Large Birds can Migrate Fast: The Post-Breeding Flight of the Purple Heron Ardea purpurea to the Sahel

[摘要] Largeandheavybirdsusuallyusesoaringflightduringlong-distancemigrationormakeregularstopoversenrouteforsubstantialrefuelling.PurpleHeronsarelarge,long-distancemigrants.Becauseoftheirsize,largeheronsmigratingsouthwardsfromEuropetoAfricawereexpectedtomakeoneormorestop-overstorefuel.However,datafromsevenPurpleHerons,fittedwithsatellitetransmitters,showedthattheheronswereabletocoverthedistanceintotheSahelofabout4000kmwithin5–7days.Oneindividualevenflew5600kmnon-stop,mostlyoversea.Theheronsmigratedmostlyatnightandpartlyduringthedaywithahightravelspeedindicativeofflappingflight.TheheronsmadefewdiurnalstopsinEuropeandNorthAfrica.Substantial‘stopover’timewaslimitedentirelytoaperiodofseveralweeksbeforedeparture,andafterarrivalsouthoftheSahara.Weassumethatthisisenergeticallypossibleforbirdswithamaximumwingloadof4–5kgbodymassperm2ofwingsurface.LargerwingloadsasinstorksorraptorsprescribesoaringorrefuellingwiththeconsequencethatmostmigratoryjourneystoAfricanwinteringgroundsthentakeatleastamonth.Theresultsemphasizetheconservationimportanceofabundantandhigh-qualityfeedinghabitatnearthebreedingareasforpre-migratoryfuellingofthisspecies.Furthermore,arrivalhabitatislikelytobemoreessentialthanpreviouslyexpected.WesuspectthatthelackofsuitablearrivalhabitatmightexplaintheobservedhighadultmortalityindrySahelperiodsbetterthan‘winter’survival.

[学科分类] 动物科学

[关键词] Conservation