Seasonality of the Arctic Warbler Phylloscopus borealis in Northern Korea, with Refutation of Previous Assumptions of Korean Breeding

摘要

StandardreviewslistArcticWarblerPhylloscopusborealisasaprobablebreederinnorthernKorea,aswellaspassagemigrant;themostrecentstatesthatspringpassagebeginsc.10AprilandfinisheswithinMay.Near-dailystructuredcountsinnorth-centralKorea(PyongyangandHyangsan)during2000a€“2003showed,bycontrast,thatregularspringpassagerunsfromearly-midMayintoearlyJune,andthatautumnreturnbeginsinearlyAugust,datesreflectingmoderndatafromelsewhereinEastAsia.SpecificsearchesintheMyohyangMountains,siteofmostpostulateda€?breedinga€?records,foundnoevidenceofsummerresidency,letalonebreeding.Koreanbreedingwasassumedfromrecordsoutsidethethen-perceivedpassageseasons,buttheseperceptionswereflawedand,combinedwithmisidentification,ledtotheunsupportableconclusionsofbreeding.Infact,asummergapinacceptablepastrecordsspansalmostthesamedatesastoday'ssummerabsencefromPyongyangandHyangsan,bothundoubtedlyonlypassagesites.ThespeciesmayyetbefoundtobreedinnorthernKorea,butthereisnoevidence,evencircumstantial,thatitdoesso.PastassessmentsthatregularpassagebeginsinmidAprilwereevidentlyinerror,reflectingpastdifficultiesofspeciesidentification.