research in Mississippi and Georgiafound that evening bats use fork-topped pine trees inthinned-pine plantations.

Snag creation: In stands where snags are limited orabsent, one option is to alter or kill living trees to createsnags. This allows the number of snags created and theirlocations to be chosen by the forest manager. Methodsfor snag creation include girdling, topping with chainsaws, injecting with herbicides and the use of mechanicalharvesting equipment (fellers). Creating snags can miti-gate the loss of natural habitat, but retaining existingstructures is the most cost-effective and ecologicallysound method.

Foraging HabitatBats feed on a variety of night-flying insects, catchingthem in the air or picking them off vegetation. Most batsprefer to hunt in smallto medium forest open-ings or gaps, like thosecreated by timber har-vests, roads and watercourses or by lakes andponds. Bats often for-age along the vertical orhorizontal edges wherethese habitats or differ-ent-aged forest standsmeet and along forestcorridors and bufferstrips.

Sm a l l e r, more ma-n e u verable bats, such asthe northern long-eare dm yotis (Myotis septen-t r i o n a l i s) and small-footed myotis (Myo t i sl e i b i i) in the east andthe long-eared myo t i sin the west, can foragein cluttered ve g e t a t i o nin the forest understoryand in ve ry small fore s tgaps. Larger, faster-flying and less maneu-verable bats, such as theh o a ry bat (L a s i u ru sc i n e re u s), often forage


Timber-harvesting machinery, such as this feller-buncher,can be used to create snags by topping live trees.

These Class 2 snags positioned on the edge of a gap inthe forest provide excellent roosting and foraging habi-tat for bats. These natural openings can be simulatedwith group-selection harvest techniques.


Even-aged management: Begins with thecomplete, or nearly complete, removal ofexisting timber to create a new stand withyoung trees of approximately the same age.Small stands of different age classes can forma diverse assemblage of habitats.

Clearcuts: Harvest of essentially all trees in astand.

Creates edge habitat for foraging. Smaller, irregular-shaped unitsare better for bats than larger blocks. Flush of herbaceous growthfollowing timber removal can provide rich food sources for insectspreyed on by bats. Snags and green or cull reserve trees left stand-ing can add value as potential roosts.

Shelterwood and Seedtree cut: Removal ofmost trees in a stand, leaving only those needed toproduce seed and/or provide shade for regenerat-ing a new stand. Overstory trees are usuallyremoved after regeneration is established. Moretrees are left with shelterwood harvests than withseedtree cuts.

Like recent clearcuts, these create edge habitat, foraging space and afood source for insects. Trees left on-site provide some mature for-est structure until they are harvested. Value to bats and other wildlifecan be greatly increased if adequate snags and green trees are leftand if overstory trees are retained through the next harvest.

Uneven-aged management: I n d i v i d u a land small groups of mature trees are harvest-ed, leaving a variety of tree sizes and ages.Uneven-aged management creates smallcanopy gaps similar to those formed by natu-ral forest disturbances.

Group selection: Small groups of trees removedfor regeneration of new age classes; width of cutrarely exceeds twice the height of the mature trees.Moderately shade-intolerant species can benefitfrom this harvesting method because larger open-ings are created.

Promotes diverse forest structure, characterized by mosaic of matureforest-roosting habitat and small to medium gaps for foraging, withsubstantial increases in herbaceous vegetation favorable to produc-tion of bats’ insect prey.

Single-tree selection: Individual trees of allsize classes removed more or less uniformlythroughout the stand to increase growth of remain-ing trees and provide space for regeneration.

Maintains diverse forest structure and roost trees, while creatingsmall gaps and enhancing edge habitat for foraging. Promotesdiverse vegetation structure and some increases in herbaceousvegetation, favorable to production of bats’ insect prey.

Prescribed fire: Prescribed burning for site preparation after harvest is conductedto eliminate undesirable vegetation and increase availability of soil nutrients for treeseedlings.

Increases herbaceous and shrub growth that can increase abundance and diversityof insect prey. Care must be taken to prevent the loss of snags and green-reserve(wildlife) trees left as roosting habitat.

Herbicides: Selective herbicide use may control undesirable vegetation. Plantresponse varies depending on the herbicide, time of application, rate and forest con-ditions.

Herbicides can be useful, often when combined with prescribed fire, for restoringearly-succession plant communities and controlling undesirable vegetation. In thesoutheastern U.S., they have been used to promote the development of herbaceousvegetation, which can increase the abundance of insect prey and open up foragingspace for bats in stand interiors by controlling woody stems.

Mechanical treatments: Shearing, raking, windrowing and bedding are allmechanical methods used to clear debris and prepare soil seedbeds for tree planting.

Increases herbaceous and shrub growth that can increase the abundance and diver-sity of insect prey.

HARVEST

SITE PREPARATION

Management Regime Treatment Description

Treatment Description

a b ove the forest canopy, in larger forest openings and along the edges, as well as over clearings,wetlands or rive r s .

Bat-foraging activity is often concentrated in riparian zones and in gaps in older, more-diverseforest stands. Riparian habitat is especially important because it provides drinking water and high-quality foraging habitat, as well as high-quality roosting habitat in more level terrain where cold-airdrainage is not a factor. Beaver ponds provide high-quality bat habitat that combines drinking, for-aging and roosting resources. Bats often follow corridors of forest when traveling from roosts tofeeding areas.

Fo rest-management practices that create small forest openings may foster development of suitableforaging habitat and may even enhance roosts located along forest gaps and edges. Bats often foragealong edges between intact forests and cut areas. Smaller harvest areas increase edge habitat per unita rea, promoting plant and insect diversity that is beneficial to bats and other wildlife. Howe ve r, somebat species cannot forage in the middle of large (at least 120 acres [48.5 hectares]) regenerating stands.Ro o s t - t ree loss should be minimized when creating openings so that the loss of roosts doesn’t offset thebenefits of increased foraging habitat. The following table lists some commonly used fore s t - m a n a g e-ment practices and their potential benefits to bat habitat.

Crevices in trees are used as roosts by anumber of forest-bat species. An endan-gered Indiana myotis is using this one.


Thinning: Thinning removes weak or sup-pressed trees and opens growing space forremaining healthy trees. Thinning can beused to remove trees from the lower or uppercrown level or to increase spacing andgrowth in forest plantations, and may beconducted at different times and intensitiesdepending on the silvicultural system andobjectives.

Thinning benefits bats by increasing flight space inthe stand and sunlight to the stand floor, whichincreases herbaceous growth for bats’ insect prey.Heavier thinning (e.g., 150-200 trees/acre [370-500 per hectare] in southern pine) is preferred forhabitat improvement.

Riparian habitat management:Maintaining the integrity of riparian zonesin managed forests is a critical aspect ofgood forest stewardship. Vegetative com-munities and landscapes associated withwater are the most important habitats formost bat species. Although these featuresrepresent a relatively small proportion ofthe landscape, they often provide moreconcentrated sources of shelter, food andwater than drier, upland forest habitats. Inconiferous forests, broadleaf deciduoustrees are often concentrated in the riparianzone, providing roosts for the foliage-roosting bats that prefer them.

Riparian areas are one of the highest quality for-aging habitats available to bats. If compatible withother riparian-habitat management objectives,selective harvest that minimizes disturbance canenhance riparian bat-foraging habitat. The widthof streamside zones affects understory develop-ment within these zones. Narrow zones will allowsunlight penetration and subsequent develop-ment of a dense midstory layer that may be unfa-vorable to bats and other wildlife species.

All state forestry agencies have Best ManagementPractices or standards and guidelines thataddress local riparian buffer area/stream manage-ment zone management. However, these guide-lines are designed to protect water quality andmay recommend narrower streamside zones thanwould be most beneficial to wildlife.

Forest corridors, leave strips, bufferstrips: Includes strips of unmanaged for-est between managed stands, windbreaks,shelterbelts and other plantings.

In addition to providing edge habitat for foraging,forest corridors and buffer strips can be used astravel corridors and may provide roost trees.

Prescribed fire: Used to reduce forestfuels to decrease the risk of wildfire and forecological restoration. Prescribed fire caneffect changes in plant community compo-sition, tree densities, stand structure andsoil and hydrological conditions. Most pre-scribed burns are carried out under cool,moist conditions to reduce the chance ofwildfire.

Bats may benefit from fire by the creation of newroost trees through direct or indirect fire mortali-ty (via disease, insect or fungal attack). Fire canalso decrease forest tree density and increaseopenings, thereby improving foraging space andtravel corridors, allow more light to reach andwarm roost trees, and increase insect prey diver-sity and abundance by increasing herbaceousand shrub growth.

Prescribed burning can have short-term detri-mental effects on bats by eliminating some snagsand stumps used for roosting. Raked firebreakscan be created around snags, or the basessprayed with retardant, to protect them.Prescribed burns and fires occurring when batsare rearing young (April-July) or in deep hiberna-tion (mid-winter) can have negative impacts onlocal populations. In the southeastern U.S., redbats and Seminole bats sometimes hibernateamong leaf litter and may be unable to escapeburns conducted on very cold days. However,these short-term losses must be weighed againstthe long-term benefits to the ecosystem.

TIMBER AND WILDLIFE STAND IMPROVEMENTS

Treatment Description

Water Resourc e sWhen active, all but the most desert-adapted batspecies must have daily access to clean water for drink-ing, especially during lactation and periods of incre a s e da c t i v i t y. Se veral species will also arouse to drink duringhibernation. Some bat species usually roost near or for-age over water. Gray myotis (Myotis grisescens), littleb rown myotis (Myotis lucifugus), Yuma myotis (Myotisyumanensis), southeastern myotis and eastern pip-i s t relles (Pipistrellus subflavus) prefer to forage ove rlakes, rivers and ponds. Eastern red bats, hoary bats,Indiana myotis and big brown bats are known to usew a t e rways for travel and foraging.

Ponds, seasonal pools and bogs and meadowswith pooled, standing water offer important drinkingand foraging resources for forest bats. Along withriparian zones, beaver ponds are among the mostvaluable aquatic resources, as they provide drinking,roosting and foraging habitat in close proximity. In

Bats typically drink on the fly. This western small-footedmyotis (Myotis ciliolabrum) has just swooped down ona pond to quench its thirst.


eastern forests, even temporarywater-holding features such as roadruts are often used by bats. Troughs,tanks and other livestock-wateringfacilities are critical watering sites forbats in some western forests and maybe an overlooked resource for easternforest bats.

Fo rest-management practices thateliminate or limit access to water ordegrade water quality through silta-tion can negatively affect bats. Fo re s tbuffers and adherence to state fore s t ry

Best Ma n a g e m e n tPractices (e.g.,c a reful placementof skid roads) areve ry effective atp rotecting waterquality at fore s tponds, seasonalpools, wet mead-ows and bogs. Note, however, thatBest Management Practices aredesigned for water-quality protection,not for creating wildlife habitat perse, so forest landowners may wantwider buffers than recommended ifthe goal is to provide more wildlifehabitat and mimic mature forest con-ditions. Landowners can get copies ofstate Best Management Pr a c t i c e sthrough their state forestry offices,

county cooperative extension offices and other landown-er assistance programs.

Small woodland ponds can often be created usingearthen catchments in locations that capture natural sur-face runoff or by piping water from natural springs. Thistype of pond can provide high-quality foraging anddrinking habitat for bats and many other wildlife specieswhen located in a small, natural or created forest open-ing. An excellent resource for creating small ponds is list-ed in the Sources of Assistance section, as is informationon obtaining copies of Best Management Practices.

Large streams provide foraging and drinking habitat for bats. I-beam style concretebridges and bridges with vertical crevices (expansion joints) can provide ideal roost-ing sites when they span such streams.

Na t u ral and created ponds prov i d ei m p o rtant drinking sites for bats.Creating and maintaining ponds like thisone in Kentucky are important considera-tions for managing bats and otherwildlife across forest landscapes.


Geologic Resourc e sSe veral species of bats that roost in trees from spring through autumnspend their winters in caves, mines and other geologic features, suchas cliff-face crevices, rock outcrops, rock shelters and boulder fields.Some species also occasionally use geologic re s o u rces as day ro o s t sduring summer. These geologic features are often found in the fore s tmatrix. Dense aggregations of bats, sometimes numbering in the

h u n d reds of thousands or even millions, hibernate, rear young orn i g h t - roostin the small percentage of caves or abandoned mines thatp rovide suitable temperature characteristics. In eastern No rt hAmerica, few caves, mines and cliff crevices are warm enough or ableto trap enough bat body heat to be used as maternity roosts. T h o s ethat do can be extremely important. Sites used for hibernation mustp rovide cool, stable temperatures while protecting bats from fre ez i n g .Because these sites are uncommon, bats may travel hundreds of milesto reach a suitable hibernation site. Sites that don’t meet these criteriamay be used by colonies of bachelors and non-re p ro d u c t i ve femalesas breeding sites, night roosts or for stopovers during migration.

Bat roosts in geologic features are easily disturbed or destroyed.The greatest threats are disturbance from human commercial andrecreational activities. All bats naturally arouse periodically duringhibernation, but forced arousals due to disturbance cause them touse fat reserves that may be required for survival. Disturbance atmaternity sites can cause females to abandon their young.

Caves, mines, cliff faces, rock shelters and talus slopes often pro-vide essential roosts that should be identified and protected duringland alterations. Habitat surrounding important caves and mines,which may include an entire watershed, should be carefully man-aged to avoid negative impacts. Timber harvests near caves andmines should be conducted carefully to avoid impacting roost envi-ronments by changing airflow patterns, sun exposure, humidity,

g roundwater flow or by increasing publicaccess.

With properly designed buffers, fore s t -management activities can be implementedwhile maintaining integrity of geologicre s o u rces. Fo rest landowners and managersshould consult state agencies responsible formanaging wildlife and cave re s o u rces to deter-mine appropriate mitigation measures. Public education, interpre t i vesigns, closing access roads and trails, fencing and gating can helpreduce roost disturbances. Properly constructed, bat-friendly gatesplaced across important cave and mine entrances can pre vent humane n t ry while allowing many bat species to enter and exit.In a p p ropriate gates, howe ve r, may exclude bats, increase predation orn e g a t i vely affect airf l ow and temperature. See the So u rces ofAssistance section for re s o u rces that provide direction for planning,building and installing bat gates.

Artificial Roosts & Other Human StructuresHuman-made structures, such as buildings, bridges, culverts, dams,abandoned railroad and highway tunnels, abandoned militarybunkers and old cisterns, have become essential roost sites for manybat species, especially where natural roosts have been eliminated.Because roost availability is a major factor influencing bat survivaland population size, artificial roosts and human structures can beextremely important conservation tools where natural roosts havebeen lost. Although artificial roosts should not be viewed as a sub-stitute for good habitat management, they can provide crucial alter-natives during habitat recovery when natural roosts are scarce.

Concrete bridges with vertical crevices (expansion joints) canprovide ideal roosts and sometimes accommodate very large, region-ally important bat colonies. Concrete bridges in forested environ-ments are often important sites for social interaction and nightroosting and may attract several species of bats. The best roosts arein concrete bridges that are 10 feet (3 meters) or more above groundand heated by the sun. Bridges and culverts can be retrofitted withsimple and inexpensive modifications that create excellent roostinghabitat for large numbers of bats. These modifications can be incor-porated during original construction at little or no additional cost.

Buildings have become primary roosts for many bats, with atleast 20 species known to use them. Big brown bats and little brownmyotis have adapted exceptionally well and now appear to rely pri-marily on human-made structures over wide areas. Older and aban-doned houses, sheds, barns and other human structures in the for-est environment often provide habitat for important bat colonies,including rare and sensitive species. In parts of the southeasternUnited States and Pacific Northwest, many of the largest knownmaternity colonies of big-eared bats (Corynorhinus spp.) have beenfound roosting in old buildings in forested environments. Oldbuildings that harbor bat colonies can be shored up and stabilized,and bats have on several occasions moved into replacement struc-tures built nearby.

At least a dozen bat species have been reported to use bat hous-es and other artificial roosts. Occupancy rates continue to increase

OT H E R RE S O U R C E NE E D S

Hubbards Cave in Tennessee is nestled in mixed forest land and is usedas a critical hibernation site by half a million endangered gray myotis.An enormous bat-friendly gate now protects the bats from winter distur-bance by humans.


Big brown batEptesicus fuscus

The big brown bat is No rt hAmerica’s largest tree-cavity-roost-ing bat. It is copper to chocolate-b rown colored with a bro a d ,sparsely furred nose. Its forearmlength is 1.7 to 2 inches (42 to 52

millimeters) and itswingspan is 13 to 16inches (330 to 406 mil-limeters). Found ine ve ry U.S. state andmost Canadian pro-vinces, it is one of our

most commonly encountered bats.While still found roosting in tree hollows during the summer, many sum-

mer roosts are now in attics, barns and other human-made structures, includ-ing bat houses. Big brown bats hibernate in caves, mines, deep rock crevices,tree snags and buildings. They can survive subfreezing body temperatures,enabling them to occupy a wide variety of winter roosts.

Big brown bats roost and forage in a variety of habitats, but are most abun-dant in deciduous forests, often in areas of mixed agriculture. They usually pre yon small beetles but also consume stinkbugs, moths, froghoppers, flying ants,caddisflies, crickets and katydids. They are an important consumer of agricultur-al and forest pests. Individuals have been re c o rded living up to 20 ye a r s .

Little brown myo t i sMyotis lucifugus

Little b rown myotis va ry fro mpale to chocolate brown and havef o rearms of 1.3 to 1.6 inches (34 to41 millimeters). Their wingspansa re 8.7 to 10.6 inches (222 to 269m i l l i m e t e r s ) .

They are often themost abundant speciesin forested areas, espe-cially near water. Su m-mer colonies form int ree cavities, buildingsand bat houses. T h e y

hibernate in caves and old mines, sometimes migrating hundreds of miles toreach a suitable site. Hibernating populations of 300,000 to 500,000 individu-als have been documented. Some abandoned mines may hold a million or more .

Mothers give birth to one young each summer. Pups are capable of adult-like flight 20 to 27 days after birth. Although most nursery colonies feed overwater, non-reproductive little brown myotis hunt in a wide variety of habitats,including stream and forest borders, trails, cliff faces, meadows, farmland andin nearly every kind of forest. Favored prey include many aquatic insects, suchas midges, mayflies, mosquitoes and caddisflies. One little brown myotis cancapture more than 1,000 mosquito-sized insects in a single hour. Life spans ofmore then 34 years have been reported in the wild.

A SA M P L I N GO F FO R E S T BAT S

as designs are tested and improved. The best-occupied bathouses are multichambered units at least 24 inches (61 cen-timeters) tall and with crevices 3⁄4 to 1 inch (19 to 25 millime-ters) wide with roughened landing and roosting surfaces. Theyare painted black in the coolest climates and lighter colors inthe warmest to facilitate appropriate solar heating. They shouldbe mounted at least 12 feet (3.6 meters) off the ground on thesides of wood or concrete buildings or on poles (not on trees)in small openings or edge habitats near streams, rivers or lakes.

In the southeastern U.S., cinder-block artificial roosts thatare 12 feet (3.6 meters) high and 4 feet (1.2 meters) across withopenings in the sides and at the base have been built in forest-ed environments to mimic the trunks of the large, hollow gumtrees once common in bottomland hardwood forests. Theseroosts are being colonized by both Rafinesque’s big-eared batsand southeastern myotis, two species of concern in south-eastern forests.

In Arizona, long-lasting and realistic-looking polyresin “batbark” has been successfully tested as a substitute for natural,peeling tree bark. Three bat species were reported using morethan 80 percent of the artificial bark roosts installed. Detailedinformation on construction and placement of all of these arti-ficial roosts is available on BCI’s website at www.batcon.org.

“Concrete trees” like this one in Texas were designed by BatConservation International to simulate the large tree hollows thatsome forest bats require for roosts. This one was occupied withinmonths by Rafinesque’s big-eared bats.

Endangered gray myotis (Myotis grisescens), like many other batspecies, hibernate on the ceilings and walls of appropriate cavesduring the winter.

P H OT OS © MA R K & S E LE N A K I S E R , B C I / 0 0 10 96 1 P H O T O S © MA R K & S E L E N A K IS E R , B C I / 00 10 9 65


No rt h e rn myo t i sMyotis septentrionalis

About the same size as the littleb rown myotis, the nort h e r nm yotis bat can be distinguishedby its long, narrow ears, whichm e a s u re0.5 to 0.7 inches (14 to19 millimeters).

In the fall, then o rthern myotis iscommonly found atcave and mine en-trances, where somehibernate. However,large numbers havebeen reported enter-

ing caves in March, leading to the suspicion that they hibernate outside,perhaps in cliff-face crevices. In summer, females congregate in groups of 3to 60 individuals at maternity roosts in snags. Small nursery colonies alsohave been found in attics, behind wooden window shutters, beneath wood-en shingles and in bat houses.

Northern myotis are relatively slow flyers that are adapted to hunting incluttered environments, where they often pick insects directly off foliage.These bats seem to prefer feeding beneath the canopy level, often 3 to 10feet (1 to 3 meters) above ground along forested hillsides and ridges. Theymostly eat moths, but also beetles, flies, midges, mosquitoes, caddisflies andleafhoppers.

Evening batNycticeius humeralis

Slightly smaller than the littlebrown myotis, the evening batis dark brown with black wingsand ears. It resembles a smallerversion of the big brown bat.Evening bats are found from

the East Coast toeastern Ne b r a s k aand south througheastern Texas ton o rthern Me x i c o.Evening bats in then o rthern part of

their range are believed to migrate southward in the fall and apparentlyhibernate beneath leaf litter on the forest floor.

Females give birth to two or sometimes three pups, which are capableof flight within 20 days of birth. In addition to roosts in tree crevices andbehind loose bark, evening bats are known to roost in cavities created wherethe tops of live pine trees fork, as well as in buildings and bat houses. Amaternity colony of over 400 individuals was recorded under the bark of

one dead pine tree.Evening bats prefer to forage along edges of mature forests, in clearings

and over waterways. A colony of 300 evening bats consumes an estimated6.3 million insects per summer, typically feeding heavily on spotted cucum-ber beetles, a costly crop pest to vine plants and corn crops. The evening batappears to have a relatively short life span, perhaps only a few years.

Long-legged myo t i sMyotis vo l a n s

The long-legged myotis, typi-cally dark brown, is identifiedby its relatively short ears andlong, dense fur extending alongthe underside of the wing mem-brane from the body to a line

joining the elbowand the knees. It issimilar in size to thelittle brown myotis.Its range s t re t c h e sacross western NorthAmerica from south-

eastern Alaska, British Columbia and Alberta in Canada to Baja Californiaand central Mexico and eastward through the Great Plains and Texas. It livesprimarily in coniferous forests, but also occurs seasonally in riparian anddesert habitats.

The long-legged myotis primarily roosts under exfoliating tree bark andin tree hollows but has also been found in abandoned buildings, cracks in theg round and cliff crevices. It will sometimes hibernate in caves and old mines.It is a rapid, direct flyer and often travels considerable distances while forag-ing. It feeds in and around the forest canopy, primarily on moths and othersoft-bodied insects. Life spans of more than 21 years have been re p o rt e d .

Si l ve r - h a i red batL a s i o n ycteris noctiva g a n s

The silve r - h a i red bat has black ord a rk brown fur with silver tips.Unlike the red or hoary bat, ithas no contrasting markings onthe wrists and shoulders. Si l ve r -h a i red bats are among the most

abundant bats in for-ested areas of nort h-ern No rth America.

Most of thesebats ove rwinter in thesouthern third of thecontinent and re t u r n

n o rth in the spring. In areas of re l a t i vely mild coastal climate, such as coastal

British Columbia, Alaska and New Yo rk, howe ve r, they may remain ye a r -round. Hibernation sites include small tree hollows, loose tree bark, wood-piles, cliff-face crevices, cave entrances and, rare l y, buildings.

Silver-haired bats are slow, highly maneuverable flyers that typicallyfeed in areas sheltered by vegetation, over streams or ponds, along roadsidesand in or near coniferous or mixed coniferous and deciduous forests. Theyfeed on flies, midges, leafhoppers, moths, mosquitoes, beetles, true bugs andflying ants. Silver-haired bats can live to at least 12 years.

E a s t e rn red batL a s i u rus bore a l i s

A medium-sized bat with a re d-dish-orange coat, the easternred bat may have white-tippedhairs that give it a frosty appear-ance and always has whitepatches of fur on the shoulders

and wrists. It is oneof the most abun-dant bats in manyp a rts of its range,but appears to be ind e c l i n e .

Red bats ro o s tin the foliage of a variety of deciduous trees and conifers. Hanging by onefoot, wrapped in their furred tail membranes, they are well concealed andresemble dead leaves. They roost alone or in family groups consisting of amother and her young, although they form groups for migrating to milderregions where they hibernate. Males and females are thought to migrate inseparate groups and may travel with other bat species.

The average litter size is three pups, but a female may have as many asf i ve offspring. In the southeastern and south-central United States, red batsa re known to hibernate in grass clumps and leaf litter on the forest floor. T h e yforage in a variety of habitats, mostly along the edges of pastures, cro p l a n d sor other openings dotted with large deciduous trees. Red bats eat mostlymoths, but also feed on beetles, planthoppers, leafhoppers and spittlebugs.

Ho a ry batL a s i u rus cinere u s

Hoary bats are larger than big brown bats and have mahogany-colored furtipped with white, which gives them a hoary (frosted) appearance. Theyhave a distinctive, yellowish-brown collar under the chin and yellowish earsedged in black. They occupy the widest range and variety of habitats of anyNorth American bat, living from Argentina and Chile northward throughCanada. Hoary bats roost in foliage in pine-hardwood forests of the easternUnited States and in deserts and ponderosa pine forests of the Southwest,but they are most abundant in mixed deciduous forests and croplands of thePlains States and in coniferous forests of the Pacific Northwest.

The hoary bat usually roosts alone or in family groups of a mother and

her young, except duringmigration. These bats are sel-dom seen. In winter, a fewh a ve been found in Sp a n i s hmoss, squirrel nests, wood-

pecker holes and onthe trunks of tre e s .

During sum-m e r, they pre f e rt ree roosts in edgehabitats close toforaging are a s .Ho a ry bats hunt

re l a t i vely large insects, mostly moths, in open areas in meadows, over stre a m sand rivers or above stands of trees at canopy level. They are highly territori-al, returning to feeding sites night after night. From August thro u g hOc t o b e r, hundreds of hoary bats may migrate together. In the U.S., mosth o a ry bats apparently ove rwinter in coastal areas. These bats are believed tol i ve 6 to 7 ye a r s .

Ra f i n e s q u e’s big-eared batCo ry n o rhinus rafinesquii

Rafinesque’s big-eared bats aregrayish-brown with very longears (1 to 11⁄2 inches [25 to 38millimeters]) and large facialglands on each side of theirsnout.

They are non-migratory and tradi-tionally roost inlarge hollow trees inmature Southeasternl owland pine andh a rdwood fore s t s ,

especially in cypress-gum stands near permanent water or in upland oak-hickory forests on the Cumberland Plateau. As this habitat has graduallydisappeared, many colonies now roost under concrete bridges or in aban-doned buildings that are prone to human disturbance and structural col-lapse. Artificial roosts may be required to provide alternatives in areas wheretraditional roosts have been lost.

Maternity colonies include up to 200 females and young, often ro o s t i n gin dimly lit areas. In northern regions, some may hibernate in caves, aban-doned mines, wells and old cisterns, either singly or in clusters. In southerna reas, most appear to remain active ye a r - round, except during the coldest andmost inclement we a t h e r. They are ve ry agile flyers, capable of picking insectsoff foliage. They often forage within three feet (1 meter) of the gro u n d .Moths are their most common pre y, but other insects, including horseflies,a re also taken. Bi g - e a red bats may live up to 10 years in the wild.


S O U R C E S O F A S S I S T A N C E

A variety of federal, state, private and nonprofit organizations can provide landowners with financial and technical assistance to improvefish and wildlife habitats in forests. The following is a partial list of agencies or organizations with programs specifically tailored toforestry and wildlife conservation.

F e d e r a l , S t a t e a n d C o u n t yNatural Resources Conservation Serv i c e : Since 1935, the Natural Re s o u rces Conservation Se rvice (originally called the Soil Conserva t i o n

Se rvice) has provided leadership in a partnership effort to help America’s private-land owners and managers conserve their soil, water andother natural re s o u rces. NRCS employees provide technical assistance based on sound science and suited to each landow n e r’s specific needs.N RCS provides financial assistance for many conservation activities. Pa rticipation is vo l u n t a ry. w w w. n rc s . u s d a . g ov

U. S . D e p a rtment of A g r i c u l t u re Fo rest Serv i c e : The Fo rest Se rvice was established in 1905 to sustain the health, diversity and pro d u c t i v i t yof the nation’s forests and grasslands for present and future generations. The mission of the Fo rest Se rvice is to achieve quality land man-agement under the sustainable, multiple-use management concept to meet the diverse needs of people. This includes providing technicaland financial assistance to state and private forest agencies and landowners, encouraging them to practice good stew a rdship and qualityland management in meeting their specific objectives. w w w. f s . f e d . u s

C o o p e r a t i ve State Researc h , E d u c a t i o n , and Extension Service (CSREES): An agency within the U.S. De p a rtment of Agriculture, CSREES isthe federal partner in a network of thousands of scientists, educators and extension staff and volunteers who carry out its programs thro u g h-out the United States, its territories and beyond. Most of these partners work at or through land-grant universities, with one or more suchinstitutions in each U.S. state and territory and in the District of Columbia. w w w. c s re e s . u s d a . g ov / q l i n k s / p a rt n e r s / s t a t e _ p a rt n e r s . h t m l

DecAID:The Decayed Wood Advisor: DecAID is a tool to help you manage snags, down wood and partially dead trees for biodiversity.The online advisor can help you to determine how much and what size of decayed wood to leave, what matches general “unharvested”conditions, and what insects and pathogens create dead wood. It also provides a synthesis of literature and statistics on wildlife use andan inventory of snags and down wood. Information: www.treesearch.fs.fed.us/pubs/6233

A Guide to Creating Vernal Ponds: Biebighauser, Thomas R. 2003. USDA Forest Service, 33 pages. Information for building and main-taining an ephemeral wetland. www.ducks.org/CMS/states/Files/Kentucky/vernal.pdf

N o n - G o v e r n m e n t O r g a n i z a t i o n sThe American Tree Farm System (ATFS): The ATFS certifies owners of tree farms and NIPF lands in the United States that maintain strict

sustainable forestry-management practices. Certification requires that landowners pass an inspection every five years. In addition to pro-ducing timber, landowners must protect watershed quality, wildlife habitat and soil and provide recreational opportunities. For informa-tion, contact the American Forest Foundation’s website at www.affoundation.org or call 1-888-889-4466.

Longleaf Alliance: Established in 1995 to coordinate a partnership between private-land owners, forest industries, state and federal agencies,conservation groups, researchers and others interested in managing and restoring longleaf pine forests for their ecological and economicbenefits. The Alliance provides information on restoring and managing longleaf pine forests for timber and wildlife in the southeasternU.S. www.longleafalliance.org

Sustainable Forestry Initiative® (SFI): A comprehensive system of principles, objectives and performance measures developed by profession-al foresters, conservationists and scientists that combines perpetual growing and harvesting of trees with the long-term protection ofwildlife, plants, soil and water quality. The SFI Program is overseen by the Sustainable Forestry Board (SFB), an independent 501(c)3organization, which is responsible for maintaining and enhancing the SFI Standard and verification procedures. www.aboutsfi.org

Forest Stewardship Council: The Forest Stewardship Council (FSC) is an international network that promotes responsible management ofthe world’s forests. FSC brings people together to find solutions to problems created by poor forestry practices and to reward good for-est management. Landowners and companies that sell timber or forest products seek certification as a way to verify to consumers thatthey have practiced forestry consistent with FSC standards. Independent certification organizations are accredited by FSC to carry outassessments of forest management to determine if standards have been met. www.fsc.org

For detailed information about bat species, bats’ habitat and conservation needs, forest management, upcoming conferences,workshop opportunities, recent research and much more, visit Bat Conservation International online at:

w w w. b a t c o n . o r g

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