Prey Availability, and not Energy Content, Explains Diet and Prey Choice of Eastern Curlews Numenius madagascariensis in Southern Australia

[摘要] EasternCurlewsbreedinSiberiaintheborealspringandsummerandmigratetoAustraliaintheaustralspringandsummer.TheEasternCurlewisnotableforitsverylong,decurvedbill;thissexuallydimorphiccharacteristicrepresentsapproximately25–30%oftotalbodylength.Femalecurlewshavethelongestbillofanywader.Dietandpreychoiceinrelationtoavailabilityandprofitabilitywereexaminedovertwonon-breedingperiodsinWesternPortinsouthernAustralia.Dietwasdeterminedfromdirectfeedingobservations,examinationofpelletscollectedathigh-tideroosts(duringdaytimeandnight-time)andbyfollowingtracksofforagingcurlews.Maleandfemalecurlewsusedtheintertidalfeedingareasdifferently:femalesusedmoresandyareasandmalesmoremuddyareas.Thisdifferencemayberelatedtosexualdimorphisminbilllengthandcouldreflectsubstantialdietarydifferences.TasselledCrabPilumnusfissifronswasthemostcommonprey,followedbyAustralianGhostShrimpTrypaeaaustraliensis,Two-spinedCrabLitocheirabispinosaandSentinelCrabTasmanoplaxlatifrons.Theavailabilityofpreywasexaminedinaquariathroughexaminationofburrowingbehaviourandotheractivitypatternsinrelationtotidalmovementsandlevelsofdaylight.PreybehaviourexplainedthegreaterconsumptionofmaleGhostShrimpsandthedifferencesindietbetweendayandnight.MoreGhostShrimpsandSentinelCrabsandfewerTwo-spinedCrabsweretakenduringthedaythanduringnight.Preychoicewasexaminedbymeasuringthecalorificvaluesofpreyandpotentialpreyspecies.Generally,curlewstookthemoreenergyvaluableprey,butpreybehaviourandpreyavailabilitymostlydeterminedpreychoice,nottheenergeticvalueofprey.

[学科分类] 动物科学

[关键词] Australia