Early Successional Stages of Reed Phragmites australis Vegetations and Its Importance for the Bearded Reedling Panurus biarmicus in Oostvaardersplassen, The Netherlands

[摘要] AstudyonBeardedReedlingPanurusbiarmicusfeedinghabitsincombinationwithasample-wisebreedingbirdsurveyofthemarshlandzonesoftheDutchwetlandOostvaardersplassenshowsclear-cutspatialdifferencesindensitiesandhabitatuse.ThemorematurestandsofReedPhragmitesaustralisconstitutethemainnestingarea,whilethemoreopen,youngerstands,particularlywheninundatedandgrazedbymoultingGreylagGeese,providethemainfeedingareas.Arthropod,andespeciallyChironomid,densitiesweregenerallyhigheringrazedReedstandsandfrequentfeedingflightswerecarriedoutbyparentbirdsbetweengrazedandungrazedpartsoftheareaduringchickraising.Chironomidsalsoprovedtoconstitutethemainpreyitemsbroughttothenests.Apartfromhigherpreydensitiesingrazedstands,betterdetectabilityaswellasbetteraccessibilityofthelowervegetationlayersarealsolikelytocontributetothehabitatpreferenceofinsect-feedingBeardedReedlings.WheninwinterthebirdsshifttoReedseeds,patcheswithhigherseedindexholdhigherdensitiesoffeedingbirds.Whenseedindexdropsbelowacertainlevel,densityofbirdsislowandindependentofseedindex.ThehighestseedproductionisassociatedwithrejuvenatedReedstands,recoveringfrompreviousgrazing.BeardedReedlingsthushighlydependontheearlysuccessionalstagesofReedstands.Temporalandspatialhabitatdiversificationismediatedbychangingwaterlevelsandrejuvenationcausedbygrazinggeese.Anumberofothermarshlandbirdspeciesdependonthistypeofvegetation,andwetlandmanagementshouldthereforeaimatfavouringthenaturalprocessesgoverningReedsuccession.

[学科分类] 动物科学

[关键词] Management