Bats of Thickson’sWoods - Matt Holder Fund€¦ · Big Brown or Silver-haired Bat Eastern Red Bat...

Batsof

Thickson’sWoodsPilotStudyandPublicEducationProgram

2015FinalReport

TobyJ.Thorne,NigelParr,andJessicaKroes

©2016MattHolderEnvironmentalEducationFund

PublishedbyHawkOwlPublishing

SummaryIn2015,apilotbatstudywasconductedattheThickson’sWoodsNatureReserveundertheauspices

oftheMattHolderEnvironmentalEducationFund.Thegoalsofthisprojectweretolearnaboutbats

intheReserveandtoengagethepublicinbatconservation.Aseriesofpublicwalkswasconducted,

withsimultaneous,formalisedacoustictransectsconductedbyvolunteer,JessicaKroes,approximately

weeklyfromJunethroughAugust2015.

AtotaloffivespecieswasidentifiedwithintheReserve.ThemostnumerousbatswereBigBrownor

Silver-haired(305sequences),twospecieswithhighlyoverlappingcallrepertoiresthataredifficultto

distinguish.SecondmostnumerouswereEasternRedBats(66sequences).Otherspeciesidentified

wereHoary,LittleBrown,andTri-coloredBats.

Batsweredetectedthroughoutthesurveyperiod,indicatingthatThickson’sWoodsisavaluablesite

foratleastBigBrown,Silver-haired,andEasternRedBats.HoaryBatsweredetectedinlownumbers

during formal surveys, but were repeatedly observed informally during public events, suggesting

theymayalsomakeuseofthesite.ThepresenceofLittleBrownandTri-coloredBats,bothrareand

threatened species, is significant despite the low numbers. Public engagement efforts were highly

successful,withatotalof180peopleattendingaseriesofeventsthroughtheyeartolistentotalks

aboutbatecologyandtoseenativebatsinflight.

Weplantocontinuethisprojectin2016,toincludefurtherpubliceventsandrepetitionoftheformal

transects, incorporating lessons learned in2015.Wewillalsoexplorepossibilitiesofexpanding the

projectwiththeuseofastaticdetectorandcapturesurveys.

ThankstoThickson’sWoodsLandTrustBoard

membersforsupportingtheongoingresearch.

Limitations:Ecologicalassessmentsprovideasnapshotofasiteataparticulartime.Observationscanbeusedtodraw

conclusionsastothelikelypresenceorabsenceofspeciesandtheiruseofthesite.Itisneitherdefinitivenorcomplete.

Seasonality,weatherconditionsandintra-sitevariationmayalsoaffectsurveyresults.

FormoreinformationaboutThickson’sWoodsandtheprogramsofferedby

theMattHolderEnvironmentalEducationFundgotowww.mattholderfund.com

Coverillustration:BigBrownBat(Eptesicusfuscus)onatree.©TobyThorne2014

1

Thickson’s Woods Land Trustbox 541,Whitby,OntarioL1N 5V3

www.thicksonswoods.com

1. Introduction 3

1.1. Objectives 3

1.2. StudySite 3

2. Methodology 5

2.1. DataCollection 5

2.2. DataAnalysis 5

3. Results 6

3.1. Surveys 6

3.2. DataSummary 6

3.3. EnvironmentalCorrelates 6

4. SpeciesDiscussion 8

4.1. BigbrownandSilver-hairedBats 8

4.2. EasternRedBat 9

4.3. HoaryBat 9

4.4. OtherSpecies 9

5. Outreach 9

5.1. PublicBatWalks 9

5.2. OtherEvents 10

6. Publications 11

6.1. Bats:AConservationGuide 11

6.2. BatsofOntario 11

7. FutureDirections 12

7.1. Qualityofrecordings 12

7.2. Transect 12

7.3. Staticmonitoring 12

7.4. Captureofbats 13

8. Appendix–EnvironmentalCorrelates 13

8.1. EnvironmentalCorrelates 13

2

1. Introduction

1.1.Objectives

1.1.1. ToinventorybatspeciespresentinThickson’sWoods,theadjoiningmeadowand

immediatesurroundings.

1.1.2. TolocateareasofhighbatactivitywithintheReserve.

1.1.3. Tomonitorseasonalvariationinspeciespresenceandactivity.

1.1.4. Toengagemembersofthepublicandpromoteinbatecologyandconservation.

1.2.StudySite

1.2.1. Thickson’sWoodsNatureReserveisaprivately-ownedconservationarealocatedon

thenorthshoreofLakeOntarioinWhitby,Ontario,ontheeasternoutskirtsofthe

GreaterTorontoArea(GTA).Thickson’sWoodsinitiallyconsistedofa6.9hectareold-

growth,mixed-specieswoodlotcontainingpine,beech,aspen,birch,poplar,oak,and

maple.Thewoodlotwaspurchasedin1983bytheThickson’sWoodsLandTrust,which

wasformedforthispurpose.TheReservewasexpandedin2001withthepurchaseof

anadjacent3.2hectaremeadowtothenorthofthewoods.Asmallwaterway,Corbett

Creek,flowsthroughthemeadowbeforeemptyingintoamedium-sized,open-water

wetlandtotheeastofthemeadowandwoodlot

1.2.2. ThecloseproximityoftheThickson’sWoodsNatureReservetothehighlypopulated

GTAresultsinrelativelyhighnumbersofvisitorstotheReserve,whichhasmultiple

publictrailsandisapopularsitewithnaturalists.Themajorityofinterestinwildlifeat

theReservehasfocusedonitsavifauna,inparticulartheprevalenceofrarerbird

speciestravellingalongthelakeshoreduringmigrationperiods.Atvariouspointsinthe

historyoftheReserve,attentionhasalsobeenpaidtosomeotheraspectsoftheflora

andfaunaofthewoodsandmeadow.

1.2.3. Tothebestofourknowledge,noparticularattentionhaspreviouslybeenpaidtobats

inThickson’sWoods,beyondtheobservationsoflocalresidents,severalofwhomhave

foundbatsroostingwithintheirproperties.

TheMattHolderEnvironmentalEducationFundwasestablishedtofindandencourageyoungpeople

withaninterestinthenaturalworld,andiscurrentlyfocusedonprojectswithintheThickson’sWoods

NatureReserve.Batswereidentifiedasagrouponwhichtofocusin2015.Well-attendedpublicevents

wereheldapproximatelymonthlythroughoutthesummer,educatingattendeesaboutbatbiology,and

assistingtheminwatchingandlisteningtobatsaroundthewoods.Additionally,moreformalsurveys

wereestablishedtomoreaccuratelyquantifybatactivityintheReserve.Thisreportsummarisesthe

methodologyandresultsofthesesurveys.

3

Thickson Bay

Thickson Point

Thickson’s Woods

The Meadow

Camp X

Waterfront Trail

Corbett Creek Marsh

Waterfront Trail

Wentworth Street

Thic

kson

Roa

dC

orbe

tt C

reek

Thickson’s Wood Nature Reserve

Aerial view of Thickson’s Woods Reserve and surrounding area

4

2. Methodology

2.1.DataCollection

2.1.1. Batactivitywasmonitoredonanapproximatelyweeklybasisthroughthemonthsof

June,July,andAugust.SamplingbeganonJune10,2015andwasconcludedon

August21,2015.

2.1.2. Transectswerenotclearlydelineated,howeverthreeconsistentsurveylocations;

outlinedinFigure1,includedthemeadow(Zone17NEasting:669017Northing:

4857859),theintersectionoftheWaterfrontTrailandCorbettCreek(Zone17NEasting:

669180Northing:4857894),andthesoutheastcorneroftheThickson’sWoodstrail

atitsjunctionwithMcIntoshAvenue(Zone17NEasting:669163Northing:4857691).

Additionalsurveylocationswereaddedeverysurveynightwhenhighlevelsofbat

activitywerefound.Theseincluded,butwerenotlimitedto,theintersectionofCrystal

BeachRoadandMcIntoshAvenue(17NEasting:669195Northing:4857600),Crystal

BeachRoadandCorbettAvenue(17NEasting:669064Northing:4857515),andthe

southwestcorneroftheThickson’sWoodstrailatitsjunctionwithCorbettAvenue.

2.1.3. Temperature,relativehumidity,andpercentmoonilluminationwasrecordedhalfan

houraftersundownatthebeginningofeachfieldvisit.Volunteersstoppedateach

surveylocationforadurationoffiveminuteswiththebatdetectorprogramedto“auto

record”.Additionally,“autorecording”continuedbetweenprimarysurveylocations.Ifa

batwasdetectedthesurveyorwouldstopforoneminuteoruntilactivityceased.

Surveyswerenotcompletedifhighwindsorprecipitationpersisted.

2.1.4. BatecholocationsoundswererecordedusinganEchoMeterTouchultrasonic

microphonemodule(WildlifeAcoustics,U.S.A.)attachedtoaniPadMini.

RecordingwascontrolledusingtheWildlifeAcoustics‘EchoMeterTouchBatDetector’

applications(versions1.1–1.7)runningoniOS.Theappwassettoautomatically

triggerrecordings.Recordingsweresavedas.wavfilesfordataanalysis.

2.2.DataAnalysis:

2.2.1. Followingthecompletionofall2015surveys,thedatawerecollatedforspecies

identificationandanalysis.Manyfilescontainedextraneousnoise,oftencausedbythe

surveyormovingthroughgroundcover,anddidnotcontaininformationofinterest.

Inordertoreducetimespentonfurtheranalyses,thedatawerefirstfilteredusing

softwaretoautomaticallyidentifyfilescontainingpotentialbatsignals(SonobatBatch

Scrubber5.4;settings:highgrade,excludecalls<20kHz).

2.2.2 Filespassedbythefilterwerethensubjectedtomanualreview.Fileswerevisualised

asspectrogramsandparametersweremeasured(Sonobat4.0.5Base).Auralreview

5

wasalsoconductedwherenecessary.Wherenobatsignalswerepresent,thefilewas

markedas‘noise’.Wherebatsignalscouldbediscernedbutnotidentifiedtospeciesthe

filewasmarkedas‘unidentifiedbat’.Otherwisethecallspresentwereidentifiedto

speciesorspeciesgroup.ThemajorityofBigBrownandSilver-hairedBatcallswere

groupedintoasinglecategoryduetothelargeoverlapincallparametersbythese

species.Similarly,callsbyMyotisspecieswerecombinedintoasinglecategorydueto

thelargeroverlapbythesespecies.

3. Results

3.1.Surveys:

3.1.1. Atotalof8surveyswereconductedin2015.Thesearesummarisedintable1.

3.2.DataSummary:

Atotalof3932ultrasonicsoundfileswererecordedacross8nights.Automaticfiltering

identified1248filesthatcontainedpotentialbatsignals.Manualanalysisshowedthat

afurther785ofthesefilescontainedonlyextraneousnoise.Theremaining463filesare

summarisedinTable2,andinFigures1and2.

3.3.EnvironmentalCorrelates

3.3.1. Avarietyofenvironmentalconditionswererecorded,andarediscussedinthe

appendix.

Table1:Summaryofsurveysconducted,withtimingsandlocalweatherconditions

SurveyStart

SurveyDuration(Mins)

MoonIllumination

%

AirTemperature

0C

RelativeHumidity

%

CloudCover

%

WindSpeedkm/hr

WindDirection

Big Brownor Silver-

hairedpasses per

min.

Red BatPasses per

min.

Total batPassesper min.

2015

June 10

June 25

July 2

July 9

July 23

July 29

Aug 8

Aug 21

21:16

21:15

21:43

21:26

21:43

21:36

20:50

21:35

33

14

46

47

56

31

115

44

39

61

100

41

45

96

33

39

18

15

16

17

21

24

18

16

72

89

63

88

46

85

73

86

100

0

50

0

75

33

3

9

3

12

4

N/A

3

NW

S

NNW

SW

NNW

SE

N/A

W

0.06

0.21

1.02

2.28

0.73

0.18

0.60

0.68

-

0.36

0.11

0.13

0.05

1.03

0.11

-

0.30

0.57

1.43

2.43

0.89

1.36

0.89

1.02

6

Table2:Speciestotalbysurveynight.

2015 June 10 June 25 July 2 July 9 July 23 July 29 Aug 8 Aug 21 Grand Total

Big Brown Bat

Big Brown or Silver-haired Bat

Eastern Red Bat

Hoary Bat

Little Brown Bat

Tri-colored Bat

Unidentified Bat

Grand Total

-

2

-

5

-

3

10

-

3

5

-

-

-

8

-

47

5

-

-

14

66

-

107

6

-

1

45

114

1

41

3

-

-

5

50

-

6

34

-

2

3

45

-

69

13

2

-

18

100

-

30

-

-

-

1

14

45

1

305

66

7

3

1

100

485

Figure 1: Breakdon of total bat sequences recorded by species

0%

63% 14%

1% 1%

0%

21%

Big brown bat

Big Brown or Silver Haired

Eastern red bat

Hoary bat

Little brown bat

Tri-colored bat

Unidentified Bat

Figure1:Breakdownoftotalbatsequencesrecordedbyspecies

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Big Brown BatBig Brown or Silver-haired BatsEastern Red BatHoary BatLittle Brown BatTri-colored BatUnidentified bat

Figure 2: Breakdon of total bat sequences recorded by species by survey

0

20

40

60

80

100

120

140

160

180

6/10/15 6/25/15 7/2/15 7/9/15 7/23/15 7/29/15 8/8/15 8/21/15

Unidentified Bat

Tri-Colored Bat

Myotis Species

Hoary Bat

Eastern Red Bat

Big Brown or Silver-Haired Bat

Big Brown Bat

Figure2:Breakdownoftotalbatsequencesrecordedbyspeciesbysurvey

4. SpeciesDiscussion

4.1.BigBrownandSilver-hairedBats

4.1.1. BothBigBrownBatsandSilver-hairedBatsarewidespreadinOntario.Thedifficulty

inseparatingthesespeciesviaacousticanalysisleadstodifficultyininterpretingour

data,confoundedbytheirdifferingecology.However,thepresenceofalargenumber

ofsignalsfromthisspeciesgroupisconsistentwithothersitesacrosssouthernOntario

wheretheyaccountforthemajorityofbatsencountered.Bothspeciesarelargerbats

andpredominantlyforageinopenspacesclosetocover.Bothspeciesalsoroostreadily

intrees,althoughBigBrownBatsoftenroostasgroupswhereasSilver-hairedBatsare

typicallysolitary.

4.1.2. Itislikelythatalargeproportionofthesignalsrecordedfromthisspeciesgroupare

fromBigBrownBats,whichareknowntoroostinnearbybuildings.However,incidental

observationsoutsidethedatacoveredbythisreportsuggestthatSilver-hairedBatsare

alsopresent.Capturesurveyswouldbethemostdefinitivemeanstoconfirmthe

presenceofbothspeciesandattempttoquantifyrelativeabundance,although

abundancemightvaryseasonallyduetomigrationbySilver-hairedBats.

4.1.3. FurtherinvestigationisrequiredtodetermineatruerelationshipbetweenBigBrown/

Silver-hairedBatactivityandcloudcover.

8

Unidentified batTri-colored BatMyotis SpeciesHoary BatEastern Red BatBig Brown or Silver-haired BatsBig Brown Bat

4.2. EasternRedBat

4.2.1. ThisspeciesiswidespreadacrosssouthernOntario.Publishedreferencesfrequently

refertoitasaruralspecieslesscommonlyencounteredinurbanareas.However,this

claimlackssubstantiationandEasternRedBatsareincreasinglyencounteredaturban

sites.Forexample,unpublisheddatafromT.Thorneindicatesasignificantpresenceof

EasternRedBatsincentralTorontoin2015.

4.2.2. EasternRedBatstypicallyroostaloneintrees.Theirroostscanbedifficulttoidentifyor

protect,butitishighlypossiblethatthisspeciesmayroostinoraroundThickson’s

Woods.

4.2.3. AlthoughourEasternRedBatdatasetseemstobeheavilyinfluencedbyasingle

surveynightwithuncharacteristicallyhighEasternRedBatactivity,therelationships

betweenairtemperature,moonphase,andbatactivitywarrantfurtherinvestigation.

4.3.HoaryBat

4.3.1. HoaryBatsareanotherwidespreadspeciesinsouthernOntario.Theyarereliably

observedforagingalongthelakeshoretotheimmediatesouthofthewoods.Itis

surprisingthatHoaryBatsarelessfrequentlyencounteredinthetransectdata.This

mightreflectthedesignofthetransectoranotheraspectofthemethodologyandshould

berevisitedbeforedrawingfurtherconclusionsaboutthisspecies.

4.4.OtherSpecies

AsmallnumberofsignalsofMyotisspecieswerealsorecorded.Thesecallswere

relativelyshortinlengthandoflimitedquality,whichprecludedidentificationto

specieslevel.AllMyotisspeciesareprovinciallyendangeredandareprotectedas

SpeciesatRisk.AlthoughthenumbersrecordedatThickson’swerelow,thepresenceof

Myotisbatssuggestsfurtherinvestigationcouldbeworthwhile,withfurthersurveys

targetedtothesespeciestoevaluatetheiractivityatthissite.

5. Outreach

5.1.PublicBatWalks

5.1.1. WeheldourfirstpublicbatwalkandbatmonitoringdemonstrationonApril30,2015.

Throughoutthespringandsummerwehosted5publicbatwalksatThickson’sWoods.

Thecombinedattendanceforthebatwalkswas180.Attendanceduringtheseevents

increasedthroughouttheseasonandweanticipategreaterturnoutswhenwerestartthe

publicwalksin2016.

9

A cool night on April 30th for our first Bat Walk

5.2. OtherEvents

1.2.1. WepromotedlocalbatconservationduringtheThickson’sWoodsLandTrustannualFall

FestivalinSeptember2015.InconjunctionwiththeOntarioSpecializedSpeciesCentre

wedisplayedtwospeciesofbatsatourboothduringthedaytimeandledapublicbat

walkintheevening.Ourexhibitwaspopular,reachingafurther600peopleduringthe

festival.

Our Booth exhibiting live bats was well attended at the Thickson’s Woods Fall Nature Festival

10

Visitors to our booth got to touch live bat wings

6. Publications

6.1.Bats:AConservationGuide

6.1.1. IncollaborationwiththeTorontoZoo’sConservation,EducationandWildlifedivision,

wepublishedBats:AConservationGuide.This32pagebookletincludesinformation

aboutthebatsofEasternCanada,tipsforattractingbatstoyourproperty,blueprintsfor

theconstructionofbatboxes.Thisbookletalsoaimstodispelthemythsaboutbats

thathaveledtotheirpersecution.

6.2.BatsofOntario

6.2.1. In2016wewillpublishBatsofOntariobyTobyThorne,acomprehensiveguide

tothe8speciesofbatsthatoccurinOntario.Thisguidealsoincludeinformationon

ecolocationwithsonogramsandisfullyillustratedwithphotographsandlife-sizeartwork

byFionaReid.

Available from www.mattholderfund.com

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7. FutureDirections

7.1.Qualityofrecordings:

7.1.1. Analysisofourrecordingsrevealedmultiplequalityissues.Mostextraneousnoise

appearedtoresulteitherdirectlyfromsurveyornoise,e.g.clothesrustling,brushing

againstthemicrophoneenclosure,orasindirectsurveyornoise,e.g.noisefrommoving

throughlonggrassandundergrowth

7.1.2. Toaddresstheseissueswewilldevelopanimprovedprotocolforvolunteersurveyors,

informationaboutminimisingsurveyornoise.

7.2.Transect:

7.2.1. Multipleissueswereencounteredwithtransectsin2015,inparticulartheidentification

ofasuitablerouteandasuitablemethodologyforpausingatlisteningpoints.Attempts

toaddresstheseissuesledtovariabilityinthemethodologyofthesurveys,butwe

consideredthesevariationsjustifiedinordertomaximisesurveyeffectiveness.

7.2.2. Inthe2016surveys,wewilluseinformationfrom2015todevelopafixedtransectroute

thatwillbesurveyedconsistentlythroughouttheseason.Wewillinvestigatethe

possibilityofproducingaGPStrackfileorplacingphysicalwaymarkersforvolunteers

conductingtransects.

7.2.3. In2015transectswereconductedonanapproximatelyweeklybasis,withsome

variation.In2016wewilltrytoschedulemoreconsistentsurveys,subjecttovolunteer

availability.

7.2.4. ItistooearlythedeterminethelongtermviabilityoftransectsatThickson’sWoods,

eitherintermsofthevalueofdataprovidedortheavailabilityofinterestedvolunteers

toconductsurveys.Wewillaimtoconductacomprehensivetransectsurveyprogramin

2016,followedbyareviewofitseffectivenessandlong-termviability.

7.3.Staticmonitoring:

7.3.1. Followingtheinformationgainedfromtransectsandotheracousticmonitoringin2015,

inparticularthepresenceofMyotisspeciesandpossibleTri-coloredBat,increased

monitoringwithastaticbatdetectorwouldbeanidealexpansionofmonitoring.

7.3.2. Astaticbatdetectorwouldbedeployedtoautomaticallymonitorandrecordbat

echolocationatafixedpointintheReservethroughouttheseason.

7.3.3. Theprimarylimitationtousingastaticdetectoristhecostoftheequipment.Atthetime

ofwritingweawaittheresultsofagrantapplicationtoincludethecostofadeviceand

dataanalysistime.Ifthisgrantisnotsuccessful,otheravenueswillbeexplored.

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7.4. Captureofbats:

Toconfirmacousticspeciesidentifications,particularlyforthemoredifficultspecies,

havinganindividualinthehandisthemostreliableoption.Unlessroostsareknown,

thisisbestdonebycapturingbatsinflight,butdoingsorequiresanMNRFpermit.A

permitapplication,includingThickson’sWoods,iscurrentlyunderwayandthisoptionwill

beexploredfurtherdependingonthesuccessofthisapplication.

8. Appendix:

8.1.EnvironmentalCorrelates

8.1.1. Avarietyoflocalclimaticconditionsareknownorbelievedtoaffectbatactivity.We

recordedavarietyofenvironmentalcorrelatesofpotentialinterestatthetimesofthe

surveys.Thesearesummarisedintable1.Oursmallsamplesizemakesitimpossibleto

drawfirmconclusionsabouttheeffectofthesefactors,andweconsiderthisa

preliminaryinvestigationtobeaddressedinmoredetail,forexamplewithdatafroma

staticdetector.

8.1.2. Airtemperature:preliminaryresultssuggestthatRedBatsaremoreactiveduring

warmertemperatures.However,thisrelationshipwaslikelyinfluencedbythehigh

frequencyofRedBatpassesduringtheJuly29survey(AppendixFigure1).

8.1.3. Moonphase:manybatobserversbelievethatlunarilluminationaffectsbatactivity,

whichmaybelowerduringperiodsofhighillumination.Ourresultsaremixedwith

respecttobatactivityandmoonillumination,thoughRedBatactivityduringoursurveys

appearedtobeheightenedduringafullornear-fullmoon(AppendixFigure2).

8.1.4. Cloudcover:BigBrownandSilver-hairedBatpasseswerelessfrequentwhencloud

coverexceeded50%(i.e.mostlycloudyorovercast;AppendixFigure3).

13

Appendix Figure 2: relationship between bat activity, expressed as average passes per minute, and moon phase

Appendix Figure 1: relationship between bat activity, expressed as average passes per minute, and air temperature

14

Appendix Figure 1: relationship between bat activity, expressed as average passes per minute, and air temperature

Appendix Figure 3: relationship between bat activity, expressed as average passes per minute, and cloud cover

15

Appendix Figure 3: relationship between bat activity, expressed as average passes per minute, and cloud cover