Food Availability for Meadow Bird Families in Grass Field Margins

摘要

AgriculturalintensificationingrasslandshasledtothedeclineofmeadowbirdpopulationsinTheNetherlandsinthelast60years.Habitatformeadowbirdchickshasdeclinedinqualityandquantity,therebyreducingfoodavailability.Agri-environmentschemes(AES)tohaltthedeclineinmeadowbirdnumbershavethusfarbeeninsufficient.TheseAESareonthelevelofentirefields,butrecentresearchsuggeststhatmarginsoffieldsmaybemoresuitablechickhabitatthancentresoffields.Therefore,itcouldbeproductivetospecificallytargetgrassfieldmarginsaspartofmeadowbirdAES.Ourstudyexaminedthedifferencesinfoodavailabilityformeadowbirdfamiliesindifferentportionsofagrassfield.Invertebratesweresampledindifferentlocationsonthefieldandresultswerecomparedtoknowndietarypreferencesoffourspeciesofmeadowbirdchicks.Weshowstrongdifferencesinfoodavailabilitywithinfields,dependingonmeadowbirdspecies.ThepreferredpreyspeciesofchicksofBlack-tailedGodwitLimosalimosaandRedshankTringatotanuspredominantlyoccurredinfieldmargins,whereasthoseofOystercatcherHaematopusostraleguschickswerefoundmostlyinthemainpartofthefield.ThepreyspeciesofNorthernLapwingVanellusvanelluschicksshowednoclearpatternwithinfields.Weconcludethatfoodavailabilitywithinafielddiffersspatiallybetweenmeadowbirdspecies.ParticularlyforBlack-tailedGodwitandRedshank,grassfieldmarginsconstituteanimportantpartofthefield.Therefore,specificmanagementtofurtherenhancefoodavailabilityinthesemarginsmayconstituteanimportantadditiontotheexistingmosaicapproach.