4/6/17

1

TechniquesforInventory&MonitoringofAmphibians

Gabrie l le Graeter

Wi ld l i fe Divers i ty B io log ist

NCWi ld l i fe Resources Commiss ion

SEPARCSteer ing Committee

Outline- Whysurveyamphibians?

- Definingyourgoal

- Beforeselectingatechnique

- Techniques◦ Active◦ EasyPassive◦ IntensivePassive

- LimitationsandTips

- Resources

WhysurveyforAmphibians?

4/6/17

2

Whysurveyforamphibians?•Amphibiansaredeclining.Abetterunderstandingofaspecies’status=betterabilitytoconservethespeciesandtheirhabitat

•Needmoreinformationaboutdistributionofmanyspecies

•Tolearnmoreaboutthelifehistory(e.g.,breedingtimes,growthcurves,movement,clutchsize)

•Toanswerimportantresearchquestions

DefiningyourGoal

DefiningtheGoalWhatistheQuestion?◦ Identifyingthespeciesthatinhabitadefinedareaorhabitat?Therefore,thereisaneedforpresence orabsencedata.

◦ Determiningthegeographicdistributionofaspeciesorgroupofspecies?Eitheramonghabitattypesoracrossadefinedregion(s)

◦ SoundslikeINVENTORY

4/6/17

3

DefiningtheGoalWhatistheQuestion?◦ Determinethestatusofaspeciesatagivensiteorhabitat?Therefore,thereisaneedforabundanceordensitydata.

◦ Determinepopulationchangesinsinglespeciesorspeciesassemblagesovertime.Eitheratagivenhabitat,amonghabitattypes,oracrossadefinedregion(s)

◦ SoundslikeMONITORING

Inventoryvs.Monitoring

• Theyarenotthesame(andprobablyshouldnotbediscussedinthesamesentence)

• However,someofthetechniqueshaveoverlappinguses

InventoryComesBeforeMonitoringFirstconductaninventory

Basedontheresultsdiscoveredduringtheinventoryprocess,furtherdecisionsaremadetomonitorparticularspecies

Examplesofspeciesmaywanttomonitor:thoseendangered,suspectedindecline,vulnerabletolandmanagementmanipulations

4/6/17

4

ValueofLong-TermMonitoringJustastheresultsofanInventory willelucidatetheneedsandgoalsofaMonitoring program,

RepeatedMonitoringmaymorphintoaResearchstudy

PointstoconsiderbeforeselectingTechniques

BeforeSelectingTechniques

• Knowbiology&lifehistoryofthespecies

• Knowthehabitats

• Considernaturalenvironmentalfluctuations

• Considertime,funds,andpersonnelavailable

• Accountforinfluenceofdetectability

4/6/17

5

Speciesandlifestagesaresometimesdifficulttodistinguish

Itisimportanttofindalllifestagessotherearenomisidentifications

Findinglarvaisimportantbecauseyouknowtheyarebreeding

Speciesandlifestagesaresometimesdifficulttodistinguish

Somespeciesareboomorbustbreeders◦ Itisnotuncommonforaspeciestonotbreedformultipleyears,andthen.........

4/6/17

6

Knowthehabitats•Knowthehabitattypesthespeciesuses

•Complexityofthehabitat

•Learnabouthowthespeciesusesthehabitat• Microhabitatselected?Woodydebris,leaflitter,etc.• Above/belowground?

•Mapthehabitattohelpwithplanning

•Sizeoftheareatobestudied

HabitatMapping•Thefirstbasicstepindesigninganinventoryormonitoringplanismappingoutyourhabitattypes

•Willhelpyouidentifythetypesofhabitatpresent

•IfyouhaveGISresourcesutilizethem,ifnot,canuseGoogleEarth

•Oftenverysmallhabitatfeaturescontainadisproportionateamountofamphibianandreptilediversity• Seeps• Streams• Wetlands• Rockoutcrops• Etc.

NaturalEnvironmentalFluctuations

• Activity&reproductionofaspeciesvarieswithnaturalenvironmentalfluctuations

• Fluctuationsoccuratsmallscales(localthunderstorms)andatlargerseasonalandannualscales

• Examples:precipitation,temperature,humidity,drought,hurricanes

4/6/17

7

SeasonalityAffectsSamplingImmigration

Callingbyadults

Eggdeposition

LarvalperiodMetamorphosis

Emigration

Seasonal wetlands hydrology

summer

winter

DryBay– Summer1993

4/6/17

8

DryBay- Summerof2002

Berealistic•Howmuchtimedoyouhavetodevotetothis?•Isfundingalimitation?Whatisthebudget?

•Howmanypersonnelareavailable?

Detectability – theprobabilityoffindingaspeciesgivensomeunitofsearcheffort.

◦ Alotofherpshaveaverylowdetectability,sotohaveanychanceoffindingsomerarespeciesyoumusthavealotofeffort(sometimesyears)beforeyoucanconfidentlysayitisnotpresent

4/6/17

9

Detectabilityisinfluencedby...• Unpredictableseasonalevents– droughts,coldwinters,heatwave,heavyrains,etc.• Reproductivecycles- somespeciesmayonlybedetectedduringtheirbriefbreedingseason• Landscapeandhabitat– complexity,won’tfindaspeciesifhabitatnotpresent• Currentweather:relativehumidity,barometricpressure,cloudcover• Air,water&substratetemperature• Soilmoisture&rainfall• Moonbrightness• Diurnalv.nocturnalactivity

Techniques

Samplingtechniques

3broadcategoriesoftechniques◦ Activesampling◦ Easypassivesampling◦ Intensivepassivesampling

Formoststudiesitislikelyyouwouldneedtocombinetechniquesforbestresults◦ Youcanalmostneverdocumentallofthediversityinanareausingasinglecategoryofsamplingtechniques

4/6/17

10

Designcomponent

TimeconstrainedTimeconstrained- Apredeterminedtimeischosen

#ofobserversXtimesampled;forcatchorvisualencounter◦ Youcanalsopredetermineifyouarelookingfornotonlyacertainspeciesbutforaspecificlifestage,sex,size,orcharacteristic

Whatthistellsyou◦ Presence◦ Lifehistoryinfo- e.g.wheneggsaredeposited◦ Specieshabitatinfo◦ Aroughestimateofpopulationsize(notactualsize,butforcomparison)

AreaconstrainedAreaconstrained- adefinedamountofhabitatisselectedforsampling◦ Randomlyselectedplots◦ Certainhabitattypes- ponds,caveentrances,etc

Samestrengthsandweaknessesoftimeconstrainedbutyoucanalsogetaverycrudeestimateofdensity

Mustbewaryofdifferentsizedhabitatsifyougothehabitattyperoute

4/6/17

11

TransectSurveysTransects- asurveylinelengthisselectedandcombinedwithadetectionmethod

Veryversatile- forexample,herearesomedetectionmethodsthatcanbeused◦ Visualencounter◦ Flippingcoverobjectswithin1m oftransect◦ Countingeggmassesinapond◦ Etc.

ActiveSampling

4/6/17

12

ActiveSamplingActivesamplingiseasytouse◦ Veryeffectiveforspeciesthatareeasilyseenorthatleavetracesoftheirpresence(eggmasses,burrows,etc.)◦ Noteffectiveforsomespecies,especiallyifstaffarenotexperienced

Themostbasicformispresence-absencesearches◦ Searchahabitatandifyoufindaspeciesyouknowit’sthere(obviously)◦ Presence/Absencetellsyouverylittleaboutpopulationsizesandotherpopulationparameters(e.g.growth,decline,etc.)

◦ Agoodtooltogetpeopleinvolvedinyourprogram(e.g.BioBlitz)butnotgoodastheonlytool

Activesamplingincludes:- Handcollecting

- Signandtracking

- Visualencountersurveys

- Dipnetting andsweepsamples

- Kicksampling

- Eggmasscounts

- Snorkelingsurveys

- Electroshocking

- Auditorysurveys- Roadcruising

Handcollecting&SignandTracking

•HandCollecting– captureviahandortools(snakehooks,long-handleddipnets).Mayinvolvelookingthroughleaflitter,underlogs,orbehindbark.• Importanttoleavesearchedhabitatsasundisturbedaspossible– putrocksandlogsback

•Sign&Tracking– maylocatethembyfollowingdistinctivefootprints,locatingrecentlyusedburrows,hibernacula,ornestsandbyidentificationofscat• Moreusefulwithreptilesthanamphibians

4/6/17

13

VisualEncounterSurveys•VESisatime-constrainedmethod:observerssampleapre-definedarea

• Timeand#ofobserversmustberecorded• DiffersfromTransectsurveyinthatdoesnothavetobelinear

•3VESSamplingDesigns:• Randomizedwalk– useaseriesofcompassdirections,distance.• Quadrat– systematicallysurveybywalkingparallelordiagonalpathways• Transect– lineartransectsareestablishedandwalkedbyobservers.

Dipnetting•Definition:Anetissweptthroughanaquatichabitat

• Meshsizeisimportant

•Mostuseful:• Insmallshallowaquatichabitats(smallerareameansgreaterchanceallspeciespresentwillbecaptured)

• Whensearchingforevidenceofreproduction

•WhendoingInventory,mustsearchasmanymicrohabitatsaspossible

•Timing:shouldcoincidewithwhenspeciesaremostlikelyfoundinaquatichabitats(breeding,larvalseasons,etc.)

SweepsamplesSweepsamples- sweepingalargedipnetthroughthewatercolumnorsubmergeddetritustocapturesubmergedindividuals◦ Usuallyamphibianlarvaeandbreedingadults

Total#ofsweepsperareaand#ofindividualscapturedarerecorded

Example- 5dipnetsweepsontheedgeofapondevery15meters

Whatthistellsus◦ Larvalspeciespresentatthattime◦ Lifehistorytraitssuchaswheneggsaredepositedandwhenlarvadevelop◦ Habitatinfo◦ Microhabitatpreferences◦ Density

4/6/17

14

KickSampling•Definition:Liftingandremovingallloosecobblefromstreambottomandhandrakingorkickingloosepebblesintoanetorseriesofnets.• CandoAreaorTime-constrained

•Netsused:• D-framenetsmostcommonlyused• Seinenetscanbeusedtocapturemissedindividuals

•Remember:• Alwaysreplaceanylargehabitatitems(≥200mmcobble,woodydebris)• Timing– whenspeciespresent,whenwaterflow/depthissuitable

•Candetermineoccupancyandabundance

EggMassCounts•Searchingapond/wetland/streamforglobularmassesorstringsofeggs

•Usefultohavemorethanoneobservertohelpwithdetection

•KeepinmindthatoneeggmassmaycontaineggsfrommorethanonefemaleANDthatonefemalemaydepositmorethanoneeggmassinabreedingpond

•Someamphibianslayeggsondryground(e.g.,marbledsalamanders,Ambystoma opacum)

4/6/17

15

EggMassCounts

Spottedsalamander

Woodfrog

Americantoad

Snorkeling•Usefulinaquaticenvironmentswithclearwaterconditions

• Maybedoneatnightorday(dependingonactivityoftargetspecies)• E.g.,Hellbendersalamanders

•Sampling:• Canhaveapermanentlyestablishedtransectline- formonitoring• Indeepwater,SCUBAmaybeneeded

•Insomecases,substratemaybemoved,butthiscanbedetrimentaltohabitatandshouldbeavoidedforlong-termstudiesorwithaspeciesofconservationconcern.

•Safety:• Canbedangerousifstrongcurrents,verycoldwater,orslipperyrocks• Mustnotbedonealone

4/6/17

16

Electro-shocking•Usehighcurrentsofelectricitytotemporarilystunaquaticanimals

•Primarilyusedforfish,butalsoaquaticamphibians,mostlysalamanders

•Current– AC,DCorDCpulsed• UseofDCpulsehaslesslethaleffectonamphibians• DCpulsemosteffectivefordrawinghidinganimalsout

•Mosteffective:• Inwaternotexceeding1mdepth• Usedsuccessfullytosurvey:hellbenders,sirens,mudpuppies

•Utility:• Pros:Canfindhard-to-findspecies,quick,lesshabitatdisturbance• Cons:Physiologicalimpacttoanimals,expensive,potentiallydangerous

•Tips:• Donotuseduringeggdepositionandnesting(Sept-Nov)especiallywhenspeciesofconcernarepresent(hellbenders)

• Goodforinventory.Donotuseformonitoring.

Auditorysurveys•Callsurveys- somespeciesoffrogsareonlyeasilydetectablebyhearingtheircall

•Aretrainingprogramsonline:NAAMP

•Provideinfoon◦ Inventoryofspeciescomposition◦ Breedingtimes◦ Maleabundance◦ Climaticconditionsthatleadtobreeding◦ Locationofbreedingponds

Roadcruising•WithAmphibians,mostusefulinareaswheretheroadbisectsorisperipheraltoabodyofwaterwithspeciesthataremovingbetweenbreedingand/orforaginglocations.

•Timingisimportant– heavyprecipitationandwarmweather

•Arebiasesassociatedwithmethod(e.g.,roadsaffectpopulations,somespecieswillavoidroads)soshouldpairwithothertechniques

4/6/17

17

RoadCruisingGetapositiveI.D.

Pickinguproad-killedspecimensScientificuseofotherwisewastedindividual

ConstrainingEffortConstrainingeffortcanhelpmakeactivesamplingmoreuseful◦ Timeconstrained(resultsarereportedas#ofspecies/individualsperpersonperhour)

◦ Areaconstrained- adefinedamountofhabitatisselectedforsampling◦ Randomlyselectedplots◦ Samestrengthsandweaknessesoftimeconstrainedbutyoucanalsogetaverycrudeestimate

ofdensity

◦ Example:Sweepnetsampling(#ofsweepsperpersonperspecies)

EasyPassiveSampling

4/6/17

18

EasyPassiveSamplingEasypassivesamplingrequiresnoobservereffortandcausesnoharmtoanimals

Basicallyitisputtingouthabitat-likecontraptionsthatmightattractamphibians,butwon’ttrapthem.◦ Coverboards◦ Leaflitterbags

EasyPassivesurveysincludes:

- Artificialcover

- PVCPipesurveys

- Leaflitterbagsurveys

- Automatedrecordingsystems

ArtificialCover– “coverboards”TargetSpecies

AdvantagesandDisadvantages

UsefulforMonitoring

Tinvs.Wood(plywoodvsparticleboard)PlacementofArrays

Flagging

Numbering

4/6/17

19

CoverboardsPROSSuitableforvarietyofspecies

Excellentforsalamandersandsmallaquaticsnakes

Donotrestrictanimalmovements- don’thavetobecheckeddaily

CONSTimetoinstall

Unsightlyappearance?

Catchraterelativelylow

Capturesuccesssubjecttoimmediateweatherconditions

Pickingthearraypatternbestsuitedforyourhabitat

Four-toedsalamanderHemidactyliumscutatum

4/6/17

20

COVERBOARDMATERIALS

Considerthepros&cons

PaperbyGrantetal.1992

204ftx4ftplywoodboards@25mintervals=400m

4/6/17

21

SamplingArborealSpecies

Theywon’tstayinthebucket!

Barkingtreefrog (Hyla gratiosa)

PVCPipesCancreatePVCpipehabitatfortreefrogs◦ Canbeattachedtotrees,stakes,orstuckdirectlyintheground

4/6/17

22

LeafLitterbagsurveys•Plasticnettingwith1.9cmmesh,smallrocksplacedonthenettingandcoveredwithleavesandcabletiesbindittogether– manyvariations

•Canbeusedtosampleforstream-dwellingsalamanders• Especiallyusefulfordetectingpresenceofmorerareandelusivespecies• Larvalsalamanders(bagmustbesubmergedcompletely)

•Bagsplacedinstreamatregularintervals– weighedorstakeddownsocan’tfloataway

•Afteracclimationperiod,eachbagischeckedforsalamanders(detailsinGraeteretal.2013)

AutomatedRecordingSystems:“Frogloggers”

4/6/17

23

• Explosive breeders that are missed with other surveys

• Good for remote or inaccessible sites

• Vouchers

• May reveal novel behaviors

Frogloggers -- Pros:

• Somewhat expensive

• Time consuming and tedious to listen to recordings

• May be more involved than necessary for inventory

Frogloggers -- Cons:

IntensivePassiveSampling

4/6/17

24

IntensivePassiveSamplingCreatingtrapsthatamphibiansandreptilescannotgetoutofwithoutassistance

Onlyfortheverydedicated◦ Labor,time,andfinanciallyexpensive◦ Trapsmustbecheckedregularlytoavoidharmtotheanimalscaptured◦ Youmustbepreparedtogetthingsoutoftrapsthatyoumightnothaveintendedtocatch

IntensivePassiveincludes:- Aquaticandterrestrialfunneltrapping

- Terrestrialdriftfencesandpitfalltraps

FunnelTrapping•Labor,time,andfinanciallyexpensive

•Trapsmustbecheckeddailytoavoidharmtotheanimalscaptured

•Traptypes:• AquaticFunneltraps:minnowtraps,trashcantraps,hooptraps• Terrestrial:wirehardwareclothcylinderorwoodenboxtraps

•Inventoryvs.Monitoring:• Goodforinventory,butmustusealotoftraps,sampleallhabitattypes,andtrapinmultipleseasons

• Monitoring– muststandardizeschemesocanrepeatitandallowcomparisonofcaptureratesovertime.

4/6/17

25

FunnelTraps

DriftFencesEssentiallyawallthattheindividualwalksuptoandthenalong.Thewallleadsthemtooneofavarietyoftraps

DRIFTFENCES

4/6/17

26

Possibledriftfence,pitfall&funneltrapconfigurations

4/6/17

27

DriftFenceConcernsToomuchrain

Toohot

FireAnts

Personneltocheck- holidays,weekendsRaccoons

Toomanycapturestodealwith!

Monitoringcancost$$

Limitations&Tips

TechniqueshaveLimitations• Eachtechniquehasunderlyingassumptions,biasesandlimitations.

• Unlikelythatonetechniquecanbeusedtosampleanentirecommunity

• Therearehumanbasedconstraints(money,people,time)-- bepractical

4/6/17

28

Tips:1. Useseveralmethods

2. Knowthespecies– identification,naturalhistory

3. Considertimingandseasonality

4. Habitatandmicrohabitatiskey5. Consultwithexperts

6. Gethands-ontraining

Resources

PARCProductsAllavailableonAmazon!

TechniquesTable– veryusefulwhendecidingwhichtechniquestouse

4/6/17

29

OtherResources:

AcknowledgementsNCWildlifeResourcesCommission

USFWSStateWildlifeGrantprogram

PARCandSEPARC

KurtBuhlmann,SavannahRiverEcologyLab/UniversityofGeorgia

JJApodaca,WarrenWilsonCollege

ManyothersthatcontributedtothePARCInventoryandMonitoringbook

Questions?