Spatial Diversity in Canopy Height at Redshank and Oystercatcher Nest-Sites in Relation to Livestock Grazing

[摘要] Inthisstudyweexaminedtheeffectofdifferentlivestockgrazingtreatmentsonbreedingbirddensitiesinasaltmarshhabitat.Toavoidanexperimentonthelargescaleneededtodirectlymeasuregrazingeffectsonbirddensities,wefollowedatwo-stepapproach.First,wemeasuredvegetationmicro-patterns(mosaicoflowervegetationandtallerpatchesat4×4m)aroundCommonRedshankTringatotanusandEurasianOystercatcherHaematopusostralegusnestsandatrandomsitespairedwiththesenestssitestojudgesuitabilityofmicro-patternsfornestbuilding.Secondly,wemeasuredmicro-patternsat120permanentplotsinfivedifferentexperimentalgrazingtreatmentstodeterminehowgrazingaffectsmicro-patterns.Wecomparedlowstockingdensityofbothcattleandofhorses,highstockingdensityofcattleandofhorses,andintermittentgrazingwithahighstockingdensityofcattle(i.e.yearlyintervalsofgrazingandnograzing).RedshankandOystercatchernestsoccurredinsiteswithtallervegetationandmorepronouncedmicro-patternsthanfoundatrandomsites.Paddocksgrazedwithlowdensitiesoflivestockorwithahighdensityintermittentgrazingtreatmenthadmicro-patternspreferredbythebirds.WeconcludethatRedshanksandOystercatchersmaybenefitintermsofpotentialnestsitesfromgrazingatlowlivestockdensitiesoratintermittentstockingdensitiesthrougheffectsofgrazingonmicro-patternsinthevegetation.

[学科分类] 动物科学

[关键词] Waders