Survey Protocol for the Little Owl Athene noctua

摘要

Weofferaprotocolforconductingstandardizednocturnalbroadcast(playback)surveysonLittleOwlsAthenenoctuaacrosstherangeofthespecies.Basedondifferingobjectivesofresearchers,twointensitylevelsofsurveyeffortsareoutlined:(1)demographicanddensitystudies,and(2)presenceandgeneraldistributionsurveys.Bothsurveyprogramsutilizethesamefieldmethod,butvaryinthenumberofvisitsrequiredacrossthesurveyarea.Objectivesanddefinitionsforthesesurveyprograms,andcriteriafordeterminingoccupancy,reproduction,andturnoverratestosupportdemographicandmonitoringstudiesaregiven.Therecommendedsurveyperiodcoincideswiththebreedingseason,anddependingonthelatitude(andelevation),isapproximatelyfrom1Februarya€”30Aprilinwestern-Europe,and1Marcha€”31MayineasternEurope,MiddleEast,andAsia.Surveysaretobeconductedfromsunsettomidnightandfromtwohoursbeforesunrisetosunrise.Surveystationsarelocated500mapartfromoneanotheralongtransects,orinagridnetwork.Thetape-recordedcallsequenceconsistsofa2-mintrackplayedthreetimes,witheachbroadcasttrackseparatedbysilentperiodsof1mineach.Theobserverlistensfor5minafterthelastsequence.Thusamaximumof13minisspentateachsurveystation.Positionsofallrespondingowlsarerecordedonafieldmap.WhileLittleOwlshavearepertoireof22vocalizations,twocalls,thehoot(a€?ghuka€?)andthea€?chewinga€?call,areusedbymalesinterritorialcontestsandarethecallsrecommendedforuseinthisprotocol.Broadcastvocalizationsshouldbeplayedatvolumeandclaritylevelsconsistentwiththatofwildowls.Fordemographicanddensitystudies,werecommend4visitsacrosseachofthesurveyroutes(andassociatedsurveystations)togainresponsesfrom95%oftheterritorialowls.Fornest-boxprogramswheretheobjectivesaredemographicstatusandtrends,andwherethemajorityofowlterritoriesarealreadyknown,surveyeffortsdescribedinthisprotocolareusedtofillingapsandofferthoroughandsystematiccoverageoftheentirestudyarea.Forpresenceandgeneraldistributionalsurveys,wesuggesta1-visitsurveybeconducted.Whilea1-visitstrategywillnotdetectsomeoftheowlsactuallypresent,theoutcomeofthesesurveyswillilluminategeneraldistributionsofowlsandhighlightareasforfurtherstudy.Weanticipatethatthisprotocolwillbeupdatedoccasionally,followinganormalscientificpeer-reviewprocess.Inparticular,weurgeadditionalresearchonthedetectionprobabilityofterritorialowlstoprovideclarificationastothenumberofvisitsneededtoaccuratelydeterminethenumbersofowlspresentinagivenarea.Priorobservationshaveindicatedapotentialfordifferentialresponsesfromowlsinhighdensitypopulations(higherresponserates)comparedtoowlsresidinginlowdensitysituations,andthisneedsfurtherresearch.