Reproductive ecology and habitat associations of Florida's crested caracaras PDF
Preview Reproductive ecology and habitat associations of Florida's crested caracaras
REPRODUCTIVEECOLOGYANDHABITATASSOCIATIONS OFFLORIDA'SCRESTEDCARACARAS By JOANL.MORRISON ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT OFTHEREQUIREMENTSFORTHEDEGREEOF DOCTOROFPHILOSOPHY UNIVERSITYOFFLORIDA 1997 Copyright1997 by JoanL.Morrison ToClydeandalltherest. ACKNOWLEDGMENTS ManypeoplecontributedtothisresearchandIamgratefultoallofthem. I particularlywishtothankPaulEbersbachandBobProgulskeattheAvonParkAirForce Range(APAFR,DOI),BrianMillsap,DonWood,andDaveCookoftheFloridaGame andFreshWaterFishCommission's(FGFWFC)Non-GameWildlifeProgram,andDave Wesley(U.S.FishandWildlifeService)forrecognizingtheneedforresearchonthis little-knownspeciesandsubsequentlyprovidingfunding. Thisprojectwouldhavenever gottenoffthegroundwithouttheirsupportandassistance. IthankthestaffatAPAFRfor theirhelp,particularlyPatWalsh,SamvanHook,ScottPenfield,SteveHanley,Julie Olson,andHarlanBlackburn. NancyDouglass,VictorEchavez,andHughClarkofthe FGFWFCalsoprovidedfieldandlogisticsupport,particularlyassistancewithaccessing state-ownedproperties. Iamgratefulforadditionalfinancialsupportreceivedfromthe SouthFloridaWaterManagementDistrict,theUniversityofFlorida'sGraduateMinority FellowshipOffice,andtheFordFoundationFellowshipProgram. Igratefullyacknowledgethecooperationandsupportprovidedbythepersonnel andstaffattheMacArthurAgro-EcologyResearchCenter(MAERC)andArchbold BiologicalStation,particularlyDrs.JohnFitzpatrick,HilarySwain,andTomBancroft, andFredLohrer. Iparticularlyappreciatedtheopportunitytoliveatandtooperatethis projectbasedoutofMAERC. RanchmanagersDanChildsandGeneLollisprovided manyhoursofinterestingconversationsregardingcattleranchinginFlorida. Ithank themforsupportingthisprojectthroughoutandforstickingupforuswiththeFlorida Cattleman'sAssociation. IalsothanktherestofthestaffatMAERCfortheirhelpand forputtingupwithouractivitiesattheranch. Ialsowishtoacknowledgetheprivate donationbyFrank"Sonny"WilliamsontotheIFASresearcheffortatMAERC. iv SpecialthanksgotoSteveMcGeheewhowasastalwartfieldassistant throughout. Hisenthusiasmforcaracarasanduntiringfieldassistance,particularlyin findingnestsandradiotracking,wasinvaluable. VickyDreitzandDanielleToddalso provedtobeexcellentfieldassistants,duringthesecondandthirdfieldseasons respectively,andcapablyhandledallaspectsoftheresearchprogramaswell. Iam gratefultoBrianMealeyforhissupportthroughoutandalsoforloanofClyde,our researchcaracara. Additionalpeoplewhohelpedwithfieldworkatvarioustimes includedJohnArnett,TylanDean,SamGibbs,LaurieGray,KevinLong,Mike McMillian,CarlosPages,MeganParker,RayPoulin,LourdasRojas,JimSanderson,Jim Solomon,andReuvenYosef. IthankScottHedges,StefanieMelvin,TomWeber,Cathy Ritchie,andShannonStullfortheirhelpatvariousstagesoftheproject. Thanksalsoto LorenzAnimalFoodsandBradStithforhelpwiththedeadcows. IamgratefultothestaffattheDepartmentofWildlifeEcologyandConservation, InstituteofFoodandAgriculturalSciences,UniversityofFlorida,whoseefforts throughoutmytenureatUFkeptourpaperworkprocessed,salariesontrack,andbills paid. SincerethanksgotoPegMargosian,BrianSheahan,RobertaPickett,Don Browning,andHelenHusemanwhocontributedmanyhoursofassistancewiththeGIS analysisandmapping,andtoKenPortierandJayHarrisonforhelpwithstatistics. Linda Kubitz,CathyHenderson,MiltPutnam,andSylviaBeauchampfromIFASMedia Servicesprovidedexcellentmediacoverageoftheproject. ThanksgotoNeilRettigand KimHayesforprovidingadditionalfilmofouractivities. IthankMaryMaltbiefor sexingthecaracarasusingthebloodsamples,Drs.DonForresterandMarilynSpalding, andGarryFosterfornecropsiesandprocessingparasitedata,andDr.ReedBowmanfor providingtheMayfieldnestsuccessprogram. IalsothankpersonnelattheMaitlandBird ofPreyCenter,theFalconBatchelorBirdofPreyCenterattheMiamiMuseumof Science,andWrede'sWildlifeRehabilitationCenterforassistinguswhenwehad caracaraemergencies. SincerethanksgotoMarkBradyandpersonnelatGladesElectric Cooperativeforhelpingustoaccessthenesttrees,toJimWyatt,KarenDunne,Reed Robbins,JohnMcGee,andMortonSundofWyattAviationwhokeptusflyingsafely duringallthelonghoursofaerialradiotracking,andtothepersonnelatWrenchmasters, whokeptourvehiclesrunning. Iespeciallythankmygraduateadvisor,Dr.SteveHumphrey,whosteppedinat thebeginningwheneverythinglookedtenuous. Hissteadyandconstantsupport throughouthelpedkeepupthemomentum. Ithankmyothercommitteemembers,Drs. LynBranch,JohnFitzpatrick,JohnSmallwood,MelSunquist,andS.DavidWebb,for theircontributions,especiallyforreviewsofthisdissertation. IalsothankDr.Mike CollopyforsparkingmyoriginalinterestincaracarasandforgettingmetoUFinthefirst place. IparticularlywanttoacknowledgethefriendshipofKimBabbitt,PattyCramer, andPatKennedy,whoweretherefromthebeginningandgotmethroughtherough times. ThanksalsogotootherfriendsandcolleaguesEduardoAlvarez,LeslieBackus, TylanDean,NathalieHamel,DaveLeonard,KenMeyer,SteveMorello,KatieSieving, andDaleStahleckerfortheirhelpandinputatvarioustimes. Ithankmyfamilyfortheircontinuedsupport,particularlymyparents,whose beliefandencouragementneverwaned. IespeciallythankJimSandersonforhisloveand supportthroughoutandforhisuntiringbeliefthatthiswasallpossible. Mostimportantly,Ithanklandownersandcattleranchersthroughoutsouth-central Florida,whosogenerouslyprovidedaccesstotheirlandsandwithwhomwehadso manyinterestingdiscussionsregardingcaracarasandcattleranches. Withouttheir cooperationandsupport,thisstudycouldnothavebeenaccomplishedatall. ThisdissertationiscontributionNo.33fromtheMacArthurAgro-Ecology ResearchCenterofArchboldBiologicalStation. vi TABLEOFCONTENTS page ACKNOWLEDGMENTS iv LISTOFTABLES ix LISTOFFIGURES xii ABSTRACT xiv CHAPTERS STUDYOVERVIEW 1 1 Introduction 1 StudySpecies—HistoryandBackground 2 StudyArea 5 StudyOrganization 5 2 BREEDINGECOLOGYOFFLORIDA'SCRESTEDCARACARAS. 9 Introduction 9 StudyAreaandMethods 10 NestLocationandVisitation 10 ReproductiveSuccess 11 ProductivityandComponentsofVariation 12 EnvironmentalData 13 StatisticalAnalyses 13 Results 14 TerritorialOccupancyandBreedingRates 14 BreedingBehaviorandSiteFidelity 14 NestBuildingandIncubation 15 LengthoftheBreedingSeasonandTimingofBroods 15 NumberofBroodsPerYear 16 ClutchSize 16 Broods 16 ReproductiveSuccess,ProductivityandComponentsofVariation. 17 PerformanceandLayingDate 17 NestFailure,Egg,andChickMortality 18 Discussion 18 Weather,Timing,andLengthoftheBreedingSeason 19 ClutchSize 20 vii TimingandNumberofBroods 20 Mortality 21 BreedingStrategyandVariationinReproductiveParameters 21 ComparisonWithOthercrestedcaracaras 22 3 EFFECTSONPRODUCTIVITYANDPOTENTIALCOSTSOF DOUBLEBROODINGINCRESTEDCARACARAS 41 Introduction 41 StudyAreaandMethods 43 Results 46 ExtentofOccurrenceofDoubleBrooding 46 TimingofBroods 47 ProductivityandNestingSuccess 47 ParentalCareandPost-fledgingSurvival 48 PotentialCoststoAdults 48 EffectsonPopulationGrowthandPersistence 48 InfluenceofFactors 48 Discussion 48 4 HABITATASSOCIATIONSANDPRODUCTIVITYOF CARACARASONCATTLERANCHES 64 Introduction 64 StudyArea 65 Methods 65 LandOwnership/LandUse 65 HomeRangeEstimationandSpatialDispersionofTerritories 66 Landscape-levelHabitatSelectionbyBreedingPairs 68 CaracarasandCattleRanches 70 Results 70 LandOwnership/LandUse 70 HomeRangesandSpatialDispersionofTerritories 70 Landscape-levelHabitatSelectionbyBreedingPairs 71 CaracarasandCattleRanches 72 Discussion 72 5 SYNTHESISANDCONCLUSIONS 92 LITERATURECITED 96 BIOGRAPHICALSKETCH 108 viii LISTOFTABLES Table page 2-1 Breedingchronologyandintervals,inweeks,betweenbroodsforFlorida's crestedcaracarapopulation,1994-1996 24 2-2 MultiplenestinginFlorida'screstedcaracarapopulation,1994-1996. Earlynestsarethosethatinitiatedegglayingbeforethemedianweekof egglayingfortheentiresample,eachyear 25 2-3 ReproductivesuccessparametersforFlorida'screstedcaracaras, 1994-1996. Nestlingsurvivaltofledging(numberoffledglings/number ofeggslaid),fledglingsurvivaltoindependence(numberofyoungalive atendofpost-fledgingdependencyperiod/numberfledged),andegg success(proportionofeggslaidthatproducedindependentyoung)foreggs fromknownsizeclutches 26 2-4 EstimatesofMayfieldnestsuccessprobabilitiesforbreedingpairsof crestedcaracarasinsouth-centralFlorida,1994-1996 27 2-5 Measuresofannualproductivity(mean+SE)andIndexofProductivity forcrestedcaracarasinsouth-centralFlorida,1994-1996. Seetextfor calculationofIndexofProductivity. Productivitypersuccessfulpair includesyoungfromrenestingattempts 28 2-6 Variabilityinreproductiveparametersforcrestedcaracarasduring3years insouth-centralFlorida. CV=coefficientofvariation(standard deviation/mean). Productivity/successfulpairincludesyoungfrom renestingefforts, n—98clutches 29 2-7 Seasonaldeclineinbreedingperformance(mean±SE)forknown-size clutchesandforallnestattemptsofcrestedcaracarasinsouth-central Florida,1994-1996. Earlynestsinitiatedegglayingbeforethemedian weekofegglayingeachyear,latenestsinitiatedegglayingafterthe medianweek 30 2-8 Fatesofeggsfromknown-sizeclutchesforcrestedcaracaranestsinsouth- centralFlorida,1994-1996 31 2-9 Failureofcrestedcaracaranestsinsouth-centralFlorida,1994-1996 32 3-1 Occurrenceandtimingofnestingattemptsbetweenyearsforcrested caracarasinsouth-centralFlorida. NA=notapplicableforthatyear 53 3-2 Clutchsize(mean±SE)andnestingsuccess(SDinparentheses)between nesttypesforcrestedcaracarasinsouth-centralFlorida,1994-1996. The sameletterindicatessignificantdifferencesbetweennesttypes. ND=no ix dataonclutchsizesoffirstorsecondnestsin1994becausethesenests werefoundafterhatching 54 3-3 Estimatedparametersforevaluatingcontributionofdoublebroodingto populationgrowthforcrestedcaracarasinsouth-centralFlorida. Parametersestimatedfromdatacollectedduring1994-1996 55 3-4 Estimationofpopulationsizeandannualgrowthratefortwohypothetical populationsofcrestedcaracarasinsouth-centralFlorida,oneinwhichall pairsonlyproduceasinglebroodeachyear,andoneinwhich approximately10%ofpairssuccessfullyproducetwobroodseachyear.... 56 3-5 Statisticsforlogisticregressionanalysisoftheinfluenceoftimingof initiationofthefirstbrood(INITWK)andthenumberfledgedinthefirst brood(NUMFRST)ontheoccurrenceofdoublebroodingincrested caracarasinsouth-centralFlorida,1994-1996.n=16double-brooded pairs,103single-broodedpairs 57 3-6 Statisticsforlogisticregressionanalysisoftheinfluenceofdouble broodingthepreviousyear(DBPREV),fledgingdate(WKPREV)and numberfledgedthepreviousyear(NUMPREV)ontheoccurrenceof doublebroodingincrestedcaracarasinsouth-centralFlorida,1994-1996. n=11double-broodedpairs,34single-broodedpairs 58 4-1 Variablesincludedindevelopmentofthelogisticregressionmodel describingcaracarahomeranges. Unlessnoted,allvariablesareexpressed asproportionsofthetotalareaofthehomerangethatwasvegetatedwith naturalorsemi-natural*vegetation 76 4-2 Landownershipandmajorlanduseforcrestedcaracaraterritoriesinsouth- centralFlorida,1994-1996. n=65territories 77 4-3 Sizeandvegetationcompositionofcrestedcaracarahomeranges. Home rangesaredefinedasthe99%kernelcontourestimatedusinga0.85 smoothingfactor. N=numberofradiolocationsusedtoestimatehome rangesize 78 4-4a Matrixofpercentoverlapof60%contours(coreareas)for9adjacentpairs ofbreedingcrestedcaracarasontheMacArthurAgro-EcologyResearch Center,HighlandsCounty,south-centralFlorida. Birdsinrowsare overlappedbybirdsincolumns 79 4-4b Matrixofpercentoverlapof60%contours(coreareas)for4adjacentpairs ofbreedingcrestedcaracarasalongtheKissimmeeRiver,Highlandsand Okeechobeecounties,south-centralFlorida. Birdsinrowsareoverlapped bybirdsincolumns 79 X
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