Oystercatchers' Bill Shapes as a Proxy for Diet Specialization: More Differentiation than Meets the Eye

Ardea

Martijn van de Pol⁵  Anne L. Rutten³  Martin De Jong²  Kees Oosterbeek¹  Joost M. Tinbergen³  Simon Verhulst⁴  Lyanne Brouwer⁶  Bruno J. Ens¹ 

[1] 3 SOVON Dutch Centre for Field Ornithology, Beek-Ubbergen, The Netherlands;6 Institute for Marine Resources & Ecosystem Studies, Texel, The Netherlands;5 Animal Ecology Group, University of Groningen, Haren, The Netherlands;4 Behavioural Biology Group, University of Groningen, Haren, The Netherlands;1 Centre for Conservation Biology, Norwegian University of Science and Technology, Trondheim, Norway 2 Research School of Biology, Australia National University, Canberra, Australia;2 Research School of Biology, Australia National University, Canberra, Australia

关键词: Trophic Polymorphism;   

DOI  :  

学科分类：动物科学

来源: Nederlandse Ornithologische Unie/Netherlands Ornithological Union

【 摘 要 】

EurasianOystercatchersHaematopusostralegusostralegusareaclassicexampleofindividualfeedingspecialization.FeedingspecializationcausesmorphologicaldifferentiationinOystercatchers'billshapesduetovaryingdegreesofabrasionassociatedwithspecifichandlingtechniquesforeachpreyspecies.Consequently,theOystercatcher'sbillshapehasbeenusedasaproxyfordietspecialization,asitprovidesaquickandeasywaytoassessthedietchoiceofthismarinetop-predator.However,billshapesofOystercatchersarecategorizedvisuallyindistincttypes,whileithasbeenarguedthattherelevantvariationiscontinuous.Also,itisunclearhowcomparablethebill-shapeclassificationisamongstudiesandbetweenthesexesandhowuniversalbillshape-dietrelationshipsare.Hereweinvestigatetheusefulnessofbill-shapetypesasaproxyfordietchoiceinOystercatchers,usingfournewandtwopublisheddatasets.Weshowthatquantitativebill-morphometricsprovidenoevidencethatbill-shapetypesarediscreteentities.Additionally,thedimensionsofthesamebill-shapetypedifferacrossstudies.Thisdifferenceisunlikelytobecausedbymethodologyandmightreflectsubtleadditionalfeedingspecializationamongbirdswiththesamebill-shapetype.Moreover,weshowthatthetipofthebillofmalesistypically7%higherthanthatoffemaleswiththesamebill-shapetype.Ahigher—andprobablystronger—billtipinmalesmayexplainwhymaleshadmoreshellfishintheirdietthanfemaleswiththesamebill-shapetype.Finally,aliterature-reviewshowsthattheexactbillshape-dietrelationshipdiffersbetweenstudiesandthesexes.Weconcludethattheinterpretationofbill-shapetypeasaproxyfordietchoiceinOystercatchersiscontextdependent.Weproposethatquantitativebilldimensionsareabetterproxyforfeedingspecializationthanbill-shapetypes.

【 授权许可】

Unknown