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210 IRCFReptIles&AmphIbIAns•Vol16,no4•DeC2009
IncreasingdevelopmentinnortheasternKansasposesadistinctthreattotimberRattlesnakes(Crotalus horridus)alongmuchofthewesternlimitsofthespecies’distribution.
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successful Relocation of a Threatened suburban Population of Timber Rattlesnakes
(Crotalus horridus): combining snake ecology, Politics, and education
mindyl.Walker1*,JenniferA.Dorr2,RebeccaJ.benjamin1,andGeorgeR.pisani3
1Departmentofbiology,RockhurstUniversity,KansasCity,mo64110([email protected])2lenexaAnimalControloffice,lenexa,Ks66215
3KansasbiologicalsurveyandecologicalReserves(Kbs/KsR),lawrence,Ks66044
ReloCAtIonoFtImbeRRAttlesnAKes
C rotalus horridushasageographicrangecoveringsomewhatmorethantheeasternthirdofthecontinentalUnitedstates
(brown1992,1993;martin1992;pisanietal.1972),withinwhichitsdistributionispatchy(Clarketal.2007).thisexten-siveareaincludesdiverseclimaticextremestowhichthespecieshasadaptedsuccessfully(brown1993;martin1992,2002;Fitchandpisani2004,2006a,2006b).oftheseveralU.s.speciesinthegenusCrotalus,C. horridushasamongthemost,ifnotthemost,interactionswithhumans,primarilybecauseitoccursnearpopula-tioncentersinsomeofthemostdensely-populatedareasofthecountry.thus,inadditiontodepredationbyhumanshuntingthesnakesforbountyorcommercialcollection(brown1993,leClere2005), increasingdevelopmentofruralareashasanimpactonaggregation(denandbirthing)sitesaswellassummerfeeding-breedingranges.thissituationisnot,ofcourse,limitedtoC. hor-ridus(ReinertandRupert1999,ernst2004;seealsotheintroduc-tioninnowaketal.2002)or,infact,eventocrotalids(butleretal.2005a,2005b). Inthelasttwodecades,increasingpubliceducationeffortsbyscientistsconductingresearchonC. horridusandothermem-
bersofthegenus(ernst2004),alongwithanincreasingecologicalawarenessbythegeneralpublic,hasresultedinanattitudeshift(howeverslight)towardincreasingtoleranceofthespecies’frequentoccurrencealongsidehumanactivities(brown1993).nonetheless,increasingdevelopment(especiallyinnortheasternKansas,whichgenerallylacksthephysiographicbarrierstodevelopmentfound
AlargeadultmaletimberRattlesnake(Crotalus horridus).theredpaintonthebasalrattleallowsforindividualrecognitionwithouthandlingtheanimal.
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likeotherspeciesofsnakesinhabitingareasexperiencinghumanencroach-ment,timberRattlesnakescrossingroadsorthermoregulatingonwarmpavementarevulnerabletovehiculartraffic.
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inmanyeasternstates)posesadistinctthreattothisspeciesalongmuchofthewesternlimitsofitsdistribution(Fitch1999,pisaniandFitch2005,edwardsandspiering2005),whichremainslit-tle-knowninthispartofitsrangedespite56yearsofearliersnakeresearchinthearea(Fitch1999).thespeciesisclassedassInC(speciesinneedofConservation)bytheKansasDepartmentofWildlifeandparks;however,thatlisting,usedinotherstatesaswell(e.g.,Adams2005),carriesnolegalprotectionsforthespeciesoritshabitat. timberRattlesnakesarehighlysecretive,which,alongwiththeirwell-knowngenerallyinoffensivedisposition(Ditmars1936,sealy2002)andtherelativeinfrequencyofenvenomationsfromsnakesencounteredinthewild(e.g.,Keyler2005),perhapshascontributedtotheirsuburbansurvival.Wherethesnakesoccurinproximitytohumandevelopment,sightingsoftencausealarmforresidentswhoareconcernedforthesafetyofhumansandpets.often,snakesdiscoveredclosetohumanhabitationeitherarekilledorareremovedbylocalanimalcontrolpersonnel.Inmostinstances,sightingsclosetohumanhabitationinvolvematuremaletimberRattlesnakes,whichhavelargerhomerangesthanfemalesorjuve-niles(sealy2002).Inpart,thiswiderrangingreflectsmatesearch-ing(Clarketal.2007). Unfortunatelybutinevitably,thepoliticsofeducated,peace-fulcoexistencebetweenencroachinghumansandnativepitvipersinvolveaveryfragilebalance.municipalitiesfacingtheveryreal
prospectofexpensivelitigationduetoanenvenomation(irrespec-tiveofwhetherthehumanoritspetwasfundamentallytoblame)occurringinapublicpark,golfcourse,orresidentialneighborhoodmostlikelywillstronglyconsidereradicationofthesnakes.Unlike,forexample,northernnewYork,withlargetractsofstate-ownedlandandsnakedensinsiteswithageologythatwouldprohibitdevelopmentforhumanuse,thisscenarioisespecially likelyinareassuchasJohnsonCounty,Kansas,whereheavypopulation
AtimberRattlesnakeinaresidentialareaneartheoriginaldensite.
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AlthoughtimberRattlensnakesusuallyareconsideredtobeterrestrialspecies,arborealbehaviorisnotuncommon.
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growthhasextendedcitylimitsintotheeasilydevelopedtimberRattlesnakehabitats.
Background: the lenexa, Kansas Population.—proposedandactualdevelopmentoflandwithintheCityoflenexausedashabi-tatbytimberRattlesnakesprovidedanopportunitytotest theeffectofrelocatinganentirepopulation(oratleastmostofone)toothersuitablehabitatremotefromdevelopment.lenexaAnimalControl(lpD-AC)occasionallyreceivedcomplaintsabouttimberRattlesnakespreviousto2005.however,duringJune2005,onelenexaresidentcontactedlpD-ACseventimestoreportarattle-snakeinhisyard,whichwaspartofanewdevelopmentborderingagolfcourse.Ineachinstance,eitherlpD-ACoralenexapoliceofficerrespondedandremovedthesnake;snakeswererelocatedtoalessresidentialareawithin2kmofwheretheyoriginated.thisresi-dentwasverytolerantofthesnakes,butdidnotwanttheminteract-ingwithhissmalldogs.hisyardwaswellgroomed—freeofdebrisormaturelandscaping.someresidentsoftheadjacentsuburbanareaseemednotoverlyafraidofthesnakes,whichwerenotatallshyabouttraversingmowedgrassyardsinresidentialareas. Construction workers on sites bordering this residenceadmittedtolpD-ACthat theywerekillingadditionaltimberRattlesnakesfoundunderscrapmaterialsontheirjobsites.severalrattlesnakesalsowerefoundinadditionalyardsanddeadonnewlypavedroadsinthearea.lpD-ACcontactedseverallocalresourcesto
learnmoreabouttheoccurrenceoftheserattlesnakesinsuchahighconcentration;theconclusionwasthatthesnakesmostlikelyweremovingtowhatwasoncetheirsummerforaginghabitat(meadow).lpD-ACinitiatedapubliceducationcampaignaboutcoexistingwithrattlesnakes,andhostedaworkshopwithareaauthorities(JosephCollins,Danasavorelli,andRodWittenberg)speakingaboutrattlesnakebehavior,habitat,andtheneedfortoleranceandconservation.WittenbergandsavorellibothassistedlpD-ACinsearchingforlocaldens,butdidnotlocateanylikelysites. In late fall 2006, Dorr was informed by a lenexa Cityemployeeofadenwith“hundredsofrattlesnakes.”Whenaskedforfurtherinformation,Dorrwasreferredtoanotheremployee,mikeshipman,whohadlocatedtheden.shipman,acityinspec-tor,advisedthathefrequentlyobservedseveralrattlesnakes(amorerealisticnumber)inaspecificareainearlyfall2006.InFebruary2007,DorrandRodWittenberg(UniversityofArkansas)evalu-atedtheareashipmanidentifiedasasnakeden.Althoughtheareawasfrozen,theydeterminedthatitseemedtobealikelylocationforapotentiallylargepopulationoftimberRattlesnakes.Dorrwasadvisedofpendingdevelopmentoftheareaforalargeretailcenterandwasaskedwhether“itwouldbebettertobulldozethesnakeswhiletheyweresleepingortrytodestroythemaftertheycameoutoftheirden.”neitherwasaparticularlytastefulorethicaloptionforAlargemalefoundbeneathadownedroadsignattheoriginaldensite.
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maleandfemaletimberRattlesnakescourtinginasuburbanbackyardinlenexa,KansasinJuly2009.notethelandscapingfabric,whichinsomeinstancescanhaveadverseeffectsonentangledsnakes.thesephotographsweretakenbythehomeowner.
table 1. publiclandownershipbystate(fromnRCm1999).
State % of State’s total Area State Rank
newYork 36.97 10
pennsylvania 14.74 20
Arkansas 11.85 22
WestVirginia 9.92 24
missouri 6.02 33
massachusetts 5.54 35
Iowa 1.04 49
Kansas 0.92 50
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DorrorWittenberg,whoweretoldthatworkwastobeginonthesiteinmarch2007. Dorr contacted the Kansas Department of Wildlife andparks(KDWp)toinformthemoftheplanneddevelopmentinanattempttostopordelaytheconstruction.KDWprespondedinlateFebruary2007andbroughtpisaniintoassessthesituation.pisaniindependentlyhadinvestigatedrattlesnakereportsfromaresidentnorthofthenewlyimpoundedlakelenexaandanadja-centrecreationareathatseemedtopisaninottohaveageologythatwouldprovidesuitablehibernationsites.WiththenewinformationfromDorrandWittenberg,adecisionwasmadetocaptureasmanysnakesaspossibleatemergenceandtomovethemtoanewloca-tiontotestanewmodelforconservationrelocation.emergenceofthispopulationwasexpectedinAprilandmay(Wittenberg,pisani,unpublisheddata).pisanidraftedafundingproposal;DorrandWittenbergmetwiththeprivatelandownertoaskforpermissiontoremovethesnakes.thelandownerwastolerantofthesnakesandexpressedinterestinthestudy.hegrantedpermissionforsnakestoberemovedfromhislandandagreedtodelayconstructiononthisportionofthesiteforaslongaspossible. thethreateneddensitewaslocatedin~2haofroadrubbledumpedintoanortheast-facingcreekvalleyduringreconstruc-tionofanadjacentKansasstatehighwaybetween1980and1984.therubblewascappedwith~1mofdirtfill.theperipheryof
therubbledumpconsistedoflargelyexposedconcreteslabsandculverts;thesoil-coveredsurfacealsocontainedconcreteculvertendsandassortededgesofconcreteslabs.Depthoftherubblewas~1.5–3.0m,andtheflatsurfaceofthedumpwasvegetatedbygrassesandforbstypicalofhighlydisturbedroadsideareas.lackinganyoverstory,thesurfacereceivedfullinsolation.WhilewedonotknowwhenthepopulationofC. horridusinitiallycolonizedthesite,thepopulationage-sizestructuresuggestedatimeperiodofatleast10–15years,probablylonger,basedonacomparisonofthispopulationstructuretothatofadenbeingmonitoredbyhenryFitchandpisanisince2003(pisani,unpublisheddata).Fitch(pers.comm.)notedthatthedenhadbeenlargelyextirpatedbyconstruc-tionactivityintheearly1990s,butcontinuingstudiesindicatedarecoveredpopulationof~60timberRattlesnakes. InadditiontoemergingC. horridus,collectorsalsoencoun-teredover90individualsofotherreptiles(Elaphe obsoleta, Terrapene ornata, Lampropeltis triangulum, Agkistrodon contortrix, Diadophis punctatus, Coluber constrictor)usingtheden.thiswasfurthersug-gestiveofawell-establishedcommunity.
Background: the Arguments For and Against Moving “Nuisance” [venomous] Snakes.—thedebateovertheefficacyofmoving“nuisance”snakes(almostuniformlyvenomousspecies),inadditiontootherherpetofauna,asaconservationmeasurehasgone
AlargemaletimberRattlesnakecoiledattheoriginaldensite.
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table 2. size, mass, and survival of transmittered timberRattlesnakesinspring2007.*=gravid.p=predation,e=exposureaftersuccessfulhibernationandemergence.
sex mass(g) sVl(cm) tl(cm) survival
F 519 92.0 6.4 Y
M 450 91.4 7.6 n(p)
F* 490 74.3 4.5 n(e)
M 1,248 116.0 9.0 Y
F* 409 75.3 4.4 Y
M 459 92.5 7.8 Y
F 327 74.0 5.8 Y
IRCFReptIles&AmphIbIAns•Vol16,no4•DeC2009 215ReloCAtIonoFtImbeRRAttlesnAKes
onovermanyyears,andnodoubtwillcontinue.opinionshaverangedfromdecidedlynegative(Doddandseigel1991,Reinert1991,ReinertandRupert1999)toguardedoptimism(burke1991,sealy2002,ernst2004,butleretal.2005a).Insomeinstances,relocationeffortssomewhatmagnifiedtheinitialproblem(butleretal.2005b).Doddandseigel(1991)madethewell-takenpointthat“...theburdenofproofisontheinvestigatortoshowthataself-sus-tainingpopulation[hasbeenestablished]beforedeclaringsuccess.”thiscanbedifficulttoevaluateifsnakesaresimplyrelocatedintoanotherpopulation.Additionally,asmorethanafewthreatenedherpetofaunalpopulationsareofspecieswithlengthylifespansandprolongedreproductivecycles,well-plannedrelocationeffortsoftenmightbebaseduponlessthanunequivocalindicationsofsuccess. overthetimelineofthedebate,muchhasbeenlearnedaboutthebehavioralcharacteristicsofsnakesingeneral,includingacon-siderablebodyofliteratureoncrotalidsocialbehavior(e.g.,Cobbetal.2005,Clarketal.2007,Clark2004,AldridgeandDuvall2002,Weldonetal.2002).Additionally,thevariousargumentsagainstthepracticeofrelocation(byanyofitssynonymsinthecitationsabove)sometimeshavebeenbroadwithrespecttotaxa,andhaveincludedtaxawithwidelydisparatedispersalpotentials(e.g.,burke1991). theconcernsadvancedinthereferencescitedabove,aswellasothers,haveelucidatedsomebasicconcernsthatconservationistsinterestedinsucheffortsmustconsider.theseare:(1)Relocationsideallyshouldnotbemadeintoanextantpopulationwithanestab-lishedsocialorder;(2)Asacorollary,relocationsofindividualsofasocialspeciesshouldbeimplementedinawaythatdoesnotforcetherelocatedanimalstosurvivethestressesthatmaybeattendanttofittingintoanestablishedsocialstructure;(3)Investigatorsshouldnotrelocateindividualsorpopulationsofvagilespecies(i.e.,fishtoadifferentdrainage,birds,insects,etc.)inawaylikelytocontaminatethegeneticmakeupofotherpopulations;(4)Investigatorsshouldascertainthesuitabilityofhabitatstotheirspecies-of-questionpriortotherelocation. Inallinstanceswehavefoundandcitedvariouslyinthisintro-duction,severalunderlyingsimilarities,whichinlightoftheabove-mentionedgainsinknowledgeofsnakebiology,seemtohavecon-tributedtotheresultsreportedbyothers.theseare:(1) nuisancesnakeswerecollectedatvaryingtimesoftheyear
(andpublishedreportssometimeshaveencompassedsnakesrelocatedatdifferenttimesthroughseveralyearsofastudy)basedupontheiroccurrenceinhumanhabitatswheretheycausedalarm;
(2) snakesgenerallywerecollected/movedsinglywithoutregardtonaturallyoccurringfamilygroups;
(3) snakesweresometimestransportedmanykmfromtheirsitesofcapture(8–172kminReinertandRupert1999);
(4) snakeswererelocatedintoestablishedconspecificpopulations(andthussocialstructures);
(5) Releasemicro-sitesatthenewlocationwerenotchosenwithregardtoforagingorhibernationhabitatsthesnakeswouldneedforsurvival;
(6) snakeswerenotnecessarilyhandledinwaysthatminimizedstresspriortorelocation.
severalpublishedreportsamongthosewecitedaboveindicatedthatdistantrelocationofindividualsnakesusuallyresultsinthedeathoftheanimal,eitherbyfailuretolocateshelterfrompreda-
torsinthenewareaorafailureinfalltolocatesuitablehibernationsites.Wedonotfindthissurprisinggiventhecurrentknowledgeofcrotalidsociality.snakestakenfromvariedfamilygroupsattimeswellafteregressanddepositedintoaresidentpopulationthathasitsownestablishedsocialorderprobablywouldbesubjecttocon-siderableexpendituresofenergydevotedtoresource-orientation,and also substantive exposure topredation through increasedmovement.particularlyinstructiveisthenotationbyReinertandRupert(1999),whoindicatedthatbyseptember1991(thesec-ondseasonoftheirstudy),sometranslocatedsnakeswereobservedtohaveformedassociativerelationshipswitheachotherandwithresidents. predationlossesalonemaynotalwaysbeagoodindicatorofrelocationfailure.so,whileincreasedmovementsurelydoesfac-torintosnakevulnerability,Fitchandpisani(2004,2005)expe-riencedcloseto50%predationlossoftransmitter-bearingtimberRattlesnakes in a resident population, most probably (pisani,unpublisheddata) fromavianpredators (Red-tailedhawksorunknownspeciesofowls).suchhighlossesinareaswithhighpopu-lationsofrelativelylargeraptors(orparticularlyadeptones—Fitchandpisani2005;ernst2008,pers.comm.)maynotbeunusual.becauserelocationeffortsoflessthan20kmmaywellmeanthattherelocationsitestillisveryvulnerabletohumanincursion,weques-tiontheweightingofallanthropogenicmortalitycausesequally,orequaltolossesfromnaturalpredation.so,forexample,exten-sivedailymovementsofadisorientedrelocatedtimberRattlesnakemayresultinitsabandoningspecies-typicalroad-avoidancebehav-ior(AndrewsandGibbons2005),anditsdeathasaroadkillcanbeattributedtothatbehavior.however,ifhumansawareofthechanceoffindingsnakesatarelocationsitedosoandkilloneormoreofthesnakes,weviewthatasunfortunatebutnotasmortalitythatnecessarilydetractsfromthesuccessoftherelocation. telemetry isatime-intensivemethodology.Consequently,most relocation studies, in addition to the variables discussedabove,haveusedreasonablyfewspecimens,andhavenotalwayshadcomparativesamplesavailable.Anexceptionisnowaketal.(2002).theyconductedalimitedbutrigorousexperimentaltestoftheeffectsoftranslocationonCrotalus atrox.evenso,snakeswererelocatedtothenewsiteatvaryingtimesofyearandnotnecessarilyfromthesamefamilygroup.
theseniorauthortrackingrattlesnakeswithimplantedradiotransmitters.
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Whilesingle-specimenrelocationsareacknowledgedtogener-allyfarepoorly,wehypothesizedthatcaptureofallavailableadultsandyounguponemergencefromasingledeninspringandrelocat-ingthemtosuitableotherhabitatwouldresultinminimalpopu-lationdisorientation,stress,andconcomitantlosses.Wefurtherhypothesizedthat,asC. horriduslargelyorientsbyscent-trailing(especiallyyoungfollowingadults—Weldonetal.1992,Cobbetal.2005),mass-reintroductionduringthespringtoarockforma-tionsuitedtofuturehibernationwouldallowdispersionofadults(tofeedingandbirthinggrounds),effectivelyestablishingscenttrailsthatwouldleadbacktothenewdensiteinthefall.Wefeltthatarelocationthustimedwouldgivesnakesthebestopportunitytoorienttonewhabitatduringwarmerweather. ourmodelwasdevelopedusingtheknowledgethatC. horri-dusisalong-lived(brown1993andpers.comm.,pisaniandFitch2002)andhighlysocial(Cobbetal.2005,Clark2004,AldridgeandDuvall2002,Weldonetal.1992)species.ourunderlyingbeliefwasthat,ifaconsiderablenumberofsnakesfromadencouldbecaptureduponfirstemergenceinspring,kepttogether,andthenreleasedtogetherintoasuitabledenning/foraging/birthinghabitatseveralkm(but<20km)distantfromtheiroriginalden,theywouldreorientandestablishthemselvesasagroupinthenewsite.
MethodsseveralpotentialreleasesiteswereassessedbypisaniandDorrduringFebruaryandearlymarch2007usingthefollowingcriteria:• presenceofalimestonestratumthatweatheredtoproduce
deep fissures,with rock fracturedbyapparentmechanicalweatheringpluspenetrationoftreeroots,andhavingseveralcreviceswithsurfaceopenings>6cminwidth;
• southerly(se–sW)exposure;• Adjacentgrasslandandforbfields(naturaland/orcultivated)
that,combinedwithedgehabitat,wouldsupportanabundantpopulationofsmallmammals(potentialpreyspecies);
• Abundantedgehabitat;• nearbysourcesofpermanentwater;• minimalnearbyhumandevelopment;• landownedbyacountyormunicipalgovernment(andthus
protectedfromdevelopment)thatwouldagreetohosttheproject;
• noknownextantpopulationofC. horridus;• Readilyaccessibletotheresearchteamfortracking.
Ingeneral,thesitesoughtwastoreflectthecharacteristicsofthehabitatsusedbyC. horridusstudiedbyFitchandpisani(2004,2005,2006a,2006b).Allbutonewererejectedforfailuretomeetallofthecriteria.thesiteselectedforthereleasewasnotknowntohavearesidentpopulationofC. horridus(thompson,pers.comm.topisani;pisani,personalobservation),andwasafewkilometersfromtheoriginaldenlocation. the forested portion of the site is dominated by matureChinquapin(Quercus muehlenbergii andQ. prinoides)andburr(Q. macrocarpa)oaksandshagbarkhickory(Carya ovata),whichistypicaloftimberRattlesnakehabitatinKansas(Fitch1958).theprairiesarecharacterizedbybigbluestem(Andropogon gerardii)aswellasprairiepepper(Lepidium densiflorum),Cord(Spartina pec-tinata),switch(Panicum virgatum),Indian(Sorghastrum nutans),andKentuckyblue(Poa pratensis)grasses,anddottedwithprairieforbssuchasvarioussedges(Carex spp.),asters(Asterspp.),andmilkweeds(Asclepias spp.).thisoak-hickoryforest interspersedwithopenareasprovidesextensiveecotonalzones,ideallyflankedbyshelterandbaskinghabitats.Inordertofurthercharacterizethesemicrohabitats,weassessedthedensityanddiversityofprey(smallmammal)speciesbyplacingthreeparallelgridscomprising100totalshermantraps.theareasampledwasanapproximately230x110-m(25,500-m2)tractoflandencompassingthreedistincttypesofhabitat.one-thirdofthetrapsweresituatedintheforest,one-thirdintheedgezone,andtheremainderintheprairie.trapsweresetintheafternoonsandcheckedforthreeconsecutivemorn-ings,andmammalsweremarkedwithtemporarydesignations.thetrapswerethenallowedtoliefallowforonenight,followedbytwoadditionaldaysoftrapping.thebailey-modifiedlincoln-peterson(bailey1952) indexwasemployedtoapproximate thepopula-tiondensityofeachspecies,andmargalef’sd(margalef1958)andshannon’sdiversity(shannonandWeaver1949)indiceswereusedtoassesssmallmammalcommunitystructure. FollowingaprotocoltrainingsessionbylDp-AC,snakeswerecapturedbyinvestigatorsandtrainedvolunteersatthelenexadensiteinApril2007,andwereprocessedasfollows:(1)markedbyuniquescale-clips(scalessavedforpendingDnAanalysis)andsub-
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RodWittenberg,UniversityofArkansas,conductsatrainingsessionforpersonsinvolvedwiththisstudy.
habitatattherelocationsite.Alargemalewasfoundbeneaththeselogssoonafterrelease.
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cutaneousimplantationofapassiveIntegratedtransponder(pIt)RFIDtag(AVIDsystems);(2)Collectedpopulationdataonsex,bodysizes,mass,etc;(3)Implantedtransmittersintoselectedsnakessotheirmovementsandsurvivalcouldbemonitored;(4)ReleasedinoneortwogroupspReFeRAblYbyheadingthemintothenewdenholesotheycouldre-emerge,scent-trailthefirstindividualstodisperse,anddisperseinapatternthat,forthem,wouldbereason-ablynormal. Inordertominimizestresstoanimalswhosenaturalmove-mentsweplannedtomonitor,capturedsnakeswereplacedasgen-tlyaspossibleusingaluminumtongsintocleanplasticbucketsfortransporttotheholdingand/orsurgeryfacilities(cf.nowaketal.2002).thisprocedureminimizedhandling,wassaferbothforthesnakes(keepingstresstoaminimum)andinvestigators,andmini-mizedthetransferofhumanscenttotheskinofsnakes.Insubse-quenthandlingduringprocessing,andthereafterasrequiredduringthestudytoassesspost-releasefeedingorreproductivestatus,snakeswere “tubed”byusing36-inchaluminumtongs and inducingsnakestoenterrigid-wallacrylictubeschosentolimittheirabilitytoturn.oncethehead/neckwereinthetube,animalsweregraspedatthetube/bodyjunctureforsafehandling,whichalsominimizedanimalstressandstruggling. twenty-ninetimberRattlesnakeswerecollectedandprocessedin2007,and22wererelocatedtothenewdensitewithin2–3daysofcapture.thesevenotherswereheldfortransmitterimplanta-tionandlaterrelease;delayedreceiptofelectronicsand,inafewcases,waitingforecdysispriortosurgeryresultedinsnakesbeingreleasedatthenewsiteanywherebetween2daysand5weeksafterinitialcapture.snakesemergingtogetherwerehousedtogetherdur-ingholdingperiods.Inmid-summer2007,lpD-ACwascalledtoremovealargemaletimberRattlesnakecourtingamaturefemaleintheyardofaresidence.thismaleboreadistinctiveseriesofdorsalscarsandwasrecognized(shipman,pers.comm.)asbeingfromthedenthreatenedwithdevelopment.thefemale’sdenoforiginisunknown.siteofcapturewas~6kmeastofthethreat-enedden(straightlinemeasure),andevenacircuitousrouteforthatmalewouldhavetakenhimthroughseveraldenselypopulatedneighborhoods.thesetwosnakeswere fittedwithtransmittersandreleasedatthenewsitetocomparetheirsubsequentbehaviorwiththatofthegroup-relocatedsnakesmovedearlierin2007.
surgerieswereperformedpertheestablishedprotocolforthespecies(ReinertandCundall1982,Reinert1992,hardyandGreene2000)usingisofluraneanesthetic.telemetrytransmittersandassociateditemswerepurchasedfromWildlifematerialsInternational,Inc.(murphysboro,Illinois;transmitterweight11–12g).transmittermassasapercentofsnakebodymassrangedfrom<1%to3.5%,withanaverageof2.2%.transmitterswerepositionedsothattheir
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hibernaculumatthereleasesiteintherelocationarea.notethefractured,southwest-facinglimestoneoutcropinmatureoak-hickoryforest.
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flattenedsurfacewasincontactwiththesnake’sventralmuscula-ture,withtheflexiblewireantennaextendedthroughtheprimaryincision, thence subcutaneously cephalad.Apreviously appliedmonofilamentanchorsuturearoundthebaseoftheantennawirewassecuredthroughthebodymusculaturetopreventshiftingofthetransmitterandpossibleintestinaltransferwithsubsequentexpulsioninfeces(pearsonandshine2002).snakesthatwereslowtorecoverfromanesthesiawereresuscitatedbyinsertinganendotrachealtube,followedbyevacuationofinhaledanestheticbyinvestigatorexhala-tionintothetubeaccordingtotheprotocol.snakesthereafterwerekeptincaptivityfor24–48hoursat21–24°Ctoassurebothcom-pleterecoveryfromanesthesiaandwoundclosure.theythenwerereleasedingroupsatthenewdensite. A timber Rattlesnake report form modeled on one inuseby thenaturalhistoryDivision,missouriDepartmentofConservation(briggler2001)wasdevelopedfordistributiontothegeneralpublicneartheselectedreleasesite.
ResultsBehavior and Relative Movements.—thetranslocatedsnakes,ingeneral,behavedasmightbepredictedfromstudiesofnearbypopulations(Fitch1999;Fitchandpisani2004,2006a,2006b).the aerialphotographs illustrate each individual’smovementsthroughoutthefirst(2007)andsecond(2008)seasons,respec-tively.snake#435crossedintoaprohibitedareaandcouldnotbepreciselylocatedin2008,butradiocontactwasnotlost.Forthisreason,shewasremovedfromstatisticalanalyses.Circumferentialforagingloopdistancesoftheremainingfivemonitoredsnakesfrombothactiveseasons,inadditiontothatofagravidsnakeintroducedin2008(#045),areindicatedinthegraph.Apairedt-testoffor-agingloopdistancesindicatedthatthe2008foragingloopsweresignificantlysmaller(P =0.0007)thanthosein2007.Duringbothseasons,snakestendedtoutilizeedgezonehabitatsmorefrequentlythanforestedorprairieareas. table2indicatesthemeasurementsandsurvivalormortalityofeachoftheoriginalsnakescapturedduringthe2007season.onelarge,vagilemaleisthoughttohavejoinedaresidentpopulationoftimberRattlesnakeswithahibernaculum~2km(1.26mi)northoftherelocationsite.Despitesomeattrition(onesnaketopredationinyear1,onetoexposureaftersuccessfulhibernationandemergence
inyear2),thetwogravidfemalesgavebirthtoanunknownnumberofyoung,perhapsasmanyastenbasedonfolliclecountsatcapture.moreover,thegravidfemalethatwasaddedtothepopulationin2008gavebirthtosix(observed)young.
Small Mammal Community Structure.—Atotalof30 smallmammals was captured and marked in the study area, withPeromyscus leucopus (White-footedmouse) andP. maniculatus(Deermouse)togethercomprising76.7%(40and36.7%,respec-tively)ofthetotalcaptures.Microtus ochrogaster(prairieVole)andBlarinabrevicauda(northernshort-tailedshrew)represented16.7and6.7%ofthetotalindividualsmarked,respectively.halfoftheanimalswerecapturedintheprairie,whereas33.3%weretrapped
WAlKeR,DoRR,benJAmIn,AnDpIsAnI218 IRCFReptIles&AmphIbIAns•Vol16,no4•DeC2009
Aerialviewofthereleasesite(¶)andnewhabitat(1903ft=580m).eachsnake’sforagingloopforthefirst(2007)activeseasonisindicatedbyadifferentcolor.
Aerialviewofthereleasesite(¶)andnewhabitat(1903ft=580m).eachsnake’sforagingloopforthesecondactiveseason(2008)isindicatedbyadifferentcolor.notethat#435crossedintoaprohibitedarea;dotsrepre-sentsitesofgreatestsignalstrengths.
Comparisonsofthetotalcircumferentialforagingloopdistances(meters)traveledbyeachtelemeteredindividualduringthe2007and2008activeseasons.
IRCFReptIles&AmphIbIAns•Vol16,no4•DeC2009 219ReloCAtIonoFtImbeRRAttlesnAKes
inthewoodsandonly16.7%intheedgezone.thismayexplainwhytherattlesnakesweremostcommonlyfoundintheecotonalareas, thereby strategically affording themselves access tobothhabitatswiththehighestconcentrationsofprey.smallmammaldensityinthesampledareawasrelativelylow,atavalueof0.001animal/m2.populationsizeestimatesinthisareaforeachspeciesweredeterminedtobe15individualsofPeromyscus leucopus,11P. maniculatus,6Microtus ochrogaster,and2Blarina brevicauda.margalef’sdiversityindex,whichevaluatessmallmammalspeciesrichnessinthearea,was0.882,indicatingaverytaxonomicallyrichsmallmammalfauna.shannon’sdiversityindex,whichconsidersevennessoftheinclusivepopulations,wasdeterminedtobe1.75.thisdiversityvalueistypicalofempiricaldata(commonlyrangingfrom1.5to3.5;magurran2004)unlessvastnumbersofspeciesaresampled.preydensityanddiversityvaluesmaybeunderestimatedduetosmallsamplesizeandsamplearea,yetthesedataseemtoindicateahealthypopulationoftimberRattlesnakepreyspeciesattherelocationsite,comparabletothatfoundinotherlocations(Fitchetal.1984).
Discussion and Conclusionsmostrelocationstudies(includingours)haveinvolvedtrackingasmallnumberofsnakes(<25)andhavenotincludedtheexperi-mentalcomponentinthedesignofnowak,etal.(2002),making
detailedstatisticalevaluationofparameterssuchasobservedhomerangesizetemptingbutbasicallyinvalid.Fitchandpisani(2004,2006a)foundthathomerangesoftrackedtimberRattlesnakesinanaturallyresidentpopulationcloselyreflectedtheoverallphysi-ographyoftheavailablehabitat(smalltractsofopenhabitattran-sectedbywoodedledges),makingdetaileddescriptionviavariousstatisticalconstructsanunprofitableexerciseforasmallsamplesize.Additionally,thecomparisonofstatisticallydescribedhomerangesizesofvariousauthors’studypopulations,whilehavinganattractivemathematicalappeal,failstointegrate(andinfactdeflectsattentionfrom)thequestionofresourceavailability.thus,asanyindividualsnakemovesfromahibernaculumtoanactivityrangeeachseason,theannuallychangingresourceavailabilityitencoun-ters(foodabundance,necessarythermoregulationsites,changesinplantcommunitygrowthorcover—inKansasnotinfrequentlyalteredbycontrolledburns,etc.)alongwithnaturaland/oranthro-pogenicbarriers,will,webelieve,determineitshomerangeshapeandsizeforthatseason.Foranextensivereviewofthepitfallsinher-enttotheapplicationofdetailedstatisticalhome-rangemodelstosmalldatasetsseeAebischeretal.(1993). Wedonotquestiontheconclusion(sealy2000,2002;nowaketal.2002)thatshortdistance(<50m)relocationof“nuisance”rattlesnakesispreferabletolongerdistancerelocations.theauthorsandcolleaguesoftenhaverespondedtoruralandsuburbancallsregarding“nuisance”timberRattlesnakes,andhavemovedthesnake50–300mfromitspointofhumaninteraction.Usually,wetellthealarmedhumanwewill“takethesnakeaway.”Althoughsuchsnakeswerenottracked,weactedinthebeliefthatthissDtwaspreferabletothehumankillingthesnake,andmostincidentsseemtohavebeenresolvedfavorablyastheencounterwaspurelybychanceandusuallydoesnotrecur. neitherdowequestiontherecommendationsregardingthedesirabilityofeducatinganencroachinghumanpopulationabouttheprobabilityofencounteringvenomoussnakes inwhathavebecomesharedhabitats.Indeed,someoutstandingsuccessesrelatetothe latter(ernst2004,sealy2000)andwearedevelopingasimilarlenexaplanwiththesupportofthecitygovernment.Webelievethat,insuchsituations,goodmodelsforrelativelyshort-distancerelocationofpopulationstomoresecureareas(possiblysupplementedbycarefulsitingandconstructionofartificialdens—seeernst2004reC. viridis)areadditionalvaluablemanage-
two-day-oldtimberRattlesnake;oneofsixnewbornsobservedoutsidetherookeryofarelocatedfemaleinseptember2008.
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menttoolsthatalsocanbeintegratedwithpubliceducation.thatthenatureoftheoriginallenexadenwasentirelyanthropogenicisitselfofconsiderableinterest,withobviousimplicationsforsnakeconservation.Augmentationorde novoestablishment(ernst2004)ofsuitabledensitesisalargelyuntestedconservationmethod,butobservationsontheoriginaldenofourpopulation,combinedwithpreliminaryresultsofernst(2004)andaveryfewothers(edwards,pers.comm.)suggestthatsnakesofseveralcrotalidgeneramayread-ilyacceptsuitableanthropogenicdens.Forexample,Agkistrodon piscivorusutilizeshibernaculainanthropogenicdamrubbleandisactiveinanthropogenicditches(savitzky2002andpers.comm.).Wehereadvancethesuggestionthatanyplannednewdensitesbepreparedinwinterorspring,andthentreatedwithwholecornandsunflowerseedtomorerapidlyattractasmallrodent(snakeprey)population. thedocumentedhighnatalphilopatry(Clarketal.2007)ofC. horridus(e.g.,individualsrecruittosamehibernaculumastheirmother)alsoisvaluabletoconservationeffortsbecauseitsuggeststhatsuccessfulrelocationofgravidfemalesthatgivebirthatthenewsiteandthendentherewillestablishthenewpopulation.themodelweemployed,headstartingthemajorityofrelocatedsnakesattheinvestigator-selectednewdensiteearlyafteremergence,makesuseofthesocialcharacteristicsofthespeciestoreducethestressofrelocationandhopefullytherebytoincreasesurvival.
therelocatedsnakesranged,survived,andbehavedseasonallyinafashionthatmirrorsundisturbedpopulationswithin50km.baseduponbehaviorandsurvivalofthetrackedsnakesthroughthesecondfullactivityseasonafterrelocation,duringwhichtimetheirforagingloopsbecamelesserraticandsignificantlysmaller,webelievethisefforthasbeensuccessful,andthatourresultsprovideamorerealisticdefinitionofsuccessthanothershavedemanded.oureffortmayhavebeenuniqueinthattheoriginaldenplainlywasslatedfordestructionandsuitablerelocationhabitatwasfoundareasonable(toofarforthesnakestoreturn;notsofarastocausepopulationgeneticsalteration)distanceaway.Wealsohopethatthisrelocationwillprovideamodelforthefuturesalvageofpopulationsofthisandrelatedspeciesthatarethreatenedbyhabitatdestructionviadevelopment.evidenceexiststhatmuchfartherrelocationsofsmallcolubridscansuccessfullyestablishapopulation(Clark1970).Carefulapplicationofthemodeltocrotalidsdeservesconsideration. thetimberRattlesnakeReportFormwillbeemployedbypersonneloftheCityoflenexaandKansasDepartmentofWildlifeandparksasdesiredtogaininformationonthisspeciesfromthegeneralpublic,aswellasraiseawarenessofthepublictothesnakesasavaluablecomponentoflocalecosystems.Wehopethatsuchfeedbackwillbeusefulinassessingtheproximityofotherpopula-tionsofthisspeciestohumanhabitation.Italsowillbehelpfulinmonitoringdispersalofreleasedsnakes.
AcknowledgmentsRandallDavisallowedusfreeaccesstohispropertysowecouldremovethesnakes,andthetwaddlefamilyprovidedaccesstotheirlandtotrackrelocatedsnakes.thelenexapoliceDepartment,lenexapublicWorks,thehumanesocietyoftheUnitedstates,KansasDepartmentofWildlife andparks, and theChickadeeCheckoffoftheKansasDepartmentofWildlifeandparkscontrib-utedfundstosupporttheproject.Additionally,thelenexapoliceDepartmentgraciouslyallowedallofthesurgeriesanddatacollec-tiontobedoneintheirtrainingroom.employeesfromlenexaAnimalControl,thelenexapoliceDepartment,lenexapublicWorks and the lenexa Information technology Departmentassistedinsnakecollection.specialthanksgotomikeshipman,beckyColin,hopemason,andsergeantDaveogilvie.Crystal,thanksfortoleratinguskeepingbucketsfullof“yourgreatestfear”in theoffice.logistic supportof JohnsonCountyparkpoliceofficerbilliethompsonandChiefDanFieldsaremostgratefullyacknowledged.Additional funding fromRockhurstUniversitythroughanRUpresidentialGrantwasimportanttothesuccessofthework.Galenpittman,Fieldstationmanager(KansasbiologicalsurveyandecologicalReserves)alloweduseofshermanlivetrapstoassessmammalpopulationsatthenewsite.membersoftheKansasCityherpetologicalsocietyandotheruniversitystudentsassistedinthecollectionandtrackingofthesnakes,asdidWilliamDonovan,seanKimbrell,lindaandDylanlehrbaum,DavidJewell,andJoeybrown.JoshuaRiepeassistedwithdataentry.midwesttongsgenerouslycontributedthepIttags,expertise,equipment,andtheopportunityforDorrtoattendVenomWeek.Wildlifematerialsagreedtobuildthetransmittersonshortnoticetosupportresearchonconservationofthespecies.thankstonateDavis,DanKeyler,Roymalleappah,RonDrain,andRulonClark;yoursupport,kindwords,andguidanceareappreciated.specialthanksgotoRodWittenbergandpatKoontz,whobroughtgreatpersonalpassionfor
Femalenearherrookery(withnewbornsinside).theseniorauthorisinthebackground.
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timberRattlesnakestotheproject.Rod,thankyouforyourhoursofresearchandthetrainingyouprovidedtovolunteers.
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