Phenology, Stopover Dynamics and Population Size of Migrating Black-Tailed Godwits Limosa Limosa Limosa in Portuguese Rice Plantations

[摘要] Between2005/06and2008/09westudiedBlack-tailedGodwitsLimosaI.limosastaginginthericefieldssurroundingtheTejoandSadoestuaries,Portugal.Godwitswerecountedweeklyandflockswerescannedforcolour-ringedindividuals.Weanalysedphenology,dynamicsofthestopover,andestimatedthesizeofthePortuguesestagingpopulationaswellasthetotalwesternlimosapopulation,GodwitsstartedarrivinginJanuary.NumberspeakedinthesecondhalfofFebruary,afterwhichtheyquicklydepartedfromthearea.Comparisonwithpreviousrecordssuggestedthatnumbershavedecreasedsincetheearly1990s,andthatgodwitscurrentlypeaklaterthansome15yearsago.Individualstagingdurationsaveraged22.6daysin2007and25.3daysin2009,andincreasedtowardstheendofthestagingperiod.Weestimatedthatatotal59200birdsusedtheareain2007and53100in2009.Usingestimatesfortheproportionofcolour-ringedbirdsintheflocks,weestimatedthepopulationsizeofthewesternpartoftheL.l.limosapopulationat133151–140722birds.Thisishigherthanpreviousestimatesbasedoninventoriesofthebreedingpopulation,butaccountsforthenon-breedingsegmentofthepopulation.Thus,weestimatethat38–44%oftheNWEuropeanBlack-tailedGodwitpopulationstageinPortugal.ItisarguedthatprocessesinIberiaarenotlikelytohavecontributedtothepopulationdeclineastheareaforricecultivationhasincreased.Nevertheless,asgodwitsstaginginIberiaaretotallydependentonhuman-madehabitats,changesinricefarmingpracticescouldhavegreatimpactonthetotalpopulationsize.

[学科分类] 动物科学

[关键词] Stopover Duration