Effect of gate installation on continued use by bats of four abandoned mine workings in western Montana PDF
Preview Effect of gate installation on continued use by bats of four abandoned mine workings in western Montana
Effect of Gate Installation on Continued Use by Bats of Four Abandoned Mine Workings in Western Montana A Report to: Montana Department ofEnvironmental Quality Mine Waste Cleanup Bureau 2209 PhoenixAvenue Helena, Montana 59620-0901 Submitted by: Paul Hendricks December, 1999 MONTANA Natural Heritage Program 599.41518 N11EGI - 1999 1 ^»fLb(Lc.l MontanaStateLibrary 3 0864 1004 6971 ox aanssi EFFECT OF GATE INSTALLATION ON CONTINUED USE BY BATS OF FOURABANDONED MINE WORKINGS IN WESTERN MONTANA December 1999 ° 1999MontanaNaturalHeritage Program StateLibraryBuilding,P.O.Box201800, 1515EastSixthAvenue. Helena,MT 59620-1800. 406-444-3009 This document should be cited as follows: Hendricks,P. 1999. Effectofgateinstallationoncontinuedusebybatsoftourabandonedmineworkingsinwestern Montana. UnpublishedreporttoMontanaDepartmentofEnvironmentalQuality. MontanaNaturalHeritageProgram. Helena. 13pp. ACKNOWLEDGMENTS ThisprojectwasfundedbytheMontanaDepartment ofEnvironmentalQuality, Mine WasteCleanupBureau, underDEQ ContractNo. 480008totheMontanaNaturalHeritage Program, NaturalResourcesInformation System, MontanaStateLibrary. SpecialthankstoJack Yates(DEQ)forhiscontinued supportofthiswork,toLeeFlath(LewisandClarkCaverns State Park)forhiscooperationand interestintheproject, andtoMarianandMaxJohnsonofRavalli forpermissiontoaccesstheMcDonaldMine. TomO'Shea(USGS-BiologicalResources Division)kindly loanedthedataloggersusedduringthisproject. SamMartinezhelpedwiththe surveysandrecordedclimatedataduringthem. INTRODUCTION In 1996the MineWasteCleanup Bureau oftheMontana DepartmentofEnvironmental Quality installed culvert gatesystems inthe portals offourabandoned mineadits in western Montana Twogates were installed at the McDonald ("Ravalli") Mineadits inLakeCounty, and twomore wereplaced inportalsat the Gypsum MineworkingsofLewis and Clark Caverns State Park inJeffersonCounty Inspection ofthese mineadits priortogateinstallation revealed that each was used at sometimeduringthe yearby bats, particularly Townsend'sBig-eared Bat (Connorhimistownsendii), a U.S. Fishand Wildlife Service speciesofspecial concern (Harvey et al 1999) Gates were installed toallow forcontinued use ofeach mineworkingby batswhile prohibitingaccidental livestock entryand unauthorized accessby humans. Gateswerebuilt with mm 13 rebarattached toan angle irongate frame, usingrecommended vetical spacingat least 5.75 inches and horizontal spacingat least 24inches(Turtleand Taylor 1994, Dalton andDalton 1995) Thegate itselfwasattached to acorrugated metal pipethat wasinserted intothe mine portal, surroundingthe pipewith fill to assurethat entry intothe minewasthroughthe pipeand gate, thegatewas secured with aprotected padlock Although thegatedesignwas supposed to be bat-friendly, no follow-up study had beenconducted at anyofthe sitesto determine ifbats were still usingthe sitesaftergateswerein place Theobjectivesoftheworkdescribed inthisreport weretwo-fold. First, determinethe effectivenessofthegatedesign in its primary functionofallowingcontinued accessby batsto the mineworkings Second, gathermine environment data(temperature, relativehumidity) continuously overaseveral month period toaid incharacterizationofthe mineenvironments where batsoccurred STUDY SITES ANDMETHODS The McDonald ("Ravalli")Mine isjust west ofthesmall community ofRavalli, in Lake County. T18NR20WS31NWNE at about 853 m(2800ft) elevation neartheJocko Riverand at the southern boundary ofthe National Bison Range Themine includesthreeopen aditsthat produced crude copperore, the lowertwoofwhichare nowgated The mine has not been worked since 1917 (Rossillon 1995) The Gypsum Mine lies within the boundaryofLewis and ClarkCaverns State Park, in Jefferson County, about275-305 m(900-1000 ft)elevationbelowthe mouth ofthecave, and overlooking theJefferson River The mine ispart ofa 118-acre claim patented in 1915 that includesa numberofprospects, a large open pit, and a coupleofadits Thetwogated aditsare in T1NR2W in S21NWNW (adit #1) and S20NENE(adit #2), atabout 1432 m (4700 ft) and 1390 m(4560 ft)elevation, respectively During mine surveys, all bats encountered were recorded and identified to species, if possible, takingcare nottodisturb the bats Location ofbats withinthe minewas noted, and a seriesoftemperature and relative humidity measurementswere made with a Bacharach sling psychrometer Mines wereexplored tothe fullest extent possible, which depended in parton underground configurationand relative hazard At leastone electronic data logger(HOBO, Onset ComputerCorporation, Bourne. MA) was installed in eachworking, usuallywithinthe areaoccupied by bats Data loggers, settorecordtemperatureand relative humidityevery 6 hours, wereattachedtoextendablealuminumpoles(Mr. Longarm, Inc., Greenwood, MO)using ducttape, andpositionedtowithin40cmoftheceiling(ca. 1.4to2.0maboveground). Locationofdataloggersrelativeto portalswasdocumented; dataloggerswereleft inminesfor 6-7 monthsbeforeretrieval. DataloggersintheMcDonaldMineaditswere installedon7 December 1998 andretrievedon 13 July 1999. AttheGypsumMine, dataloggerswereinstalled on6January 1999 andretrieved 13 July 1999. SummaryFiguresportrayingdataloggerresults arepresentedattheendofthisreport. RESULTS McDonaldMineSites. On7 December(13:10-16:30MST),thetwo(eastandwest)gatedadits wereenteredand dataloggersinstalled. IntheEastAdit, 8 hibernatingTownsend'sBig-eared Bats(Corynorhinustownsendii)werefound onthewallsoftheentrancehallwayinthefirst39.7 m(130 ft)beyondthegate. Adatalogger("shallow")wasplacedatthispoint 39.7mfromthe portal, wherethemainpassageanglessharplytothewest(left). Aseconddatalogger("deep") wasplaced 106.7m(350ft) fromtheportal inthiswest-trendingpassage, shortlybeforethe workingsopenintoalargeroomascendingtoatleastoneadditional level. Nobatswerefound inthis sectionofthe mineontheDecembersurvey, andthesecond level beyondthe largeroom werenotchecked. Onthe 13 July survey, asingleunidentifiedMyotisflewfromtheentrance whenitwasentered(08:17)but noadditional batswerepresentinthefirst partofthemine. One Townsend'sBig-earedBatwas seenflying intheupperpartsofthelargeroom. Itispossible otherbatswerepresent inthisportion ofthe mine. IntheWestAdit nobats werefound duringthe 7Decembersurvey. Thisworkingwas surveyed entirely(about 50m; 164 ft), and adataloggerwasleftwherethe mainhaulwayangles sharplytotheeast, 12.7m(41.7 ft) fromtheentrance. Onthe 13 July survey, a single Townsend'sBig-earedBat flew fromtheentranceareaandanurserycolonyof20-25 individuals wasfoundclusteredtightlyonthewall oftheeast-trendingpassagenear itsjuncturewiththe entrancepassage, about 2.0 m(6 5 ft)beyondthedatalogger. Theupperungatedadit was surveyed on7December; no batswerefound. Theworking isrelatively shallow, extending 17.1m (56 ft) beyondtheportal. Climatedatafromthe lowergated adits(Table 1, Figures 1-6) showall workingswere relativelycool duringtherecordingperiod (8 December 1998to 13 July 1999). Temperature TABLE 1. Maximumandminimumelectronicdataloggervaluesfortemperature(°C)andrelative humidity(RH;%)attheMcDonaldMinesacs(8December 1998to 13July 1999)andGypsumMinesites(7 January 1999to 13July 1999). MineWorking Adit 106 7 m from the portal Maximum temperatureswererecorded duringthe firsttwo weeks ofJuly in each adit, minimum temperatureswererecordedon 21-22 December 1998 (see Figures 1. 3, 5) The pattern ofvariation in relative humidityamongadits was identical tothe pattern for temperature Relative humidity varied by 81 9% atthe shallow location inthe East Adit (Figure 2). butonly by 10.5°o atthedeep location (Figure4, Table 1) Inthe West Adit, relative humidity varied by 38.8% duringthe sample period (Figure6) Maximum valuesoccurred on a rangeofdates in eachadit, from 29Januaryuntil July deep in theWest Adit and between 5 May and July shallow in the same adit, toa shorterperiod (18 Juneto 6July) inthe West adit Minimum relative humiditywasrecordedon 21 December in theEast Adit, buton 13 July inthe West Adit Gypsum MineSites. Thetwogated Gypsum Mineadits(#1 "upper" and #2 "lower")were surveyed completely on6January 1999, when a singledata loggerwasinstalled in each The upper Adit #1 extends straight back for22 4m(73.5 ft) from theportal, the lower Adit #2 extends straight back for44 m (144 4 ft) In Adit #1, oneTownsend'sBig-eared Bat was hibernating 1 m (3.3 ft)abovethefloor 5 8 m(19 ft) fromthedrift face. In Adit #2, one unidentifiedMyotis(probablythe LittleBrown BatA/, lucifugus)was found hibernatingwedged in acrack about 5 m (16.5 ft) from theportal, fourTownsend'sBig-eared Batswere hibernatingbetween 3 4 and 8.0m(11.2 and 26 2 ft)fromtheportal Threeadditional Townsend's Big-eared Batswere hibernatingabout 25 5 m (83 7 ft) from theportal Nobats wereobserved in eitheradit when data loggerswereretrieved on 13 July 1999 In Adit n\ adataloggerwas installed wherethe lonebat washibernating 5 8m fromthe drift face Unfortunately, thisdata loggerfailed to recordany dataduringtherecording period (7 Januaryto 13 July 1999) However, atthetimethedata loggerwas installed, temperature inthis adit ranged from 3.9-64°C (39-43 5°F), thewarmest valueabout 3 m (9 8 ft)fromthedrift face, relative humidity was 53% 12 6m(41 3 ft)fromtheportal tothedrift face In Adit #2 adata loggerwas installed 8 m (26.2 ft)fromtheportal (36 m fromthe drift face), at thefarend ofthe primary zoneofbat occupancy At this location minetemperature varied by 6 8°C (12 2°F) in 6 months, relative humidity varied by 27 8% (Table 1) Maximumtemperature and relative humidity(Table 1, Figure 7 and 8, respectively)wererecorded in the first partofJuly,just prior todata loggerretrieval, minimum values foreach variablewererecordedon 24 January DISCUSSION Workingsat both mine sites weregated becausethey wereknown to harborbatsin winter Townsend's Big-eared Bat (('orynorhmus townsendii) hasbeen known tooccupythe McDonald Mine workings sinceat least 1965 (specimens UMZ9942 through UMZ9945, collected 5-6 December, P L Wright Vertebrate Museum, UniversityofMontana) More recently thethreeaditsofthis minewere surveyed on 6 November 1996 Five hibernating Townsend's Big-eared batswerepresent intheEast Adit (20-61 m from the portal) and another was activelv thing, no batswere present in the West Adit One fresh dead big-eared bat was found in the upperadit as wasoneactive individual, probably the same activebat in the East Adit UseoftheGypsum Mineadits is less well-documented, but bat activity in and around Lewisand Clark Caverns hasbeen reported for many decades(Lee Flath, pers comm ) The surveys reported here indicatecontinued use ofall gated mineworkingsby bats, certainly an encouraging finding that indicatesthegatedesign in use is. indeed, bat friendly Furthermore, thenumberofbatspresent (8)attheMcDonaldMineaditson 7December 1998 wasnearly identicaltothenumber(7) found inthe sameportionofworkings surveyed on6 November 1996,justpriortogateinstallation. Thisfurthersupportstheideathatthegating had little impact ontheattractivenessofthese mineworkingstobats. TheWest Adit oftheMcDonaldMineappearstobeused mostlyasamaternitysite, whereastheEastAdit isusedasa hibernaculum. TheWest Aditwas warmestwiththeleast humidity, bothofwhichpromotemorerapiddevelopmentofyoung(HumphreyandKunz 1976). TheMcDonaldEastAditandthetwoGypsumMineaditsprovideconditionssuitableforuseas hibernaculabyTownsend'sBig-earedBat: temperatures< 10°C but abovefreezingwithhigh relativehumidity(Table 1, Figures 1-8). Highrelativehumidity reduceswaterlossand desiccationwhilebatsareinactive, lowtemperaturereducesmetaboliccostsanduseoffat stores. Thetemperaturevaluesaresimilartothosereportedforbig-earedbathibernaculainnorthern California(Piersonetal. 1991), Idaho(Genter 1986), Kansas(Twente 1955), and Oklahoma (HumpreyandKunz 1976), butnotaswarmas inotherpartsofitsrange(summary in Webbet al. 1996). RECOMMENDATIONS 1) ThegatedesignattheMcDonaldandGypsumminesisbatfriendlyand works. Continue usingthisdesignwhereappropriateatotheraditsasadditional abandoned minesare reclaimed. 2) Othergatedesigns havebeeninstalledbythe stateonabandoned mineworkingselsewhere in Montanathatarenot effective in preventingunauthorized humanentry. Someofthese designs, usingbrickwallsthatmayalterairflow, could alsoaltermineenvironmentsand affecttheirsuitabilityashibernaculaormaternityroosts(Richteretal. 1993). Consider replacingthesewiththecurrentdesign, especiallyat siteswhereuseby batshasbeen documented. 3) Continue monitoringbatuseattheMcDonald andGypsum mines. Bothsitesareideal for long-termmonitoringofabat speciesofspecialconcern, andprovidebothhibernaculaand maternityroosts. Monitoringcould includemultiplevisits(everyothermonth)byqualified batbiologiststo documenttimingofoccupancy and location in eachworkingthroughoutthe year; special care mustbetakento minimizedisturbanceofbatsifmonitoringisdonethis frequently. However,thesedatawillprovideabetterunderstandingofroost requirements thatmay help determinethe suitabilityorlackofsuitabilityofotherabandoned mines, and aid indecisionsto closeorgateothersites. LITERATURE CITED Dalton, D. C, andV. M. Dalton. 1995. Mineclosuremethods includingarecommendedgate design. Pp. 130-135 inRiddle, B. R. (ed). Inactive minesasbat habitat: guidelinesfor research, survey, monitoringand mine management inNevada. Biological Resources ResearchCenter, UniversityofNevado, Reno. Genter, D. L. 1986. Wintering batsoftheUpper SnakeRiverPlain: occurrence in lava-tube caves. GreatBasinNaturalist 46:241-244. Harvey, M J , J S Altenbach, and T L Best 1999 Batsofthe United States. ArkansasGame & Fish Commission, and the U S Fish and Wildlife Service 64 pp Humphrey, S R, and T H Kunz 1976 Ecologyofa Pleistocenerelict, theWestern Big-eared Bat {Plecotustownsendii), in the southern GreatPlains Journal ofMammalogy 57:470- 494 Pierson, E D , W E Rainey, and D M Koontz 1991 Batsand mines: experimental mitigation forTownsend's Big-eared Bat at the McLaughlin Mine in California Pp. 31-42in Proceedings V: Issuesand technology inthe managementofimpacted wildlife Thome Ecological Institute, Boulder, CO. Rjchter, A R., S R Humphrey, J B Cope, and V. Brack, Jr 1993 Modified cave entrances thermal effectonbody massand resultingdeclineofendangered IndianaBats(Myotis sodalis) Conservation Biology 7:407-415 Rossillon, M. 1995. The McDonald Mine, west ofRavalli: acultural resource inventoryand Tuttle, MevalDu,atainodn DReAn.ewR.abTlaeylToerchn1o9l9o4gieBsa,tsInca.n,dBumtitnee,sMTB.atUCnopnusbelrivsahteidonreIpnotretr.nat2i4onpapl ResourcePublication Number 3 41 pp Twente, J W, Jr. 1955. Someaspectsofhabitat selection and otherbehaviorofcavern- dwelling bats Ecology 36:706-732. Webb, P I , J R Speakman, and P A Racey. 1996. Howhot isahibernaculum9 Areviewof thetemperaturesat whichbats hibernate Canadian Journal ofZoology 74:761-765. 02/06 03/08 04/07 05/07 06/06 07/06 New logger S/M213620 TEMP/RH S/N 213620 Figure 1. MinetemperatureoftheMcDonaldMineEast Adit(shallow location), LakeCounty, Montana, fromDecember 1998-July 1999. Electronicdatarecorderwas39.7mfromthe mineportal.
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