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Hihi(Stitchbird)BreedingonTiritiri
MatangiIsland
2015–2016BreedingSeason
MhairiMcCready1&JohnG.Ewen1,2
1) InstituteofZoology,ZoologicalSocietyofLondon,RegentsPark,NW14RY,London,UnitedKingdom.2) Contactemail:[email protected]
Suggestedcitation:McCreadyM.andEwenJ.G.2015.Hihi(Stitchbird)BreedingonTiritiriMatangiIsland:2015-2016BreedingSeason.InternalReport.DepartmentofConservation,NewZealand.Note:ThereisadataembargoinplacesopleasecontactJohnEwenpriortousingdatareported.
©MhairiMcCready
1. Summary1.1KeyresultsforthecurrentyearThisseasonhasseenafurtherdeclineinthenumbersofhihionTiritiriwiththepre-breedingcensusprovidingnumbersaslowasthosein2004.Productivityhoweverwashigherthanthepreviousseasonandnumbersoffledglingsproducedperfemalewasthehighestforthelast5years.Onthecontrarytothisthepercentagehatchingsuccesswasatanall-timelow.129and141individualswererecordedintheSeptember2015andFebruary2016censusesrespectively.Thefirsteggwaslaidon20thSeptember2015andthelastchickfledgedon15thMarch2016,thiswasalongandextendedbreedingseason.
Table1NumberoffemalesbreedinginthepopulationonTiritiriMatangi
Firstyearfemales Olderfemales SeeninSeptembersurvey 9 29 Breedingthisseason 13 40 Fledglingsproduced 18 112 1.2Pit-taggingTheapplicationofpittagshascontinuedthisyear;theyareembeddedinplasticcolourbandswhichareslightlylongerthanthosetraditionallyused.Thesebandsactasuniqueidentifiersfortheirbearers,whichcanbereadwirelesslybyadataloggermounted,forexample,onafeeder.Thistechnologywouldallowforricherandmoreaccuratepopulationdata,amongstotherpossibilities.Allbuttwooftheadultmalepopulationhavebeentaggedashaveallofthejuvenilesfromthisseason.Allofthetagshavebeenappliedintheabovemetalposition.Therehavebeenslippagesoverthemetalandintwocasesdownontothefoot.Theseslippageswerefromtagsthathavenotbeenweldedandworkcontinuestocatchallbirdsandweldtheirpittagsandcolourbands.Theremaybeanoptiontomovetoasmallerpittagsizetofurtherreducetheriskofslippages.
2. Introduction2.1BackgroundThehihi,orstitchbird(Notiomystiscincta),isanendemicforest-dwellingpasserinethatwasoncefoundthroughoutthenorthisland.Thespeciesdeclinedrapidlyinthelate1800sduetoalossofhabitat,introducedpredators,andpossiblydisease.Theonlyremainingnaturallyoccurringpopulationisonlittlebarrierisland.Inaddition,therearefivetranslocatedpopulationsmaintainedonTiritiriMatangiIsland,KapitiIsland,KarorisanctuaryinWellington,MaungatautarinearHamilton,andBushyParknearWhanganui.Hihiaresexuallydimorphic,territorialcavitynesterswithamatingsystemcharacterizedbyextra-pairandforcedcopulations.TheybreedbetweenSeptemberandMarch,averagingtwoclutchesof4-5eggseach.Hihiforagefornectar,fruitandinsectsandtranslocatedpopulationsrelyheavilyonprovisionedsugarwaterintimesofscarcity.2.2SitedescriptionTiritiriMatangiisa220hectareislandroughly3kilometreslongandonekilometrewide.ItislocatedintheHaurakiGulf,28kilometresnorthofdowntownAuckland.Extensivelyfarmedinthe1900’s,Tirihasbeenreplantedwithover280,000treessince1984inanattempttorecreatetheoriginalnorthernbroadleafcoastalforest.TheremnantmatureforestonTiritiritiMatangiisdominatedbykohekohe,taraireandpohutakawa.Otherspeciesontheislandinclude:taupata,karamu,hangehange,mahoe,mapou,whau,ngaio,puriri,totara,rewarewa,hoheria,hinau,pigeonwood,kowhai,karo,akeake,manuka,kanuka,kawakawa,fivefinger,houpara,wharangi,rangiora,cottonwood,mingimingi,taurepo,nativebroom,koromiko,kumarahou,astelia,flax,muehlenbeckia,nativejasmine,supplejack,andtreeferns.TiritiriMatangiisfreefromintroducedpredators,althoughthereareseveralpairsofmorepork(Ninoxnovaeseelandiae)andtheyareknowntoeathihi.Twospeciesofhoneyeater,tui(Prosthemaderanovaeseelandiae)andbellbird(Anthornismelanura),occurnaturallyonTiriandcompetewiththehihiforfood.Aggressivebellbirdsregularlydisplacehihiatthesugarfeeders.Tui,however,areexcludedfromthefeedercagesbyvirtueoftheirlargersize.
2.3PersonnelThe2015-16breedingseasononTiritiriIslandwasmanagedandmonitoredbyMhairiMcCready.VictoriaFrankswascontinuingherPhDfieldworkandwasherethroughoutthebreedingseason.Volunteersthisseasonwere:ChristineFriis,KateLee,KerynMcCrackenandEmilieVergauwe.Volunteerhelpisalwaysusefulandappreciated.Allvolunteerswerecompetentinthetaskssetforthem.ThesevolunteerswereorganisedbyMhairiMcCreadyandDaveJenkins(islandranger),asthenormalroutethroughDOCwasnotworking.Unfortunatelythismeantthevolunteersarrivedlateintheseasonafterthebusiestbreedingtimewheretheycouldhavebeenagreaterhelpandhadamorecompleteexperience.
3. Methods3.1SurveysApre-breedingsurveyandapost-breedingsurveywereconductedattheendofSeptember2015andFebruary2016.Eachoftheseinvolvedapproximately40person-hoursspentrecordingbandcombinationsofbirdsfoundthroughoutbushpatchesandatsugarfeeders.Aless-experiencedvolunteerwasenlistedfortheFebruarysurvey.Atrialofrecordingbirdsusingtheirpittags,antennaanddataloggerssituatedatsugarfeederswascarriedoutalongsidetheFebruarysurvey.3.2DistributionandplacementofnestboxesAllmajorbushpatchesontheislandcontainhihinestingboxes.Nonewboxeswereinstalledthisseason,thereare190boxescurrentlyspreadacrosstheisland,whichismorethanenoughboxesavailableforthepopulation.3.3NestsitemonitoringCompletednestswerecheckedalmostdailyuntileggswerelaid.Wheneggswerefoundtobewarmorthefemaleobservedsittingformorethan10minuteson2consecutivedaysincubationwasconfirmed.Thesenestswerenotcheckedagainuntilday13ofincubation,afterwhichtheywerecheckedeverydaytocheckforhatchinganduntilthechickswere10daysold.Afterday10thenestswerecheckedevery-otherdayuntilday21whenthechickswerebanded.Afterbandingthenestswerenotcheckedagainuntilday29andeverydaythereaftertodeterminefledgingdates.3.4NestboxmaintenanceThirtythreenestboxeswerereplacedwithnewoneastheyhadbeenoutinthebushforsixyears.Allothernestboxeswerecleanedatthebeginningoftheseason.Duringtheseasonallboxesthathadbeenusedforabreedingattemptwerebroughtbacktobaseandscrubbedwithwater,sprayedwithtrigeneandlefttodryinthesunfor24hoursbeforebeingreturned.Thebackboardswerescrubbedandsprayedwithtrigeneatthetimeofboxremovalsotheycoulddrybeforetheboxwasreturned.3.5SupplementaryfeedingregimeSugarwaterwasprovidedadlibituminchicken-feeder-styleplasticfeedersplacedinfeedingstationsat5-6locationsontheisland.Feederswerecleanedinhotsoapywater,rinsed,andthensprayedwithtrigene,allowingaminimumof5minutescontacttime.Thesewerethenrinsedandlefttodry.FeedingstationswerecleanedanddisinfectedwithtrigeneonMondays,WednesdaysandFridays.3.6BandingandmeasurementsNestlingswerebanded,weighed,measuredandhadblooddrawnat21daysold,onafewoccasionsday22or23.Tarsusmeasurementswere“tothenotch”and“fulllength”;“head-to-bill”wasmeasuredfrombackoftheheadtothetipofthebeak.Eachnestlingwasgivenac-sizemetalband,agreypittagandacombinationof2plasticcolourbands.Allplasticbandsweresealedusingthenewweldingmethod.ForalistofbandcombinationsandmeasurementspleasecontactJohnEwen([email protected]).3.7HealthMitecontrolwascarriedoutthisyear.NestlingswithmitesweretreatedwithfrontlinetwiceBeforenestboxeswerereplacedwithnewboxes(asdetailedin3.4)andnestsreplacedwithafakenestmadefromwiremeshandpolarfleecefollowingtheSOP.Onlytwonestsrequiredtotalreplacementsuggestingthemiteinfestationsthisseasonwerelow.Fourbirds(2male,2female)werefounddeadthisseasonandonemalefoundsickwhichlaterdiedincaptivity,necropsyreportsarefoundintheappendix.
4. ResultsVisitornumberstoTiritiriMatangihavebeenestimatedusingthenumberofpassengerstravellingontheferry,thiswas30,525for2015.
Figure1Numberofnests,eggs,chicksandfledglingsproducedonTiritiriMatangifrom1997to2015
Figure2HatchingsuccessonTiritiriMatangifrom1997to2015
Figure3NumberofbirdsrecordedeachyearonTiritiriMatangiduringthetwoannualsurveysfrom1997to2016.Notethatthesurveyof09/10tookplaceimmediatelyafterjuvenilesweretranslocated;thesinglediamondshowsthesurveyresultincludingthoseremoved.
Theresultsofthetrialsurveymethodusingdataloggersandantennaonthefeedercageswere:48individualsrecorded,10ofthesewerenotsightedbyobserversand1malehadnotbeenseenallseason.
5. ColourbandlossThelossofoneormorecolourbandsfromanindividualhihiresultsinanincompletecolourcombination,makingidentificationduringpopulationsurveysandbreedingmonitoringambiguous.Thisproblemhasincreasedinrecentyearstothepointthat26%ofbirdsrecordedintheSeptember2014surveyweremissingoneormorerings.Duringthe2014-15seasoneffortsweremadetoreducethisproblemandbandswerefixedwithsuperglue.DuringtheSeptember2015survey19%ofbirdswerenotedasmissingoneormorebands,unfortunatelythisislikelytomeanthatthesupergluefixingwasunsuccessfulasalongtermsolution.Itwasdecidedthisseasontotrialheatsealingthejointoftheplasticband.Abatterypoweredsolderingironwasusedtomelttheplasticandformaweldedjoin.Alljuvenilesfromthisseasonand36%oftheadultpopulationhavehadtheircolourbandsweldedandsofartherehavebeennojointfailuresorlossofbands.Thetypeofplasticthebandsaremadefromhasaneffectontheeaseofmelting,theacetalbandsareeasiesttomeltandformthebestjoin.
6. AcknowledgmentsTheDepartmentofConservationandtheSupportersofTiritiriMatangi(SoTM)arecriticalcomponentsofthisproject.ManythankstoDaveJenkins,theever-supportiveTiriranger.SomanySoTMmemberswerehelpful,enthusiasticandinterestedasalwaysandweappreciatetheircommitmenttothehihiandthisislandproject.HihiconservationalsobenefitshugelyfromtheHihisponsors,WesfarmersIndustrialandNZSafetyLtd.
7. Appendix(necropsyreports)
