Nest Concealment and Nest Defence by Two Passerines

Protection of broods from predators using aggressive behaviour of other species is one of the most unusual strategies used by birds to evade predation. One such strategy is the creation of protective nesting association in which one or more species relate and directly benefit from nesting within the protective umbrella created by other species. In this project I evaluate whether nesting associations of two species influence nest defence intensity. A model system in the study are the Barred Warbler and the Red–backed Shrike. Barred Warblers nesting within shrike breeding territories strongly defended their nests. Shrikes not nesting together with warblers were significantly more aggressive than those breeding in the protective nesting association. This study suggests that positive interactions within the heterospecific network of relations in ecosystems may be one of the factors responsible for diversifying the intensity of avian nest defence.

Barred Warbler (by Marek Kołodziejczyk)

Red-backed Shrike (by Marek Kołodziejczyk)

Read the full article, published by Zoological Studies, here

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