Timing, Nest Site Selection and Multiple Breeding in House Martins: Age-Related Variation and the Preference for Self-Built Mud Nests

摘要

AlmostallaccountsofthereproductivebiologyofHouseMartinsDelichonurbicumarebasedonstudiesofbirdsbreedinginartificialneststhataremonitoredeveryfewdays.Here,IprovideastudyonHouseMartinsusingself-builtmudnestsatasinglecolonyinGaast,TheNetherlands(225nestattemptsin2004a€“2011);thestagesofbreedingwereinferredfroma€?remotea€?observationsofparentalandchickbehaviour.Smallchickswerenoticedfrom30Mayonwards,withafirstpeakofnestlingappearancein5a€“9June.Asecond,andlarger,peakinsmallchicksoccurredinlateJune.LargechicksfromfirstbroodswerenoticedfrommidJunetomidAugust,andthefirstlargechicksfromsecondbroodsfromlateJulyonward.ThelastfledglingsleftnestsinlateSeptember.Amongthe205successfulnestattempts,62%hadonebrood,and38%hadtwobroods(threeinonecase).Thefirstnestsitestobeoccupiedinmid-Aprilwerealwaysoldneststhathadsurvivedthewinter.Surprisingly,theuseofoldnestsdidnotresultinearlierincubationandchick-rearingactivities.Nevertheless,re-usednear-intactoldnestshostedmultiplebroodsin72%ofcases,amuchhigherpercentagethaninnewlybuiltnests(20%).TheearlieroccupationofoldnestsandthegreaterincidenceofsecondbroodswasfurtherassociatedwitharelativelyhighpercentageofolderHouseMartins.Whereasonly8%of126nestshostingonebroodwereoccupiedbyatleastoneknown2ndcalendaryearbird,nofewerthan30%ofthe79nestswithtwobroodswere.Despiteasteadyofferingofcleanwood-concretenestsatthecolony,suchartificialalternativeswereoccupiedinonly23outof307possiblecases,ratherthanthenear-100%occupancyofoldmudnestsandnestremains.Also,thestartdateofoccupationwaslaterthanthatofintactorpartialoldmudnests.Thisstrongpreferencebyolderbirdsfor(theremainsof)existingmudnestsandtherejectionofclean,strongartificialnests,impliesthatanycostsofbeingexposedtogreaternumbersofectoparasitessuchaslousefliesCrataerinahirundinisoverwinteringinoldnestsareoutweighedbythesignalofqualityinherentintheoccupationofparasite-infestedoldmudnests.