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ASIANTOADERADICATIONFEASIBILITY
REPORTFORMADAGASCAR
Fig.1a.Duttaphrynusmelanostictus,Asiantoad.Female,TamataveMadagascar.PhotoJ.Reardon.
PeteMcClelland,JamesT.Reardon,FredKraus,ChristopherJ.Raxworthyand
ChristianRandrianantoandro
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Fundedby:
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Supportedby:
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Reviewedby:
KeithBroomeandAndyCox(IslandEradicationAdvisoryGroup,New
ZealandDepartmentofConservation).
Citation:
McClellandP.,J.T.Reardon,F.Kraus,C.J.RaxworthyandC.Randrianantoandro.AsianToadEradicationFeasibilityReportforMadagascar.2015.
TeAnau,NewZealand.75p.
Correspondingauthor:[email protected]
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FOREWORD
ItisimportanttorecallthatMadagascarisacountryofexceptionalbiodiversityworldwide.Forexample, among the 300 species of amphibians reported, the rate of endemism is nearly 100%. The
recentincursionoftheinvasiveAsiantoadconstitutesadirectthreattothisuniquebiodiversitybut
alsotohumanhealthandthecountry’seconomy.Wesuspectthetoadsimpactmaybecomparable
totheCanetoadinAustralia;wemustactswiftlytopreventasimilardisasterunfoldinginMadagascar.
Thepublicationofthisreportisbeingenthusiasticallyawaitedbythescientificcommunityandconservation, organizations as well as government authorities in Madagascar. In order to ensure the
successofthiseradicationfeasibilityreport,recommendationsrequirethesupportandcommitment
ofallstakeholders;anydelayindecisionmightlessenourcapacitytoresolvethisurgentissue.
Thepresentreportareresultsofworkcarriedoutbyeradication,invasivespeciesandherpetology
experts:PeteMcClelland,JamesT.Reardon,FredKrausandChristopherJ.Raxworthy.Nationaland
local authorities, Malagasy scientists and non-governmental organizations have contributed immeasurablytotheeradicationplan.
TheplanincludescurrentknowledgeoftheAsiantoadsituationinMadagascar,nextstepsanddiscussion of available options. Critically, the eradication feasibility criterion of possible corrective
measures is given careful consideration against the facts. It is important to emphasize capacitybuildingactivitiesandtestingoferadicationmethods(whichhasneverbeforebeenattempted)beforealargeprogrammeofthissortcaneffectivelycommenceandbesuccessful.
Dissemination of this report is essential for all stakeholders working in the fields of conservation,
resourcemanagement,humanhealth,importandexporttradeandeconomicpolicy.TheMalagasy
governmentauthoritiesandvariousentitiesshouldbewellrecognizedforhelpingmakepossibleits
completion.
CHRISTIANRANDRIANANTOANDRO
NATIONALCOORDINATOR
EMERGENCYCELLAGAINSTTHEASIANTOADINVASION
MADAGASCAR
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TABLEOFCONTENTS
EXECUTIVESUMMARY 1INTRODUCTION
2GOALS,OBJECTIVES&OUTCOMES
2.1Goals
2.2Objectives&outcomes
3THESITE
3.2Targetspecies
3.3Impacts
3.4Benefitoferadication 4REQUIREMENTSFORSUCCESSFULERADICATION 4.1Technicalapproach 4.2Sustainability
4.3Socialacceptability 4.4Political&legalacceptability 4.5Environmentalacceptability 4.6Capacity
4.7Affordability 5CONCLUSIONS 6ACKNOWLEDGEMENTS 7REFERENCES APPENDIXI:SiteVisit
APPENDIXII:TermsofReference APPENDIXIII:PreliminaryTechnicalStrategy
1URGENTISSUES
1.1Governing/leadershipbody
1.2Management&administration 1.3Financing
1.4Biosecurity&education
1.5Mapping/GIS 1.6Delimitation 2METHODTESTING&EVALUATION
2.1Baselinedata,importantissuesandmonitoringmethods 2.1.1Densityestimation 2.1.2Humaneeuthanasia 2.1.3Trackingtunnels
2.1.4Acousticmonitoring 2.1.5EnvironmentalDNA 2.2Detection&eliminationmethods
2.2.1Detectionandremovalthroughdelimitedhandsurveys
2.2.2Driftfencing&pitfalltrapping
2.2.3Citricacid/sucrosespray
2.2.4Acousticlocationandphysicalcapture.
2.2.5Tadpoletraps
2.2.6Herbicides 2.2.7Eggcollection
2.2.8Refusemanagement
2.2.9Toaddogs 2.2.10Cappingwaterbodies
2.2.11Chemicaltreatmentofwaterbodies 2.2.12Toadtraps
2.3.Prioritisationofmethods&proposedtestingschedule 3BUDGETPLANNING
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EXECUTIVESUMMARY
Aneradicationofanamphibianspecieshasneverbeenachievedonthescalebeingconsideredhere
andtheAsiantoadincursioninMadagascarpresentsaplethoraoflogisticalchallenges.
However,therehasbeennosystematictestingordevelopmentoferadicationtoolsforthisspecies
inthisenvironmentandsotechnicalfeasibilitycannotbeproperlyjudgeduntilmethodsaretested.
Humanhealth,ecologicalandeconomicimpactsofdisregardingeradicationasanoptionaresimply
too great for the authors to recommend abandoning eradication under our current state of
knowledge.Wethereforerecommenddevelopmentoferadicationmethodsproceedinatwo-stage
processthusevaluatingtheviabilityofmethodologiesbeforeadvancingtoemployingthosepracticesatthelandscapescale.
Shouldtheevaluationoferadicationmethodsdemonstrateseriousfailureofmultiplemethods,seriously threatening the likelihood of success of an eradication attempt, we recommend eradication
efforts be abandoned to avoid wasting resources that could be better used toward mitigation
measures, species and habitat focused conservation efforts and public health education programmes to ameliorate the damage and impacts of Asian toads in Madagascar. It is important to
notethatmitigationinthelong-termislikelytocarryafarhighertotalcostthaneradicationinthe
shortterm.
Fig.1b.AsiantoademergingafterraininKandy,SriLanka.Photo:J.Reardon.
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This report considers the logistics and feasibility of eradicatinga population of Asian toads, Duttaphrynus melanostictus (Fig. 1.), a non-native invasive species recently established in Madagascar.
Theseconsiderationsareforgovernance/leadershipbodiesthatmustmakerapidanddecisivedecisionswhicharepracticalandappropriategiventhecurrentstateandsituation.
Eradicationfeasibilityreportsusuallystateclearlywhetheraneradicationoperationshouldproceed
ornot.Unfortunatelyinthiscase,theissuesarecomplexandsofollowstherecommendations.
TheCurrentsituationasweunderstandit
Basedonthecurrentsizeoftheincursionandobservationsbylocals,Asiantoadsarrivedin
Madagascar by at least 2010 and have now spread over an area of approximately 98 km2.
Givenanaverageapproximateddensityof400toadsperhectare(basedonreplicatedsampling across stratified habitat types in areas where no previous disturbance of toads is
known)itisestimatedthecurrentpopulationisestimatedataroundfourmilliontoads.The
invasionfrontoftoadsappearstobeexpandingapproximatelytwokmperyear.Toadscurrentlyoccupylowlandhabitats(bothruralandurban)andtherearenolikelyknownbarriers
totheirpopulationexpansioninMadagascar.Thesetoadsarerapidbreedersproducingup
to40,000eggsperyear,longlived,poisonoustootheranimalsandopportunisticpredators
devouringanythingtheycanswallow.
Whatwepredictwillhappenifnothingisdone
Iftheseinvasivetoadsarenoteradicated,oratleastcontrolledandcontained,theywillcontinue to spread over the majority of Madagascar. The presence of these invasive toads is
likely to cause major ecological and economic negative impacts with the potential for the
majorreductionoreventotallossoftoadpreyspecies,both endemicanduniqueinvertebrateandvertebratespeciesinMadagascarandthusexacerbatingspeciesextinctions.Predatoryspeciesthatfeedontoadswillalsobeimpactedandthreatenedthroughtoadpoisoninguponingestion.Economicimpactsincludeanincreasein Blackrat(Rattusrattus)numbersoncepredatorpopulationsarereducedbytoadpoisoning,leadingtoincreasedlossof
stored food supplies and damage to commercial goods and equipment. An increase in rat
numberswillhavehumanhealthramificationsthroughratbornediseaseselevatingtheincidence of plague already present in the incursion area. Economic costs will be incurred
throughimpactstotheexportindustrywherebiosecurityconcernsincreasefreighthandling
timesandcostsorbecomingbarrierstoexport.
ThetoadsundermineMadagascar’senvironmentaltourismsector—anindustrywhichhashugevaluetothenation,nowandinthefuture.CriticallytheAsiantoadisarisktohumanhealthofMalagasycitizenswherefrogsareacommonpartofthediet.Asiantoadshaveprovedtobelethallytoxic
tohumaninSouthEastAsia(Chietal.1998).
Therearefourbasicstrategicoptionsfordealingwiththeissue:
1. DonothingandacceptthesetoadswillbecomeapermanentpartofMadagascar’sbiodiversitywiththeconsequentialenvironmental,economicandhumanhealthimpacts.
2. Undertakesustainedcontroloftoadpopulationsinprioritysiteswhichmayprotecthigh
priorityspecies,orsites,but(thiswillhaveanongoingfinancialcostinperpetuity)and
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accept any environmental, economic and human health impacts across most of the
country.
3. Contain the spread of toads to their current distribution, if this is possible given the
rangeofhabitatstheypresentlyinhabitandtheuncertaintyofdetectingandremoving
toadsatlownumbers.
4. Completely eradicate these toads from Madagascar. This would eliminate all possible
ecological, economic and social impacts the toads may have on Madagascar; with no
long-termcostimplicationsotherthanon-goingbiodiversityimprovements—whichare
presumedaprerequisiteforalloptions.
Prosandconsofoptions
While eradication is the most financially expensive option in the short term, benefits of
permanentlyremovingalltoadsandthustheirimpactandassociatedriskfaroutweighthe
benefitsofsustainedcontrol.Controlprogrammesrequirecommitmentinperpetuitysince
any benefit(s) would be lost shortly after the programme was discontinued. Control programmesquicklybecomemoreexpensivethaneradication,thuscompleteeliminationoutranksopposingcontrolmethods.
Eradication, along with high intensity control, requires the development/confirmation of
techniquestodetecttoadsatlowdensityandefficientlyremovetoadsatalldensities.
Recommendedstrategicoption(eradication)
WerecommendanattemptbemadetocompletelyeradicatetoadsfromMadagascar.This
strategicoptionoffersthebestsolutioninthelong-termbutwillhavethedisadvantageof
highshort-termcost.Aneradicationplanshouldbeimplementedunderconsistentreviewas
newmethodologiesaretestedandlogisticalmethodsofeliminationarefurtherestablished.
Whatisrequiredtoachieveeradication?
ToeradicatethesetoadsfromMadagascarwillrequiredetectionmethodswhichwillbesensitive to every individual animal, across the entire incursion area. Toad capture/removal
methodsmustremovetoadsfromthepopulationfasterthantheybreedandrecruit.Finally,
acriticalfactorforsuccessistoensurenofurtherAsiantoadsarebroughtintothecountry.
ThereareanumberofpotentialremovalmethodswhichwillrequirefurthertestingandtrialstodeterminewhatcombinationoferadicationtechniquesworkbestunderMadagascan
conditions.Trialswillberequiredtodeterminewhatlevelofeffortwillbeprescribedtodeploythedeterminedmethodsacrossthelandscapepredictedtobeinfestedbythetimethe
projectbecomesoperational.
Withsomanyunknownsatthisstage,particularlythechoiceofdetectionandremovaltechniquestobesuccessfullyusedineradication,itisdifficulttoestimatethefinalcostandthat
eradicationispossible.OurbestcostestimateproducesacostofbetweenUS$2millionand
US$10million,butthisfigurecanbefurtherrefinedthroughtheprocessrecommendedbelow.
Toundertakeeradicationrequires:
• Establishmentofagovernanceandleadershipbody.
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Installationofasuitablemanagementandadministrationstructure.
Confirmationoffinances—initiallyfortrialsfollowedbydevelopederadicationoperationsshouldtrialsofferfeasibleeradicationoptions.
Establishmentofadequatebiosecuritymeasurestopreventhumanassistedspread
of toads into, out of and within Madagascar; to prevent the introduction of additional invasive species, and if the eradication is successful, to prevent the reintroductionoftoadsbackintoMadagascar.
Educational programmes established to inform residents of the impacts and risks
posed by toads, the techniques to be used for eradication, how to assist with the
eradicationandhelpingidentifythescaleoftheincursionanddetermininganypossiblesatellitepopulationswhichcouldexistoutsidetheincursionarea.
Maphabitats,theextentoftheincursion,andanypotentialbarrierstotoadmovement.
Developadensityestimationfortoadsacrossvarioushabitatstoinformthestrategicdeploymentoftoadeliminationmethods.
Develop/confirmhumaneeuthanasiatechniques.
Develop/confirm sensitivity of detection techniques including acoustic detection,
trackingtunnelsandenvironmentalDNA.
Confirmation of detection and removal techniques including hand removal; barrier
fencing and pitfall traps; citric acid/sucrose spray; acoustic location; tadpole traps;
herbicide; egg collection; refuse management; toad detector dogs; capping or
treatmentofwaterbodiesandtoadtraps.Thesepotentialmethodsofdetectionand
eradicationwillrequireinitialtrialstoconfirmtheirefficacyforuseinanAsiantoad
eradicationprogramme.
Regardless of whether the eradication proceeds or not, it is recommended that biosecurity
measures are put in place to prevent further incursions and a public awareness programme
establishedtoeducateMadagascanresidentsaboutthetoads,theirnegativeenvironmental
influenceandassociatedhealthriskstohumans(toadpoisoningisknowntobefatalbutneverthelessassociatedsicknessesareextremelyunpleasantandcostlyifhospitalized).
Howtoproceed:
Decideonstrategicoption(s)–iferadicationisdecided:
1. Identifyparticipatingagenciesandinstituteproject.
2. Securephaseonefunding:testeradicationmethodsandevaluateoperation.
3. Initiaterequiredbiosecurityandeducationprograms.
4. Carryouttheprescribedexperimentaltrialsforevaluationoferadicationmethods.
5. Reassessfeasibilityandcosts.
6. Securephasetwofundingtoexecuteapprovederadicationprogramme.
7. Createacomprehensiveplancoveringallaspectsofproposalandapprovedworkingplan:projectgovernanceanddecisionmaking;methodsandprioritiesforremoval;publicengagement;
research and adaptive management; procurement and recruitment; training and development.
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INTRODUCTION
Thisdocumentconsidersthefeasibilityoferadicatingarecentlyestablishedpopulationof
Asiantoads(Duttophrynusmelanostictus)fromMadagascar.
Tobesuccessfulaneradicationprogrammustmeetsevenessentialcriteria:
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•
•
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Technical feasibility: Technique(s) to be used at the project site are able to remove
allindividualsofthetargetpopulation(s).
Sustainability:Preventingre-invasionbytargetspeciescanbeachieved.
Socially acceptable: The project has full support from the community and other key
stakeholders.
Politicallyandlegallyacceptable:Allrequiredpermitsandconsentssecured.
Environmentallyacceptable:Environmentalimpactsoftheeradicationaremanageableandacceptable.
Capacity:Alldeterminedskills,resourcesandequipmentcanbeacquired.
Affordability:Therequiredfundingisavailableandsecured.
Toachieveeradicationyouneedtobeablekillthetargetspeciesfasterthanitcanbreedatall
densities.Tobeabletoachievethisrequirestheabilitytodetectthematlowdensitiesinall
habitats.
ThisreportconsidersthecurrentinvasiveAsiantoadsituationinMadagascar,asofJune
2015,againstthesestatedcriterialisted.Itsaimistostatewhatisneededinordertoachieve
eradication,whatlimitationsstandinthewayofthatobjective,andwhatneedstobedonetosurmountthoselimitations.
Theconceptsandpracticeofspecieseradicationcanbecomplex.Itiscriticalthatreaders
of this report are familiar with the basic conceptual differences between “pest control”
and“pesteradication,”asthesetwoobjectiveshaveverydifferentgoalsrequiringequally
different strategic approaches (Table 1.). There is growing data supporting the present
thinkinginthisreportbutmanyofthefundamentalsoferadicationhavebeenwellunderstoodformorethantwodecades(BomfordandO’Brian1995).
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Table1.Comparisonoferadicationversusongoingcontrol.
Projecttarget
CONTROL
Tomaintaintargetspeciespopulationtoanagreedlevelwhereimpactsaretolerable.
Strategy&tactics
Focusonsitesofhighestvalueor
wherebenefitsofcontrolexceed
costsofcontrol.
Focusonsustainabilityofaction–
socially,financiallyandtechnically.
Monitorbenefits,costsandimpacts.
Impactsonnon-targetspeciesand
humanswillbeongoingrelativeto
theagreedlevelofcontrol.Avery
highlevelofcontrolisrequiredto
gainameaningfullevelofbenefit.
Internalbiosecuritystillrequiredto
preventtheexpansionoftheincursionarea.
ControlfortheAsiantoadisunlikely
tobepossibleonalargescalemeaninglimitedhighvaluesiteorspecies
leadprotectionislikely.
Ifforanyreasonfundingorsupport
ceasescontrolwillstopandbenefits
rapidlylost.
Ongoingriskofexpansionofincursionareaincreasingthecostsofa
controlprogrammeormakingitunfeasible.
Ongoingimpacts
Biosecurity
Risks
FinancialCost
Note:actualcostsfor
bothcontroland
eradicationcanonly
becalculatedonce
techniquesandscale
ofcontrolareagreed
upon.
Benefits
ERADICATION
Toeliminatethetargetspecies
entirely,thereforerequiringno
ongoingmanagementexceptfor
externalbiosecurityattheborder.
Preventspread,targeteveryindividual,andpreventreinvasion.
Focusonmeetingeradicationcriteriathroughskilleddeployment
andadaptationofmethodsand
appropriatescaleofeffort.
Nonexistent–oncetoadsareremovedtherearenoongoingimpacts.
Initiallylowerthaneradicationbut
ongoinginperpetuitysototalcost
likelytosoonexceederadication
costs.Thisstrategymakeson-going,
albeitreducedeconomicandsocial
impactsinevitable.
Externalbiosecurityrequired;
(whichwouldcovermanyspecies)
topreventreinvasion.
Thereisaninherentriskoffailure
inanyeradication.Henceitisimportanttoadequatelytestthe
proposedtechniquesbeforecommittingtoanyeradicationprogramme.Inadequatefunding
meansthattheprojectcouldnot
befullyimplementedandthereforeisverylikelytofail.
Failuretoadequatelyimprove
borderbiosecuritymightmeanrisk
ofreinvasion.
Initially,largeone-timecostbutif
eradicationsuccessful,nocontinuedlargecostsexceptbiosecurity;
long-termeconomicandsocial
costsofpestspeciesareameliorated.
Reducedinitialcosts(butvarygreaterovertime).
Targetspeciesremoved,noongoingcostsexceptbiosecurity;no
ongoingimpacts.
Further, differences between pest control and pest eradication it is important to acknowledge the
differentcostmodels.Pestcontrolfocusesonidentifyingcosteffectivecontrolmethodscapableof
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targetingthelargestproportionofthepestpopulation(s).Incontrast,eradicationbeginswithtools
thattargetthemajorityofthepopulationinthemostcosteffectivemannernotcompromisingthe
efficacyofsubsequentmethodsandusuallyreservesthemostsensitivetoolsfortargetinghardto
capture individuals that remain. As such, the cost profile of multi-method eradications are one
wherethecostofremovingtheinitialmajorityisequaltoorlessthanthecostofremovingthe
finalfewindividuals.
The Asian toad, Duttaphrynus melanostictus (also known as the Asian common toad, Blackspectacledtoad,Asianblack-spottedtoad,Commonsundatoad,andJavanesetoad,Fig.1a,1band
1c) is widespread throughout Asia, occurring from Pakistan through central Asia and
across southern China, including Taiwan, extending across South Asia, covering Sri Lanka,
the Malay Archipelago and Indonesia incorporating the island of Borneo and associated
island groups. Across this range the species is known to occur from sea level to 1,800 m
and is generally associated with disturbed and agricultural habitats (van Dijik et al. 2004).
Asian toads do occur in undisturbed habitats, including rainforest (southern Sri Lanka,
eastern central Thailand, Sabah, Northern Borneo, Reardon, pers. obs.), but apparently at
low densities. The species is listed as “Least Concern” under the IUCN Red List of Threatened Species. The Queensland State Government (Australia) lists the Asian toad as a significantpestintheirpestriskassessment(Pestanimalriskassessment2010).
Asiantoadsareanintroducedspeciesinanumberofcountries,includingwesternregions
of New Guinea and theIndonesianislandsofBali,Sulawesi,TimorandAmbonbutnoinvestment
hasbeenmadetomeasuretheirimpacts.Across its range the species appears to be regarded
asbenign,althoughithasbeennotedasanuisanceinSriLankabecauseofitsabundance
inwatertanksusedforlaundryandcookingwaterinvillages.
The Asian toad females can reach 200 mm in snout-to-vent length with typical dry warty
skin and is a crepuscular predator of invertebrates and small vertebrates captured largely
byambushpredation.
Asiantoadreproductionbeginbymalescallingtoattractfemalesfrominoraroundbreeding pools where toads later engage in amplexus and end in production of strings of eggs
layed by the female. Females are able to produce many thousands of eggs per season,
whichhatchintotadpolesmetamorphosingintotoadletsthesameseason.
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TheAsianToadinMadagascar
The Asian toad was anecdotally noted inMadagascar as early as 2010 (Moore et al. 2015)
butnotreporteduntil2014(Arnaud2014).HowtheoriginalfounderanimalsgottoMadagascarhasnotyetbeenconfirmed,howevertheirpathwaywasalmostcertainlyviafreight
and/or containers brought to the site of the incursion from South East Asia. TheMalagasy
populationofD.melanostictuswasstudiedfromafragmentofmitochondrialND3gene,basedon
11specimensprovidedbyR.D.Randrianiaina,twospecimensprovidedbyR.DolchandF.Glawand
onespecimenprovidedbyA.P.Raselimanana.Allspecimenshadanidenticalhaplotype,suggesting
anoriginfromthesamesourcepopulation(M.Vences,unpub.data).Phylogenetically,comparedto
arange-widedataset,thishaplotypebelongstoalineageoccurringinChina,Vietnam,Thailandand
Cambodia, and the haplotype is identical to one found in Cambodia likely to be representative of
Asian toad populations from Thailand, Cambodia and Vietnam (G. Wogan and B. Stuart, pers.
comm.)—thisstronglysuggestsanintroductionoriginatingfromthisgeographicalregion.Researchis
on-goingintotheflowofmaterialsviafreightfromSouthEastAsiaintotheareaoftheMadagascan
incursion of Asian toads. Multiply companies import shipping containers into the region making it
difficulttopinpointtheexactoriginofintroduction.Itisnoteworthythattheincursiondoesnot
appeartoextendtotheTamataveportthoughnothavingdirectaccesstothisporthasnot
allowedustoverifythisinformation.
From our visit it appears there are negligible biosecurity measures in place at either the
port of Tamatave or at the Ambatovy mine. While we did not inspect any other major
businesses in the region it is likely lack of biosecurity measures is widespread among the
businesscommunity.Futureinvasionsarepossiblewithoutimprovedbiosecuritymeasures
inplace.
Wehavebeenabletoidentifyanumberofimporterfacilitieswithintheincursionarea,all
of which have, in theory, the potential to have brought the toads to Madagascar from
SouthEastAsia.Towardsthecoreoftheincursionareaare:
1. Malgapro – Importer of products such as rice, sugar and oil from China, Dubai, IndiaandPakistan.
2. Ambatovy–TheAmbatovyplantsitewasconstructedwithconsiderableassistancefrom
theSrirachaConstructionPublicCompany,basedinThailandandworkingwiththeAmbatovyprojectsince2008.Itislikelythatduringplantconstruction,considerablequantitiesof
materials,suppliesandequipmentwereshippedfromThailandbySrirachaConstruction
(http://www.sricha.com/eng/current_projects.html).
3. COLAS–Construction,involvedinImportationofunspecifiedgoods/materials.
Towardstheperipheryoftheincursionislocated:
4. SolCimentCallidu–Importersofunspecifiedgoods/materials.
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Further research is necessary to investigate the timing and quantities of freight imported
by these companies and the geographic origins of freight shipments. With these data, it
maybepossibletoidentifythemostlikelypathwayofinvasion.Identifyingthispathwayis
a vital element of learning and ensuring biosecurity measures are appropriately improved
topreventreinvasion.
Thereislittleinformationavailableonthespecificlikelyimpactsofthetoadsontheecology of Madagascar. However, there is a significant literature describing the effects of the
Cane toad, Rhinellamarina,(Fig.2.)as it has spread across Australia (Burnett 1997). Due to
the general ecological similarity between the two toads, both having cosmopolitan diets
andhabitatrequirements,itisreasonabletoanticipatesimilarecologicalimpactsfromthe
Asian toad invasion in Madagascar. Like the Cane toad, the Asian toad is potentially poisonous to naive predators and is likely to negatively impact many native and endemic
predators, including snakes and mammals.Madagascar has no native toads but does have
a globally significant, rich and vulnerable endemic herpetofauna. Research and climate
modellinghasinvestigatedthepotentialecologicalreachoftheAsiantoadinMadagascar
and a recent publication illustrates that the Asian toad has the potential to establish
acrossthemajorityofthecountry(Pearson2015).
A high profile concern for the Asian toad incursion in Madagascar is the potential for lethal poisoning from the consumption of toads and toad tissue by humans. This along with
other details of the toads potential impacts are given a more detailed description in section3.3butitshouldbeclearlynotedthatmultiplecasesofpoisoning,includingdeathsin
childrenarereportedfromLaos,whichiswithintheAsiantoadsnaturalrange,andwithin
communities with a high level of awareness of the toxicity of Asian toads (Keomany et al.
2007).
ItistooearlytopredictwhatformtheeconomicconsequencesoftheAsiantoadinMadagascar will take but they may include negative impacts on agriculture, tourism (through
loss of biodiversity) and World Trade Organisation restrictions on exports from Madagascarduetothe risk of transporting toadsto newlocations. Such sanctions are a possibility
iftheAsiantoadisdeemedtobeanecologicalandeconomicthreattotradepartnersasa
resultofitsimpactsinMadagascar.
Soon after the identification of the toads in Tamatave their potential ecological impact
was recognised by scientists and the desirability of eradicating them promoted by the
Malagasy government, non governmental agencies (NGO) and individuals. International
expertsworkedwithNGO’s,includingtheMadagascarFaunaandFloraGroupandAssociation Mitsinjo and the Madagascan Government to gather support for an Asian toad eradicationprogrammeandseekfundingforaformalstudyofitsfeasibility.
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The Asian toad incursion has raised serious concerns among the conservation community.
Not only are direct impacts on native biodiversity feared but there is concern the toad
might vector amphibian diseases such as Ranavirus. However, the science community actively engaged with amphibian issues in Madagascar lack experience and skills in pest
eradication. As such, three of the authors, who have research and applied experience in
pest-animal eradication were contacted and requested to lead the study. Mr. Peter
McClelland has extensive expertise and experience in eradications globally, including New
Zealand, Australia, the USA and the Pacific. Although primarily having worked on rodents,
the operational parameters and processes for eradication programs apply across taxa.
Doctor James Reardon is a herpetologist with operational experience in eradication programmes targeting reptiles and amphibians. He is currently working on two invasive herpetofaunal eradication programmes in New Zealand. It was decided that in combination
theyprovidedtherequiredexpertiseonamphibianspecificapproachestoeradicationand
its requirements. The feasibility study is also supported by Dr. Fred Kraus, who is a global
authority on invasive herpetofauna, and was the instigator of the eradication feasibility
study. Our team includes Dr. Christopher Raxworthy, who first identified this species of
invasive toad in Madagascar, and who has 30 years of herpetological experience working
in Madagascar, and Christian Randrianantoandro,whoisanexperiencedherpetologistinMadagascar,andhasbeendesignatedtheinterimnationalcoordinatorfortoaderadicationefforts.
Localpopulationperspectives
During the feasibility report field visit the authors made an effort to gather opinions and
information on the Asian toad from members of local communities within the incursion
area. Little additional knowledge was gathered beyond that of Moore et al. (2015). There
was a common opinion in Tamatave/Toamasina among local communities surveyed that
the toads arrived with the establishment of nickel-mining and processing facilities. In this
area the toads were referred to as the 'Dynatec' toad, Ambatovy's predecessor. No evidence was presented for this belief other than apparent timing of the toads first detection,whichoccurredatthesametimetheplantsitewasbeingconstructed.
Theauthorsareawareofrecentreportsofa“spinytoad”likenedtotheAsiantoadknown
inToamasina,beingreportedfromMahanoro,lessthan200kmtothesouthofthecurrent
incursion. The report by Michella Raharisoa is difficult to verify without local inspection
and includes implausible claims of cow death caused by the toads. However, given the direct road connection to this site with the Asian toad incursion a satellite incursion is entirely plausible and verifying this report is now among the priorities of the programme
(http://www.lexpressmada.com/blog/information-live/biodiversite-le-crapaud-epineux-debarque-amahanoro-12315/).
Eradicationperspectives
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Therehasbeenlimitedinvestmentinamphibianeradicationsglobally,withonlythreesuccessful toad eradications recorded: 1) a small-scale operation in Europe which utilised
techniques that are not suitable for the Asian toad incursion in Madagascar (shooting); 2)
the removal of a small incursion on an American military base in Okinawa, Japan; and 3)
theeradicationofCanetoadsfromaverysmall(6.5ha)islandinBermuda(Wingate2011).
The difficulties with even controlling the spread of Cane toads in Australia and reducing
their rate of spread highlight the likely problems to be faced in undertaking a toad eradicationinMadagascar.
OptionsforthemanagementoftoadsonMadagascarare:
1. Donothing.ThiswouldhaveimplicationsforMadagascar’sbiodiversityandeconomyaswell
asthehealthandwell-beingofMalagasycitizens.
2. Developandputinplaceacontrolprogrammetopreventorlimitthespreadofthespecies
eitherindefinitelyoruntileradicationtechniquescanbedeveloped.Thisisahigh-riskstrategy due to the difficulty in maintaining a non-physical boundary i.e., not fenced. Containmentcostswillquicklygrowtosurpasseradicationcosts.Identifyspeciesathighriskofextinctionfromtoadimpactsandundertakeprotectioneitherinsituorincaptivity(species-led
program). The resources to achieve this are large and the management outcomes likely to
befinanciallyandlogisticallyunsustainable.Further,notallimpactedspeciesarelikelytobe
identifiedapriori,meaningthatsomewillbeleftunprotecteduntiltoolate.
3. Identify high-value sites containing a range of species of concern, and undertake work to
protectthosesites(site-ledprogram).Again,itisquestionablesuchlong-termprogrammes,
evenifpracticable,couldbefinanciallysustainedinthelong-term.
4. Undertakeaneradicationandputinplaceanassociatedbiosecurityprogramtopreventreinvasion.Althoughthiswouldbeexpensiveintheshort-term,itwouldbefarcheaperinthe
medium to long-term than any serious ongoing control programme, which would need to
existinperpetuity.
Unless physical barriers are possible 2, 3 and 4 all require the development of techniques for the
detectionandremovaloftoadsatlowdensity,whicharealsocrucialfortheeradicationoption.
Eradication is the preferred solution to any invasive organism incursion, but not always
feasible.Assuch,eradicatingtheAsiantoadfromtheTamataveregionhasbeenadefault
positionoflocalauthorities,environmentalNGOsandtheAmbatovyMiningCompany,although the author’s encountered serious confusion over the technical difference between
“eradication”and“control.”Unfortunately,itseemsthatwhiletoadswereapparentlyobserved by locals at least as early as 2011 and possibly earlier, the issue only became recognisedbyboththemineandNGOsandreportedtogovernmentin2014—bywhichpoint
preliminarysearcheshaveshowntheextentofthetoadincursiontobeatleast98km 2 .
Given the technical and logistical challenges involved in undertaking a toad eradication in
Madagascar,itwasagreedthefirststepwastoundertakeaneradicationfeasibilitystudy.
Thisisinternationallyrecognisedasabestpracticeforeradicationsallowingadecisionto
be made with confidence and with good knowledge of the costs, benefits and risks involved.
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It is important to note that this feasibility study is designed to consider all the requirements for undertaking an eradication and then advise on the overall feasibility of Asian
toad species eradication from Madagascar. It covers the known constraints and requirements of undertaking an eradication programme and highlights where additional information needs to be compiled. It is NOT an eradication plan, which would require significant additional work on confirming eradication techniques, application strategies, project
governanceandmanagementstructures,costsandatimeline.
This report is designed to be used to decide whether eradication is feasible and practical
topursuebytherelevantMalagasygovernmentagenciesandNGOsholdingresponsibility.
Ifitisdeemedworthwhiletoproceedwitheradication,thisdocumentcanbeusedtohelp
developanappropriatestrategy,raisesupportandfundingthroughadiscussionofpotentialtoolsasbrieflydescribedinAppendixIII.
Itisimportanttorecognisethedifferencebetween“control,”wheretheaimissimplytoreducethe
populationtoadesiredlevel,and“eradication,”whereeveryindividualofthetargetspecieshasto
beremoved.Itisalsorecognisedreducingthepopulationbyeven99%istheeasypartofanyeradicationproject.Thedifficultpartistoeradicatetheremaining1%andthenconfirmnoneareleft.Indeed,itshouldbeexpectedthecostmodeloferadicationsusuallydemonstrateafargreaterproportionofaneradicationbudgetisspentdetectingandremovingthefinal1%thanspentremovingthe
initial99%—thiscannotbestressedenough,especiallyforthosewithoutexperienceinpesteradications.
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1. GOAL,OBJECTIVESandOUTCOMES
2.1
Goal
ToexaminethefeasibilityofcompleteeradicationofAsiantoadsfromMadagascar—includingidentifyingtechniquessuitableforlocatingandremovingtoadsandwhatisrequiredtodeterminetheir
efficacy.Ifitisdecidedtoattempttheeradication,theproject(AsianToadEradicationfromMadagascar)willaimtoeradicatethetargetspeciesD.melanostictusfromtheislandcountryofMadagascar,thuseliminatingexistingandfutureimpactofthisspeciesontheislandsecologyandeconomy.
Successfuleradicationwillrequireseveralseparatebutinterlinkedtasks:
•
•
•
•
•
•
•
•
•
Confirm and maintain required political and public support for the project for the
durationoftheoperation.
Setupappropriateoperationalandfinancialmanagementsystemsandgovernance.
Delineate current extent of invasion, including identifying the location and size of any
possible satellite populations; this will need to be continually confirmed and updated
duringtheproject.
Prevent establishment of satellite populations through transport of goods from the
currentincursionarea.
Establishsuitablebiosecuritysystemsatlikelyportsofentryandhighlighttheneedfor
such mechanisms to be future industrial investments in Madagascar; to prevent toads
(andotherbiosecuritythreats)reinvading—thiswillhaveadditionalbenefitsinkeeping
outotherpotentialinvasives.
Confirm methods to be used for the eradication. As there is no current “one hit”
technique comparable to a single aerial bait drop for rodents, eradication would likely
requireuseofmultipletechniques.Itiscrucialthatnotonlythetechniquestobeused
butalsotheorderinwhichtheyareusedbeconsidered.
Confirm suitability and accuracy of detection methods to both establish the extent of
theincursionandtogivetherequiredlevelofconfidenceinknowingtherearenotoads
leftinthetreatedarea.
Confirm funding for the project. The two stage approach involving a testing of
methodologies,aheadoffull-scaleeradication,enablessomefundingflexibility.
Begineradicationasearlyaspossiblesoastominimisetheareatobetreatedandthe
costsinvolved.
A secondary issue not dealt with in this report, but will need consideration, is what response
could/shouldbeundertakeniferadicationisdeemedinfeasible.
Eradicationistheonlyobjectivethathasadefinitiveendpoint.Allotherresponseswouldneedtobe
carriedoutinperpetuity.
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Theauthors’believe/meaningfulcontroltocontainthetoadtoitscurrentrangecannotbeachieved
consideringtradeandinfrastructurewithinMadagascar.Itwouldbeeasytokillthousandsoftoads,
but at best this will only slow the rate of spread, as most killed animals would come from highdensityareasduetothedifficultyinlocatingtoadsatlowdensities.
2.2
ObjectivesandOutcomes
Thisdocumentrepresentsapreliminaryfeasibilitystudyfortoaderadication.Theobjectivesofan
eradicationprojectandtheoutcomesthatwouldresultare:
Objectives
Objective1.Primeobjective
• RemovalofallinvasivetoadsfromMadagascar–PHASE2.
Outcomes
Outcome 1.1. Toads removed from Madagascar.
Outcome1.2.Nativespeciesprotected.
Outcome1.3.Associatedsocial/human/economicimpactsremoved,and
benefitsachieved.
Objective2.
Outcome 2.1. Options for methodologies
• Developandtestmethodologies
investigated.
requiredtoeradicatetoads.–PHASE1. Outcome2.2.Methodstested.
Objective3.
Outcome3.1.Fieldtrials(large-scale)under• Feasibility study updated as new takentoconfirmefficacyofselectedtechniques.
informationbecomesavailable.
Outcome 3.2. Feasibility agreed upon or
discounted.
Objective4.
Outcome 4.1. Biosecurity plan developed
•Biosecurity implemented to prevent rein- andimplemented.
vasion.
Outcome4.2.Reinvasionoftoadsprevented
(iferadicationissuccessful).
Outcome4.3.Preventionofestablishmentof
additionalinvasivespecies.
As there are no confirmed techniques for eradicating toads on the scale required in
Madagascar, it will be important to consider the feasibility of all possible techniques and
then test the efficacy of the most promising methods; costs would then need to be
determined.Itisprobablethatnoonetechniquewillbesuitableandmultipletoolswillbe
required, e.g., manual captures, chemical control and ability to target different life history
stages.
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Itiseasytoremovelargenumbersoftoads,butthosenumbersmustexceedreplacementratesfor
eradicationtobesuccessful.Giventhehighfecundityoftoads,thiswillbedifficulttoachieve.Further,itisthelastfewindividualtoadsthemostdifficulttodetectandremove,butwithouttheircaptureallpreviouseffortwouldbewastediftheysurviveandreproduce.Thelastremainingindividuals
ineradicationprogrammesoftenexhibitaberrantbehaviours,sometimestheresultofconditioning
by previous eradication methods. While toads are less likely to exhibit learned behaviours than
mammals (rodents and ungulates have been known to adopt very unusual behaviours following
eradicationefforts)thoselasttoadsmaysurvivebecauseofunusualbehaviourssuchasextremely
conservative movement patterns, or use of novel refugia or choices of breeding sites, non-calling
breedingmales.Hence,techniquesadoptedforatoaderadicationonthescalerequiredwillneedto
beappliedstrategically.
Acrucialcomponentofanyeradicationisbeingabletoensuretheriskofreinvasionismanageable.
Todothiswillrequirethedevelopmentandimplementationofsuitableborderbiosecuritysystems.
Appropriatebiosecuritywouldideallybeinplacepriortocommencingtheeradicationinorderfor
testingbutduetotheurgencytocommencetheeradicationquicklytheywouldneedtobeimplemented in conjunction with the eradication. Because of the multi-agency nature of biosecurity,
working through multiple government agencies, national and regional governments, port companies, transport companies and major industries, this may be unrealistic. Implementing suitable biosecuritymeasureswillnotonlyminimisechancesofreinvasionbytoadsbutalsobyotherunwantedspecies.Eveniftoadsarenoteradicated,therearemajorbenefitstoimplementingbiosecurityto
preventotherinvasiveshavingmajorecological,economicand/orhumanhealthimpacts.Thisobjectivecanbecompletedregardlessofwhethertoaderadicationproceedsornotandislikelytohave
significantenvironmentalandeconomicbenefitstothecountry.
Aseparatebutrelatedissueisoutgoingbiosecurity.Whilethecurrentincursionpersists,thereisa
risktotradepartnersoftoadsbeingtransportedingoodsandmaterials(mechanicalmachineryand
materials).Thetoadshaveshownhowtheycanbesuccessfullytransportedlongdistances(thisincursion),andthereisarealriskoftransferringtoadstoanyportthatisservicedfromMadagascar,
andespeciallyfromTamatave.ThisincludesReunionandMauritius,butalsomostotherportsregularlyreceivingcargofromorviaMadagascar.
Inadditiontotestingeradicationtechniques,itwillbeimportanttoconfirmasuitabletechniquefor
detectingtoadsatlowdensitieswithaveryhighlevelofconfidence.Thisisforbothdelineatingthe
areatobetreatedandtoconfirmthesuccessoferadication.Asignificantportionofthecostofthe
projectislikelytogointothelatter,asifeventwotoadsarelefttogether,thepopulationislikelyto
returntopreviousdensitieswithinafewyears.
Suitabletechniqueswillneedtobetestedatascalethattrulyreflectsthefieldsituationi.e.,coveringthediverserangeofhabitats,landownership,etc.foundintheincursionarea.
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Fig.1c.Asiantoadfemale,Sabah,MalaysianBorneo.Photo:J.Reardon.
NFig.2.Canetoad,Rhinellamarina,PapuaNewGuinea.Photo:J.Reardon.
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3 THESITE
Thetreatmentsiteforanyeradicationeffortcanbeconsideredinthreeways:
-
The confirmed incursion site. This includes the port city of Toamasian/Tamatave and the
adjacentAmbatovynickelprocessingoperationsandextensiveurbanandagriculturalareas
includinganumberofwaterways,andisatleast98km2.
- The probable incursion area. This is almost certain to be significantly larger than the
confirmed 98 km2 site. Toad populations will constantly increase while an eradication is
being considered and planned. It will require further survey effort to delimit the extent of
population(s),includingsearchforadditionalsatellitepopulations.
- Thepotentialincursionarea.ThiscoversmostofMadagascar(587,041km2),basedonthe
transport of goods from Tamatave around the country with no biosecurity in place and
minimalecologicalbarrierstospread.
The confirmed site of the Asian toad incursion covers a broad range of habitats found throughout
theprobableandpossibleincursionsitesincluding:
1. Urbanareas,includinglowersocio-economicurbanandruralcommunities,i.e.,closeliving
andlimitedfacilities.Includedareareasofhighersocio-economiccommunitieshavinglarge
enclosedhouses.
Fig.3.DrainagechannelincentralTamatave.Photo:J.Reardon.
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Fig.4.DrainagesumpfilledwithrefuseandoccupiedbyAsiantoadsincentralTamatave.
Photo:J.Reardon.
Fig.5.PotentialtoadrefugiainwellmaintainedurbancentralTamatave.Photo:J.Reardon.
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Fig.6.Evenwellmaintainedpropertiessuchasthishavemanypossiblerefugia,suchasunderhouses(CentralTamatave).Photo:J.Reardon.
2. Industrialareas,includingtheextensiveheavyindustrialcompoundsoftheAmbatovymine.
Fig.7.AmbatovyMinenickelrefineryisthelargestindustrialareawithinthecurrentdistributionrangeoftheAsiantoadincursion.Photo:Ambatovy.com.
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3. Agriculturalareas.ThecityofTamataveissurroundedbyextensiveagriculturalareasincludingricepaddiesandmarketgardens.
Fig.8.Adrainage“sump”inanareaofextensivericepaddy.Photo:J.Reardon.
Fig.9.Floodedricepaddiesadjoiningvillage.Photo:J.Reardon.
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Fig.10.Extensivericepaddiesadjoiningregeneratingexoticforest.Photo:J.Reardon.
Fig.11.AsiantoadmaleinhumanrefuseatruralfringesofTamatave.PhotoJ.Reardon.
4. Secondaryandregeneratingvegetation.Areasoutofurbanandagriculturaldevelopmentin
theincursionareaappeartobedominatedbyseralwoodycommunitiespredominatewith
exoticspeciessuchasEucalyptus,MimosaandTamarix.Nosignificantnaturalhabitatareas
appeartoexistwithintheincursionarea.
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Fig.12.Mixedlargelyexoticregeneratingforestwithinincursionarea.Photo:JReardon.
AllofthesehabitattypesappeartocontainAsiantoads.Nationally,itisdifficulttoidentifyecological
barrierstodispersalandcolonisation.Thedryareasofthewestandsouthmaybelesssuitedtothe
Asiantoads,butthepresenceofAsiantoadsinthedrycentralnorthernregionsofSriLankacertainly
highlights the fact that these toads are highly adaptable. The potential role of altitude in limiting
toadsurvivalisalsounclearastoadsareknowntooccurupto1,800mabovesealevel(vanDijket
al.2004).Speciesdistributionmodellingresults,basedonthenativedistribution,indicatethatAsian
toadswilloccupyalmostallofMadagascar(Pearson,2014).
Theproportionalrepresentationofthesehabitatshasnotbeenaccuratelycharacterisedfortheincursionareabeyondrecognisingallarewellrepresented.Amongthetasksforadvancingthisproject
istheneedforGISskillstobeappliedtoaccuratelydescribehabitatandland-usemosaics.Survey
efforthastodatefocusedondelimitingtheincursionarearatherthancloselyexaminingoccupancy
ordensityacrossthatarea(Fig.13.)
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N
Port
Ambatovyprocessing
plant
Asiantoadincursionarea
IvondroRiver
Scale
2km
Fig.13.AmapoftheknownincursionareaasofFebruary2015withgreenmarkersindicatingsites
surveyedwheretoadswerenotdetectedandredmarkersindicatingtoadsdetected;redpolygon—
theminimumpresumedincursionarea(98km2).Note,anadditional12negativesurveylocationssit
outsideofmap(adaptedfromMooreetal.2015).
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Civilsocietyintheincursionarea
Madagascar has centralised government based in the capital of Anatanarivo (Tana), approximately
320kmfromtheconfirmedincursionarea.AtsinanaRegionalgovernmentisbasedinTamatave,and
villagesareoverseenbyanelectedVillagePresident.
The current incursion area includes a large portion of Tamatave city and is likely to incorporate in
excess of half a million people in urban and rural areas. Land ownership covers the full spectrum
fromprivateresidential,corporateandgovernment-ownedlands.
Mostlandisutilisedforagricultureandfoodgathering.Thereislittleforestremainingintheincursionarea,althoughmanyofthehillareasareinearlystagesofregeneratingforest,oftenwithintroduced species (e.g., Eucalyptus) dominating but appear to be heavily disturbed by fire (Fig. 11)—
these are often used for charcoal production. Flat lowland areas are predominately used for rice
production.Mostwaterwaysarecommerciallyharvestedforfish.
AccesstoTamataveisgood,withamajorport,airportandahigh-qualityroadslinkingittothecapital and the rest of the country. Access within the incursion site is highly variable, ranging from a
comprehensiveroadandalleynetworkintheurbanareastolimitedroadaccessinruralzones.As
the toads have moved south and crossed the Ivondro River they have entered an area where the
primaryhumanaccessisalongarailwaylinehavingnoadjacentroadsorvillages.
Physicalaccessforanintensiveeradicationproject,orevenforthedelineationsurvey,islikelytobe
difficultbecauseofthelackofroadaccesstosomeareas.
There is a defined wet season, November to April, which is likely to be the predominant breeding
periodfortoads,buttherearesuitablewaterbodiespresentthroughouttheincursionareawhich
couldpermitbreedingallyearlong.TheAsiantoad’sreproductivepatternsareyettobedescribed
inMadagascarbutbasedonobservationstodate,andstudieselsewhere,malescongregatearound
watersourcesandcalltoattractfemaleswhothenlayeggsinthewater.Mostwatersourcescanbe
utilisedincludingbrackishwaterandephemeralpoolsprovidedtheylastlongenoughfortheeggsto
hatchandtadpolestometamorphoseintotoadlets.
3.2TargetSpecies
3.2.1GENERALDESCRIPTION
TheAsiantoadisalargeandrobustmemberoftheBufonidaereportedlyreaching200mmsnoutto
ventlengthinfemaleswithanaveragesizeof85mmreportedbyMercy(1999);malesareusually
smaller(vanDijketal.2004;Mercy1999).Adultcolourationisvariable(seeFigs.1a,bandc)andcan
rangefromplainbrickred,creamtoalmostblack.Themostcommoncolourpatternispaleyellowbrownmarkedboldlywithdarkorreddishbrownstreaksandspots.Theirdorsalsurfaceandlimbs
arecoveredwithwartsvaryinginsize,usuallywithaspinousprotrusionandoftenpigmentedblack.
Males have a subgular vocal sac coloured yellow-orange in breeding males which also exhibit the
inner side of the first and second fingers and having nuptial pads. Juveniles apparently possess a
blackbandaroundthethroatrunningbetweenthechinandbreastandhavenowarts,havingavery
smallTympanumaccordingtoMercy(1999).Thetoadshavemanyattributesmakingthemanideal
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invasivespecies–theyarephysicallyrobust,canliveinawiderangeofhabitatsandecotypes,highly
fecund(maylayupto40,000eggsperseason)andhavecosmopolitanbreedingtolerance.Theydo
requirewaterforbreeding,butitcanbestandingorslowflowing,ofwhichthereisnoshortagein
theincursionarea.
3.2.2REPRODUCTIONANDDEVELOPMENTALBIOLOGY
Breedingdependsonaccesstowater.Wherewaterisavailablebreedingwillpersistyearroundbut
inmoreseasonallydryhabitatsadistinctbreedingseasonisobservedwithmaximumreproductive
effortatthebeginningofthewetseason(Mercy1999).Thelunarcycleinfluencesovulation,which
occursinassociationwithafullmoon.Theovariescanmakeup30%ofthetotalbodyweightofthe
toadatthistime.Femaleslayalongstringofblackeggs,externallyfertilizedbythemale.Eggsare
enclosed in a thick mucus membrane and deposited usually on submerged vegetation. Breeding is
mostcommonlynotedinephemeralorvernalpool(s).MaleAsiancommontoadshaveacontinuous
spermatogenic cycle however a study in Taiwan showed there was a larger concentration of spermatophoresinthemaletoadduringaspecifictimeoftheyear(Huangetal.1997;Kahn2000;Mercy
1999;SaidapurandGirish2001).Malescongregateatbreedingsitesandcallfemales.Theircallcan
benotedassoundinglike“creo-o,o;cro-ro-ro-ro-ro-ro-ro”andintensecompetitionamongmalesfor
females means many males are often found clinging to a single female (Kahn 2000; Mercy 1999).
Thisbehaviourclearlyoffersanexcellentopportunitytotargettoadswhentheyarehighlydetectable,aggregatedandbreeding—anobviousadvantagetoaneradicationeffort.
FemaleAsiantoadscanproduceupto40,000eggsperseasonandthispotentialhasbeenconfirmed
inMadagascar(R.Danielle,pers.comm.)andeggshatchwithin24to28hours.Tadpolesaresmall
andblackusuallyaround15mminlengthandassociateingroups(Khan2000).Researchhasshown
thatAsiancommontoadtadpolesrearedwithsiblinggroupsgrowatahigherrateanddevelopfastercomparedtolarvaerearedinmixedgroups(SaidapurandGirish2001).AstudydonebyMogaliet
al(2011)illustratesthattadpolesofAsiantoadsemergeatdifferenttimesandsizesinthepresence
ofpredatorsandundersuchcircumstancestadpoleswilldecreaseinbodymassupto46%andmetamorphosiswillalsooccurearlier.
ThesedataarelargelydrawnfromworkwiththeAsiantoadinitsnativerangeandthereiscurrently
verylimitedinformationavailableonthebiologyandecologyoftheAsiantoadinMadagascar.
ThecurrentareaofincursioninMadagascarsuggeststheyareveryabledispersers,atleastindisturbed and urban habitats. Like all toads, the Asian toad has parotoid glands behind the eyes and
abovethetympanumoneithersideoftheneck.Theseglandsproducebufotoxins,whicharesteroid
lactonealkaloids,synthesisedtoactasarepellenttopredators.Itisthesetoxinsthatleadtomuch
oftheconcernthatinvasivetoadswillimpactnativepredatorspeciesevolutionarilynaivetotoads
aspreyitems.
LongevityhasbeenestimatedasanaverageoffouryearsinthewildandrecordsexistofAsiantoads
reaching10yearsofageincaptivity(Mercy1999;Khan2000).
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Fig. 14. Duttaphrynus melanostictus, Asian toad female in suburban drainage, Tamatave. Note the
melanic canthal, pre-orbital, supra-orbital, post-orbital, mandibular, maxilla and orbito-tympanic
ridgesthatthespecificnamemelanostictus,describes.Photo:J.Reardon.
Fig.15.ResearchstudentwithmaleandfemaleAsiantoadcapturedduringdayinthedry,open
vegetationpicturedinbackground.Photo:J.Reardon.
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3.2.3INCURSIONORIGINS,RANGE,DENSITYANDABUNDANCE
The presence/absence surveys carried out to date give a minimum incursion area of 98 km2 (Fig.
13.). However this is very much a minimum estimate as the survey techniques were conservative
(visualobservationoftoadsalongtransects),anditwouldbeeasytooverlooktoadsifnotinhigh
density.Duringtheinitialsurveysonlyonesurveywasundertakenateachsite;itwasnotpossibleto
checkforsatellitepopulationseitheralongwaterwaysortransportedbyhumansinrubbishorproduce.
Geneticworktoconfirmtheoriginalsourcelocationfortheinvasioniscurrentlybeingundertaken.
Thesesamplescouldbeusedasvoucherspecimensforanyfutureincursions.Iftoadsaredetected
after an eradication was deemed successful, genetics can determine if it was a new incursion or
whethertheeradicationattempthadfailed.
Preliminarysurveyshaveattemptedtomeasuretoaddensityinthreedifferentecotypes:urban,rural/agricultural and non-production forest habitat, which largely consists of regenerating exotic
woodyspeciesappearingtobedominatedbyEucalyptus.Ateachecotypethreesiteswereselected
(non-randomly) so nine sites were searched in total. On average, across these sites there are 5.8
toadsper100m2or580perhectarewithamaximumdensityof18toadsper100m2or1,800toads
perhectare.Thisestimatecontrastswithaquotedfigureof65toadsperhectarequotedbyAmbatovy (Mark Sitter, pers. comm. to IUCN ASG) for the area under their management. However it is
unclearifthisdensityestimatewasgeneratedpreorpostoftheon-goingeffortstoremovetoads,
assuchactionswillhavedensitydependenteffectsinfluencinganyestimateofdensity.
Athirdofthesites(3of9),didnotappeartohavetoadspresentandthesesiteswereallrural,nonproductionhabitat.Itisveryencouragingtoknowtoadabundanceissuperficiallylowerinthisecotypealthoughwemustremaincautiousastheincreasedstructuralcomplexitywillreducetoaddetection probabilities. Equally, the ecotype with the greatest apparent density of toads was urban
withanaverageof51toadper100m2.Thisfiguremaybeinfluencedbythemoresearchablenature
ofurbanhabitatandweshouldbemindfuloftheheterogeneityofhabitatsuitabilityinallecotypes.
Thesefiguresareofcourseonlylooselyindicativebeingderivedfromasmall,non-randomsampling
effortbutdidnotallowustounderstandthenumericalmagnitudeofthisincursion.Thesefigures
allowustoextrapolateanestimateoftoadnumberswithintheknownincursionarea.Ifweassume
thatonly2/3ofthe98km2areaisoccupiedbytoadsthenthereis65km2or6,500haofoccupied
habitat.Atanaverageof580toadsperhathatisapopulationof3.77milliontoads,notconsidering
tadpoles.
Theusefulnessofthisextrapolationistoemphasisethateveniferadicationmethodsmissonly0.01
ofthetoadpopulation,weareleftwith37,700toadsremaining.Suchanumberwouldbreedand
recruitataratethatwouldneutraliseanyeradicationeffortwithintwoorthreeseasons.
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Fig.16.TheAsiantoadteamdevelopingtechniquestoconductabriefevaluationoftoaddensities
acrossallpossibleecotypesranges.Photo:J.Reardon.
Fig.17.Leioheterodonmadagascariensis,theMadagascangianthognosesnake,potentiallypoisoned
byAsiantoads.Photo:AndrewRouth.
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3.3Impacts
3.3.1THREATSTOHUMANHEALTHANDWELLBEING
TheAsiantoadposesarealandlethalrisktohumanhealthinMadagascar.Itiswithsomesurprise
theauthorsdiscoveredthisspecies,ubiquitouswithinitsnativerangeisimplicatedasthecauseof
poisoning multiple humans and has been documented as the cause of death and cardiac arrest in
childrenwhohaveconsumedtoadtissue(Keomanyetal.2007).Itisalsosuprisinginthesestudiesis
the common knowledge among those communities suffering these cases of poisoning, that the
toadsarepoisonous.Wefeelthatthishealthriskiselevatedwhenconsideringthetoad’sestablishmentinanenvironmentsuchasMadagascarwherethereisanextensiveruralpopulationthatpartly
relyonhuntingandgatheringfortheirsourcesofproteinandwhoareentirelynaïvetothepoisonousnatureoftheAsiantoad.Further,astudy(Keomany2007)pointsthatanumberofotherrecords
intheliteratureconsidercasesofpoisoningafterconsumingtoadsortheireggs(Chernetal.1991;
Kuoetal.2007;Chietal.1998;YeiandDeng1993;Chengetal.2006;Janetal.1997).Together,this
bodyofliteraturesuggeststhehealthimpactsofAsiantoadsinMadagascarmaybesignificantand
lethaltohumansespeciallyincommunitiesfamiliarwiththeconsumptionoffrogsasaregularpart
ofthediet.
Anyreductioninthenumberoflargersnakes,refer3.3.2couldalsoleadtoasurgeinBlackrat(Rattus rattus) populations, leading to serious economic consequences such as loss of stored rice and
other food supplies, and damage to commercial goods and equipment as electrical wiring. In the
1990’s,theover-collectingofAcrantophissnakesfortheboaskintradeintheAmbato-Boenyregion
ofMadagascarreportedlyledtoadramaticincreaseinblackratpopulations,withseriouseconomic
consequences.ThiswasthesubjectofastudyfundedbyGTZ(C.J.Raxworthy,pers.comm.).
3.3.2THREATSTOMADAGASCARSFAUNAANDFLORA
TheimpactsthatAsiantoadswillhaveontheMadagascarfaunaandfloraarecurrentlyunknown.
Fullimpactsfromthetoadscannotbeknownwithoutdetailedstudieswhichwilltakeyearstocomplete.Althoughthisworkshouldbedone,thetimetakentoobtainthedatawouldallowtheinvasiontoexpandbeyondanyhopeoferadication.Consequently,managementdecisionsforthetoads
mustnecessarilybebasedonimpactsseenfromwhatisknownaboutecologicallysimilarspecies.In
this instance, we can derive reasonable estimates of likely impacts from what is known about impacts derived from the ecologically similarCane toad, Rhinella marina, in Australia. In both MadagascarandAustralia,largegeneralisttoadsadaptabletohuman-degradedenvironmentswereintroducedtoisolatedlandscapeswhosenativefaunawerehistoricallyunexposedtotoadsand,hence,
highlysusceptibletotheirnoveltoxins.BasedonimpactsseeninAustralia,thehightoaddensities
alreadyreportedinMadagascar,andthepredictedmassivespreadoftoadsintomostregionsofthe
island(seePearson2015),wecanexpectthatnegativeimpactswillbesubstantialandoccurinmany
habitatsandcommunities.
Themostobviousdirectthreatconcernspoisoningofnaïvepredators.ThistoohasbeenthegreatestimpactfromCanetoadsinAustralia.Largefrog-eatingendemicsnakesarelikelytobeespecially
vulnerable (e.g., Leioheterodon, Ithycyphus and Dromicodryas spp.). There have already been reported observations of snakes dying after eating toads in the Tamatave area (M. Moore, pers.
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comm.) now confirmed as Leioheterodon madagascariensis (Fig. 17). In the remaining native habitats, many other locally endemic smaller species of snakes will also be vulnerable if they feed on
toadlets or tadpoles—the reduction of snake populations would disrupt the food supply to other
predators(suchashawks).
Otherendemicgroupsthatfeedonfrogsarelikelytobevulnerable,includingTenrecs(Tenrec,Microgale spp.), carnivorous mammals such as the Fosa (Cryptoprocta ferox), and the endemic mongooses (Mungotictis spp.), Mouse lemurs (Microcebus spp.) and birds such as the spectacular endemicradiationsofMadagascargroundrollers(Brachypteraciassp.,Geobiastessp.,Uratelornissp.
and Atelornis spp.) and Vangas (Family: Vangidae). Many of these species represent an important
part of Madagascar’s charismatic biodiversity, helping drive the ecotourism industry. In addition,
toads are voracious feeders. Their high density is likely to reduce populations of ground-dwelling
invertebrates and small vertebrates, such as endemic frogs (Stumpffia spp. Gephyromantis spp.,
Mantidactylus spp.), skinks (Amphiglossus spp.) and chameleons (Brookesia spp.) due to predation
(Figs.18,19,20).Directcompetitionforfoodmayalsoaffectotherlargegrounddwellingendemic
amphibians such as Dyscophus, Scaphiophryne and Plethodontohyla genera, although this of less
certain.Alloftheseimpactsareexpectedtobegreatestinthemostdiverseandsensitivecommunities, which are located in the 10% area of surviving naturalhabitat in Madagascar. These negative
impacts are thus likely to affect most of the protected reserves and national parks in Madagascar
below1,800melevation.
Toads could also have more indirect, but potentially serious, impacts on invaded communities. In
particular,theymayalteranimalcommunitiesthroughservingasnutrientsinks,storingnutrientsin
their bodies that would normally be passed up the food chain by predator consumption. Because
nativepredatorswilleitherquicklydiefromtoadconsumptionorlearntoavoideatingthem,toads
willquicklybeavoidedasafoodsourceandendupasadead-endstoreofnutrientsinlocalcommunities.Thiswillshort-circuitnativefoodchains,therebydeprivinghighertrophiclevelsofnecessary
nutrients.InAustralia,theinvasiveCanetoadhasbeendocumentedtohavethiseffect,formingfour
times the mass of the pre-invasion native frog communities, nutrients now unavailable to support
nativepredatorcommunities.
Lastly, toads may serve to introduce or spread foreign diseases to native amphibian communities.
ThegreatestconcerninthisrespectisthedualthreatfromRanavirusandchytrid,Batrachochytrium
dendrobatides,whichhasbeenspreadgloballybytradeinalienfrogspeciesandhascausedmassive
declinesandextinctionsinamphibianfaunasworldwide.Todate,chytridhasnotaffectedMadagascar’slargeanduniquefrogfaunabutconcernsareelevatedduetoitsrecentdiscoveryamongnumerous Anuran taxa (Bletz et al. 2015). However, should toads carry this disease, it would be expectedtoproducewidespreadextinctionsinMadagascar,asithaselsewhere.
Insummary,despiteitsheavilydegradedstateMadagascarstillhasalargenumberofendemicspecieslikelytobeimpactedbythetoad.Toadswillimpactfoodchainsfromboththetop(consuming
prey and serving as an energy sink) and the bottom (poisoning predators), either of which could
eventuallyaffecttheecologyacrossmuchofthecountry.
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Fig.18.Dyscophusantongilii(Tomatofrog),apotentiallyvulnerablespeciestotheadvanceofAsian
toadsintoremnantnativeecosystems.Photo:C.J.Raxworthy.
Fig.19.Mantidactylusmelanoplura,apotentiallyvulnerablespeciestotheadvanceofAsiantoads
intoremnantnativeecosystems(MantadiaN.P.Madagascar).Photo:J.Reardon.
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Fig.20.Brookesiasupraciliaris(Leafchameleon)apotentiallyvulnerablespeciestotheadvanceof
Asiantoadsintoremnantnativeecosystems(Andasibe,Madagascar).Photo:J.Reardon.
3.4BenefitsofEradication
Thebenefitsoferadicationwilllargelybeecologicalthroughremovingtheriskofpoisoningofnaive
predatorsnaivetotheAsiantoad.Toaderadicationwouldalsoeliminateanyimpactsoftoadpredation on many smaller species which in turn reduces an unnatural level of competition with native
species. Many species in Madagascar are already under significant human-induced stress through
habitat destruction, hunting and collecting and the impacts of other introduced species. The toad
willincreasethatpressureandmaydrivesomespeciestoextinctionoratleastreducethemtothe
pointwherespecificsite-ledorspecies-ledmanagementisrequiredtosavethem.
Economicimpacts,suchasmajorchangestotheislandsecologyoragricultureareunknownbutmay
include an increase in rat numbers affected by reduction of larger snakes—most likely to be poisonedbythetoads.Thisisaconcernasrats(Rattusrattus)arealreadyamajoreconomicproblemin
Madagascar.
ThebenefitstohumanhealthofaneradicationoftheAsiantoadisclear—removingtheriskoflethal
poisoningtohumansandanimalspecies.Attheveryleast,failuretoeradicatetheAsiantoadnecessitates the Madagascan government engage in an effective education programme to promote the
messagethatthesetoadsarepoisonoustopeopleandsomelivestock.Thereisalsoariskthatthe
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toads, by reducing predators like snakes through poisoning, will increase the prevalence of plague
infectionswhicharealreadypresentwithinthetoadincursionarea.
Puttinginplacecomprehensivebiosecuritysystemswillhavebenefitsfarwiderthanjustthereducing toad populations and/or expansions. Incoming biosecurity, if put in place, will significantly reducethechanceoftoads,aswellasotherfutureinvasivespecies,establishingthuspreventingany
negativeimpactstheymayhave.
Outgoing biosecurity also requires attention, especially if the toads are not eradicated. Consideration will need to be given to possible actions which may stop them establishing at other locations
whichreceivegoodsfromorareservicedbyshipswhichhadvisitedMadagascar.Failuretodothis
couldleadtoWorldTradeOrganisationsanctionsbeingputinplaceongoodsoriginatingfromMadagascaraccordingtothelegislationsupportingtheWTOsTradeLiberalisationagenda.
4 RequirementsforSuccessfulEradication
4.1Technicalapproach
As there are no examples of amphibian eradications over such a large area, it is important that
methodologies are tested and evaluated for their efficacy for eradicating toads from Madagascar.
ThereisarangeoftechniquesavailablethattargetvariouslifestagesasdetailedinAppendixIIIand
summarisedhere:
•
•
•
•
•
•
Tadpolesviaremovalwithtadpoletrapsorchemicaltreatmentofwaterbodies.
Breeding adults via physical removal, including using audio stimuli to elicit calling from hidden
males.
Juvenilesviaspot-sprayingwithcitricacidorsugarsolutions,physicalremoval.
Eggsviaremovalofstringsfromponds.
Breedingadultsthroughfencingordrainingsomewaterbodies.
Non-breedingterrestrialadultsandjuvenilesthroughphysicalcapture.
It is therefore crucial to develop by trial an array of options to measure their efficacy. The informationfromthetrialswillthenbeusedtodeterminethetechnicalapproachtobeconsidered,along
withthescaleofthetreatmentsitetoseeiferadicationcanbetechnicallyfeasibleacrosstheentire
incursionlandscape.Ifsuitabletechniquesareidentifiedtheywouldbeimplementedusinganadaptive-managementprocess,constantlyreviewingtheirefficacyandadaptingthemasrequired. Ifinsufficientsuitablemethodsarevalidatedduringtrials—eradicationwillnotbefeasible.
ItmaybehelpfultonoteherethatrecentworkonthecontrolofCanetoadsinAustraliahasprovided some hope for the containment of toads where eradication is deemed impossible (Letnic et al.
2015).InthiscaseitneedstobestressedthattheAsiantoadincursionareainMadagascarissignifi38
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cantlymorehumidwithfargreateraccesstowatersourcesthanthearidareaofAustraliaconsideredintheLetnicetal.(2015)study.
ItisestimatedtherearecurrentlyapproximatelyfourmilliontoadsinMadagascarbasedonanextrapolatedcalculation.Thisiscertainlynotexactlyaccuratebutanessentialpreliminarycalculation
toprovidesomenumericalperspectivefortheissue.Inthecalculationweexpecta1:1sexratioand
that75%ofthepopulationareofbreedingage.Whileeachfemalecanlayupto40,000eggsthereis
onlyanaverageof20,000laidperfemaleperyear,andonly1%ofeggssurvivefromhatchingtojoin
thebreedingpopulation.Undertheseplausibleassumptionsacontrolprogrammerequiresustokill
1,500,000toadsperyearjusttomaintainnumbersattheircurrentlevel.Inordertoeradicatethem
within four years it will be necessary to kill over 2,500,000 per year. Failure to remove toads at a
greaterratethanthiswillresultinthefailureofaneradicationeffort.
4.2Sustainability
Foraneradicationtobesuccessfulitiscrucialthatoncetoadsareremoved,theyarenotallowedto
re-establishbyrenewedimportation.Thecurrentincursionshowsthatunlesschangesinbiosecurity
aremade,thereisaclearpathwayfortoadstobetransportedagaintoMadagascarfromSoutheast
Asia.
Althoughundertakingacomprehensivebiosecurityprogrammecanbecomplicatedandexpensive,
therearebasicactionsthatcanbeimplementedcheaplyandquickly,whichcansignificantlyreduce
theriskofnewpopulationsestablishing.Thiscanincludeeducatingstaffespeciallyattheportandat
businessesorfacilitiesengagedinimport/exportactivities;tonoteandreportanynewspeciesthey
observe;inspectinghigh-riskgoods;andhavingarapid-responseplaninplacetofacilitateimmediateremovalactionifandwhenanewincursionoccurs.Enforcingstandardsofcleanlinessandorder
canalsoincreasetheabilitytodetectinvasiveorganismswhilealsoraisingthegeneralstandardsof
operation.Expertassistanceshouldbesoughttodevelopabiosecurityplanthatisappropriatefor
thelocalconditions.
ParticularthoughtwillneedtobegiventobiosecurityinandaroundTamatavewhetheraneradicationproceedsornot.Ifaneradicationproceedsitwillbeimportanttominimisetheriskoftoadsbeing moved outside the infested area where they could establish satellite populations elsewhere in
the country, potentially putting the whole eradication project at risk of failure, or at least, significantlyincreasingtheoperationalriskandcostoftheproject.
Ifaneradicationprojectisnottoproceed,thoughtwillneedtobegiventowhetheritisfeasibleto
trytoreducetherateofexpansionofthetoads.Itispossiblethatsomeofthetechniquesthatare
putforwardforconsiderationforaneradicationareeffectiveatsignificantlyreducingtoadnumbers
butwon’treachthelevelrequiredforeradication;thesecouldbeusedforanongoingcontrolprogrammeiftherequiredongoingresourceswereavailable.Thiswouldpotentiallybuytimewhileadditionalworkontoadcontrol,anderadicationoptionsareinvested.Thatis,itispossiblethatgiven
adequate resources, a methodology could be developed which is not currently available, and it
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shouldbenotedthegreatertheareathetoadsinhabittheharderandmoreexpensiveitwillbeto
implementsuchamethod.Itisnotconsideredlikelythatacontrolprogrammewilldoanythingotherthanreducetoadnumbersandpossiblydecreasetheirrateofexpansion.
AlthoughallevidencecurrentlyindicatesthatAsiantoadshavenotyetreachedtheportfacilityof
Tamatave,giventhecurrentrateofspreadestimatedtocurrentlybeapproximatelytwokmperyear
(seeFig.13andconsideranincursiontimeframeof4–7years),itwillnotbelongbeforetheydo.This
willposeagreatriskofintroducingtoadstonewsitesacrossMadagascarandinternationally.
4.3Socialacceptability
Whilefurtherworkwillberequiredtoconfirmthelevelofsupportwithinthecommunity,fromour
sitevisitthereappearstobeaveryhighlevelofsupportwithinthecommunitytoremovethetoads.
Thereisakeendesireforeradicationand,insomequarters,anexpectation;althoughthereisnota
goodunderstandingofwhatisrequiredtodothis(asopposedtocontrol).Somelocalisedcontrolis
alreadybeingundertaken,andmanypeoplebelievethateradicationissimplyintensivecontrol,i.e.,
thatitissimplyanumbersgameandthelasttoadwillbeaseasytoremoveasthefirstifyousimply
keepatit—hisisnottrue!
Concernsoverhumanhealthrisksarelikelytobeamajorreasonforthecommunitysupportshown
fortheeradicationtodate,andtheconcernislikelytoremain.Similarlythereareconcernsabout
the impact of toads on chickens, which are common through the inhabited area and of economic
importance,especiallytolowereconomicgroups.Therearestoriesofchickensbeingkilledbytoads
reported to Reardon and McClelland during the site visit but no carcasses were observed. Once
againthisconcernhasledtosignificantsupportforeradication.
Communitysupportmaydependoncontroltechniquestobeused;hence,itwillnotbeabletoconfirmfinalcommunitysupportuntilthepreferredtechniquesareidentified.Forexample,peoplemay
be very happy with physical removal but not happy with the use of chemicals, even though some
levelofremovalviasafechemicalssuchascitricacidandsugarsolutionmaybefeasible.
Requiredaspectsofpublicsupportneededforsuccessfuleradication:
• Access to all properties in the possible incursion area both for removal and monitoring
acrossmultiplevisits.
• Acceptanceofthetechniquestobeused.
• Avoiding the use by the public of any techniques that may be required for follow up
monitoringsoastoavoideducatingindividualtoads(behaviouralmodification).
• Animpressionthatabountysystemwillnotbeanelementofaneradicationplantoprevent
the stock-piling and manipulation of toad populations. The eradication effort will still yield
extensiveemploymentopportunities.
• Ongoing support for biosecurity, initially to prevent the establishment of satellite
populationsandtodetectanythatmayalreadybepresentandthentodetectanyfurther
incursions.
Therewillinevitablybesignificantpressuretointroduceabountysystemasaquick,easyandsociallydesirable(itputsmoneyintothecommunity)wayofreducingtoadnumbersthatwillbeseenas
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doingsomething.Bountieshavebeenusedforanimal-controlprojectsgloballyforcenturiesandalthoughtheydoreduceanimalnumbers,veryfewhavesucceededineradicatinginvasiveanimals.Itis
more common for them to lead to “farming” of the animals to provide a sustainable income. One
additionalproblemwithbountiesistheyplacethesamevalueonallindividuals,whereasremoving
animalsattheperipheryofanincursionismorevaluablethanremovingthosetowardsthecoreof
the range, as doing so reduces the rate of spread, whereas those towards the core are generally
mucheasiertocatch.Also,animalssurvivingtowardstheconclusionoftheproject,whenthereare
veryfewandhardtocatch,aremoreimportantthaneliminatingthoseatthestart,whentheyare
plentiful.Inshort,thenegativeaspectsofattemptingabountyoutweighanypossiblebenefits,and
theideashouldbeclearlyavoidedpublicly.
TableofKeyContributors
Keystakeholdersidentifiedsofar:*
Name
Organization/function
Contactdetails
MadameSahondra
Rabesihanaka
Mr.Eric
Robsomanitrandrasana
Ms.MayaMoore
Mr.DevinEdmonds
Dr.JamesReardon
Dr.FredKraus
Dr.ChristopherRaxworthy
Mr.PeteMcClelland
Dr.JamesLewis
Malagasy Government – MEEMF: Head of Service,
BiodiversityConservation
Malagasy Government – MEEMF: Responsible for
nativefauna.
MadagascarFaunaandFloraGroup
MitsinjoAssociation
NewZealandDepartmentofConservation
Invasivereptileandamphibianexpert
AmericanMuseumofNaturalHistory
Independenteradicationconsultant
AmphibianSurvivalAlliance
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
*Weacknowledgethattherewillbenumerousincountrystakeholdersplayingacriticalroleinanyprogrammeofworktoaddressthe
Asiantoadincursionbutthefeasibilitystudydidnotenableustodiscussthesituationwithsufficientpotentialstakeholderstomakelisting
themhereappropriate.
4.4Political&legalacceptability
From the limited discussions had with MEEF Represented by Madame Sahondra, it appears that
there is a high level of governmental support for the eradication of the toads. It needs to be confirmedthatthisisreflectedatapoliticallevelandwillresultinongoingsupport.Thefuturepolitical
situationinMadagascarisunknown,butifthereisstrongsupportinitially,theprimaryriskwouldbe
withdrawalofsupportbytheGovernment.
NGOs,National,RegionalandLocalgovernmentwouldneedtoworkcloselytogetherwithclearlines
ofcommandandcontrolsothatoncetheoperationstartedtherearenounexpecteddelays.
Whether eradication is legally acceptable will depend to a large part on the techniques used, as
some of these may require governmental permits or consents, although environmental legislation
seems minimal in Madagascar. An example could be registration of a possible ranicide, which will
notbeabletobeconfirmeduntiltherequiredtrialsarecompleted.Alternatively,ifatechniqueis
notabletobelegallyimplementedthereisnouseincarryingoutthetrials.Issuesmayincludeanimalwelfareandhumanhealthconcerns.
AmajorconcernisobtainingaccesstoALLpropertieswithintheknownincursionareaaswellasany
potentialoutliers,bothcurrentandfuture.Thereviewteamwereinformedthataccesswouldnot
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beaproblem,butwhendealingwiththousandsoflandowners,aswouldbethecaseforthisproject, not having access to even one property could lead to failure if it harboured toads. Although
thereislittledoubtthatmostlandownersaresupportive,thereareconcernsaboutsomeindustrial/businesssitesthathaveahighlevelofsecurityandalsosomeofthegatedhousesinthecity.It
would be important to have a legal mechanism to allow access to such areas if required. It is not
knownifthiscurrentlyexists.Ifnot,itneedstobeprovidedbyeitherlocalornationalgovernment.
Thebiosecurityrequiredfortheeradicationwillalsoneedpoliticalandlegalsupporttoenforcethe
standards required to prevent reinvasion—there are many examples of island biosecurity systems
availableworldwidetobasethison.
4.5Environmentalacceptability
The environmental impact of the eradication on non-target species or habitats will largely be dependentuponthetechniquesused.Forexample,theimpactsofastand-alonephysicalremovalprogrammecouldbequitedifferenttoaprogrammewhichinvolvestheuseofchemicals.
Aphysicalremovalprogrammewouldhaveahighlevelofdisturbance,i.e.,anintensivegridsearch,
butprobablyonlyshort-termimpact.Thiscomparestotheuseofsomechemicals,whichmayeither
destroyvegetationorharmotherwildlifee.g.,anychemicalwhichkillstoadsorinanywayaffects
theirbiologymayhaveanequalorgreatereffectonnativeamphibiansdependinguponhowthey
areapplied.Itisbelievedthattheareasofarinhabitedbythetoadshasonlyafew,common,widely
distributednatives.Theircollaterallossisunlikelytobesignificant.Anyimpacthastobeconsidered
againstthelikelylong-termimpactacrossthewholecountryofnoteradicatingtoads.
Oncetrialshavebeenundertakentoconfirmpreferredcontroltechniques,theacceptabilityoflikely
orpotentialimpactsofthosemethodswouldneedtobeconsidered.
4.6Capacity
This relates to the systems that would need to be put in place to give the required administrative
supportfortheprojectandthecapacityoftherelevantorganisationstoprovidethatsupport.
ProjectAdministration
EradicationoftoadsfromMadagascarwouldbeamultiyear(estimatedtobeatleastsevenyears,
includingplanningandresultmonitoring),logisticallychallengingandveryexpensive(millionsofdollars)project.Thescaleoftheprojectwouldrequireextensivegovernanceandfinancial-management
systemstobeinplace.
ProjectGovernance
Any eradication attempt would require clear governance and management structures with agreed
roles,responsibilitiesandaccountabilities.Thisnotonlyreducestheriskofpotentialdisagreement
amonginvolvedparties,whichcanbehighlydisruptivetoaneradicationprogramme,butallowsfor
fastdecisionstobemadeonoperationalandfundingactivities.
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Fortunately the Madagascar Fauna and Flora Group (MFG) under the local direction of Ms. Maya
Moorehaveagreedtofunctionastheleadorganisation.CriticalskillsprovidedbyMFGincludethat
itisalreadyworkingontheisland,intheareaoftheincursionandwithastaffandcontactnetwork
at the local and national level and excellent links to the international conservation community. It
would be infeasible for a new organisation to be established solely to run the project, as it would
needtosetupalltherequiredinfrastructureaswellasprocesses,e.g.,labormanagementwithout
anyexistinglocalknowledge,takingtoolongconsideringthetoad’srangewouldhaveincreasedin
theinterim,increasingcostanddurationoftheproject.Aswithmanysuchdevelopingnations,the
most important skill a governing organization will need to have to be successful is familiarity with
thelocalsociety,governmentandabilitytofacilitateskillstransfertolocallysourcedlabour,while
beingskilledinnavigatingpoliticalandprocessweaknesses.
AlthoughitmaybetheoreticallypossibletoruntheadministrationfromalocationremotefromTamatave,itisconsideredimportanttohavethemajorbaseinTamatavesothatthereisacloselink
withthefieldprogramme.This,combinedwiththerequirementforlocalknowledgefortheoperationitself,meansthattheNGOwouldneedtobebasedinorclosetoTamatave.TheonlyorganizationwhichappearssuitableforthisistheMadagascarFaunaandFloraGroup(MFG),basedinTamatave. Although it has a staff of approximately 30, they are already fully committed to their other
work,andtakingtheroleonwouldmeansignificantlyexpandingtheirstaffandsystems.Thiswould
obviouslyneedtobecostdeterminedintoanyeradicationbudget.
Therewouldbearangeoforganisationsandindividualsthateitherhavetobeorareinterestedin
beinginvolvedinaprojectsuchasthis.Manyofthesewouldhaveminimalunderstandingofwhatis
required for undertaking a successful eradication, as opposed to control i.e., they are focused on
killinglargenumbersoftoadsandnotonkillingthelasttoad.Howthesegroupsinteractwillneedto
becarefullymanagedtoavoidconflictordiversionofresourcesfromtheeradicationitself.
Astructurewhichhasbeenshowntoworkwellforengagingkeyplayersthroughtheplanningand
implementation of a major eradication is the model used in Australia for the Macquarie and Lord
HoweIslanderadicationswhereasteeringcommitteewasestablished.Thisincludedrepresentation
fromthegovernment,whohaveoverallresponsibilityfortheenvironment,majorfundersandthe
implementation organisation(s), as well as eradication expertise. It is important that this group be
keptsmall(nomorethansixpeople)tofacilitatefunctionalitybecauselargegroupsinvariablyspend
alotoftimediscussingtangentialissuesandare,consequently,inefficientatreachingdecisions.This
groupcanthenactastheconduitforinformationbothintoandoutofthesteeringgrouptotherelativeagenciesandindividuals.
Therolesandresponsibilitiesofthesteeringgroupneedtobelaidoutclearlyina“TermsofReference”forthegroup.Thiswillincludewhichgroupsordepartmentseachgroupmemberisresponsible for keeping informed. A crucial component of a successful working group is that all members
have as their goal a successful eradication so the debate is overon what can be done to facilitate
thatgoalratherthanrepresentingtheinterestsoftheirparentorganizations.Whileultimatelyapoliticaldecisiononwhethertheprojectshouldcontinue,needstobeinformedbyeradicationexperts.
Itisfurtherrecommendedthatascientificandtechnicaladvisorygroup(TAG)beestablishedassoon
aspossible,bothtooverseethetrialsandanyeradicationitself.Thisgroupcanprovideadvicetothe
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projectmanagerandthesteeringcommitteeontechnicalissuesrelatingtoeradication.Thisislikely
to include eradication expertise, non-target expertise and social/local expertise. Once again, this
groupshouldbekepttoamanageablesize(nomorethaneightpeople),withadditionalpersonnel
with specific skills and expertise able to help on specific issues as required. It is recognized that a
largenumberofindividualsandgroupsmaywanttobeinvolvedwiththisgroup(e.g.,peopleworkingonpotentiallyaffectednon-targetspecies),somanagingthesocialdynamicofthisgroupwillbe
important,asisrecognizingthegroupisadvisoryonly,andthesteeringcommitteeandoperational
teamwillmakedecisionsbasedonallinformationavailable.
As with any eradication, the quality of the work and hence the skills and motivation of the work
force,isparamount.Althoughthereisaplentifulandrelativelycheaplabourforceavailable,careful
considerationwouldneedtobegiventoensurethatallfieldstaffarefocusedondoingtheworkto
therequiredstandardsothatonceanareahasbeenclearedtheteamcanmoveontonewareas
withahighlevelofconfidence—fieldleadershipskillswillbeimportant.
Whether partner organisations or businesses become a functioning part of an eradication
programmeitiscriticalthattheyworkcollegiallywiththecoordinatorsoftheeradicationeffortand
showcommitmenttoapplyagreedoperationalstandardsandprofessionalism.
Table1.Keyskillsneededtocompletetheproject.Note:thisonlyrelatestoStageOneEradication
anddetectiontechniquedevelopmentandanincursiondelineationsurvey.
KEYSKILL
PROJECTMANAGEMENT
FIELDOVERSIGHT
FIELDWORKERS
APPLIEDSCIENCE
ADMINISTRATION
PURPOSE
Oversightandadministration:
eradicationexperience.
Oversightofthefieldtrialsand
distributionsurvey.
Undertakethetrialsand
survey.
Designandcoordinatethe
requiredtrialsandproduce
relevantreports.
Coordinatebudgetandproject
reporting.
METHODTOOBTAINSKILLS
Targetpersonnelwiththe
requiredskillsandexperience.
Sourcelocallabour.
Uselocallabour,tobeselected
usinglocalcontract,ideally
skilledpersonnel.
Jointroleforinternaland
externalpersonnel,probably
providedbytheTAG.
LocalNGO.
4.7Affordability
Itisnotpossibletodevelopadetailedbudgetforaneradicationitselfuntil:
• Techniques for both the eradication and surveying for toads at low density have been
developed.
• Sizeoftheincursionisconfirmed,includinganysatellitepopulations.
• Administrationoftheprojectisestablished.
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ItisapparentthatanyeradicationwillcostprobablybetweenUS$2millionandUS$10millionandas
insufficientfundingwillinevitablyleadtofailure.Itisimportantthatadequatefundingisidentified
before the project is started as otherwise, it is a waste of time, money and goodwill. The need to
confirm the funding must be balanced against the need to commence the eradication as soon as
possibleastheincursionareaandhence,costsarelikelytoincreaseexponentiallywithtime.
CostsforPhase1—selectionofdetectionanderadicationtechniquesandconfirmationoftheextent
oftheincursionneedtobeundertakenbypersonnelwhoknowthecostofoperatinginMadagascar.
Weestimatethecostsforyearonetobeapproximately$US385,000(seeAppendixIII).
Delays in implementing the eradication will increase the cost as the incursion will continue to expand,includinganincreasedriskofsatellitepopulationestablishingthroughhumanassistedmovement.
6CONCLUSION
WebelievethattheeradicationofAsiantoadsfromMadagascarisnotcurrentlyfeasiblebecause:
1. No proven methods of removal are known which will eliminate toads faster than they
reproduceandrecruit.
2. No tested detection methods are sufficiently sensitive to ensure all animals are detected
withaprobabilityenablingremovalgreaterthanreproductionandrecruitment.
3. No sufficient confidence of the current toad distribution and how rapidly the incursion is
expanding,includinghumanassistedmovements.
Howeveriftheseissuescanallbeanswered,andthereissufficientfundingavailable,itispossible
thateradicationispossible.
AppendixIIIofthisreportbrieflydetailsthetechnicalinvestigationsneededtoundertakeinorderto
confirmwhethertoadscanbeeradicated.Iftechniquesaresuitable,anoperationalplancanbedevelopedandcostdeterminedtoconfirmthefinancialfeasibilityoftheproject.
KEYISSUES.Requiredtoenableeradicationprogramme:
Issue
Action
Detectiontechniques.
Eradicationtechniques.
Delineatingtheextentincursion.
Develop a complete operational
plan.
Costoferadication.
Refinepossibleoptionsandundertaketrials.
Refinepossibleoptionsandundertaketrials.
Useselectedtechniquetoundertakesurvey.
Basedonatechnique(s)beingavailable.
To be cost determined once the operational plan is
developed.
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6Acknowledgements:
The authors thank the Amphibian Survival Alliance and Paris Zoo for funding this feasibly
study;MadagascarFaunaandFloraGroup(MFG)forprovidinglogisticsandadministration
supportforsiteinspections;MayaMoore(MFG)andDevinEdmonds(AssociationMitsinjo)
for supporting a site visit, as well as coordinating the distribution surveys (a crucial componentofthisstudy)andforlastlyundertakingatranslationrole.Itisrecognisedthatthis
took these individuals away from their existing commitments and added significantly to
their work load—for this we are appreciative of their efforts and contributions to this report.
WeespeciallythankJeanFrançois(ParcIvoloina/MFG)forundertakingmanyofthedistributionsurveysandforcoordinatingthesitevisitsincludingliaisonwithlocalresidents.We
are very grateful to MFG and Association Mitsinjo for providing staff for the distribution
surveys.
We greatly appreciate the contributions of Dr. Roger Daniel Randrianiaina of the University
D’Antananarivo for valuable input to the discussions and translation assistance. We thank
Lydia Randrianasolo for coordinating the site visit to the Ambatovy processing plant and
waste site. The authors acknowledge Madagasikara Voakajy for their kind provision of Christian
Randrianantoandro’stimetotheproject.
7REFERENCES
Arnaud,R.2014."InvasiondecrapaudsvenimeuxàToamasina:unemenacepourl'écosystème
malgache."MidiMadagasikara(04/17/2014).Available:http://www.midimadagasikara.mg/societe/2014/04/17/invasion-crapauds-venimeux-toamasina-menacelecosysteme-malgache/[Accessed:08October2015].
Bletz,M.C.,G.M.Rosa,F.Andreone,E.A.Courtois,D.S.Schmeller,N.H.C.Rabibisoa,F.C.E.Rabemananjara,L.Raharivololoniaina,M.Vences,C.Weldon,D.Edmonds,C.J.Raxworthy,R.N.Harris,M.C.
Fisher,andA.Crottini.2015.WidespreadpresenceofthepathogenicfungusBatrachochytriumdendrobatidisinwildamphibiancommunitiesinMadagascar.ScientificReports5:8,633.
Bomford,M.andP.O’Brian.1995.Eradicationorcontrolforvertebratepests?WildlifeSocietyBulletin23(2):249–255.
Burnett,S.1997.ColonizingCaneToadsCausePopulationDeclinesinNativePredators:ReliableAnecdotalInformationandManagementImplications.PacificConservationBiology.3(1):65–72.
Cheng,C.J.,C.S.Lin,L.W.Chang,andS.H.Lin2006.Perplexinghyperkalaemia.Nephrol.Dial.Transplant21:3,320–3,323.
Chi, H-T. M., D-Z. Hung, W-H Hu, D-Y. Yang. 1998. Prognostic implications of hyperkalemia intoad
toxinintoxication.HumanExperimentalToxicology17:343–346.
CrosslandM.R.,M.N.Hearnden,L.Pizzatto,R.A.Alford,R.Shine.2011Whybeacannibal?Thebenefits to cane toad (Rhinella marina) tadpoles of consuming conspecific eggs. Animial Behaviour 82:
775–782.
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Huang,W-S,J-Y.Lin,J.Y-L.Yu1997.MaleReproductiveCycleoftheToadBufomelanostictusinTaiwan.ZoologicalScience14(3):497–503.
Jan,S-L.,F-L.Chen,D-ZHung,C-S.Chi1997.Intoxicationafteringestionoftoadsoup:reportoftwo
cases.ActaPaediat.Sin.38(6):477–480.
Khan,M.2000."Duttaphrynusmelanostictus.AmphibiaWeb.Available:http://amphibiaweb.org/cgibin/[Accessed:17February2012].
Keomany,S.,M.Mayxay,P.Souvannasing,C.Vilayhong,B.L.Stuart,L.SrourandP.N.Newton2007.
ToadpoisoninginLaos.AmericanJournalofTropicalMedicineandHygene77(5):850–853.
Kuo,H.Y.,C.W.Hsu,J.H.Chen,Y.L.Wu,Y.S.Shen2007.Life-threateningepisodeafteringestionof
toadeggs:acasereportwithliteraturereview.Emerg.Med.J.24:215–216.
Kraus,F.2009.AlienReptilesandAmphibians:Ascientificcompendiumandanalysis.SpringerScienceandBusinessMediaB.V.,Dordrecht,Netherlands.563p.[ISBN:978-1-4020-8945-9].
Letnic.M.,J.K.Webb,T.S.Jessop,andT.Dempster.2015.Restrictedaccesstoinvasionhubsenables
sustainedcontrolofaninvasivevertebrate.JournalofAppliedEcology52(2):341–347.
Mercy,M.1999.StudiesonsomeaspectsoftheBiologyandEcologyoftheCommonIndianToad
BufomelanostictusSchneider(ClassAmphibia;OrderAnura).MahatmaGandhiUniversityTheses
Library.
Moore,M.,J.Francois,andD.Edmonds.2015.Thenewtoadintown:DistributionofDuttaphrynus
melanostictusintheToamasinaareaofeasternMadagascar.TropicalConservationScience8(2):
440–455.
Mogali,S.,S.Saidapur,andB.Shanbhag.2011.LevelsofPredationModulateAntipredatorDefense
BehaviorandMetamorphicTraitsintheToadBufomelanostictus.JournalofHerpetology,45(4):
428–431.
O’Shea,M.,A.Kathriner,S.Mecke,C.Sanchez,andH.Kaiser2013.‘FantasticVoyage’:alive
blindsnake(Ramphotyphlopsbraminus)journeysthroughthegastrointestinalsystemofatoad
(Duttaphrynusmelanostictus).HerpetologyNotes6:467–470.Available:
http://www.herpetologynotes.sehherpetology.org/Volume6_PDFs/Shea_HerpetologyNotes_volume6_pages467-470.pdf[Accessed:08
October2015].
Pearson, R.G. 2015. Asian common toads in Madagascar: an urgent effort to inform surveys and
eradicationefforts.GlobalChangeBiology21:9.
Pestanimalriskassessment:Asianspinedtoad(Duttaphrynusmelanostictus)TheStateofQueensland,DepartmentofEmployment,EconomicDevelopmentandInnovation,2010.Available:
https://www.daf.qld.gov.au/__data/assets/pdf_file/0003/56658/IPA-Asian-Toad-RiskAssessment.pdf[Accessed:16October2015].
Saidapur,S.,S.Girish.2001.GrowthandMetamorphosisofBufomelanostictusTadpoles:Effectsof
KinshipandDensity.JournalofHerpetology35(2):249–254.
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vanDijk,P.P.etal.2004."Duttaphrynusmelanostictus".IUCNRedListofThreatenedSpecies,Version2012.2.IUCN.Wingate,D.B.2011.ThesuccessfuleliminationofCanetoads,Bufomarinus,from
anislandwithbreedinghabitatoffBermuda.BiologicalInvasions13(7):1,487–1,492.
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APPENDICES
AppendixI:SiteVisits
Two of the authors (McClelland and Reardon) visited the incursion site from 23–29th November
2014.Thefirsttaskwastodevelopa“termsofreference”forthevisitandsubsequentreport.This
waspromotedbytheapparentmisconceptionbysomepeopletheoutputfromthetripwastobe
theprovisionofaneradicationplantellingthemhowtoeradicatethetoadsandhowmuchitwould
cost.Thetermsofreferenceweresignedoffbytherelevantpartiesanddisseminatedtoeveryone
currentlyinvolvedintheproject.
Duringthestaytheyvisitedarangeofdistributionsurveysitesaswellaslookedatthefullrangeof
urbanandruralhabitats,includingmajorwaterways,potentialbreedingareas,bothinthecityand
inruralareas,andarangeofterrestrialhabitats.VisitedweresiteswithintheAmbatovynickelprocessing plant and associated staff accommodation, including a meeting with Samuel, the environmentalmanagerforthecompany.Guidedby:JeanFrancois,secondinchargeattheMFG,whohad
undertakenmostofthedistributionsurveys;accompaniedbyDevinEdmondsoftheMitsinjoAssociation,whohadbeeninvolvedinmanyofthesurveysalongwithMayaMooreofMFG;andDr.Roget
DanielleoftheUniversityofAnatanarivo,whohasbeenundertakingsomepreliminaryresearchon
thepossibleimpactsofthetoad.
ThroughJeanFrançois’localknowledgeandconnectionsthegrouptalkedtoseveraloftheVillage
Presidents(theelectedvillageleader)tofindoutthelocalviewonthetoadsandtrytoidentifyany
potentialissueswithundertakinganeradicationoftheirarea.
Onthe24ththegroupmetwithAroRatovomonehjaryandLydiaRandrianasolooftheAmbatovyminingcompanytodiscussthesituationandAmbatovy’sroleinanyeradication.TheystatedthatAmbatovy were currently undertaking survey work within their site and they would follow the requirements of any eradication plan, i.e., they would undertake the work on Ambatovy land rather than
haveanyexternalpersonnelworkingontheirproperty.ThisapproachwasconfirmedduringalldiscussionswithAmbatovypersonnel.
Onthe27ththegroupwasjoinedbyChristianRandrianantoandro,nationalcoordinatorfortheAsian
toadprojectandEricRobsomanitrandrasanaofMEEF(MinistryofEnvironment,EcologyandForests)
to discuss the issues and thoughts to that point. The following day, McClelland, Reardon, Danielle
andRandrianantoandrometwiththeRegionalOfficeofEnvironment,EcologyandForeststoupdate
themontheproject’sprogress.
McClellandandReardon,alongwithDanielleandRandrianantoandro,mettheSecretaryforMEEF,
as well and other government officials and NGO representatives in Anatanarivo. On the 5th of December.McClellandandReardonupdatedthegroupontheirthoughtstodateandstressedthedifferencebetweenacontroloperationandaneradication,inwhicheverylastindividualhadtoberemoved,asitappearedtherewassomeconfusionbetweenthetwomethods.Theyalsostressedthey
weretheretolookatthe“feasibilityofundertakinganeradication”andthereportwouldcoverfeasibilityonly,andnotbeaneradicationoperationalplan.Therewasarealdesiretostartaresponse
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straightawaysoitwasnecessarytostatethataneradicationrequiresplanningandcoordinationand
whileitwouldbeeasytogooutandkillthousandsoftoadsimmediatelythesewouldbeinthehigh
densityareasand,giventheanimal’srapidbreedingrateandotherfactors,wouldmakeverylittle
differencetotheoverallexterminationofthespecies.Therewasdiscussiononputtingabountyon
toads but it was agreed that this would have the same effect as just killing toads—killing the easy
ones,withtheaddedriskoffarmingtoads.
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AppendixII:TermsofReference
This report has been requested by the Amphibian Survival Alliance and the IUCN SSC Amphibian
Specialist Group Madagascar on behalf of the Government of Madagascar. The feasibility study is
beingdevelopedbyMr.PeterMcClelland,anexpertineradicationofpestanimals,Dr.JamesReardon, a scientist for the New Zealand Government Department of Conservation who specializes in
eradicationofinvasivereptilesandamphibians,Dr.FredKraus,theheadoftheeradicationfeasibility study group and expert in global invasive reptile and amphibian issues and Randrianatoandro
Christian,nationalcoordinatorfortheeradicationproject.Ourcontributionofexpertopiniontothe
governmentofMadagascarandotherstakeholdersisintendedfortheinclusivebenefitofsecuring
securityforMalagasysocial,economicandbiodiversityvalues.
1. Thedocumentisnotaneradicationoperationalplanbuta“feasibilitystudy.”
2. Thisdocumentisdesignedtoexploreanddiscussfeasibilityofaneradicationprojectbased
oncurrentincursionstatusincludingenvironmental,socialandtechnicalparameterstominimizeriskoffailureandwasteresources.
3. Controlanderadicationareverydifferentconcepts:thecontrolofapestanimalaimstodiminishtheirabundancetoaprescribedlevel.Eradicationisthetotalremovalofallindividualsinanincursion,andassuchspecificoperationalparametersmustbemet.Theseare:
a. Technical feasibility: Technique(s) be used at the project site must be capable of
removingallindividualsofthetargetpopulation.
b. Sustainable:Re-invasionofthetargetspeciescanbeprevented.
c. Sociallyacceptable:Theprojecthasfullsupportfromthecommunityandotherkey
stakeholders.
d. Politically and legally acceptable: It is possible to secure all required permits and
consentstoconductaneradicationproject.
e. Environmentallyacceptable:Anynegativeimpactoftheeradicationareacceptable
fortheenvironmentduetothebenefitsoferadication.
f. Capacity:Itispossibletoassembleordevelopthenecessaryskilledindividuals,resourcesandequipmentfortheeradicationproject.
g. Affordability:Theeradicationprojectmustbeachievablewiththeresourcesavailable(beingconsciousoftheoveralllong-termcostsofcontrol).
h. Detectionandinterception:Itmustbepossibletodetectallindividualsintheincursionareaandplacethemallatriskofcapture.Thisislikelytorequiretheuseofmultiple techniques in carefully prescribed order to reserve the most sensitive techniquesforthelastremainingandthereforemostdifficulttotargetindividuals(This
iswhywemustbecautiousaboutrushingintoemployingtoadremovaltechniques).
4. AnyplanninganddevelopmentofaneradicationplanmustbeconsiderateofMalagasysocialandpoliticalconditions.
5. Anydevelopmentofaneradicationprojectfollowingthisfeasibilitystudymustbeacknowledgedasan“eradication-by-research”projectasnotoolsorprocessesarecurrentlyproven
fortheeradicationoftoadsfromlargeareas.
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6. It is critical that prior to the receipt of the feasibility study report that accountability and
leadershipstructuresbeacceptedbyasuitableorganizationorpartnershipoforganizations
leadbyaMalagasyorganisation.
7. ThisfeasibilitystudyreportwasintendedfordeliveredtoMalagasypartnersbyJanuary30th
2015.Duringthewritingofthefeasibilityreportitbecameclearthatthedocumentneeded
to function as much more than the traditional feasibility report for a broader audience
includingNGOs,Governmentandstakeholders.Becauseofthisthereporthadbeendelayed
in it’s release until November 2015 to allow for further research and discussion with
partnersonitscontent.Followingthesubmissionofthisreportanditsrecommendationsitis
importantthatpartnersunderstandthetime-boundednatureofprogressinganyeradication
planning.Testingandevaluationoftoolsandtechniquesfordetectingandremovingtoads
mustprecedetheirwide-scaleemployment.
8. Giventherisksofextendingthedelaytooperationalizingeradicationduetofundraisingdelays, it is important to immediately begin canvassing for financial support on the provison
thatiftheeradicationdoesnotproceedthenfundswillbereturned.
Anumberofassumptionswillneedtobemadeinthedevelopmentofthefeasibilityreportandthesewillbestatedinthereport.
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AppendixIII:PreliminaryTechnicalStrategy
This document is not an eradication operational plan, however it is acknowledged there is urgent
need to consider the potential operational methodologies and parameters to be able to make a
quantitativelyinformeddecisiononwhethertoprogresstheprogrammeofwork.Thisrequiresusto
considercostand,insomecases,testprospectivemethodologiestoinformthatdecision.Also,some
urgentissuesneedtoberapidlyaddressedtomaintainoptionsforadvancinganeradicationoperationandprovidingaframeworkandaccountabilitiesforthedecisionsthatneedtobemade.
Wemustacknowledgethataneradicationofanamphibianhasneverbeenachievedonthescalewe
areconsideringhere,orinsuchacomplexenvironment.Thus,wecannotconfirmwhethereradicationisfeasibleuntilwehaveevaluatedpotentialeradicationtools.Eachpotentialtoolmustbetestedpromptlytoevaluateitsrelativeefficacy,bearinginmindfactorssuchaslife-historystage(eggs,
tadpoles,metamorphs,juveniles,adults,breedingadults),seasonandecotype,whenrelevant.Itis
probablethatanyonemethodwillbeinadequatetoachieveeradicationwithinagivenarea.Therefore,wehavetoconsiderastrategythatusesmultipletools(Methodswillneedtobeusedconcurrentlytoo.),basedonefficacyataparticularpopulationdensity.Thisorderofapplicationofthose
toolsisalsoastrategicallycriticalelementofsuccessfuleradicationtoavoidcreatingadifficult-totargetresidualpopulation.
1URGENTISSUES
1.1Governing/leadershipbody–Itisextremelyimportantasmallbodybeidentifiedtoleadalleffortsrelatedtothetoadincursionissue.Noeradicationprogrammeispossibleuntilaccountabilityis
clearlyidentifiedandtheremittoleadtheprogrammeofworkisdefined.
Recommendation: Discuss with current lead organisations and key in-country partners to
date(Malagasygovernment,MFG,AssociationMitsinjo,ASA)howthisbodyshouldbemade
upandhowtheywillbesupported.Itisvitallyimportantthatagovernance/leadershipbody
bedesignatedassoonaspossibleasitisnecessaryforevaluatingandactingontherecommendationsofthisreport.Thisbodyneedstoberesponsibleforimmediatelyraisingfunds
toachievethegoalsdiscussedbelow.Oncefundingisavailableandadministrativestructure
in place (see next item), secondary administrative structure can be responsible for raising
subsequentfunding,asneeded.
1.2Managementandadministrationstructure–Beyondtheleadershipandaccountabilitynecessary
to steer such a programme of work it is essential there is accountability for administering the resources and infrastructure required. This ideally would be undertaken by a single organisation so
thatthereareclearlinesofaccountabilityandresponsibilityandpreferably,byanorganisationthat
has an existing structure in place in Madagascar—facilitating faster implementation of any work.
Considering the limitations on capacity in Madagascar, this function may need to be sourced elsewhere.
Recommendation:DuringdiscussionsinMadagascar,itwassuggestedadequateresourcing
wereavailabletosupportthefullcosts;MFGmaybeabletoconsidersucharole.Thispossi54
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bleoptionshouldbeurgentlyexploredfurther.Theauthorsarenotawareofalternativeoptions.
1.3Financing–Costsofdevelopmentoferadicationmethodsortheunderpinningresearchtosupport such methods will require funding. It is extremely difficult to secure funding without a very
clear,prescribedproposal,yetdelaysinsecuringfundswillseriouslyundermineeradicationpotential.
Recommendation:Leadorganisationshouldcommunicatewithmajorpossibledonors,funders and partners (e.g., IUCN, UNEP, UNDP, ADB) to highlight the issue and potential requirement for rapid funding. Our proposal here is to seek US$385,000 for the first twelve
monthsofresearch,developmentandtesting.Shoulderadicationproceedbeyondthispoint
theprojectislikelytocostbetweenUS$2m–US$10mandtakeatleastafurther5–6years
tocomplete.
1.4Biosecurity&education–Itisanimmediateconcernthatthetoadmaybeinadvertentlyspread
beyonditscurrentincursionareabyaccidentaltransportationingoodsandequipmentbeingmoved
outoftheincursionarea.Itisclearlyextremelychallengingtoachieveadequatebiosecurityforall
internal trade moving through the incursion area. However, minimum measures should include a
nation-wideawarenesscampaignidentifyingthetoadsandrecommendingactions,includingreporting any interceptions with the accountable governing body of any eradication effort as well as reportinganynewincursionsites.
ThesecondmajorconcernregardingbiosecurityistheseaportofToamasina/Tamatave.Duringour
evaluationwewerenotabletogainaccesstotheinnerportarea,butexaminationoftheareaand
itsperimeterhighlightsthefactthatthereisnoeffectivebarriertothespreadofthetoadintothe
portarea.Thepresenceoftoadsintheportfacilitywouldsignificantlyincreasetheriskoftoadsbeingtransportedtootherlocations,especiallythosewithsignificanttradefromTamatave.
Recommendation: Lead organisation should develop a communication and education programmetoraiseawarenessoftheinvasivetoadandprovidechannelsforreportingnewlocation sightings. Although international standards in biosecurity vary greatly, and we
acknowledge the limited infrastructure in Madagascar, suggesting actions as simple as enforcing cleanliness and tidiness in port storage and handling areas, together with welldisplayed and easily understood instructions to collect and report any organisms to staff
maderesponsiblefortheirremoval,couldsignificantlyreduceriskoftoadsandotherorganismsbeingtransportedtoandfromtheport.
1.5Mapping/GIS–Thereisaneedtoaccuratelymapanddelimithabitattypesandidentifytheextent of the incursion area as well as potential barriers to toad movements within and around the
incursionareatoassistinstrategicplanningofanyeradicationeffort.
Recommendation:LookforGISmappingexpertswithingovernmentandtheprivatesector
whocanbecontractedtoworkontheproject.Itisimportanttheyhaveaclearunderstandingofworkingwithenvironmentaldata.
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1.6Delimitation–Althougheffortshavebeenmadetodescribethefullextentofthetoadincursion,
themethodsusedarelikelytobeinsensitivetotoadsinlow-densitypopulations.Aswedonotunderstandthepopulationdynamicsoftheexpandingincursionwemustassumetoadsmayoccurover
awiderareaindensitieslowenoughtoavoidcasualobservation.
Recommendation: Specific efforts should be made through a communication plan to raise
awarenessofthetoadsintownsanddestinationslikelytohavereceivedsignificantfreight
fromtheincursionarea.Surveyteamsabletoefficientlyquestionlocalcommunitiesabout
toad presence and conduct their own searches should be dispatched to the highest-risk
sites.Toachievethis,thecommunicationplanwillneedtohaveanationalreachandbeappropriatelydesignedtoensurethekeymessagesreachrural,aswellasurbancommunities.
2METHODTESTINGANDEVALUATION
Although this report is not an eradication operational plan, it is essential any eradication plan will
consistoftheapplicationofasuiteofdetectionanderadicationtoolstogivetheprogrammehope
ofmeetingtheminimumcriteriaoferadication.
Alleradicationmethodswillrequiretestingtoevaluatetheirefficacytoremovethetargetanimal.As
eradication against this species has never been attempted before, nor any eradication conducted
around Tamatave, nor any amphibian eradication conducted at such a large spatial scale, we are
considering the use of methodologies untested against such a large incursion. Hence, it is critical
thatweevaluateefficacyofpotentialtoolsacrosstherangeofecotypesoverwhichweneedtooperate.Theapplicationofmethodswillrelyonunderstandingthenumbersofindividualsbeingtargeted,theirlife-historystagesandtheproportionofthoseindividualsthatcanbeinterceptedand
removedwitheachtechnique.
Due to the time constraints of this project the methodologies proposed are not exhaustive, but
hopefully cover the majority of tools and methods likely to be relevant for an eradication effort.
Shouldresearchanderadicationbeoperationalised,thenfurtherinvestmentshouldbemadeinconsultingthoseinthefieldofvertebrateeradication.
2.1BASELINEDATA,IMPORTANTISSUESANDMONITORINGMETHODS
The following methodological proposals focus on baseline data gathering and detection tools. It is
necessary for us to evaluate variables such as average density to assist in the evaluation of techniquesasacomponentofaneradicationplan.Estimatesareacknowledgedasindicativeonlybutare
necessarytoprovidethebestinformationtoinformresponsedecisionsneededtobemadeswiftly
andpragmatically.
It may seem inefficient to consider methodologies only able to detect toads rather than methods
thatbothdetectanddestroytoads.Inaneradicationscenarioitisimportanttoconsidermethods
thathavethegreatestprobabilityofdetectingthetargetanimalaswellasmethodsthatdetectand
kill.Iftherearemonitoringmethodssignificantlymoresensitivetotoaddetectionthanthoseableto
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alsoresultintoadcapture,thentheywillbeimportantcomponentsofaccuratelydelimitingtheincursionarea,aswellasconfirmingsuccessfuleradication.
2.1.1Densityestimation
Purpose:Fromthedatagatheredtoestimateaveragetoaddensitywithintheincursionareaitwill
bepossibleforustoevaluatetheapparentdemographics(ageandsex)ofthetoadpopulationand
anyanomaliesthatmayprovideopportunitiestostrategizeeradication.Mostimportantlywillbethe
abilitytoextrapolatethedatatothefullknownextentofthecurrentincursionandmakemoreappropriateestimationsoftheeffortrequiredforeradicationplanning,andtherelativeriskofmethodologiesbeinginadequatetoachieveeradication.
Method:Aninitialandmoderatelylow-costactionshouldbetoevaluatetheapparentdensityina
rangeofecotypesknowntocontainmoderatetohightoaddensities:urban(suburbansettlement),
intensiveagricultural,andunmanagedvegetatedhabitat.Werecommendthattoaddensitiesbeestimatedatseveralsites,preferably,2–3sitesinallmajorecotypes.Thiscanbedonequicklyandcost
effectivelybysmall-scaledestructivehabitatclearance.Thescaleonwhichsuchmethodsshouldbe
employedshouldbelimitedtoonly2–3sitespermajorecotypeastheinformationgatheredisindicativeonlyforthescalingofsubsequentmethodstesting,forextrapolatingapproximatetoadpopulationsize,andthereforeforenablinganimprovedevaluationofriskofproposederadicationstrategies.Theproposedmethodologyistodemarkanareabeingnolessthan10x10mandnogreater
than20x20m.Ifpossible,constructa“toad-proof”temporaryfenceusingstandarddrift-fencedesignsor,ifthismethodisnotpossible,employadditionallabourtocleartheperipheryoftheareato
besearchedandensurethearearemainsunderobservationsotoadsdonotmoveinoroutofthe
area.Ateamofsearchersthenworkthroughtheareafromonesideoftheareatotheotherwithin
2–3mofeachotherclearingvegetationandanymaterialsinorunderwhichtoadsmaybehiding.It
willbenecessarytohavemacheteandspadesavailablefortheclearanceofvegetationthatcannot
beeffectivelysearchedwithoutremoval.Assuchitisimportanttheareasselectedforthesearches
meetcertaincriteria:
1. Landownerconsentisachievedamicably.
2. Theareatobesearcheddoesnotcontaincropsoranythingtheownerisnotcomfortabletobemovedordamagedduringasearch.
Alltoadsobservedmustbecollectedandplacedinanescape-proofbucketprotectedfromexcessive
directsunlight.Oncetheteamhavemadeonethoroughsweepoftheareatheyshouldrepeatthe
processensuringthatnoopportunityremainsfortoadstooccupytheareabeingsearched.
Once the search is completed the collected toads should be swiftly examined and each individual
measured(SVL),sexedandhumanelyeuthanisedbypithing,orbyothermeansdeemedhumaneby
veterinaryexperts.Ifskeletalchronology(furtherdiscussionofthismethodbelow)istobepursued,
thenlimbsamplesshouldbecollectedandstoredinlabelledappropriatemedia.
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Logisticsandcosts:Thisproposedworkwillrequireateamofatleastsixindividualsledbysomeone
with complete oversight and understanding of the technique being pursued and the skills to accurately record the data gathered. Transport will be necessary, involving vehicle and driver. Teams
shouldbeabletoexaminethreesitesperday,andifweaimfor3xsitesinurban/suburban,3xsites
inruralagriculturaland3xsitesinunmanagedhabitatwewillneed21mandaysforthesurvey,an
additional seven man days to reconnoitre sites, and four man days to record data and synthesise
intoabriefreport.WorkingonabudgetofUS$20/person/dayplusUS$120forvehiclecosts(both
costsapproximatedfromobservedcostsduringfeasibilitystudyvisit)thenthisworkwillcostaminimumof:
•
Surveylabour:US$3,080.
•
Vehiclecosts:US$600.
•
Analysisandbriefwriteup:US$80.
Total:$3,760
The logistics of such an effort will require local knowledge and community-relations skills that appeartobeexclusivelyofferedbyMFGintheregionoftheincursion.Staffwouldthenbeamixof
those with skills (as previously provided by the Association Mitsinjo), local knowledge (MFG) and
probablysometechnicaloversightfromsomeonewithecologicalskills(e.g.,DevinEdmonds,Roger
DanielRandrianiana).Itisourunderstandingthatthisworkisinpartalreadyunderway.
2.1.2Humaneeuthanasia
Purpose: Methods of humane euthanasia are essential to the testing or employment of any toad
eradication tools. Methods need to be approved by an appropriate animal ethics body. This is an
importantissueastheuseofhumanemethodswillbeaprerequisiteforanydonorsupportingan
eradication or research programme. Failure to develop and adhere to ethical practices risk both
fundingandthereputationoftheprogramme.Thismayseemlikeanunnecessarycomplicationbut
itisanessentialcomponentofconsideringtheeradicationofanyinvasivevertebrateorganism.
Method:Theleadbodyaccountablefortheeradicationshouldconsultwithveterinaryexpertsand
anappropriateanimalethicscommitteetoidentifyappropriatemethodscurrentlyacceptedforthe
humaneeuthanasiaoftoads.Thiswillneedtobedoneinaninformedmannerwithconsiderationof
theneedtohavemethodsappropriateforusebyunskilledworkerswithinthecontextoftheincursion environment in Madagascar. It is necessary different methods will be developed for different
life-historystages.Eggsmayhavetobeeuthanizedusingdesiccationmethodsensuringalleggsare
quicklyrenderedincapableoffurtherdevelopment.Thereareestablishedchemicalmethodsforthe
euthanasiaoftadpolesprobablynotsuitableforthewidespreadusebyunskilledlabourers.Therefore, a method of trauma or rapid exposure to extreme heat may be appropriate, such as the decantingoftadpolesandtoadletsintomeshbasketscanberapidlyexposedtofire.Similarly,newly
metamorphed toadlets and small juvenile toads may require similar methods of euthanasia. Adult
toadsarelikelytobequiterobustanimalsandwillrequiremethodsensuringswiftdeath,probably
throughtrauma.Pithingand/ordecapitationusingspecifiedtoolsarelikelytobethesolution.Due
to the large numbers of toads that will need to be killed in this operation, the development of a
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spring-loadeddevisethancanreleaseaboltunderpressuretocauselethaltraumatothebrainmay
beaworthwhileinvestment.Obviouslydecapitationwithamacheteisamethodwellworthconsideration,asunskilledworkersareabletohandlesuchtools,andthestrategyavoidsdevelopmentand
manufacturing costs of alternative devices. Personnel training will ensure proper execution of any
chosenmethod(s)andensureunnecessarysufferingtoanimalseuthanizedasquickandpainlessas
possible.
Costsandlogistics:Verydifficulttoestimatewithoutfurtherinvestigationbutweimaginethetime
costofanimalethicsgroups,togetherwiththedevelopmentoftoolsislikelytocostintheregionof
US$10,000. The production of any tools to support eradication would require the manufacture of
hundredsofdevices.Theuseofavailabletechnologysuchasmachetedecapitationandtheuseof
fire for tadpoles/toadlets would significantly reduce this cost but must be approved by an animal
ethicsauthorities.
2.1.3Trackingtunnels
Purpose: Tracking tunnels are a low-tech method of passively detecting the presence of animals
throughtherecordingoftheirtracks.Althoughvisualsearchesandlocalreportsmaybeveryeffectiveasmethodsofdeterminingpresenceorabsenceatmoderatetohighdensitiesoftoads,weneed
tofocusonmethodsabletodetecttoadsatmuchlowerdensitiesavoidingfalsenegativeswhenassessingdistribution.SuchmethodshavebeenincreasinglyusedforthepassivemonitoringofherpetofaunainNewZealand(NZ).
Method:Trackingtunnelsaremass-producedcardswithacentralportioncoveredinpersistentink.
They work either passively, recording the tracks of whatever animal passes through them during
theirdeployment,orcanalsoincludealuretoincreasethelikelihoodofthetargetanimalentering
the tunnel. They are used extensively in New Zealand to monitor abundance of invasive rodents
baitedwithpeanutbutteranddeployedinlinesoftenatspecificspacingsforasinglenight(Fig.1).
Thetrackingcardsareplacedwithinplasticorcorflutetunnelsthatcaneitherbepurchasedorconstructed.
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Fig.1.AtrackingtunnelshowingrattracksinNewZealand.
Thesedevicescouldbetestedtoevaluatetheirusefulnessbydeployinglinesoftentunnelsatprescribed spacings (e.g., no less than 20 m) focusing on likely locations, such as against walls, within
vegetation,andadjacenttowaterbodies.Ideallythetoolwouldbetestedinareasofknowndensitiesoratleasthigh-densityandlow-densitysitesandwithinexperimentalenclosedareaswherevery
lowtoaddensitiescanbecontrolled,todeterminetheirusefulness.Asnotestedanuranlureiscurrentlyavailable,itisrecommendedtunnelsbetestedunbaited.Againthisavoidsattractingrodents,
whosetrackswouldpotentiallyobscuretoadtracks.Theinkdoesdryoutslowlyanddependingon
weather,tunnelsshouldberetrievedwithin3–5daysandtheirabilitytodetecttoadsassessed(e.g.,
how dry the ink has become, the level of print coverage from non-target animals). The tracks of
toadsshouldalsobecollectedbyencouragingcaptivetoadstotravelthroughtunnelssoobservers
havegoodreferenceprintsofdifferent-sizedtoadsaswellaslikelylocalnon-targetspecies(rodent
print patterns are readily available digitally, but other non-target native species, especially frogs,
wouldneedtobeobserved).Ifprovenuseful,thistoolcanbedeployedrelativelycheaplyatmultiple
locationsandislikelytoprovidegreatersensitivitytoatleastmoderatetoaddensities,comparedto
visualsearches.Itdoesnotseemthismethodhasbeenusedtomonitorthepresenceofamphibians
elsewhere;hence,theneedtotestthismethodisofutmostimportanceindeterminingitsusefulnessfortoadmonitoringpurposes.
Logisticsandcost:Theprimarylogisticalconcernisinterferencewiththedevices.Inurbanareas,the
publicmayremoveordisturbtunnelsoutofcuriosityandiftheconstructionmaterialsaredeemed
useful,theymaybecollectedforalternativeuses.However,iftheyaredeemedeffective,staffare
abletoidentifytoadprints,theinkremainseffectiveforasufficientperiodandtracksarenotregularly obscured by non-target animals, then they may be an appropriate detection tool. Their de60
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ploymentcostswilldependonthenumberofsitesdeployedandthenumbersusedateachsite.The
costsofexperimentallyevaluatingthesetoolsarehardtoestimate,butUS$5,000isprobablysufficient.Ifprovenusefulasamonitoringtool,asingleworkershouldbeabletodeploylinesoftentunnelspersiteatfourlocations/day,allowingtimeforcarefulplacement.Thiswouldinvolvethefollowingcosts:
•
50 tracking cards and 40 tunnels: US$470 (example costs: http://www.gotchatraps.co.nz/
theremaybemorecost-effectivelocalalternatives).
•
Vehiclecosts:US$240.
•
4xfulldaylabour(driverandworker,deploymentandcollection):US$80.
•
Totalperfoursites:US$790
Allfieldworkwillneedtoincludeacommunity-relationscomponentseekingpermissionfromlocal
landownersandcommunityleaders.Thismayaddadditionalcostspriortotunneldeployment.
2.1.4Acousticmonitoring
Purpose:Listeningfortoadcallsmaybeanextremelyeffectivewayofdetectingthepresenceofa
population of Asian toads. The development of remote acoustic recorders and analysis software
makesthistechniqueevenmoreeffectivebutwithsignificantaddedcost.Thetechniqueisonlysensitivetocallsofadultmalesandsowillbebestutilisedduringearlywetweatherperiodswhencalling frequencies are highest among males (advertisement calling). This is a passive monitoring tool
designedtobesensitivetolow-densitypopulationsinwhichonlyafewindividualsmaybecalling.
While accompanying a recorder with a system broadcasting toad calls may illicit call responses in
maleswesuspectthatsomethinglikefivedaysrecordingperiodwouldofferasimilarprobabilityof
detectionwithlesscomplexityandcost.Thetoolisexpensiveandlogisticallycomplex(seebelow)so
isonlysuitableforthetargetedanalysisofincursiondelimitationandpotentiallyinthemonitoringof
eradicatedareasinthefinalyearsoferadication.Foramajorityofsitesitwouldprobablybemore
appropriatetotrainlocalstafftolistenforandrecordtoadcallsandlocationstodescribetherange
andextentofbreedinghabitat.
Method: For the use of electronic recorders, there is a number of commercially available acoustic
recordersavailable,andwhichevermodelistobeevaluatedfirstneedstobetestedforitseffective
rangefordetectingthecalloftoadsunder“average”conditions(ambientnoiseofwind/rainetc.).
We then need to consider recording periods, as recorders can record continuously or only during
programmedtimes.Iftoadsaredemonstratedtoonlybecrepuscular/nocturnalcallersthentherecorders should be programmed accordingly. At the sites chosen in close proximity to potential
breeding pools, it will be necessary to have fieldworkers manually record the frequency of calls in
conjunctionwiththerecorderstodemonstratetheirsensitivityasadequate.Therecordersareunlikely to be as sensitive as the human ear (similar trials with kiwi call recordings in New Zealand
demonstratedthis)butwealsoneedtoknowtherecordersaresensitiveatleasttoanareaof50m
radius to be a useful monitoring tool. The greater the sensitivity the more useful the tool will be.
Some acoustic recorders have bespoke software for analysis, whereas other methods will require
theuseofsonogramanalysissoftwaresuchasRaven.Ifdemonstratedassufficientlysensitivetobe
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usedasamonitoringtool,thedeviceswillneedadeploymentstrategydesignedlikelytofocuson
proximitytowaterbodies.
For the majority of easily accessed sites it will be more cost efficient to train and dispatch local
workerstolistenforandrecordthelocationsoftoadbreedingpools.
Logisticsandcost:AcousticrecordingdevicesrangeinpriceandsensitivityfromtheUS$849Bioacoustics recorders (http://www.wildlifeacoustics.com/store?slider2=song-meter-sm3#song-metersm3) to much less expensive units, such as those developed by the Department of Conservation
(NewZealand),thatareavailableforUS$200perunit.Softwarecostsvarywithuse.Aswithother
device-reliantmethods,theprimarylogisticalconcernisinterferencewiththedevices.Inurbanareas,thepublicmayremoveordisturbrecordersoutofcuriosityortosell.Thisriskconsideredwith
thepotentialalternativeofusingfieldworkerstolistenandrecordtoadcallingmeansacousticrecordersareprobablyonlyusefulforsitessuspectedtobelowdensitytoadareasandsufficientlyinaccessible that costs of regular visitation and diminished risks of recorder loss or theft mean this
methodispreferable.Amajorcostofthistechniquewouldbetheanalysisofacousticdatagathered.
It also offers logistical challenges of staff access to computers and necessary training, making this
methodexpensiveandfortargeteduseonlyatperipherysiteswhereeffortsarebeingmadetodelimitincursionarea.
Asmentioned,itwillbemorecostefficienttodispatchtrainedstafftosurveyforcallingtoadsatpotentialbreedingpoolsandthiscouldbeachievedattheusualcostoftransportandtrainstafflabour
togetherwithcostsofdatacollation,analysisandreporting.
•
Using a vehicle and driver with a trained field worker (calculated at US$320) this would
probablyallowthesurveyingof3–4sitesperday.
2.1.5ENVIRONMENTALDNA
Purpose:Amajorconcerninthedevelopmentofincursionresponsestoinvasivespeciesistheability
toensuretheareaofincursionisfullydelimited.Severalmethodsareavailableforconsiderationas
described here, and possibly the most efficient and sensitive is the use of environmental DNA
(eDNA)sampling.Animalspermanentlyshedtissueandcellsintotheirenvironment,andthosewith
aquaticlifestylesshedtheirtissuecontainingDNAintowaterbodiestheyinhabit.ModernDNAamplificationtechniquesaresopowerfulandcosteffectiveitispossibletonowidentifythepresenceof
a species from a series of water samples. The power of this technique is obviously not to confirm
presenceof,inourcase,theAsiantoad,inawaterbodyinwhichtheyareabundantandeasilyobserved. The power of the technique comes when evaluating waterbodies of any size that may be
beingusedbyonlyaverysmallnumberoftoadsintermittently.Eveniftoadshavebeenabsentfor
severaldaysorevenweeks,theirDNAislikelytopersistinthewatercolumnandisavailablefordetection.UsingthismethoditispossibletodetectthepresenceofAsiantoadsinareasoflowdensity
orattheveryperipheryoftheircurrentrange.Poolsthetoadsareusingforbreedingwilllikelyhold
eggs and tadpoles at varying developmental stages, which promises to provide a strong molecular
signal of Asian toad presence. Fortunately, Madagascar does not contain Bufonidae congeners so
theprobabilityoffalsepositivesarealsoreduced.ThelongevityofDNAinsedimentsmeansthatthe
techniqueisofreducedvalueforfollowupmonitoringonceanareahasbeenclearedoftoadsalt62
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hough this issue has not been examined in tropical environments where degradation of DNA fragmentsmaybeaccelerated.
Methods: Sampling of waterbodies is a very straightforward procedure of collecting multiple samplesfromthewatercolumn.ConcernsexistthatDNAmaypersistinsedimentforextendedperiods
andsoinotherinstancescarehasbeentakennottodisturbsediment,asthiscancompromiseresults. This is less of a concern when delimiting species such as in our instance, unless we believe
theremayhavebeendynamicchangesintheareatoadsareoccupyingovertheperiodoftheincursion.Themainrisktothemethodiscontaminationbetweensamples,andthereforeasinglesiteuse
kitwouldneedtobedevelopedsothatcollectionequipment(dippers,etc.)andcontainersareonly
usedonce.Staffwillneedtobetrainedincollectionprotocolstoensuretheyareawareoftherisks.
Sampletransportandstoragerequiressamplesaremaintainedinachilledstate(2–4degrees)but
notfrozen.
We are not aware of the existing development of primers to sequence D. melanostictus samples.
Oncelabmethodsareavailableitisafairlysimpleautomatedprocessoftestingsamplestodeterminepresenceorabsenceoftoads.Laboratoryanalysisofsamplesisusuallybestdonecommercially,butthismaybeasituationwhereitisdesirabletodevelopskillsincountrythroughcollaboration
withMalagasyuniversities.
Logistics and Cost: The major logistical challenge with this method will be ensuring all staff are
trained in appropriate collection protocols and all samples are appropriately stored until analysis.
ThedevelopmentoflaboratoryfacilitiesinMadagascar,ifnoneexistcurrently,mayposesomelarge
challenges but none insurmountable with good collaboration with an experienced lab. The recent
useofeDNAtechniquestodelimitaninvasivenewtinNewZealandallowedustoaccuratelycostthe
methodology:
•
•
•
•
•
•
Technicaldevelopmentofprotocolstohandlesamples:US$8,000.
Sampleanalysisper100samplesUS$1,000.
Samplingequipmentkitsper1,000sitesUS$5,00023k.
Labourandtransporttocollectsamples(@fivesitesperday)US$320perday.
Samplestorageandtransport(guesstimateforfridges,etc.)US$2,000.
Totalfor1,000sitesUS$89,000
2.2DETECTIONANDELIMINATIONMETHODS
The following methodological proposals focus on tools necessary to remove toads from the environment.Toreiterate,whereasonemethodmayprovetobeextremelyeffective,itishighlyunlikely
tobeadequatetoremoveallindividualsofatargetanimalsuchastheAsiantoadthathassucha
rangeoflifehistorystagesrequiringnecessitatingdifferentmethodsofcapture.
2.2.1Detectionandremovalthroughdelimitedhandsurveys
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Purpose:TheAsiantoadispresentinsuchnumberswithinmuchoftheincursionareathesizeofthe
toadpopulationandlocaleconomymeanhandcollectionispotentiallyaviablemethodoftargeting
the animals. While toads are mostly active by night, it is potentially possible to search the habitat
duringthedayandachieveanacceptablerateofcollectiontojustifythismethodinclusionintrials.
Thismethodwouldrelyonlocallabourandprobablyactasanearlystagetoolforanyeradication
effort.Withlocallyrecruitedteamsoftoadcatchers,therewillbeaneedtoevaluatetheproportion
of toads collected in different ecotypes. Before the methodology can be considered as part of an
eradication plan it will be necessary to measure its effectiveness. Thus, there are two parts to the
discussionofthismethod:
Method:Testingmethodology-Totestthismethoditwillbenecessarytoidentifyexperimentalareasthatcanbeenclosedbytoad-prooffencing.Suchfencescanbeofthestandardamphibiandrift
fencetypebutmayneedtocoveranareaofatleastseveralhectarestoprovidethedatarequired.
Sites should be selected in areas of high toad density and preferably replicated in urban, ruralagriculturalandrural-unmanagedecotypes.Oncefenced,theareaissearchedbyasmallteam,and
alltoadslocatedarerecorded,removedandkilled.Followingthisknock-downoftheeasilydetected
individualstheareaissurveyedbyexperiencedstaffthatcollectasmanytoadsofallagestagesas
possible putting in maximum effort to ensure as many individuals as possible are located. As the
toads are detected, a second team implant PIT (Passive Integrated Transponder) tags into toads
largerthan40mmSVL.FortoadletssmallerthanthissizeweshouldconsiderimplantingVIFETs(VisibleImplantFluorescentElastomerTags)intothetoads.Alltoadsarethenreleasedattheexactsite
ofcapture.
Oncecompleted,theareaandtaggedtoadsareleftforaminimumoffivedaystoensuretheyreturn
tonormalbehaviourandrefugia.Atoad-collectionteamconsistingofatleastfourworkersperhectarethensearchtheareausingsomedestructivemeasures(e.g.,vegetationremoval)toremoveas
manytoadsasfound.Thedaysearchshouldberepeatedatdusk/nighttotrytointercepttoadsas
theybecomeactive.Thesearcheffortshouldberepeateduntilacompletesweepoftheareayields
nofurthertoadcaptures.
Analternativeandpossiblypreferredstrategywouldbetofindahabitatcurrentlyunpopulatedby
toads,buildtheexperimentalenclosuresandthenpopulatetheenclosureswithtoads,allofwhich
aretaggedandconductcollectionsurveysasdescribedabove.Theriskofthismethodistheneedto
populate experimental enclosures with toads but considering the extent of the current incursion,
thissmallpotentialexpansionisinconsequentialtotheinvestmentinmethoddevelopment.
Astoadsarecollected,theyarescannedforPITtagsandarecordmadeofeachindividualidentified.
Theresultswillbescrutinisedaccordingtotwoissues:first,theproportionofthetaggedtoadsthat
aredetected,andsecond,thenumberoftoadscollectedthatwerenotpittagged.Thefirstanalyses
willinformusofthesensitivityofmanualsearchingfortoadswiththeeffortinvested.Thenumber
ofuntaggedtoadswillhelpindicatetheproportionofthepopulationthatshouldbeexpectedtobe
difficulttodetectwithnon-intensivemethods.
Shouldtheproportionofthetaggedtoadscapturedprovetobeextremelyhigh,bywhich,consideringthe120km2areaoftheincursion,shouldbegreaterthan99%,andnountaggedtoadsaredetectedthenwewouldproposethatthemethodologyisappropriatelysuccessfultosuggestdeclaring
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eradicationfeasiblewithintheecotypeinwhichthetrialshavebeenconducted.Ideally,wewould
recommendreplicatingthetrialtoatleastthreelocationswithineachecotype.
To operationalise this method there will need to be considerable investment in the strategic deploymentofbarrierfencestoenableclearedareastobedelimited.
Logisticsandcost:Costsofatrialarelikelytobe:
Costpersite:Labour(12xdays6xlabourersatUS$20perday,includingoverheadcosts)–US$1,440.
Transport(12days@US$120perdayplusdriverat$20perday)–US$1,680.
Fencingmaterials(@US$20perlinearmeterNZmaterialcostsest.)-US$12,000.
Pittaggingequipment(US$4,000–includingreaderone-offcost)–US$2,500.
Total–US$17,620
One-offcosts
Scientific&fieldmanagement–US$8,000.
PitTagreader–US$1,500.
Soforthreelocationsthetotaltrialcostwouldbe:US$62,360
Theconceptofmanuallysearchingaminimumof120km2usingthistechniqueoveratleastthree
seasons entails the employment of probably hundreds of workers and enormous management,
communications, transport and administration structures. If we speculate that the delimitation is
achievable,thelabouravailableatUS$5perday,anditwilltakefourworkersanaverageoftwodays
toserviceeachhectare,then,byextrapolation,thecostsofthistechniquewillbeUS$240,000per
annumwithoutconsiderationofinfrastructure,transport,communicationsandadministrativecosts.
WewouldguessthetotalcostofthismethodandadministrationwouldapproachUS$1mperyear.
Therearemanylogisticalriskstothismethod,notleastthecomplexityofcoordinatingsuchahuge
labour force, negotiating access to all areas and ensuring a communication programme that preventsmisinformationortheunderminingofefforts.
Forthetrials,atechnicalriskhereisthenaturalejectionofPITtags,whichideallywouldrequireresearchonsub-cutaneousorintra-coelomicimplantationstodeterminewhichmethodworksbetter.
2.2.2Barrierfencingandpitfalltrapping
Purpose:Itwillbenecessarytodelimitareasthathavebeensearched,fromareasthathavenot,so
astopreventreinvasionoftoads.Itwillalsobenecessarytodelimitareasrequiringdifferenteradi65
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cationmethods,suchaswaterways.Delimitationwillneedtobemaintainedatascaleadaptedto
the areas being treated and maintained for the period of the eradication. The inclusion of pitfall
traps along such fences would enable the capture of any toads attempting to disperse within the
area.Aspecificfocusofthismethodwouldobviouslybebreedingpoolswhereitmaybepossibleto
interceptaveryhighproportionofthelocaladulttoadpopulation,iffencesandpitfalltrapsarewell
maintainedandserviced.
Method:Standarddriftfencedesignswillbeappropriateforthesebarriersbuttheuseofdurable
materialswillbenecessarytoensurelongevity.Thefenceswillneedtobedugintothesubstratea
short distance and their deployment should make use of natural barriers such as walls, or accesswayssuchasroads/tracks.Pitfalltrapscanbesimplebucketsdugintotheground,buttheirhumane
userequiresdailychecksandtheremovaloftoadsforhumaneeuthanasiaandthereleaseofnontargetorganisms.Thereisnoneedtotestbytrialthismethod,asitssuccessesanddesignarewell
documentedintheliteratureandbyourpersonalexperience.
Logisticsandcost:Theissuehereisfeasibility,scaleandtheissueofinterferencebypeople,vegetationandlivestockifdeployedforlongperiods.Thecostsofdelimitationarelikelytobelarge.Ifwe
assume that there is a small pool requiring fencing every five ha we would require approximately
US$660,000inmaterialandconstructioncosts.
The primary logistical concern is interference with the devices. In urban areas, the public may removeordisturbfencesforalternativeuses.
2.2.3Citricacid/Sucrosespray
Purpose:A16%citric-acidsprayisknowntobeeffectiveinkillingfrogswithmoistskinandhasbeen
usedtoeliminatepopulationsofCoquifrogs(Eleutherodactyluscoqui)inHawaiiformanyyears.The
methodworksbyinducingrapiddehydrationoffrogsduetoosmoticimbalancebetweenthespray
andtheinternaltissuesofthefrog.Theoretically,thissameosmoticeffectcanbehadwithanyconcentratedsolutesprayedonfrogs;hence,sucrose(sugar)mayalsobeusefulinthisregard,although
it remains untested for toads. Sucrose could be an attractive alternative, if effective, because it
shouldbeeasierandcheapertoobtaininMadagascar.However,neithersolutionhasyetbeentested on toads, which, because of their dry skin, may not be as susceptible to osmotic water loss as
mostfrogs.Hence,testsneedtobedonetoassesswhethereithersolutioncouldbeeffectiveforthis
purposeagainstD.melanostictus.
Ifeffective,thismethodislikelytobeofgreatestuseforrapidlytreatingthehighdensitiesofnewly
metamorphosedtoadletsastheyleaveandaccumulatearoundpondmargins.Treatingtheconspicuous adults with this method is liable to be no more effective than hand capture would be, so its
utilityislikelytobeprimarilyforhigh-densityconcentrationsoftoadlets.
Method:Simplelaboratorytrialssprayingahandfuloftoads(ca.teneach)witha16%citric-acidsolution or a 27% sucrose solution need to be tried. Toads would be housed in individual small containers,removedtosprayenoughtowettheirbacks,returnedtothecontainersandobservedfor
mortality/morbidityin24hrs.Iftoadsdonotdiewithinthattimeperiod,themethodwillbeineffectiveforcontrol.Testsofeachcompoundshouldbedonebothonasampleofadultsandasampleof
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newlymetamorphosedtoadlets.Adultswouldbetestedprimarilytoascertainspeciessusceptibility
tothemethod,eventhoughitisanticipatedthatthegreatestneedforthemethodwouldbeagainst
toadlets.Ifeffective,sprayingoftoadletswouldallowforrapidandeffectivekillingoflargenumbers
andavoidtheneedtocaptureeachsmallanimalwhenathighdensities.
Logisticsandcost:Bothcompoundsaresafeforhumanuseand,indeed,arepresentinnumerous
foods hence, concerns about human poisoning are virtually non-existent. If effective, either compoundwouldonlybeappliedtoterrestriallifestagesofthetoads.Experimentalcoststotestefficacy
areexpectedtobelowasallthatisrequiredarethematerialsandasampleof,forexample20metamorphsand20adulttoadsandbasiclabequipmentsuchasholdingtanksandspraybottles.Some
costwouldbeincurredensuringscientificoversighttoquantifytheconcentrationsandthelevelof
subjectexposure.Wewillalsohavetotesteffectiveapplicationmethods.Ideallythiswouldbedone
using helicopter mounted agricultural spray equipment but it is doubtful that such equipment is
availableinMadagascar.Therefore,weneedtoevaluatetheuseofbackpacksprayingandtheuseof
locallabour.CostsareestimatedtobeUS$8,000tocoverlabcostsandadvisorexpertise.
Aneducationprogrammewillberequiredtoensurethatlocalsareawaretheuseofthesprayposes
no risk to them or the environment so as to ensure that local support for the eradication is not
threatened.
2.2.4Acousticlocationandphysicalcapture
Purpose:Virtuallyallfrogsreproducebymalesattractingfemalestobreedviaacousticcalling.Callingamongmalesiscompetitive;hence,malesthathearanothermalecallarefrequentlyinducedto
callthemselvesinordertocompeteforthefemales’attention.Thisattributecanoftenbeusedto
surveyforfrogs:ifarecordingofthespecies’advertisementcallisplayed,nearbymalescanoftenbe
inducedtocallinresponse,therebyindicatingtheirpresenceinthearea.Thismethodcanpotentially be used to illicit toad calls during the breeding season even when they occur at low densities.
Hence,thisprovidesasensitivemeansofsurveyingthelimitsofthetoad’sdistributionaroundTamataveandalsoapossiblemethodforinterceptingmaletoadsatextremelylowdensities.
Method:Visitpotentialbreedingsitesatnightduringthewetseason,playthecallofthespeciesfor
ten minutes or so, and listen for responding males. If males are heard to respond, they should be
trackeddown,capturedandkilled.Withtwosearchersandalittleexperienceitisusuallyquiteeasy
totriangulatethelocationofacallingtoadandremoveit.
Logisticsandcost:Recordingsofthisspeciesarealreadyavailableontheinternet.Theymerelyneed
tobedownloadedorobtainedfromtheoriginalposterwithpermissionstouse.Equally,itwouldbe
veryeasytorecordcallsfromwithinthecurrentincursionarea.Equipmentneededwouldbeafew
digitalrecordershavingpowerfulenoughaudioplaybacktobroadcastthecallaroundsurveyedwetlands. Professional equipment is available for this purpose, such as the Foxpro
(http://www.gofoxpro.com/site/products/digital-calls/wf2), which is robust to field use and cost
US$200each.Costsfortheuseofthistechniquewoulddependonthenumberofteams,amountof
transportrequiredandthenumberofcallplayersrequiringpurchase(one/team,withafewbackups
in case of damage to original equipment). The method might be combined with remote acoustic
monitoringforthedetectionofextremelylow-densitytoadpopulations.
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2.2.5Tadpoletraps
Purpose:ResearchontherelatedCanetoadinAustraliahasshownthattadpolesofthatspeciesare
attractedtothechemicalssecretedbythepoisonglandsoftheadulttoad.Experimentshaveshown
ifthesepoisonsecretionsarecollectedonmicroscopeslidesandplacedinsideasmallaquatictrap,
tadpolesofcanetoadscanbecollectedinlargenumbers,evenremovingmostoralltadpolesfrom
smallpondswithinafewdays.WhetherthismethodcanworkforthespeciesoftoadatTamatave
needstobeassessed.
Method:Constructadozenorsotadpoletraps(designgiveninCrosslandetal.2012),collectadult
toadsfromwhichtoobtainpoisonsecretions,collectthesecretionsonmicroscopeslidesandplace
theslidesinthetrapsandthetrapsintestpondsknowntoharbourtadpoles.Checkthetrapsevery
day,removeandcounttrappedtadpolesanddeterminehowlongthetrapsremaineffectiveineach
pond.Ifsmallisolatedpondsaretestedbytrial,oncethetrapsareremoved,visuallycheckfortadpolesorusefinenetstocheckforefficacy(i.e.,howmanytadpolesremain).
Logisticsandcost:Thismethodshouldbeabletobetestedinfairlycost-effectivemannerin“lab”
conditionspotentiallysomewhereliketheParcIvoloinabylocalresearchers.Costswillbethematerialstoconstructthetraps,microscopeslides,oneboxoflatexsurgicalgloves,labourandvehicleto
collecttadpoles/toadsanddeploythetraps.AnestimatewouldsuggestabudgetofUS$5,000would
coverfieldandlabcostsforamethodstrialthatdeterminedrelativeeffectivenessunderdifferent
environmentalconditions.
2.2.6Herbicide
Purpose:Itmaybeappropriatetoconsidertheuseofcertainherbicidestoclearriparianvegetation
surroundingwaterbodiesusedbytoadsforbreedingandalsofortheclearanceofdensevegetation
thatotherwiserestrictstheabilityofsearcherstoexamineandcapturetoads.
Method: Standard application of glyphosate herbicides such as Roundup can be used. The use of
suchchemicalsaroundwaterbodiesiscontentiousandsoformulationswithhigherglyphosateconcentrationsandnosurfactantshavebeendeveloped.
Logisticsandcost:Labourandchemicalcosts,togetherwithsometrainingofoperators,wouldresult in a per ha cost that will be influenced by the cost of locally acquiring glyphosate herbicide.
Planningandtransportwouldbeadditionalcostsand,duetothevisualimpactsandpotentialecologicalimpacts,bothlocalecologicalassessmentandaconsultationandcommunicationplanwould
needtobecomponentsofthiswork.Weimaginethetotalcostsofthismethod,ifappliedbroadly
withintheincursionarea,wouldbeintheregionofUS$100,000,consideringtheopportunitiesfor
itsuse.WearenotawareoftheenvironmentallegislationthatmayexistinMadagascartodescribe
thelimitsofuseforsuchmethods.
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Fig.2.Asiantoadeggstringsinsmallpond,HongKong.Photo:LungFuShanEnvironmentalEducationCentre.
2.2.7Eggcollection
Purpose: Prior to hatching into tadpoles, Asian toad eggs may be able to be efficiently collected,
thus reducing population productivity in areas where the toads breeding pools can be easily accessedandsearched.ThismethodhasbeenusedasacomponentofsuccessfulBullfrogcontrolprogrammes in North America but we acknowledge that the Asian toad is known to lay eggs at all
depthswithinwaterbodies(Fig.2)andsotheeffectivenessofsuchcollectionmightberestrictedto
smaller,shallowwaterbodies.
Method:Workerswouldvisuallysearchwaterbodieswithbagsorbucketsintowhichtheeggsare
collected.Acost-effectivemethodofdestroyingtheeggswouldbedesiccationinthesun,buryingor
incineration.
Logisticsandcost:Labourandtransporttosites.ItmustbenotedthatthismethodwillbequestionableifAsiantoadslayeggsatvaryingdepthsinwaterbodies.Also,itwouldrequirethesearchingof
allwaterbodiesinanyareadelimitedassuitable.Theproximityofanylargeunsearchedwaterbodies
andevenamodestnumberofsmallerwaterbodieswouldquicklynullifyanyeffortsmadeduetothe
numbersofeggsproducedbyAsiantoads.
2.2.8Refusemanagement
Purpose: The incursion area in and around the port city of Tamatave has a serious urban refuse
managementproblem.Althoughthisissueislikelytobeahumanhealthissue,itisalsoapotential
reservoirandvectorfortheAsiantoad.Refuseappearstoaccumulatealongroadwaysintheurban
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areasandiscommunallydumpedatsitesaroundtheperipheryofthecity.Thesepilesofrefuseprovidehabitatfortoadstoseekrefugeandareextremelychallengingtosearchfortoadsbecauseof
their complex and hazardous nature. The transportation of waste to these sites is also a potential
vehicleforthespreadoftoads.Therefore,werecommendthatrefuseclearanceanddisposalprotocolsbedevelopedfortheincursionsitethatdonotriskspreadingthetoadsfurtherandusemethods
todestroytoadsconcealedintherefuse.
Method: The details of this proposed method require civil engineer input, but we will tentatively
suggest conventional land-fill type disposal of refuse accompanied by the rapid covering with soil
couldbeasolution.Currentlythereisaprogrammeofworkthatistakingrefusetothetailingsdisposal site of the Ambatovy nickel processing plant. This might be appropriate, but to prevent the
spreadoftoads,thisprogramshouldbeevaluatedintermsofthesecurenatureofthetrucksused
to transport the refuse and also the timeframe from refuse dumping to coverage. This should be
doneswiftlyenoughtopreventtoadsescaping.DataprovidedbytheAmbatovyMinesuggeststhat
thetransportofrefusetothesitehasalreadyspreadAsiantoadstothearea.
Logistics and cost: Local civil authorities and municipal engineers would be necessary to properly
designandcommentonthissuggestion.
2.2.9Toaddogs
Purpose: To those with limited experience in vertebrate eradications, the suggestion of training a
“toaddog”mayatfirstappearexpensiveandinefficient.However,shouldaneradicationeffortbe
undertaken and prove to be making positive progress towards success, then the training of toad
dogsmayprovetobeextremelyusefulforthelocationofthefinalindividuals.Dogsarewellrecognisedfortheirolfactoryskillsandabilitytobetrainedtoaspecifictarget.Althoughthereisnoreasontobelievetoadsposeaproblemtothistechnique,itmustbestatedthatitwillbeessentialto
useoperatorswithexperiencetooverseeatoad-dogprogramme.
Method:WhiletraineddogscouldbebroughttoMadagascaritisprobablybesttoconsiderengagingthetimeofanexperiencedhandler/trainertoworkoveraperiodofmonthswithaprospective
handlerandcandidatedogsinMadagascar.Wecan’tdeterminewhetherMadagascarhasanexisting
detector dog programme attached to either the military or other government agencies. A method
thathasprovidedquickresultsinNZistheretrainingretiredsecuritydogsthathavedemonstrated
their ability in detecting explosives/narcotics. This has been achieved with retired bomb-locating
dogsinNZforlocatingtheinvasivealpinenewt.Itwilltakeatleastayeartosuccessfullytrainadog
tobeareliabletoaddog,andprovisionmustbemadetomaintaintheskillsofanydogtrainedfor
thedurationoftheeradicationprogramme.Itiscriticalthattheeffectivenessofdetectordogsbe
determinedthroughcontrolledtrials.
Logisticsandcost:Internationalexpertisewillbethelargestcostinvolvedinthismethod.Wewould
estimate that training would require at least three extended visits by a trainer, which if obtained
fromacountrysuchasNZ,wouldprobablycostintheregionofUS$90,000forthreevisits,eachof
aneightweekduration(includingflights).
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2.2.10Cappingwaterbodies
Purpose:Theincursionareaisunfortunatelyinanareawithagreatdealofstandingnaturalwater
and drainages, which provide obvious obstacles to any amphibian eradication. However, in many
areas,includingurbanareas,itmaybepossibletodrainandfillsmalltomedium-sizedwaterbodies
thatareofnomunicipalorsignificantecologicalvalue.Thismayhavethedualbenefitofreducing
potentialbreedingsitesfordiseasevectoringmosquitoes.
Method: Civil engineer engagement will be essential for larger projects, but smaller waterbodies
should be easily drained using conventional wajax pumps and earth-moving equipment to fill and
captheareawithsoil/substrate.
Logisticsandcost:CostswillbeaspercivilengineeringcostsinMadagascar.Nodoubttherewould
be challenges of obtaining skills and access to a plant in a location like Tamatave. Communication
andconsultationwithlocalcommunitieswillbeessentialforthismethod.
2.2.11Chemicaltreatmentofwaterbodies
Purpose:AstadpoletrapsareasyetuntestedforAsiantoads,itisimportanttoconsideradditional
means of targeting tadpoles. One method worth consideration is the use of rotenone or similar
compounds to kill tadpoles. Rotenone is only effective on individuals with gills and so will not be
equallyeffectiveforalldevelopmentalstages.However,theuseofsuchamethodhasgreatapplicationforwaterbodiesotherwisedifficulttosearchoraccess.InNewZealand,wearecurrentlyconductingtrialsfortheuseofrotenonewithnewtlarvae.Weshouldalsoconsiderwhetherthereare
existinglocalmethodsusingplantbasecompoundsforfishingpurposes.
Method:Thereisliteratureavailabletoinstructontheuseofrotenoneforthecontroloffishthat
couldbeeasilyadaptedforthispurposeintadpoles.Itwouldbeveryusefultosequentiallyexpose
Asiantoadtadpolestoknownconcentrationsofrotenoneatdifferentdevelopmentalstagestodetermineefficacy.Wealsorecommendinvestigatinglocalmethodsofchemicalfishcapture.Itmaybe
thatlocalplantsorplantbasedsubstancesarecurrentlyusedandthereforearesociallyacceptable
andappropriateforourpurposes.Standardcontrolledmethodsinvolvingtheengagementofskilled
individualssuchasDevinEdmondsoftheAssociationMitsinjowouldseethiseasilyachieved.
Logistics and cost: Material costs for a lab trial should not be high in that all is required are small
containers, basic husbandry skills and rotenone. If rotenone is not available in Madagascar, there
may be some issue with its importation. The operationalisation of the method involve transport,
planning and chemical costs that are difficult to estimate but probably are comparable to the described survey methods. A major risk could be community perceptions and consequences of this
method,especiallyiflocalcommunitiesrelyonfishfromthesewaterbodies.
2.2.12Toadtraps
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Purpose:Whilesomeofthemethodsproposedfortestingherearedesignedtoreduceorremove
access to breeding pools we may use the toads natural ability and need to locate waterbodies for
breedingasatrappingopportunitythroughtheconstructionoftemporarywaterbodies.Thesemay
be specifically suitable for use in locations where other waterbodies have been capped and this
strategyiscurrentlybeingusedinNewZealandtointerceptalpinenewtswhosebreedingpoolshave
beendrainedandcappedtosomesuccess.
Method:Itmaybepossibletodesignanddeveloptrapsforbreedingtoadsifwaterbodiessuchas
barrels are used as an attractive source of water, surrounded by easily searched refugia to retain
toadsneartheinaccessiblewatersourceandaccompaniedbytoadcallrecordingstoattractbreeding females and males. The trap sites would then be either surrounded by a helical fence to help
containtoads(Fig.3)or,ifhabitatallowsaone-way“drop-wall”thatpreventsthetoadsfromleaving. Refugia should be complex and solidenoughtoprovidegoodcoverandsuitablemicroclimate
for toads so they are not encouraged to try to leave the traps. The retaining wall structure of the
dropwalldesignshouldbeconstructedoffirmplasticormetalsheetingtoensureanunclimbable
surfaceismaintained.Thedropwallshouldbeatleast40cmdeepanditwouldbeworthwhiletestingthetoadspreparednesstoentertrapswithdifferentheightwallstoensurewehaveanoptimum
heightforcaptureandretention.Ifplasticmineralbarrelsareusedasawaterbodybybeingcutverticallyinhalfthenthesurfaceareaofwaterwouldapproach2.5m2whichhopefullyissufficientwatertoactasanattractant.Suchtrapswillworkbestwhendeployedwithdriftfences.
Drop-walltrap
withmetal/plastic
wall
Drift-fencetrap
Artificialrefugia
Driftfencetohelpcontainattractedtoads
Artificialwaterbodynot
accessibletotoads
Waterbodyaccessible
totoads
SIDEVIEWPLANVIEW
Fig.3.Twotoadtrapdesigns,adrop-walltrapandadriftfencetrapwitheasilysearchedrefugia.
Logisticsandcost:Theconstructionoftoadtrapsneednotbeterriblyexpensiveorcomplicated.The
issuesforbothdesignswillbetheregularcheckingoftrapsforcollectionanddestructionoftoads.
The“drop-wall”designwillneedsomemaintenancetoensurethatthetrapsremaineffectiveand
thedriftfencetrapwillneedbothmaintenanceandregulartoadcheckingastheyaremoreableto
escape from this design. It is estimated that a team of three workers could construct these traps
quickly so that 3–4 might be constructed per day. Allowing for US$100 materials per trap and the
labouroftwoworkersplusadriverandvehiclewewouldexpecttheconstructionofthesetrapsto
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costUS$520perdayorUS$130pertrapwithoutservicingcosts.Itmightbepossibletocontractlocalcommunitiestoservicethesetrapsandkeeprecordsoftoadscapturedanddisposedof.
Foratrialofthemethodswewouldwanttocloselymonitortoadentryandanyescapesfromthe
trapspreferablywithinanenclosedareacontainingmarkedtoadssowecanevaluatetheeffectivenessofthetrapsovertimeandparamteriseexposuretimestomaximizecapturesofbothsexesand
ofthemaximumdemographicrange.Withexpertinvolvementandfieldtimethisworkisexpected
tocostnomorethanUS$10,000.
2.3Prioritisationofmethodsandproposedtestingschedule
Thepurposeofproposingthetestingofmethodsistoreducetheriskofcommittingtoalargeand
expensivebodyofworkwithoutknowingthatwehaveappropriatetools.
1. PHASEONE–TESTINGANDCAPACITYDEVELOPMENT:Raiseinitialfundsandcreatecapacity to test key eradication and detection tools to evaluate options to eradicate Asian toad.
Thisworkshouldstartimmediatelyandbecompletedwithin12months.
2. PHASETWO–ERADICATION:Iferadicationisviable,fundraisewhiledevelopingastrategic
plantodeploydetectionanderadicationtoolsfortheremovalofAsiantoadswithaprobablefieldcommitmentofthreeyears.Iferadicationisnotfeasible,thenresearchintomitigationandimpactsbecomethepriority.Theeradicationoperationisnecessarilyiterativeinits
progressinformedbylevelsoftoaddetections.Weguessthatitwilltakeatleastthreeyears
oftheapplicationofmost,ifnotallofthetoolsdescribedheretoprogresstoapointwhere
toadsarenolongerdetected.Iftheratesofdetectiondonotdiminishaccordingtoexpectationthentheprojectwillneedre-evaluation.Howevertheprojectshouldbeevaluatedannuallyforperformanceagainstgoalsandexpectations.
3. PHASETHREE–POSTERADICATIONMONITORING:Afterhopefullythreeyears(orless)of
eradicationoperationsnomoretoadswillbedetectedbytheexistingsurveillancemethods.
At this point the programme needs to prioritise toad detection across the entire incursion
areaandmaintainastrongcommunicationstrategytoensurethatanyresidualtoadsarelocatedanddestroyed.Thisphasecouldeasilylastforadecade.
Byadoptingaprocessthatfirsttestsefficacyofpotentialeradicationtoolsandifprovedineffective,
wecanabandonthegoaloferadicationwithclearandquantitativereasonsforsuchadecision.
Duetothecostsofemployingthesetechniques,itwillbeimportanttoimplementtheleastexpensive and most efficacious (by area) methods as early as possible, delaying use of more costly
measuresuntiltherearefarfewertoadstobelocated.Itisalsoimportanttoensurethemethods
usedlaterinaneradicationprogrammeareadequatelysensitivetotoadstobeeffectivefortoadsin
extremelylowdensity,aswewouldhopetheywouldbebythefinalstagesofaneradicationeffort.
Wealsohavetoconsidermonitoringandresponseoptionsforevaluatingeradicationresultsacross
the incursion area and triggers for declaring success or abandonment of the project. Although the
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methodsproposedheremightcompriseaneradicationeffort,weneedclearmeasuresofsuccessor
points of failure. We estimate that even if the proposed methods prove extremely successful, it is
likelytorequireatleastthreeyearsoferadicationefforttoachieveaneradicationoutcome.However,withourabilitytodetecttoadsatextremelylowdensitiesuntested,wemustbepreparedforat
leastafurtherthreeyearsofmonitoringtoensurethatnosmalltoadpopulationswereabletoescapetheeffort.Methodsofmonitoring,asdescribedabove,areasyetunprovenforextremelylowdensitytoadpopulations.
Therefore,weproposethefollowingimmediateactions:
1) Designate the governance group and invest inoperational capacity building with local organisationbasedwithintheincursionarea.
2)IdentifycollaboratorsandsupporterstobeginPhaseOneofmethodologytestingthatwillexamineattheveryleast,thefollowingmethods:
•
Handcapturemethods.
•
Testofcitricacid/sucrosespray.
•
Testoftoadtraps.
•
Testoftadpoletraps.
And equal priority is the development of a national communication and response plan to identify
anysatellitepopulationsandtopreventfurtherinadvertentspread.
It is also critical that drift fencing and toad capture programmes be developed and installed at all
majorwaterbodiessuitablefortheirbreedingpriortothenextrainyseason.
AttheendofthePhaseOneoperationalperiodsoatminimum,beforeJuly2016,theexpertgroup
mustconvenetoevaluateresultsandconsidertheevidenceforproceedingtoafulleradicationplan.
Accompanying this must be a strategic plan for the eradication operation that is informed by trial
outcomes.
3Budgetplanning:
Yearonecostestimates.
Infrastructurefororganizationoverseeingoperations.
Inthecostdeterminationdetailedabovelabourhasbeenaccountedfor,forthetrialefforthowever
otherdemandsmustbemetbythehostorganizationandthesemustbecostdetermined:
ProjectmanagerFTE(fulltimeequivalent)
US$35,000–75,000
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AssistantmanagerFTE McClellandetal.2015
US$8,000
US$4,000
Humanresources(employmentandpay)FTE
US$5,000
Communityliaisonstaff2.0FTE US$6,000
AccountantFTE
US$6,000
DriverFTE
US$2,400
Additionalofficespace US$12,000
Communicationsmaterials
US$1,000
InternaltravelbetweenTanaandTamatave
US$3,000
4WDrental/purchaseoneyear US$15,000
Computingcapacity
US$3,000
Datamanagementcapacity0.5FTE
Communicationscosts(postage,internet,phone)
US$1,000
GISoperator
US$8,000
Consultation(time&traveloferadicationexperts)
US$40,000
Evaluationworkshopandsupport(foryearonereview) US$60,000
INFRASTRUCTURE&SUPPORTTOTAL US$243,400
Minimumessentialoperationalcostsyearone
Testhandcapture
US$62,360
Densityestimation
US$3,760
Testcitric/sucrosespray
US$8,000
Testtoadtraps US$10,000
Testtadpoletraps
US$5,000
Communicationplanandbiosecuritydevelopment
US$6,000
Furtherdelimitationeffort(usingcombinedmethods) US$15,000
OPERATIONALTOTAL US$106,360
Contingency(10%)
US$32,000
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YEARONEPROJECTTOTAL McClellandetal.2015
US$385,520
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