Yearly and Seasonal Variation of Breeding Parameters in a Declining Multi-Brooded Passerine, the Tree Sparrow

[摘要] Overafive-yearperiodwemonitoredbreedingparametersinacolonyofTreeSparrowsPassermontanusincentralSpain.Thismulti-broodedspeciescanraiseonetothreebroodsperseason.Inthisstudy,weanalyzedinter-broodvariationinreproductivesuccesstoinfertheexistenceofseasonalpatterns.Wealsoexploredinter-annualvariationoflife-historytraits,whichisofparticularinterestinadecliningspeciesliketheTreeSparrow.Inagreementwithourexpectationofamulti-broodedspecies,clutchsizeshowedaquadraticrelationshipwithlayingdate.Wefoundthattheinter-broodintervalvariedsignificantlydependingonthenumberofbreedingattempts,whichsuggeststhatthespeciesmayengageintime-savingbehavioursasreportedforothermulti-broodedpasserines.Nestlingsfromsecondbroodsfledgedinbetterconditionthannestlingsfromfirstandthirdbroods.Fewerfledglingswereproducedinthirdbroodsthaninprecedingbreedingattempts.Thereproductiveoutputofthirdbroodsvariedtoalargeextentamongyears,whereasinter-annualvariationwasmuchlessmarkedinfirstandsecondbroods.Overtheyears,wealsodetectedadecreaseinnestlingsize(tarsusandwinglength),whichwasconsistentamongbreedingattempts.Finally,theproductivityofthecolonyremainedfairlystableoverthestudyperiod.Thispatterncontrastswithnegativepopulationtrendsdetectedbynationalmonitoringprogrammes.Theproximityofwetlandhabitatsinthesurroundingsofourcolony—essentialforadequateinvertebratesforthechicks—issuggestedasamainreasonforthisdifference.

[学科分类] 动物科学

[关键词] Seasonal And Inter-annual Trends