Avian nest defence, which is expected to serve both antiparasite and antipredator functions, maybenefit or be detrimental to birds, although selective forces that potentially operate on nest defencehave not been quantified as a whole. Together with fitness values, we analysed two traits of nestdefence, intensity and plasticity, in two distantly related passerine species, yellow warbler (Setophagapetechia) in North America and reed warbler (Acrocephalus scirpaceus) in Europe, both favouritehost species for brood parasites. Breeders that escaped parasitism were the most vocal among reedwarblers, whereas there was no specific defence phenotype that predicted prevention of parasitismin yellow warblers. Breeders that escaped nest predation were, in both species, those with the mostdistractive response at the first exposure to a nest-threatening event, such as the experimentalpredation or parasitism simulated at the nest. However, increasing defence intensity benefited yellowwarblers but was detrimental to reed warblers, because intense defence responses attracted predators.Adaptiveness of nest defence was revealed by nest defence phenotypes when examined in concert withthe seasonal fitness (i.e. measures of reproductive success). Results revealed selective forces favouredyellow warblers with strong defence phenotypes. Opposite forces were instead revealed among reedwarblers whose favoured phenotypes were strong, yet less flexible, defenders.
|Numero di pagine||10|
|Stato di pubblicazione||Published - 2018|
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