Hihi (Stitchbird) Breeding on Tiritiri Matangi Island · The hihi, or stitchbird (Notiomystis...

Hihi(Stitchbird)BreedingonTiritiri

MatangiIsland

2016–2017BreedingSeason

MhairiMcCready1&JohnG.Ewen1,2

1) InstituteofZoology,ZoologicalSocietyofLondon,RegentsPark,NW14RY,London,UnitedKingdom.2) Contactemail:john.ewen@ioz.ac.uk

Suggestedcitation:McCreadyM.andEwenJ.G.2017.Hihi(Stitchbird)BreedingonTiritiriMatangiIsland:2016-2017BreedingSeason.InternalReport.DepartmentofConservation,NewZealand.Note:ThereisadataembargoinplacesopleasecontactJohnEwenpriortousingdatareported.

©MhairiMcCready

1. Summary1.1KeyresultsforthecurrentyearThisseasonhasseenanincreaseinthenumbersofhihionTiritiriMatangiwiththepre-breedingcensusnumbershigherthantheprevioustwoyears.Productivitywasalsohigherthanthepreviousseason,anadditional10femaleswereobservedtobebreeding.Hatchingsuccesshasalsoincreased;mostlikelyduetoalowernumberoffemaleslayingsecondclutches,thisinturnincreasedthefledgingsuccessto53%.141and204individualswererecordedintheSeptember2016andFebruary2017censusesrespectively.Thefirsteggwaslaidon23rdSeptember2016andthelastchickfledgedon11thFebruary2017.

Table1NumberoffemalesbreedinginthepopulationonTiritiriMatangi

Firstyearfemales Olderfemales SeeninSeptembersurvey 26 22Breedingthisseason 30 32Fledglingsproduced 53 981.2PIT-taggingThedecisionwasmadeatthebeginningoftheseasontoremoveallPITtags,unfortunatelytheweldingmethodwasnot100%successfulonthetagsandsomeslippagesontometalbandsandfeetonceagainoccurred.Thisriskcoupledwiththeevidencethatsometagshadbrokenandwouldnolongerrecordthebird’spresencehasshownthatthetechnologyisnotyetatthestagetoprovidericherandmoreaccuratepopulationdata.HugeefforthasbeenmadetoremoveallPITtagsandonly13birdssightedintheFebruarysurveywerestillwearingtags.Workisongoingtoprovideanalternativetaggingmethodforthefuture.

2. Introduction2.1BackgroundThehihi,orstitchbird(Notiomystiscincta),isanendemicforest-dwellingpasserinethatwasoncefoundthroughoutthenorthisland.Thespeciesdeclinedrapidlyinthelate1800sduetoalossofhabitat,introducedpredators,andpossiblydisease.TheonlyremainingnaturallyoccurringpopulationisonHauturu-o-Toi,LittleBarrierIsland.Inaddition,therearefivetranslocatedpopulationsmaintainedonTiritiriMatangiIsland,KapitiIsland,Zealandia(Karori)inWellington,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,althoughtherearemanypairsofmorepork(Ninoxnovaeseelandiae)andtheyareknowntoeathihi.Twospeciesofhoneyeater,tui(Prosthemaderanovaeseelandiae)andbellbird(Anthornismelanura),occurnaturallyonTiriandcompetewiththehihiforfood.Aggressivebellbirdsregularlydisplacehihiatthesugarfeeders.Tui,however,areexcludedfromthefeedercagesbyvirtueoftheirlargersize.

2.3PersonnelThe2016-17breedingseasononTiritiriIslandwasmanagedandmonitoredbyMhairiMcCready.Volunteersthisseasonwere:AnneBoergers&ChristineFriis.Volunteerhelpisalwaysusefulandappreciated,bothvolunteerswerecompetentinthetaskssetforthem.Annevolunteeredforatotalof35daysthroughNovember-Januarywhichwasparticularlyhelpfulasshehadtimetolearnandimprove;shealsohopefullyfounditmorerewarding.Itisperhapssomethingtoconsiderforupcomingseasonsastheconsistencyofonepersonisuseful.ThesevolunteerswereorganisedthroughMichelleJenkinsonatDOC.ThreePhDstudentshavebeencollectingdataontheislandduringthisseason;AlexKnightsampled89hihiforparasitesduringOctober.VictoriaFranksreturnedforathirdandfinaltime,shearrivedinJanuaryandwillbeobservingjuvenilebehaviouruntilMay.CaitlinAndrewsalsoarrivedinJanuaryandiscollectingdataonindividualforagingpreferencesofthehihi.

3. Methods3.1SurveysApre-breedingsurveyandapost-breedingsurveywereconductedattheendofSeptember2016andbeginningofFebruary2017.Eachoftheseinvolvedapproximately40person-hoursspentrecordingbandcombinationsofbirdsfoundthroughoutbushpatchesandatsugarfeeders.3.2DistributionandplacementofnestboxesAllmajorbushpatchesontheislandcontainhihinestingboxes.Twonewboxeswereinstalledthisseason,toprovideasecondboxinterritoriesthatonlyhadoneandwerebeingusedbyfemales.Thereare192boxescurrentlyspreadacrosstheisland,whichisadequateforthepopulationsizeasitstands.3.3NestsitemonitoringCompletednestswerecheckedalmostdailyuntileggswerelaid.Wheneggswerefoundtobewarmorthefemaleobservedsittingformorethan10minuteson2consecutivedaysincubationwasconfirmed.Thesenestswerenotcheckedagainuntilday13ofincubation,afterwhichtheywerecheckedeverydaytocheckforhatchinganduntilthechickswere10daysold.Afterday10thenestswerecheckedevery-otherdayuntilday21whenthechickswerebanded.Afterbandingthenestswerenotcheckedagainuntilday29andeverydaythereaftertodeterminefledgingdates.3.4NestboxmaintenanceTwenty-fivenestboxeswerereplacedwithnewastheyhadbeenoutinthebushandusedforbreedingattemptsforfiveyears.Allothernestboxeswerecleanedatthebeginningoftheseason.Duringtheseasonallboxesthathadbeenusedforabreedingattemptwerebroughtbacktobaseandscrubbedwithwater,sprayedwithtrigeneandlefttodryinthesunfor24hoursbeforebeingreturned.Thebackboardswerescrubbedandsprayedwithtrigeneatthetimeofboxremovalsotheycoulddrybeforetheboxwasreturned.3.5SupplementaryfeedingregimeSugarwaterwasprovidedadlibituminchicken-feeder-styleplasticfeedersplacedinfeedingstationsat6locationsontheisland.Feederswerecleanedinhotsoapywater,rinsed,andthensprayedwithtrigene,allowingaminimumof5minutescontacttime.Thesewerethenrinsedandlefttodry.FeedingstationswerecleanedanddisinfectedwithtrigeneonMondays,WednesdaysandFridays.Allfeedercageswerebroughtbacktobaseforathoroughdeepcleanonceduringtheseason,thewoodwaspermeatedwithsugarresidueandpooanditwouldbeadvisableforadeepcleantobeonamoreregularbasis.3.6BandingandmeasurementsNestlingswerebanded,weighed,measuredandhadblooddrawnat21daysold,onafewoccasionsthechickswerenotlargeenoughtobandorsamplebutwerestillmeasuredforconsistencyandbanded&sampledatalaterdate.Tarsusmeasurementswere“tothenotch”and“fulllength”;“head-to-bill”wasmeasuredfrombackoftheheadtothetipofthebeak.Eachnestlingwasgivenac-sizemetalbandandacombinationof3plasticcolourbands.Allplasticbandsweresealedusingthenewweldingmethod.ForalistofbandcombinationsandmeasurementspleasecontactJohnEwen(john.ewen@ioz.ac.uk).

3.7HealthMitecontrolwascarriedoutthisyear.Nestlingswithmitesweretreatedwithfrontline;nonestswereinfestedtothepointofneedingareplacement.Fourfemalehihiwerefounddeadthisseason,2wereverydecomposedand2weresentfornecropsy,reportsarefoundintheappendix.

4. ResultsVisitornumberstoTiritiriMatangihavebeenestimatedusingthenumberofpassengerstravellingontheferry,thiswas30,665for2016.Allofthesevisitorswillhavehadtheopportunitytoseeahihiontheisland.

Figure1Numberofnests,eggs,chicksandfledglingsproducedonTiritiriMatangifrom1997to2016

Figure2HatchingsuccessonTiritiriMatangifrom1997to2016

Figure3NumberofbirdsrecordedeachyearonTiritiriMatangiduringthetwoannualsurveysfrom1997to2017.Notethatthesurveyof09/10tookplaceimmediatelyafterjuvenilesweretranslocated;thesinglediamondshowsthesurveyresultincludingthoseremoved.

5. ColourbandlossThelossofoneormorecolourbandsfromanindividualhihiresultsinanincompletecolourcombination,thismakesidentificationduringpopulationsurveysandbreedingmonitoringambiguous.AlthoughtheresultsfromthenewweldingmethodweredisappointingforthePITtags,sofarithasshownthebestresultsforbandclosureachievedforbuttbandsonhihi.DuringtheSeptember2016surveyonly3%ofbirdswerenotedasmissingoneormorecolourbands.Allbandshavebeenweldedthisseasoninthehopethatsimilarresultscanbeachieved.Thetypeofplasticthebandsaremadefromhasaneffectontheeaseofmelting,theacetalbandsareeasiesttomeltandformthebestjoin.

6. AcknowledgmentsTheDepartmentofConservationandtheSupportersofTiritiriMatangi(SoTM)arecriticalcomponentsofthisproject.ManythankstoDave,Matt,Kata&VonnythesupportiveTirirangerteam.SomanySoTMmemberswerehelpful,enthusiasticandinterestedasalwaysandweappreciatetheircommitmenttothehihiandthisislandproject.Hihiconservationalsobenefitshugelyfromthehihisponsors,NZSafetyLtd.Appendix(PathologyReports)