BATSAND

MINES

MERLIN D. TUTTLE &DANIEL A.R. TAYLOR

Bat Conservation International, Inc.

RESOURCE PUBLICATION NO. 3 REVISED EDITION

Copyright ©1998 Bat Conservation International, Inc.Permission is granted to reproduce any pages from page 34 to page 50 of this book. For reproduction ofany other contents, permission should be requested in writing from Bat Conservation International, Inc.All rights reserved. No parts of this book, other than those listed above, may be reproduced, distributed,transcribed, or transmitted in any form by any means, electronic or mechanical, by photocopying orrecording, or by any information storage or retrieval system, without the written permission of the pub-lisher, Bat Conservation International, Inc., P.O. Box 162603, Austin, TX 78716.

BATSAND

MINESMERLIN D. TUTTLE

DANIEL A.R. TAYLOR

Bat Conservation International, Inc.

RESOURCE PUBLICATION NO. 3

We especially thank the many individuals who generously provided informationfrom their many years of research and experience. Their critical reviews andsuggestions helped make this handbook possible.

In particular, we thank: J. Scott Altenbach, University of New Mexico; Patricia E.Brown, Brown-Berry Biological Consulting; Robert R. Currie, USDI Fish andWildlife Service; Virginia M. Dalton; Sheryl Ducummon, Bat ConservationInternational; Laurie Fenwood, USDA United States Forest Service; Michael Gobla,USDI Bureau of Mines; Kenneth J. Kingsley; Laura Mazanti, USDA SoilConservation Service; Kirk W. Navo, Colorado Division of Wildlife; Debra C. Noel,Arizona Game and Fish Department; Mark Perkins; Elizabeth D. Pierson; RoyPowers, Jr. and David Foster, American Cave Conservation Association; FredStabler, USDI Bureau of Land Management; and Michael Washburn, VirginiaDivision of Mine Land Reclamation.

This publication was produced by the North American Bats andMines Project, co-founded by Bat Conservation International and theBureau of Land Management. We gratefully acknowledge a grantfrom the Asheville Field Office of the U.S. Fish and Wildlife Serviceand additional support from Verne and Marion Read, the NationalFish and Wildlife Foundation, the U.S. Forest Service, and theNatural Resources Conservation Service.

Acknowledgements

Natural ResourcesConservation Service

Importance of Mines for Bats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Environmental Consequences of Losing Bats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

How and When Bats Use Mines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

How Mine Structure, Location, and Human Disturbance Affect Bat Use . . . . . .12

Assessing Mines for Bats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Protection of Bats in Mines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Appendix I. Helpful Literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Appendix II. Available Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Appendix III. Plans for Bat Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Appendix IV. Mine Survey Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

List of Illustrations

Figure 1. Typical Mine Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Figure 2. Mine Airflow Patterns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

List of Tables

Table 1. Species List of Bats That Use Mines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Table of Contents

MANY OF NORTH AMERICA’S largest remaining bat popula-tions roost in mines. These include a majority of the 45 batspecies living in the continental United States and some of thelargest populations of endangered bats. More than half of U.S.bats are already listed as endangered or species of concern, andclosure of abandoned mines without first conducting biologicalsurveys could endanger even currently abundant species. Giventhe key ecological role of bats as primary predators of night-fly-ing insects, which cost American farmers and foresters billionsof dollars annually, additional threats to bat survival are causefor serious concern.

Closure or other alteration of old mines without biologicalassessment can, in single events, eliminate some of America’slargest remaining bat populations. This publication will aidresource managers and others involved in decisions to close orreclaim abandoned or inactive subsurface mines, or to permitnew mining in historic districts. It provides the basic informa-tion required to assess whether a mine is, or could serve as, animportant bat roost, and it describes safe and responsible meth-ods for protecting both humans and bats without total closure.Before surveying, closing, or gating mines, experts knowledge-able about bats and mine safety should be consulted. A list ofresources is provided at the end of this publication.

6 BATS AND MINES

Introduction

BATS AND MINES 7

Importance of Mines for Bats

Some of our largest remaining populations of endangeredIndiana bats rely on abandoned mines for hibernation.These bats and many other species often have few alterna-tives as their traditional roosts in caves are lost to humandisturbance.

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ABANDONED MINES SERVE AS important year-roundsanctuaries for bats. Throughout the UnitedStates, human disturbance of caves, cave commercial-ization, deforestation, and urban and agriculturaldevelopments have forced many bats from their tradi-tional roosts in search of new homes. Although cavesare numerous in some regions, most are now too fre-quently disturbed by humans to permit bat use. Batsadditionally have lost countless traditional roosts inold tree hollows due to logging of old-growth forests.Over the past 100 years or more, many displaced batshave gradually moved into abandoned mines, whichoften provide microclimates similar to caves. Even inareas where traditional roosting habitat has not beendisturbed or altered by man, abandoned mines attractbats due to their often ideal environmental condi-tions. Bats may now have few alternatives or may beso instinctually committed to certain sites that theycannot change roosts in the time permitted by currentrates of mine closure. Loss of a single mine hiberna-tion site can affect a multistate region, eliminatingmany summer colonies of bats over thousands ofsquare miles.

Of the more than 8,000 mines surveyed byresearchers across North America, 30 to 80 percentshowed signs of use by bats, with an average of 10percent containing important colonies. From theGreat Lakes region north and eastward in the UnitedStates and Canada, up to 70 percent of open, unflood-ed mines may be used by large bat populations.Moreover, because most mines have not been checkedfor bats, a large proportion of bats living in themremain undiscovered. For example, in December1992, an estimated one million little and big brownbats (Myotis lucifugus and Eptesicus fuscus) were foundin the Millie Hill Mine in Iron Mountain, Michigan. Itwas slated for closure the next spring. These bats con-stituted the second largest hibernating bat populationever discovered in North America.

In Wisconsin, more than 600,000 bats of fourspecies were saved because just two mines were sur-veyed and protected from closure. The largest record-ed hibernating population of western big-eared bats(Corynorhinus townsendii pallescens), another species indecline, was recently destroyed in a New Mexicomine shaft where vandals set old timbers on fire. InNew Jersey, the state’s largest population of hiber-nating bats was inadvertently trapped in the HiberniaMine when it was capped. These bats also wouldhave died had not biologists convinced state authori-ties to reopen the entrance immediately. Likewise, the

8 BATS AND MINES

California leaf-nosed bats areextremely dependent on aban-

doned mines. Most of theirknown winter roosts in the

Southwest are in mines. MERL

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Canoe Creek State Park limestone mine in Pennsyl-vania was reopened in time to save its bats and nowshelters the largest bat hibernating population in thestate.

Unfortunately, at the rate at which mines arebeing closed, such incidents are far more commonthan recognized. A local mine inspector reported that,of the 12 mines already closed prior to 1993 in IronMountain, Michigan, some contained large numbersof bats, perhaps more than were saved in the MillieHill Mine.

Due to the colonial behavior of most bats, theyare especially vulnerable to mine closures. Endan-gered Indiana bats (Myotis sodalis) and cave myotis(M. velifer) have each been found in mines in numbersup to 100,000. Similarly, the largest known hibernat-ing populations of the southeastern big-eared bat(Corynorhinus rafinesquii), a species of concern, live inabandoned iron and copper mines in small groupsranging from a few dozen to over 500. A majority ofthe remaining nursery roosts of the endangered lesserlong-nosed bat (Leptonycteris curasoae) in the UnitedStates are also in mines.

In the northern United States, little brown bats,among America’s most successful and abundant bats,are now so reliant upon abandoned mines for hiber-nation that a majority of the entire species overwin-ters in mines. Closure of mines without first checkingfor bats could drastically reduce their numbers, need-lessly endangering the species. The danger of killingextremely large numbers of these animals is probablygreatest in old mines of the northern Midwest, fromthe Dakotas to Wisconsin and Michigan, as well asfarther north into Canada, but it is certainly notrestricted to these areas. Populations of over 100,000bats are also known to live in mines of the northeast-ern United States and may be discovered whereverbats live near mines cool enough for hibernation.

Other bat species rely heavily on mines for hiber-nation, even though large proportions of their popu-lations are not normally found in any one mine.These include the eastern small-footed myotis (Myotisleibii), western small-footed myotis (M. ciliolabrum),California myotis (M. californicus), eastern long-earedmyotis (M. septentrionalis), eastern pipistrelle (Pip-istrellus subflavus), and big brown bat.

BATS AND MINES 9

Mexican free-tailed bats rank among North America’smost valuable wildlife, consuming enormous quantities ofinsect pests each summer night.

Bats are primary pollinators and seed dispersers for manyof the most ecologically important plants of the desertSouthwest. This lesser long-nosed bat is about to pollinatea saguaro cactus.

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MINE CLOSURES WITHOUT ASSESSMENT for bats havepotentially serious ecological and economic con-sequences. Bats are primary predators of vast num-bers of insects that fly at night, and many such insectsrank among North America’s most costly agriculturaland forest pests. These include cucumber, potato, andsnout beetles; corn-borer, corn earworm, cutworm,and grain moths; leafhoppers; and mosquitoes. A sin-gle little brown bat can catch more than 1,200mosquito-sized insects in an hour, and the 25 millionMexican free-tailed bats (Tadarida brasiliensis) that for-merly occupied Eagle Creek Cave in Arizona con-sumed over 250 tons of insects nightly, the majority ofwhich were agricultural pests.

A colony of Mexican free-tailed bats living in theold Orient Mine in Colorado consumes nearly twotons of insects nightly, largely moths. Just one of themany moths that such bats eat, the corn earwormmoth, attacks a wide variety of crops, from corn andcotton to tomatoes and pumpkins. Since each femalemoth is capable of laying hundreds of eggs, as few as100 can force a farmer to spray a large area of croplands.

Illustrative of the impact that even small coloniesof bats can have, just 150 big brown bats can eat suffi-cient cucumber beetles each summer to protect farm-ers from 33 million of these beetles’ root worm larvae,pests that cost American farmers an estimated billiondollars annually.

Long-nosed (Leptonycteris curasoae and L. nivalis)and long-tongued bats (Choeronycteris mexicana) arebelieved to be important pollinators for some 60species of agave plants and to serve as both pollina-

tors and seed dispersers for dozens of species ofcolumnar cacti, including organ pipe and saguaro,which rank among the southwestern desert’s mostfamiliar and ecologically important plants. Loss ofthese bats could further jeopardize these alreadydeclining plants, harming an entire ecosystem.

Environmental Consequences of Losing Bats

10 BATS AND MINES

How and When Bats Use Mines

These little brown bats arehibernating in an abandonedMichigan mine. A single site

may attract hundreds ofthousands of bats from a

multistate area each winter.

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MINES ARE KEY SITES for rearing young in summer,for hibernating in winter, and for use as tempo-rary havens. They also can serve as crucial migratoryrest stops during spring or fall. Loss of these migrato-ry stopover sites can have serious consequences foran entire population. Old mines are often the onlysuitable shelters left midway between a bat’s summerand winter roosts; without these protected restingplaces, species’ migratory mortality could greatlyincrease.

Bats also use mines as temporary night roosts,where they can retire to digest an evening meal insafety. Select mines are also frequently used forcourtship and mating. Bats need mines for all thesereasons, but for many species the most importantcontribution mines make to their survival is as essen-tial sites in which they can raise their young or hiber-nate.

Be it a mine or natural cave, the microclimate of asite, especially the temperature, determines if andwhen bats use it. Roosting habits of differentspecies—whether they tend to gather in small groupsor in dense clusters covering thousands of square feetof walls—largely determine the kinds of roosts theycan occupy.

Large colonies can share the energy cost of heat-ing a site to the high temperature required for rearingyoung, and so can tolerate much lower ambient tem-peratures. Only four U.S. bat species are known toform nursery colonies of many thousands of individ-uals, and all live primarily in southern areas. Becauseof their large colony sizes, such species can some-times raise young in mines with ambient tempera-tures as low as 56°F, though they prefer temperaturesof 66°F or more. Colonies of gray bats (Myotis gris-escens) and cave myotis sometimes include 100,000 ormore individuals. Gray bats were declared endan-gered in 1976, and the cave myotis is a species of con-cern. The endangered lesser long-nosed bat alsoforms colonies of 10,000 or more individuals in mines.In the Southwest, Mexican free-tailed bats formcolonies numbering in the millions, and are thelargest aggregations of mammals known. However,even these bats have declined to less than one percentof former numbers in several areas where they oncewere the most abundant species. As colonies becomesmaller, their ability to share the cost of heating rela-tively cool roosts diminishes. They are thus forced tochoose warmer roosts, decreasing the number of suit-able roost sites available to them.

BATS AND MINES 11

Baby Mexican free-tailed bats clusterat densities of up to 500 per squarefoot. Colonies of up to 100,000 ormore may live in a single mine. Be-cause the species concentrates in largenumbers in relatively few places, it isextremely vulnerable and has declinedalarmingly over the past 30 years.

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Bats that roost in smaller groups typically requireroost temperatures between 70° and 90°F to raiseyoung successfully. Big-eared bats are an apparentexception. Their nursery roosts have sometimes beenrecorded in sites where ambient temperatures are aslow as 60°F.

The California leaf-nosed bat (Macrotus californi-cus), a species of concern, is incapable of hibernationand does not migrate. It typically selects temperaturesclose to 90°F in summer and 72° to 80°F in winter,often in mines warmed by geothermal heat. Mostcolonies of leaf-nosed bats in the United States nowlive only in mines. Long-nosed bats and most Mexi-can free-tailed bats that use U.S. mines in summermigrate south to Mexico for the winter.

Nearly half of U.S. bat species live in regionswhere mines provide suitable temperatures for bothsummer and winter use (see Table 1, page 28). Thesebats can sometimes find appropriate temperaturesfrom season to season by moving to different parts ofa single mine. As with caves, the configurations ofsome mines trap air of varied temperatures, and batscan move between areas that provide warm or coldair, depending on their physiological requirements.They may also temporarily move to other mines orcaves that provide appropriate seasonal temperatures.

Suitable hibernation sites in all regions must pro-tect bats from freezing and, for most species, shouldprovide temperatures between 40° and 50°F for mostof the winter. Big brown bats can survive subfreezingbody temperatures, and several bats, including big-

eared bats, pipistrelles (Pipistrellus subflavus and P.hesperus), and a few myotis bats, sometimes hibernateat temperatures between 32° and 40°F. Mines thatprovide a range of temperatures between 32° and50°F are not common, and bats often must travel hun-dreds of miles to reach them. A few bats, especiallysoutheastern and Pacific big-eared bats (Corynorhinustownsendii townsendii), are exceptional. They may feedduring mild winter weather, enabling them to hiber-nate for shorter periods of time in locations that arenot stable enough for other bats, often at tempera-tures ranging between 50° and 60° F. This alsoappears to be true for several other bats in mildcoastal areas of the West. The needs of many westernspecies are still poorly known.

Approximately one quarter of U.S. bat species arebelieved to hibernate almost exclusively in old minesor caves. These bats typically must find roosts wheretemperatures do not exceed 53°F at the time theyenter hibernation between September and November,and that average between 34° and 50°F by midwinter,although a few species can tolerate temperatures aslow as 27°F. The greater the range of temperature pro-vided in a single cave or mine, the easier it is for batsto find appropriate temperatures by changing roostswithin the site during exceptionally warm or coldwinters. In the northern United States and in Canada,species such as the little brown bat and eastern pip-istrelle thrive in mines where temperatures often varyonly one or two degrees annually, remaining stablebetween 40° and 50°F.

12 BATS AND MINES

How Mine Structure, Location, and Human Disturbance Affect Bat UseKNOWLEDGE OF SEASONAL roosting requirements andan understanding of the typical configurations ofunderground mines is helpful in evaluating them aspotential bat habitat. Table 1 (page 28) lists speciesknown to have the greatest reliance on mines as nurs-ery or hibernation sites, and indicates the species’approximate geographical distributions, the kind andtiming of mine use, and their current conservationstatus. Some western species may depend on minesmore than is yet documented. Figure 1 is a diagramof an abandoned mine, showing the typical configu-rations and terminology associated with undergroundmine workings.

Airflow and temperature are key determinants ofhow, when, and where bats will use mines. Internalmine temperatures typically approximate the meanannual surface temperature unless the mine’s config-uration and/or multiple entrances set up chimney-effect airflow patterns or geothermal heating occurs.Thus knowledge of an area’s mean annual surfacetemperature, combined with information on a mine’sapproximate volume, configuration, elevation, andnumber and location of connected surface entrances,can help greatly in predicting seasonal bat use pat-terns. These factors will suggest where, and in whichseason, bats are most likely to be present. However, itmay be difficult or impossible to predict some inter-nal mine configurations from observing only surfaceworkings, and in rare cases internal temperatures canbe altered at sites where there is geothermal heating.The following discussion of temperature, airflow, andmine ventilation is provided to help explain howsuch factors affect bat occupancy.

Temperature Mines with internal temperatures as low as 55°F arerarely used as summer nursery sites. They are simplytoo cold. Consequently, bats rarely raise young inmines located at high elevations or in the northernUnited States or Canada. Exceptions occur in areas ofthe Northwest where warm climates extend north-ward or where extraordinarily effective heat traps orgeothermal activity exists.

Many northern or high-elevation mines are, how-ever, ideally suited for bat hibernation in winter,because they provide stable, year-round temperaturesin the 40° to 50°F range. Some of these harbor NorthAmerica’s largest remaining populations of bats. Afew mines may be unacceptable due to radioactivity,

flooding, geothermal heat, or toxic gas.The farther south, or the lower the elevation, the

less likely a mine is to provide temperatures suitablefor winter use and the more likely it is to be warmenough for summer use, especially by nurserycolonies. In areas where internal mine temperaturesare predominantly in the 50s, a high proportion maybe too warm for winter use and too cool for summeruse. Exceptions occur when “chimney effects,” creat-ed by multiple entrances at different elevations, allowwarm air to enter and become trapped in stopes orraises near entrances or when cold air is trapped inthe lower sections of a mine. Nursery colonies ofsoutheastern big-eared bats are often found in warm-air traps near the entrances of mines whose tempera-tures would otherwise be too cool.

At lower elevations in southern areas, manymines will be warm enough to support bat nurserycolonies. However, species that form nursery coloniesof hundreds of individuals or less, often must findexceptionally warm areas, even in southern mines.These may be in stopes or raises, especially nearentrances through which warm air from outsideenters and is trapped.

Where mean annual surface temperatures rangebetween 50° and 60°F, knowledge of cold- or warm-air trap configurations can be especially important.For example, Missouri’s Pilot Knob Mine, located insuch an area, is critical habitat for an estimated100,000 endangered Indiana bats. The size and inter-nal contours of this mine allow entrapment of cold air,permitting deviation (at least in some parts of themine) markedly below the mean annual surface tem-perature.

Where average surface temperatures rangebetween 40° and 50°F, virtually any mine deepenough to prevent freezing is potentially important asa hibernation site, although the largest and most com-plex mines are likely to be the most suitable. Somemines in these regions may contain millions of batsand serve as vital refugia for bats from multistateareas. Only a few losses of these critical mines couldendanger an entire species.

Mines where average surface temperatures exceed70°F typically are used only in summer, though somemines in western desert areas are exceptional due toextreme daily and seasonal fluctuations in surfacetemperatures. Also, both hibernation and nurserysites are used to varying degrees in spring and fall,

BATS AND MINES 13

Adit — A horizontal mine passage driven from the surface.

Back — The ceiling of an underground passage.

Blind — Without lateral workings.

Collar — The entrance to a shaft.

Crosscut — A horizontal underground mine passagedriven to intersect an orebody.

Decline — A mine passage driven up or down along theorebody (also called incline).

Drift — A horizontal underground mine passage followingan orebody.

Dump — Waste rock removed from a mine.

Face — The termination of an adit or drift.

Foot-wall — The rock below an orebody.

Hanging-wall — The rock above an orebody.

Levels — Drifts at different elevations.

Figure 1. Typical mine features and terminology. In this example, the highest and lowest temperature air would betrapped at locations A and B respectively.

Orebody — A mineral deposit that is being mined for itsmetals.

Portal — The entrance to an adit or tunnel.

Raise — A mine opening driven upward from inside toconnect upper levels or explore areas above a level.

Rib — The side of an underground passage.

Shaft — A vertical mine opening from the surface.

Stope — An underground cavity made by the removal of oreabove (overhand) or below (underhand) a drift.

Sump — The bottom of a shaft below all levels; used tocollect water.

Tunnel — A horizontal mine passage that is open at bothends.

Vein — A definable linear zone of mineralized rock.

Winze — A mine opening sunk downward from inside toconnect lower levels or explore areas beneath a level.

Mining Terminology

TUNNEL

ADIT

VEIN

DUMP

DRIFT

PORTAL

COLLAR

LEVEL 1

SH

AF

T

LEVEL 2

LEVEL 3

WINZE TOLOWERLEVEL

A

A

A

A

DECLINE(OR INCLINE)

WIN

ZE

CROSS SECTION

UNDERHANDSTOPE

DRIFT

DRIFT

TUNNEL

ADIT

DRIFT

DRIFT

DUMP

CROSSCUT

FOOT-WALL

CROSSCUT

CROSSCUT

SECTION OF UNDERGROUND OPENING

RIB RIB

BACK

FLOOROR SILL

STOPE

HANGING-WALL

OREBODY

DUMP

A

B

FACE

WINZE WITHLADDER USEDAS A MANWAY

DRAWN BY J. SCOTT ALTENBACH AND JIM KENNEDY

BLINDRAISE

OVERHANDSTOPE

LONGITUDINALSECTION

OREBODY

CROSSCUT

SUMP

14 BATS AND MINES

and some warm mines may be used year-round bybats in mild coastal or desert climates of the West.

In general, mines with the largest internal volumeand more than one entrance are the most likely to beimportant for bats, especially when entrances are ateven slightly different elevations. However, even amine with a single entrance can be extremely impor-tant, especially if it is located in an area of extra warmor cold climate or is geothermally heated.

Airflow Airflow rates in mines are typically determined

by the difference between external and internal airtemperatures due to seasonal or daily weatherchanges, combined with mine configurations that cre-ate, enhance, or restrict airflow. Without airflow fromthe outside, or geothermal heating, mine tempera-tures rarely deviate from an area’s mean annual sur-face temperature. The fact that hot air rises and coldair sinks is the driving force behind internal minetemperature deviations above or below mean annualsurface temperatures. Other factors, such as thegreater weight of moisture-laden air or the pressurecreated by winds blowing into mine entrances, alsocan affect airflow in and out of mines, but theirimpact is typically minor compared to that of temper-ature. Thus, only temperature will be considered inthe following discussion.

Figure 2 provides four examples of how the inte-rior configuration of a mine can affect seasonal air-flow and bat roost site choices. Example 1 illustrates amine configuration that creates a strong “chimneyeffect,” combined with an excellent cold air trap. Lit-tle airflow occurs here in summer when external tem-peratures are above the mean annual surface temper-ature, allowing relatively cool, heavy air to remaintrapped inside. However, as colder air arrives in fall,it sinks inside (A) and warmer air escapes (B), creat-ing a potential hibernating site. Each time the externaltemperature falls below that of the mine’s walls(which approximate the mean annual surface temper-ature) more cold air is trapped and stored, whilewarmer air rises and exits. Even when mine entrancesare thousands of feet apart, “chimney effects” typical-ly occur if entrances exist at different surface eleva-tions. If there is sufficient volume for cold-air storagebelow the lowest entrance, the average temperaturein the lowest levels may remain 10°F or more belowthe mean surface temperature. Thus, even though amine with these configurations may be located at ele-vations or in mid-latitudes where the mean annualsurface temperature averages in the 50s, such a sitecould still provide the cooler temperatures necessaryfor bat hibernation. In northern latitudes or at high

elevations, such mines might be too cold for batswithout reduction of airflow at one of the entrances.

Air circulates in the adit illustrated in Example 2only when outside air temperatures rise above themean annual surface temperature, typically in sum-mer. Cool air flows out the lower part of the mineentrance, allowing warm air to enter along its ceiling.If a raise or stope exists above and near the entrance(X), it might trap enough warm air to be used as a batnursery site, even in an area where temperatureswould normally be too low. Entrance and passagediameter have a major impact on how much warm aircan enter. The temperature of the lower chamber (Y)remains nearly constant year-round, because it is dif-ficult for the light summer air or the heavy winter airto reach it.

Since this lower chamber always remains atapproximately the mean annual surface temperature,the site cannot be used for hibernation in a regionwhere the mean annual temperature averages abovethe bats’ mid-winter temperature needs (usually inthe 40s or low 50s, lower for some species). If themine were located where the mean surface tempera-ture is between 40° and 50°F, however, this chambermight be ideal for hibernation. Due to its shape, itwould never be in danger of freezing, since cold airfrom outside could not move upward to reach it, evenduring an unusually cold winter.

Example 3 illustrates a restriction near theentrance that blocks most of the airflow year-round.In lowland mid-latitude locations, where mean annu-al surface temperatures are mostly between 51° and56°F, such a mine probably would not meet the nurs-ery or hibernation needs of most bats. As one movessouth into areas where surface temperatures averagecloser to 60°F or above, more and more such sites willbe used by nursery colonies large enough to shareheating of the dome-shaped stoped area (B). In warm-enough locations, even small nursery colonies mightfind such a site ideal. Conversely, if this site werelocated in the north, where average surface tempera-tures would be below 50°F, it could be used for hiber-nation.

The fourth example illustrates a configurationthat permits bats to change their roost sites seasonallywithin the same mine. In such a mine, airflow direc-tions would reverse between summer and winter. Inwinter, upward movement of a large volume of rela-tively warm air creates sufficient suction to draw coldair up hill. In mid-latitudes or at elevations where themean surface temperature is in the mid-50s, thestoped area (Z) would be unacceptable to most batsyear-round. However, cavity (X) might trap enoughwarm air to permit use by a nursery colony, and loca-

BATS AND MINES 15

Example 1 illustrates any mine situation where adits, raises, winzes, or stopes are located below the lowest entrance andare connected to one or more additional entrances located even a few feet above the lowest one. This sets up chimney-effect airflow, as indicated. The strongest flow occurs on the coldest winter days. The larger the volume of chambers belowthe lowest entrance, the more effective the cold-air trapping.

Airflow in Example 2 is strongest when the adit is tall and extensive and at times when the outside temperature is highest.

Example 3 illustrates how cold- or warm-air “dams” can restrict airflow. The temperature in this sample mine will approximatethe mean annual surface temperature for the same reason that location Y in Example 2 does.

Example 4 is similar to Example 1, except for drawing cold air uphill and for illustrating how greater complexity enhances asite for bats. Because it provides extensive tunneling, in addition to both warm- and cold-air traps, it will have strong airflowthrough both upper and lower portals whenever the outside temperature deviates far above or below the area’s mean annualsurface temperature.

Figure 2. Seasonal airflow and the locations of cold- and warm-air traps play a key role in determining how, when, andwhere bats use mines.

Example 3

Example 4

Example 2Example 1

Winter

Summer

Y

X

ZB

A

B

A

Y

X

16 BATS AND MINES

tion (Y) might trap enough cold air to permit hiberna-tion. Larger spaces trap more warm or cold air andtherefore provide the most reliable conditions for batuse.

PredationEntrance and passage size also affect a bat’s vul-

nerability to predators. Species that form nurserycolonies of fewer than 1,000 individuals sometimesuse entrances less than three feet in diameter or rooston ceilings less than eight feet above floors. However,only mines with larger entrances and high-roofedpassages are suitable for species that form nurserycolonies numbering in the tens of thousands of indi-viduals.

Bats tend to be more tolerant of varied entranceand roost dimensions in hibernation sites. Coloniesnumbering more than 1,000 bats rarely overwinter inplaces with ceilings less than six feet high unless oth-erwise protected from predators by deep pits, shafts,or other obstacles. Small groups, or scattered individ-uals, may roost within three feet of the floor, simplyrelying on not being discovered. Such bats may alsotolerate entrances as small as two feet or less in diam-eter. Since bats about to enter hibernation often arriveand exit a few at a time, they have fewer problemswith predators. Entrance size is therefore not as criti-cal a factor as it is in choosing a summer site.

Proximity to food and waterA major consideration in bat choice of summer

roosts is their proximity to feeding habitat and water.Distances to drinking or feeding sites can be severelylimiting factors for nursery colonies of insectivorousbats. Most species prefer sites located less than a halfmile from water and feeding habitat. However, fast,long-distance flyers, like Mexican free-tailed bats, canlive much farther from key resources, and long-nosedand California leaf-nosed bats may not require waterat all. Long-nosed bats typically live within 40 milesof the nearest agave, saguaro, or organ pipe cactusplants, on which they feed. California leaf-nosed batsnormally roost within five miles from their feedinghabitat over desert-wash vegetation.

Human disturbanceMines that humans can easily enter may be ideal

for bats, but may lack bats due to high levels of dis-turbance. Human exploration of abandoned mines isincreasing, both for recreation and extraction of min-erals and historic mine artifacts. To avoid disturbance,many of the most important bat hibernation popula-tions now live in mines that are especially dangerousfor humans to enter. By using these sites, bats avoidpotentially lethal disturbances that exhaust their lim-ited fat supplies before spring. One of North Ameri-ca’s largest remaining hibernating populations ofendangered Indiana bats is in a mine that is too dan-gerous to be entered by people. An estimated millionlittle brown bats were discovered hibernating in amine with a nearly vertical entrance 300 feet deep. Ineither case, bats are difficult to detect except as theyenter and exit in fall and spring. Bat biologists can bealerted to the potential importance of a site too dan-gerous to enter, or which currently has no bats due tohuman disturbance, based on knowledge of meanannual surface temperatures, combined with informa-tion on mine entrance types and locations.

SummaryUnderstanding how mean annual surface temper-

ature, “chimney-effects,” and thermal traps affectmine temperatures can greatly enhance the probabili-ty of identifying mines or locations inside mines thatwill be most important to bats. Assessments of preda-tor pressures on the bats and whether the surround-ing area meets foraging requirements, especially for asummer-use site, are additional factors to consider.Such knowledge also can be used to identify idealsites where bats would live if protected from humandisturbance. In some cases protecting a mine where nobats now live can do much more good for the conservationof bats than protecting one nearby where bats are barelysurviving marginal conditions in order to avoid humandisturbance. Knowing bat roost needs may also indi-cate the season in which a mine should be checkedfor bats and certainly is helpful when dealing withsites that are too dangerous to enter.

BATS AND MINES 17

Assessing Mines for Bats

An internal survey of amine is the most thor-

ough and accuratemethod of determiningwhether bats use a site

and in which seasonthey are present. Thismethod, however, re-

quires training andexperience.

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THERE ARE TWO PRIMARY TECHNIQUES for surveyingmines for bats: internal and external surveys. Asimplied, internal surveys involve a thorough searchof a mine’s interior for bats or bat sign, while externalsurveys involve observing or capturing bats from out-side a mine entrance as they exit or enter. For bothmethods, it is critical that surveys be conducted at theproper time of year, since the types of use and sea-sons of use differ widely. While an internal mine sur-vey is generally the more thorough and accuratemethod for determining bat use, it is also more haz-ardous and requires the most training and experience.

The exploration of abandoned undergroundmines may be regulated in some states by the federalOffice of Safety and Health Administration (OSHA),Mine Safety and Health Administration (MSHA), orthe state mine inspector’s office. Appropriate authori-ties in each state or region should be contacted beforeconducting or contracting for underground aban-doned mine surveys. Underground surveys shouldnot be attempted without appropriate training andexperience. Human and financial resources, and the

level of expertise available to natural resource man-agers, will likely play a major role in determining themethod of survey used.

When time permits, an external presurvey ofabandoned mine sites should first be conducted todetermine if mines have potential as bat roosts. Aninitial site visit, and knowledge of how mine environ-ments determine bat use, will help determine if addi-tional surveys are necessary and if so, how and whensurveys should be conducted. Sample survey formsare provided on pages 47 through 50.

External presurveysSafety training is recommended even for those

conducting external mine surveys. There are severalsafety issues to be aware of when conducting externalsurveys. Mine openings are often the most dangerouspart of an old mine. The rock around entrances isoften weakened by weathering and fractured fromexplosives. Care should be taken to approach theedges of shafts and other vertical openings with greatcaution, as edges can break away unexpectedly.

18 BATS AND MINES

Furthermore, sudden collapse and falling rocks repre-sent potential hazards even at horizontal openings.

Presurveys can be conducted anytime the site isaccessible, but should be planned well before sched-uling of mine closures, providing adequate time ifadditional internal or external surveys are warranted.Information to be collected during presurveys shouldinclude: (1) number, dimension, location, and descrip-tion of all entrances; (2) airflow direction, if any,through entrances; (3) outside air temperature; (4) thepresence of any restrictions at or near entrances (veg-etation, old timbers, trash, loose piles of rock, etc.); (5) the presence of standing water or evidence ofprior flooding; (6) internal features that can be safelydetermined from outside, such as depth, side pas-sages, ventilation shafts; and (7) visual signs of bats,such as droppings, roosting bats, carcasses, or piles ofinsect parts.

The information from the presurvey should thenbe evaluated by a person experienced in workingwith bats and mines. If all mine entrances are com-pletely blocked by debris, rock, soil, or dense vegeta-tion, the site is unlikely to be used by bats. However, insome cases, especially where mine or cave habitat may belimited, these sites could be further evaluated for theirpotential value as habitat if the entrances were to be clearedand secured. If the mine is shallow (generally less than50 feet for adits and shafts) and all sides are visiblewhen viewed from outside, confirming there are nodrifts, internal shafts, etc., it probably has low poten-tial as a roost site. Mine adits flooded to the ceiling orwithin a foot of the ceiling, or vertical shafts that fillwith water can also be eliminated, unless there is adrift above the waterline. If there is a possibility ofbat use, a more detailed evaluation should be consid-ered.

Mines that can be enteredAn internal survey is often the quickest and least

time-intensive survey method. Winter surveys typi-cally can detect summer use, since guano piles fromactive bats remain visible. However, summer surveyscannot detect winter use, since hibernating bats leavevery little guano. Paying close attention to airflowpatterns and a mine’s temperature can save muchtime by focusing searches for bats in places wherethey are most likely to be during the season of inspec-tion.

Abandoned mines can be dangerous, with cave-ins and falling rock, rattlesnakes, deadly gases, oxy-gen deficiency, hidden shafts, and old explosives allposing potentially serious threats to human safety.Thus, internal mine surveys should be conductedonly by individuals trained in bat biology and mine

safety. As an additional safety precaution, a minimumof two people should participate in all surveys. Forinformation on mine safety and training, contact thestate mine inspector’s office.

When internal surveys fail to reach all potentialareas where bats might live, they should be backedup by entrance observations made in the appropriateseasons (see “Mines that cannot be entered”). Sincebats usually emerge nightly to feed, warm-seasonsurveys do not typically require mine entry to detectbat use. Furthermore, entrance observations avoid therisk of disturbing nursery colonies, which can causeloss of young.

When conducting warm-season internal surveys,listen for the sounds of bat squeaks and chatter, andwhen approaching a roost area, move quietly along awall, staying as low as possible. Make counts and col-lect data as quickly as possible, reducing talking andother sounds to a minimum. Speak softly in low tonesif talking is necessary. A red light may help, but ifclustered bats begin to take flight, immediately backaway. Do not attempt to capture active bats at theirroost. Identification and reproductive status can bechecked through trapping or netting at entrances.

Most non-hibernating bat colonies deposit piles ofdroppings beneath their roosts. These are easilyobserved in any season, though they can be missed incomplex mines. The droppings of insectivorous batspecies are simple to distinguish from those ofrodents. Bat guano is easily crushed and is composedmostly of shiny bits of insect exoskeleton. By compar-ison, rodent fecal pellets are usually hard to crushand are composed mostly of plant matter. Further-more, bat droppings are typically deposited near themiddle of passages where ceilings are highest andwhere the bats have stained the rock surfaces. In con-trast, rodent droppings are more likely to be concen-trated along walls or in low places too small for batsto use. With experience, some species identification ofinsectivorous bats is possible from the size, color,odor, inclusion of insect parts (such as wings, cara-pace, or legs), and deposit pattern of the guano. Nec-tar-feeding long-nosed and long-tongued bats mayproduce formed droppings, but characteristicallyleave yellow or reddish “splat” marks on mine floorsand walls, colored by pollen or cactus fruit.

Since even large numbers of hibernating batsoften leave very few droppings or other evidence,internal surveys for hibernating bats must be con-ducted in the winter, preferably between Decemberand February. Because mines with deep vertical shaftsoften provide the best cold air traps and protectionfrom disturbance by humans and predators, these canbe especially important resources for hibernating bats.

BATS AND MINES 19

In mines that cannot be entered, external surveys at appropriate times of year can determine whether bats are using the siteand may also aid in assessing the approximate population size. A bat trap placed over the entrance is a reliable method.

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Such sites may attract many thousands, or even mil-lions, of bats from thousands of square miles around.Those too dangerous to enter require entrance sam-pling in late summer or early fall (see “Mines thatcannot be entered”).

It is extremely important to minimize disturbancewhen inspecting the interior of a bat hibernation site.Once in hibernation, each arousal forces a bat to burnfrom 10 to 60 days’ worth of its limited fat, whichmust last until spring. Repeated arousal can easily killbats. Visits into hibernation areas should be brief andnever repeated more than once in the same winter.

Mines that cannot be enteredMany mines will be too dangerous for humans to

enter. However, because these receive the least distur-bance, they often shelter the largest bat populations.In fact, some such mines are so predictably ideal for batsthat they should be assumed crucial bat sites unless provenotherwise.

Entrance observations, made between mid-Juneand early August, are often the best method for veri-fying summer use of mines. Since bats usuallyemerge each night to feed, determining their presenceat dusk is reasonably simple. Surveys should be con-ducted for at least two hours after dark, beginning atsundown on nights that are free of rain and excessivewind or low temperatures. Observers should be readyat least 30 minutes before sunset and should keepnoise to a minimum. Noise may alter or inhibit emer-gence behavior.

Observers should be seated at least 15 feet awayto one side of the entrance, ideally positioned so thatemerging bats are silhouetted against the evening sky.All entrances associated with the mine (if known)should be surveyed at the same time, if possible. Anight-vision device with an infra-red light source willprovide the most accurate observations, but ifunavailable, a dim red light (aimed across, not into,the entrance) can be used to assess the approximate

20 BATS AND MINES

colony size. Flights of even relatively small coloniestypically can be detected by an observer positionedlow enough to both listen and watch the skyline.Even after dark, listening for wingbeat sounds ofemerging bats normally can aid in assessment. Anultrasonic bat detector may be used to help detectemerging bats. Night-vision devices are especiallyhelpful for detecting some bats, such as big-earedbats, which are difficult to hear on a bat detector andwhich may exit after dark and at slow rates.

The best time to check mines for winter use isusually when bats begin arriving to inspect a site forhibernation. This is typically in August and Septem-ber in the eastern and northern United States orCanada, extending into October in the Southeast. Inwarmer southwestern areas, arrivals are more likelyto peak in October or November. Spring emergencealso can be observed, but is less reliable, since activitythen is often less predictable or detectable. Entranceobservations at potential hibernation sites are bestmade between a half hour after sunset and midnight.Bats entering a hibernation site may arrive all nightlong each night for a month or more. Within that peri-od, arrival rates vary considerably, but a flow of evena few dozen bats per hour on a given night couldsuggest a hibernating population of thousands ormore. Sometimes, large groups of bats arrive togetherwithin just a few minutes.

Bats at many important hibernating sites exhibit“swarming” behavior, which is believed to be relatedto breeding and selection of hibernation sites. Swarm-ing consists of many bats flying in and out andaround the entrance of a mine or cave, with peakactivity occurring between two to three hours aftersunset. In the eastern United States, north into Cana-da, this behavior is intense in August and Septemberand is easily used to detect hibernation sites. Suchbehavior sometimes occurs in the West, but can bemore difficult to detect since greater numbers ofmines are used for hibernation and are occupied bysmaller numbers of bats. Swarming activities in theWest, therefore, may be missed during early wintersurveys.

Bat traps or mist nets can be used to capture andidentify bats at mine entrances. Persons conductingcapture surveys must have appropriate state and fed-eral permits and have previous experience handlingbats or be accompanied by someone who does.Although bats bite only in self-defense if handled, peo-ple who plan to handle bats should receive rabies pre-exposure vaccine, now relatively painless and highlyeffective.

A bat trap is effective in checking horizontal mineentrances for emerging or arriving bats. These traps,weighing as little as five pounds, can be made withcapture areas as small as four feet high and three feetwide. If a mine entrance is considerably larger than thearea covered by the trap, inexpensive cloth, plastic, ornetting can be used to block alternate access. Remov-ing bats with gloved hands is quick and efficient. Trapscan rapidly capture hundreds of bats without entan-gling them, but they must never be left unattended,since traps can quickly fill with bats that may then suf-focate. Also, traps containing bats readily attractpredators.

Mist nets also can be used to capture bats and maybe useful in checking difficult-to-reach locations. Thedisadvantage is that each bat must be individually dis-entangled from the net, which is time consuming andrequires experience. Never set a net across an unfamil-iar mine entrance before first observing the level of batactivity. A net over a busy entrance will quickly catchmore bats than can be removed effectively, destroyingthe net and needlessly injuring severely tangled bats.

Neither nets nor traps should be used over verticalshafts. However, by observing the flight paths ofemerging bats, they may be set effectively nearby. Forsome such sites, combined use of bat detectors anddim red lights or night-vision devices may be required.Since western big-eared bats are often active periodi-cally throughout the winter, electronic countingdevices may be helpful in documenting their use atsites that cannot be entered by people.

BATS AND MINES 21

Protection of Bats in Mines

Siebert Cowley (UniminCorp.), Ray Smith (US

Forest Service), andSheryl Ducummon (Bat

Conservation Interna-tional) demonstrate the

removable bar on thisangle-iron gate at

Unimin Corporation’sMagazine Mine, an

abandoned silica mineon the Shawnee National

Forest in SouthernIllinois. The gate

protects humans as wellas a growing population

of endangered Indianabats. This design has

proven highly successfuland difficult to breach.

BATS THAT LIVE IN MINES face three primary humanthreats: closure of mine entrances for reclamationor safety reasons, human disturbance due to recre-ational entry, and loss of old mines and surroundinghabitat if mining is renewed. Since mines are nowessential habitats for many of America’s most impor-tant remaining bat populations, they always shouldbe assessed for bat use prior to any of these activities.

Reclamation and safety closuresIf a biological survey reveals bat use of a mine,

there are alternatives to total closure that provide forpublic safety and allow bats to continue using thesite. Often the most effective solution is a steel gateplaced over or across the entrance, which can includea small, lockable door or removable horizontal crossmember for official access. Many bat species respondwell to such structures. Bat gates must meet the landmanager’s objective of protecting the public from ahazardous situation, while ensuring safe access tobats. In areas where favorable roost temperaturesrequire cold or warm-air traps (see “How Mine Struc-ture, Location, and Human Disturbance Affect Bat

Use”), it is essential that gates not obstruct normalairflow through entrances. Proper design and place-ment is extremely important; bat colonies have oftenbeen driven from a site because of an inappropriategate.

Modern gate designs are both difficult for van-dals to breach and often less costly than traditionalclosure methods, such as capping mines with con-crete or bulldozing entrances shut. A primary pur-pose of a gate is obviously to keep unauthorized visi-tors out. This requirement results in furtherlimitations on the type of materials used, as well asthe spacing of horizontal and vertical members of thegate. The minimum distance between vertical gatesupports should be 24 inches (anything less mayrestrict bat movement). The ideal spacing for verticalgate supports is between 4 and 10 feet, dependingupon the design and strength of material used.

The widest vertical and horizontal spacings are alwayspreferred by bats, but in no case should human safety becompromised. Horizontal members should normally bespaced no less than 5 3/4 inches apart. Near heavilypopulated areas or recreation sites where small

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This protective cage at the Neda Mine in Dodge County, Wisconsin, ensures human safety while also protecting one ofNorth America’s largest hibernating bat populations. It cost less than alternative methods of closure and was built throughcollaboration of the Wisconsin Department of Natural Resources, the University of Wisconsin at Milwaukee, and theFriends of the Neda Mine—a private group led by Bat Conservation International Chairman Emeritus Verne (pictured)and Marion Read.

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children might attempt to gain entry, expanded metalgrating can be used on the bottom third of the gate,or the spacing of the horizontal members on the bot-tom third can be reduced slightly. Spacing horizontalgate members less than 5 3/4 inches apart can severelyrestrict bat movement, while distances greater than5 3/4 inches may permit small children to squeezethrough.

Gates constructed of 4 x 4 x 3/8-inch angle iron,reinforced by stiffeners (see Appendix III, Design A,for plans), have been successfully used to protect batsin caves and mines throughout North America. Thisdesign is extremely strong; hundreds of these gateshave been installed thus far, and very few have beenbreached. When located properly, the gate has mini-

mal effect upon airflow because of the orientation ofthe angle iron.

Gates should not constrict mine openings morethan absolutely necessary, especially along floors andceilings. Whenever possible, construction shouldoccur during the time of year when bats are not usinga mine, in order to avoid disturbance. If constructionmust take place while bats are present, it should notoccur within two hours of dusk or dawn. Further-more, care must be taken so that welding fumes arenot drawn into areas where bats are roosting.

Where either horizontal or vertical mineentrances are unstable, they often can be secured byuse of galvanized or concrete sections of highway cul-vert. Vertical shafts further require specially designed

BATS AND MINES 23

Galvanized high-way culvert can be

used to stabilizevertical mine

entrances.

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cage-type gates, since horizontal gates over shaftentrances can easily become blocked by debris andalso force bats to slow down or land, greatly increas-ing mortality from predation. All cage-type closuresshould be high and wide enough to provide adequateflight space (minimally 6 to 10 feet square) for bats tomaneuver safely through the bars without beingcaught by predators. Cage-type closures have beenused successfully at many sites across the country.Because cage-type gates and vertical shafts entail spe-cial bat and engineering considerations, individualsor agencies familiar with their construction, such asBat Conservation International or the American CaveConservation Association, should be consulted (seeAppendix II).

A cage-type design was built over a verticalentrance at the Neda Mine in Dodge County, Wiscon-sin. The foundation was constructed of poured con-crete reinforced with steel. The cage was constructedfrom 4 x 4 x 3/8-inch steel angle iron, with a roof ofexpanded metal grating (see Appendix III, Design B,for plans). An expanded metal collar can be used atthe base of cage closures to prevent small childrenfrom climbing up to the bars. A solid steel collar canbe used in lieu of expanded metal where the entry ofsurface water is a concern, but should be avoidedwhere cold-air trapping is especially important, as it

may inhibit airflow.When carefully installed to avoid alterations of

roost temperatures, bat-friendly angle-iron gates haveproven highly successful in ensuring both human andbat safety at numerous locations throughout NorthAmerica. Available evidence suggests that all hiber-nating North American bat species will accept gatesat overwintering sites. Big-eared bats have acceptedgates at both hibernation and nursery sites and Cali-fornia leaf-nosed bats accept gates during all seasons.However, gates often are not suitable for protectingnursery colonies of more than 1,000 individuals ofother bat species, and are not tolerated at all by some.Bat tolerance of gates is roughly proportional to gatesize, larger gates allowing more bats to exit through alarger area with less risk of being caught by preda-tors. Gray bat nursery colonies rarely tolerate gates,and this is probably due to the fact that they typicallynumber in excess of 10,000 individuals. Small tomedium-sized nursery colonies of several species ofthe genus Myotis have accepted gates. Gates are neveracceptable to Mexican free-tailed bats, and little isknown regarding gate tolerance of long-nosed orlong-tongued bats, ghost-faced (Mormoops megalophyl-la), Allen’s lappet-browed (Idionycteris phyllotis), orpallid bats (Antrozous pallidus).

Experimentation has shown that at nursery sites,

24 BATS AND MINES

This horizontal entrance wasstabilized with a concrete cul-vert. Attachment of the gate tothe inner end of a culvert re-duced predation risk to thebats. The Homestake MiningCompany in northern Califor-nia reopened and gated thispreviously closed adit to pro-vide an alternate home for acolony of western big-earedbats, which would otherwisehave been displaced when mining was renewed nearby.The bats successfully movedinto their new roost.

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myotis bats may more readily tolerate gates locatedinside an entrance, beyond the twilight zone. Suchpositioning reduces the danger from visually orient-ing predators, but in some cases may not meet humansafety needs or may make gate inspection and moni-toring more difficult. This approach warrants furthertesting. When using culverts to stabilize entrances,gate attachment to the inner end of the culvert canalso help bats avoid predation.

Other options exist for summer sites that cannotbe protected by gates. Cyclone fences can be placed atleast 12 feet back from an entrance to provide ade-quate space for bats to fly over, and half-gates havebeen used successfully in unusually large entrances,where sufficient space can be left for bats to fly over.Silent alarm systems can provide suitable backup.

Gates located in small entrances can greatlyincrease predation, especially where large nurserycolonies are involved. They also are the most likely torestrict airflow, forcing bats to abandon even a pro-tected mine if inside temperatures are raised or low-ered beyond those they require (see “How MineStructure, Location, and Human Disturbance AffectBat Use”). When entrances are smaller than four feet

in diameter, consideration should be given to use ofcage-type designs that do not further restrict eitherairflow or the bats’ space for negotiating the gate.

The largest nursery colonies attract the mostpredators which may be one reason they are least tol-erant of gates. In these cases, fences or silent alarmsystems may be the only option. All signs of accessfor gate or fence construction should be eliminated, oraccess blocked, so that additional human activity isnot attracted.

It is impossible to predict how untested specieswill react to gates constructed at their roost sites.Therefore, it is essential that any gates used in unusu-al situations, or to protect untested species, be careful-ly monitored after they are installed. Consultationshould be sought when questions arise (see AppendixII). At a minimum, the following steps should betaken before and after gate construction:(1) If possible, estimate the number of emerging bats,and make observations of their emergence and returnbehavior before constructing a gate (include timesthat emergence begins and ends, location of flightpaths through the entrance, and the amount of cir-cling at the entrance).

BATS AND MINES 25

(2) Repeat the preliminary observations immediatelyafter construction is completed. Periodically repeatthese observations through the first season of use,and once again a year later, to ensure that the bats arenot suffering adverse effects from the gate.(3) Utilize the information gained in the post-con-struction observations to modify future gate designsand correct any mistakes revealed during monitoring,if necessary.

All protective barriers require appropriate sign-age and periodic monitoring to ensure structuralintegrity. Signs should be clearly visible and attachedto mine walls, not to gates, where they might obstructairflow or bat movement and be accessible to vandals.Once a site is protected, no one should be allowed toenter during periods when bats are present, except toperform official surveys or for clearly justifiedresearch. Hibernation site surveys should not berepeated more than once every two to five years.

Federal, state, or private assistance is often avail-able to help plan and fund gate construction or otherprotective measures at key sites that must be saved.Federal and state governments also can assistimmeasurably through passage of legislation limitingowner liability. When mining companies or private-land owners are asked to cooperate in conservation-relevant activities involving inactive mines, everypossible effort should be made to protect them fromincreased liability exposure.

Renewed miningContemporary mining operations usually occur

in historic mining districts and can have major impacton bats, either positive or negative. New samplingmethods, such as drilling, often detect ore depositsmissed by previous miners and the ore is typicallyextracted with open-pit mining techniques. When thishappens existing adits and shafts are often destroyed.Exploratory operations can have a major impact onbats due to disturbance from mine personnel enteringbat roosts for ore samples or bulldozers burying his-toric mine openings during road construction fordrilling equipment. Today, underground miningmethods are seldom employed, except where high-quality ore is located deep beneath the surface.

In addition to roost destruction, other aspects ofrenewed mining can have adverse impact on bats,even bats not living in mines. Destruction of riparianvegetation and other foraging habitat can threaten thesurvival of bat species that rely on this habitat forfeeding. Open cyanide leaching ponds, or other waterin which toxic chemicals accumulate, can poison largenumbers of bats. New roads may lead to increasedrecreational visitation, and nearby blasting associated

with mine construction and operation can disturbroosting bats. When current mining operations cease,reclamation requirements and liability often require acompany to close any remaining historic workings.

Mitigation for bats during mining or mine recla-mation fall into two major categories: safe exclusionof bats from the mine, and the identification and pro-tection of replacement roosting and foraging habitat.If a bat roost must be destroyed, this should be doneduring a season when bats are not present or onlyafter exclusion of bats. Where large colonies of batsare at risk, a bat biologist with the necessary experi-ence and equipment should be consulted. As alreadynoted, many bats use mines only in certain seasons. Ifthere is a maternity colony occupying a mine, then noclosure should be made between late April andAugust. Closures should not be scheduled for thewinter months at mines that may contain hibernatingbats. If bats live in a mine year-round, then exclusionshould occur in spring or fall to reduce harm, whichwould be most intense during summer nursery orwinter hibernation use. Exclusions should not beattempted during severe weather, as bats may notemerge to forage or may die before finding alternateroosts.

Exclusion is best achieved by covering the mineentrance with one-inch chicken wire soon after mostof the bats have exited to feed on a warm evening.Chicken wire can be molded to create a funnel shapedone-way escape door so that bats inside the minedetect a window, while those on the outside of themine perceive a barrier. Bats still trapped inside canbe allowed to escape by partially removing the chicken wire just before sundown on the followingevening, then re-closing it after sundown once anyremaining bats have left. One or two repetitions onwarm evenings should successfully exclude mostmembers of any summer colony. Other bat speciesmay enter a mine to night roost before, during, andafter the emergence of the resident bat colony. In thesecases the creation of funnels as one-way escape valvesin the chicken wire closure is especially important. If amine contains multiple entrances that connect orcould potentially connect, then all of the openingsshould be systematically closed as above. If the cov-ered mine is not destroyed or permanently sealedwithin a few weeks of the bat exclusion, then chickenwire closures should be checked periodically toensure that they are still effective.

It is sometimes possible to mitigate for the loss ofevicted bats, either by protecting nearby mines or, insome cases, by reopening ones already closed. Aban-doned mines within a radius of approximately fivemiles of the mine to be destroyed should be surveyed.

26 BATS AND MINES

Mines housing the same species or with micro-climates similar to the mine to be closed should beprioritized for protection. These should be protectedby gates or fences prior to the eviction of bats fromtheir current roosts. This was successfully accom-plished by the Homestake Mining Company at itsMcLaughlin Mine in northern California. When anursery colony of big-eared bats had to be evictedfrom a mine about to be destroyed by expansion of anopen-pit mine, two nearby mines were reopened andgated. The bats were excluded from their originalroost in spring and now live in one of the alternatesites where they are permanently protected. At theAmerican Girl Mining Joint Venture in southern Cali-fornia, some of the newly mined underground areaswere gated and left open to create new bat habitatwhen recent mining ceased.

The creation of artificial roostsA new approach for mitigating the loss of under-

ground bat habitat or enhancing habitat at active min-ing operations is the construction of artificial under-

ground roosts that mimic habitat conditions found inmines and caves. Several mining companies havealready constructed experimental roosts by buryingsurplus mining materials such as large diameter cul-vert or mine truck tires beneath waste rock.

The Homestake Mining Company used old minetruck tires configured to create four separate adit“arms” connecting to a central precast concretebunker at their McLauglin Mine in Northern Califor-nia. The entire structure was buried under waste rock,which was then re-contoured and planted with nativevegetation. A concrete flange with a steel bat gate wasinserted into two of the entrances. At Solutia’s (for-merly Monsanto Corporation) Enoch Valley Mine inSoda Springs, Idaho, two steel culverts measuringeight feet in diameter and forty feet long were modi-fied, connected, and buried in such a way as to trapwarm air in the upper culvert for summer use andcool stable air in the lower culvert for hibernation. Aspart of a bat conservation program to mitigate for theloss of underground mine bat habitat, CanyonResource’s Briggs gold mine constructed an artificial

At Homestake Mining Company’s McLaughlin Mine in California, surplus truck tires were buried beneath waste rock tocreate an innovative and cost-effective bat roost. If careful consideration is given to design and construction, artificialstructures can provide important roosts for bats.

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BATS AND MINES 27

underground roost using surplus drums from cementmixing trucks buried beneath waste rock. Fourdrums were used, connected by an adit constructedof used mine truck tires. Environmental managers atEcho Bay Mineral’s McCoy Mine in Nevada are con-structing an artificial roost in a mine waste rockdump consisting of two rectangular metal bunkersconnected by old mine truck tires, with an entranceon each side of the 200-foot-long structure at differentelevations to promote airflow.

In order to be successful, artificial roosts must bedesigned to create an internal roost microclimate thatmeets the life history needs of the target bat species.First, information must be obtained on which speciesare likely to be present in the vicinity and how andwhen these species use underground roosts. Next, theartificial roost structure must be designed with anunderstanding of how airflow, mean annual surfacetemperatures, and seasonal and daily climate patternswill affect the internal climate conditions of the com-pleted roost. Special consideration must also begiven to factors such as ensuring that places within

the structure where the bats will roost are not accessi-ble to predators. They must also have a rough non-metallic surface for the bats to hang on (see “HowMine Structure, Location, and Human DisturbanceAffect Bat Use”). When possible, the actual site wherethe artificial roost will be located should be safe fromflooding and be as near as possible to water and for-aging habitat. While bats needs are often predictable,it is highly recommended that companies attemptingto create new or alternate habitat should seek expertadvice.

In summary, bats are a key natural resource,which now rely heavily on old abandoned mines fortheir survival. Installing a bat gate that protects bothhumans and bats often costs less than traditionalmine-closure methods. By checking mines for batsprior to closure we can avoid unnecessary and costlyendangered species problems and contribute greatlyto ecosystem health. Artificial bat roosts show greatpromise for economically creating or enhancing bathabitat where it has been destroyed.

28 BATS AND MINES

1 Formerly known as Category 2, candidate for federal threatened or endangered listing.2 Bats known to be especially dependent on abandoned mines.

Species Group Size Range Use Time Status

Ghost-faced bat Dozens to hundreds AZ & TX Year-round Species of Mormoops megalophylla Concern 1

California leaf-nosed bat 2 Dozens to over a thousand AZ & southern CA Year-round Species ofMacrotus californicus & NV Concern 1

Mexican long-tongued bat A dozen or fewer AZ & southern CA Summer Species ofChoeronycteris mexicana Concern1

Lesser long-nosed bat 2 Hundreds to thousands AZ & NM Summer EndangeredLeptonycteris curasoae

Greater long-nosed bats Hundreds to thousands TX & NM Summer EndangeredLeptonycteris nivalis

Southeastern myotis Hundreds to thousands Southeastern U.S. Year-round Species ofMyotis austroriparius Concern1

California myotis Up to a hundred Western U.S. Year-round UnknownMyotis californicus

Western small-footed myotis Up to hundreds Western U.S. Year-round Species ofMyotis ciliolabrum Concern1

Long-eared myotis Dozens Western U.S. Year-round Species ofMyotis evotis Concern1

Gray bat Hundreds to 50,000 or more Southeastern U.S. Year-round EndangeredMyotis grisescens

Eastern small-footed myotis Dozens Eastern U.S. Winter Species ofMyotis leibii Concern1

Little brown bat 2 Hundreds to a million + Northern U.S. Year-round UnknownMyotis lucifugus lucifugus

Arizona myotis Hundreds Southwestern U.S. Year-round Species of M. l. occultus Concern1

Eastern long-eared myotis Hundreds to thousands Eastern U.S. Winter UnknownMyotis septentrionalis

Indiana bat 2 Hundreds to 100,000 or more Eastern U.S. Winter EndangeredMyotis sodalis

Table 1. Species List of Bats that Use Mines

BATS AND MINES 29

1 Formerly known as Category 2, candidate for federal threatened or endangered listing.2 Bats known to be especially dependent on abandoned mines.

Species Group Size Range Use Time Status

Fringed myotis Dozens to hundreds Western U.S. Year-round Species ofMyotis thysanodes Concern1

Cave myotis 2 Hundreds to 100,000 or Southwestern U.S. Year-round Species of Myotis velifer more Concern1

Long-legged myotis Hundreds Western U.S. Year-round Species of Myotis volans Concern1

Yuma myotis Hundreds to thousands Western U.S. Year-round Species of Myotis yumanensis Concern1

Western pipistrelle Dozens Western U.S. Year-round UnknownPipistrellus hesperus

Eastern pipistrelle Dozens to thousands Eastern U.S. Winter UnknownPipistrellus subflavus

Big brown bat Dozens to hundreds North America Year-round StableEptesicus fuscus

Allen’s lappet-browed bat Dozens to about two Mostly AZ, also Year-round Species ofIdionycteris phyllotis hundred parts of NV, CO Concern1

Southeastern big-eared bat Dozens to several Southeastern U.S. Year-round Species of Corynorhinus rafinesquii hundred Concern1

Pacific big-eared bat 2 Dozens to hundreds Western U.S. Year-round Species ofC. townsendii townsendii Concern1

Ozark big-eared bat Dozens to hundreds Ozark Year-round EndangeredC. t. ingens Mountains

Western big-eared bat 2 Dozens to thousands Western U.S. Year-round Species of C. t. pallescens Concern1

Virginia big-eared bat Dozens to thousands KY, VA & WV Year-round EndangeredC. t. virginianus

Pallid bat Dozens to hundreds Western U.S. Year-round DecliningAntrozous pallidus

Mexican free-tailed bat Hundreds of thousands Southwestern U.S. Summer Declining Tadarida brasiliensis north to OR

30 BATS AND MINES

Helpful LiteratureGeneral Bat Identification, Behavior, and DistributionAltringham, J. D. 1996. Bats Biology and Behaviour. Oxford University Press, Oxford, 262 pp.Barbour, R. W. and W. H. Davis. 1969. Bats of America. University of Kentucky Press, Lexington, 286 pp. Fenton, M. B. 1992. Bats. Facts on File Inc., New York, 207 pp.Hall, E. R. 1981. The Mammals of North America, Volume II. John Wiley and Sons, New York, 1,181 pp.Hill, J. B. and J. D. Smith. 1984. Bats: A Natural History. University of Texas Press, Austin, 243 pp.Kunz, T. H. (ed.) 1982. Ecology of Bats. Plenum Press, New York and London, 425 pp.Kunz, T. H. and P. A. Racey. 1998. Bat Biology and Conservation. Smithsonian, 576 pp.Richarz, K. and A. Limbrunner. 1993. The World of Bats. Franck-Kosmos Verlags-GMBH & Co., Stuttgart, Ger-

many (English translation by W. Charlton), THF Publications, 192 pp.Nowak, R. M. 1994. Walker’s Bats of the World. Johns Hopkins University, Baltimore, 287 pp.Whitaker, J. O., Jr. 1996. National Audubon Society Field Guide to North American Mammals (revised edition).

Alfred A. Knopf, Inc., New York, 942 pp.Wilson, D. E. 1997. Bats in Question: The Smithsonian Answer Book. Smithsonian Institution Press, Washington,

D.C., 168 pp.

Detecting and Censusing Bats and Protecting SitesAltenbach, J. S. and H. E. Milford. 1995. Evaluation and Management of Bats in Abandoned Mines in New Mexi-

co. Pp. 326-330 in 1993 National Cave Management Symposium - XI Proceedings, Carlsbad, New Mexico (D.Pate, ed.). National Cave Management Symposium Steering Committee.

Altenbach, J. S. and E. D. Pierson, 1995. The Importance of Mines to Bats: An Overview. In Riddle, B. R. (ed.).Inactive mines as bat habitat: guidelines of research, survey, monitoring and mine management in Nevada. Bio-logical Resources Center, University of Nevada, Reno.

Altenbach, J. S. 1995. Entering mines to survey bats effectively and safely. In Riddle, B. R. (ed.). Inactive mines asbat habitat: guidelines of research, survey, monitoring and mine management in Nevada. Biological ResourcesCenter, University of Nevada, Reno.

Brown, P. E. and R. D. Berry. 1997. Renewed mining and reclamation: impacts on bats and potential mitigation.Pp. 196-201 in Proceedings of American Society for Surface Mining and Reclamation 14th Annual NationalMeeting, Austin, Texas

Brown, P. E., R. D. Berry, and C. Brown. 1995. The California leaf-nosed bat (Macrotus californicus) and AmericanGirl mining joint venture—Impacts and solutions. Pp. 54-56 in Proceedings VI: Issues and Technology in theManagement of Impacted Wildlife. Thorne Ecological Institute, Boulder, Colorado.

Kunz, T. H. 1988. Ecological and Behavioral Methods for the Study of Bats. Smithsonian Institution Press, Wash-ington, D.C., 533 pp.

MacGregor, J. 1993. Responses of winter populations of the Federal endangered Indiana bat (Myotis sodalis) tocave gating in Kentucky. Pp 364-370 in 1991 National Cave Management Symposium Proceedings, AmericanCave Conservation Association, Horse Cave, Kentucky (D. L. Foster, ed.).

Navo, K. W. 1994. Guidelines for the survey of caves and abandoned mines for bats in Colorado. Colorado Divi-sion of Wildlife, Monte Vista, Colorado, 55 pp.

Pierson, E. D., W. E. Rainey, and D.M. Koontz. 1991. Bats and mines: Experimental mitigation for Townsend’sbig-eared bat at the McLaughlin Mine in California. Pp. 31-42 in Proceedings V.: Issues and Technology in theManagement of Impacted Wildlife. Thorne Ecological Institute, Boulder, Colorado, 223 pp.

Tidemann, C. R. and D. P. Woodside. 1978. A collapsible bat-trap and a comparison of results obtained with thetrap and with mist-nets. Aust. Wildl. Res., 5:355-362.

Tuttle, M. D. 1974. An improved trap for bats. J. Mammal., 55:475-477.Tuttle, M. D. 1977. Gating as a means of protecting cave-dwelling bats. Pp. 77-82 in 1976 National Cave Manage-

ment Symposium Proceedings (T. Aley and D. Rhodes, eds.). Speleobooks, Albuquerque, New Mexico, 106 pp.*Tuttle, M. D. and D. E. Stevenson. 1978. Variation in the cave environment and its biological implications.

Pp. 108-121 in 1977 National Cave Management Symposium Proceedings (R. Zuber, J. Chester, S. Gilbert and D. Rhodes, eds.). Adobe Press, Albuquerque, New Mexico, 140 pp.*

* Reprints available from Bat Conservation International.

Appendix I

BATS AND MINES 31

Regional References about BatsWestern RegionArmstrong, D. M., R. A. Adams, and J. Freeman. 1974. Natural History Inventory of Colorado, No. 15:

Distribution and ecology of bats of Colorado. University of Colorado Museum, Boulder, Colorado, 85 pp.Carraway, B. J. and L. N. 1998. Land Mammals of Oregon, University of California, 800 pp.Clark, T. W. and M. S. Stromberg. 1987. Mammals in Wyoming. University of Kansas Press, Lawrence, 314 pp.Findley, J. S., et. al. 1975. Mammals of New Mexico. University of New Mexico Press, Albuquerque, 360 pp.Hoffmeister, D. F. 1986. Mammals of Arizona. The University of Arizona Press, Tucson, 602 pp.Ingles, L. G. 1965. Mammals of the Pacific States. Stanford University Press, Stanford, California, 506 pp.Jameson, E. W., Jr., and H. Peeters. 1987. California Mammals. University of California Press, Berkeley, 403pp.Ulrich, T. 1986. Mammals of the Northern Rockies. Mountain Press, Missoula, Montana, 160 pp.

Central RegionCaire, W., et. al. 1989. Mammals of Oklahoma. University of Oklahoma Press, Oklahoma City, 582 pp.Choate, J. R., et. al. 1994. Handbook of Mammals of the South-Central States. Louisiana State University Press,

Baton Rouge, 304 pp.Hazard, E. B. and N. Kane. 1982. Mammals of Minnesota. University of Minnesota Press, Minneapolis, 286 pp.Hoffmeister, D. F. 1989. Mammals of Illinois. University of Illinois Press, Chicago, 356 pp.Jackson, H. T. 1961. Mammals of Wisconsin. University of Wisconsin Press, Madison, 504 pp.Jones, J. K., Jr., D. M. Armstrong and J. R. Choate. 1985. Guide to Mammals of the Plains States. University of

Nebraska Press, Lincoln, 371 pp.Jones, J. K., Jr. and E. C. Birney. 1988. Handbook of Mammals of the North-Central States. University of

Minnesota Press, Columbia, 346 pp.Schmidley, D. J. 1991. The Bats of Texas. Texas A&M University Press, College Station, 188 pp.Sealander, J. A. and G. A. Heidt. 1991. Arkansas Mammals: Their Natural History, Classification, and

Distribution. University of Arkansas Press, 308 pp.

Eastern RegionBarbour, R. W. and W. H. Davis. 1974. Mammals of Kentucky. University Press of Kentucky, Lexington, 321 pp.Brown, L. N. 1997. A Guide to Mammals of the Southeastern United States. University of Tennessee Press,

Knoxville, 256 pp.Harvey, M. J. 1992. Bats of the Eastern United States. Arkansas Game and Fish Commission, Little Rock, 46 pp.Kurta, A. 1995. Mammals of the Great Lakes Region. University of Michigan Press, Ann Arbor, 350 pp.Linzey, D. W. 1996. Mammals of Virginia. McDonald and Woodward Publishing Co., Blacksburg, 450 pp.Merritt, J. F. 1987. Guide to the Mammals of Pennsylvania. University of Pittsburgh Press, Pittsburgh, 408 pp.Mumford, R. E. and J. O. Whitaker, Jr. 1982. Mammals of Indiana. Indiana University Press, Bloomington,

Indiana, 537 pp.Webster, W. D. et. al. 1985. Mammals of the Carolinas, Virginia, and Maryland. University of North Carolina

Press, Chapel Hill, 267 pp.Whitaker, J. O., Jr. and W. J. Hamilton. 1998. Mammals of the Eastern United States. Third Edition. Cornell

University, 608 pp.

CanadaNagorsen, D.W. and R.M. Brigham. 1993. Bats of British Columbia. University of British Columbia,

Vancouver, 176 pp.van Zyll de Jong, C. G. 1985. Handbook of Canadian Mammals: Volume 2, Bats. National Museum of Natural

Sciences, Ottawa, 212 pp.

32 BATS AND MINES

Available Resources

Appendix II

Training Opportunities and Educational Materials

Bat Conservation InternationalP.O. Box 162603, Austin, TX 78716, 512-327-9721.BCI provides several Bat Conservation andManagement Workshops annually, including somespecifically devoted to bats and mines issues. BCIalso produces a wide variety of slide and videoprograms, posters, and other educational materialsabout bats. For more information, or for a freecatalogue, write or call BCI

Bat Conservation International Web SiteVisit our web site at www.batcon.org for up-to-date information on bat conservation workshops,available grants, on-line library of bat resources,and more.

Consultation ResourcesAmerican Cave Conservation Association

P.O. Box 409, Horse Cave, KY 42749, 502-786-1466.The ACCA is a leader in development of vandal-resistant, bat friendly gate designs and can provideinformation on gate design and construction.

Bat Conservation InternationalBCI maintains a list of bat experts throughoutNorth America who are knowledgeable about batecology and behavior and who are willing toconsult on bat conservation issues. The Director ofBCI’s North American Bats and Mines Project,founded in partnership with the U.S. Bureau ofLand Management, is also available forconsultation.

U.S. Fish and Wildlife Service, Asheville Field Office 160 Zillicoa Street, Asheville, NC 28801-1038. 704-258-3939. Available for consultation, either onendangered species issues or on gate designs, use ofgates, and alarm systems to protect bats. Alsocontact the Asheville Field Office for locations ofthe nearest Fish and Wildlife Offices responsible forformal or informal consultation under theEndangered Species Act.

Bat Line. An international electronic information forum forthe exchange of research ideas, questions, andinformation on bat ecology, management, andconservation. Information about subscribing toBATLINE can be found at gopher://gopher.unm.edu: 70/00/academic/biology/batline/about/BATLINE (or through a link at BCI’s web page:www.batcon.org)

Equipment SourcesAlarm Systems

Light sensitive systems for detecting and recordingmine/cave visitation.

Ozark Instruments, Route 2, Box 322, Russelville,AR 72801

Onset Computer Corporation, P.O. Box 3450,Pocasset, MA 02559-3450, Tel: 508-759-9500, FAX: 508-759-9100

Bat DetectorsAnabat2 Ultrasound Detector; Titley Electronics,P.O. Box 19, Ballina, NSW 2478, Australia, FAX/Tel. 066-86-6617

Batbox III, Stag Electronics, 1 Rosemundy, SaintAgnes, Cornwall TR5 OUF., United Kingdom, Tel: [+44](0) 872-553441, FAX: [+44](0) 872-553074

Eco-Tranquility, by David J. Bale, 3 Suffolk Street,Cheltenham, Glouchestershire GL50-2DH, UnitedKingdom, Tel/FAX: [+44](0) 1242-570123

Mini-3 Bat Detector, by Ultra Sound Advice;available from Bat Conservation International, P.O.Box 162603, Austin, TX 78716, Tel: 1-800-538-BATS

Pettersson Ultrasound Detector D 100; availablefrom Bat Conservation International, P.O. Box162603, Austin, TX 78716, Tel: 1-800-538-BATS

Ultra Sound Advice: 23 Aberdeen Road, London N52UG, U.K., Tel: 44 171 359 1718, FAX: 44 171 359 3650

BATS AND MINES 33

Bat Traps May be individually constructed from plans—seeAppendix I - Detecting and Censing Bats andProtecting Sites: Tidemann, et al. 1978 and Tuttle1974 or available from:

Ausbat Research Equipment, 32 Longs Road,Lower Plenty, Victoria, 3093, Australia, Tel/FAX: [+61] (0) 3-9435-7004

General Gear for Underground WorkHeadlamps, opaque lenses, red filters, helmets,ropes, and more.

Bob and Bob, P.O. Box 441, Lewisburg, WV 24901,Tel: 800-262-2283, FAX: 304-772-3076

Guadalupe Mountain Outfitters, P.O. Box 2429,Carlsbad, NM 88220, Tel: 505-885-9492

Inner Mountain Outfitters, R1, Box 263, Greenville,VA 24440-9727, Tel: 540-377-2690

Speleobooks, P.O. Box 10, Schohaire, NY 12157, Tel: 518-295-7978

Mine Safety EquipmentIncluding headlamps, gas detectors and respirators(be sure to order the correct size respirator andhave it fitted to properly seal completely againstthe face prior to using in a hazardousenvironment).

Mine Safety Appliances, 600 Penn CenterBoulevard, Pittsburgh, PA 15235

National Mine Safety Service Co., 4900/600 GrantStreet, Pittsburgh, PA 15216

Nite Lite: P.O. Box 8300, Little Rock, AR 72222, Tel: 1-800-648-5483

Forestry Suppliers, Inc., P.O. Box 8397, Jackson, MS39284-8397, Tel: 800-430-5566

Mist Nets and Poles (permit needed)Avinet, Inc., P.O. Box 1103, Dryden, NY 13053-1103,Tel: 607-844-3277 or 800-340-6387

Spotlights — Quartz HalogenRechargeable 500,000 (or more) candle powerlight