Protective nesting association between the Barred Warbler Sylvia nisoria and the Red‐backed Shrike Lanius collurio: an experiment using artificial and natural nests

Marcin Polak

doi:10.1007/s11284-014-1183-9

Abstract

AbstractThe pressure of predators may significantly affects the distribution pattern of nesting birds. Some individuals may reduce the risk of predation by nesting near other species with an aggressive nest defence. In the present study I tested the predator protection hypothesis using experimental (artificial nests) and observational (real nests) approaches on two ecologically similar passerine birds–the Barred Warbler Sylvia nisoria and the Red‐backed Shrike Lanius collurio. Studies have been conducted in eastern Poland in two types of habitat: river valley and farmland. The main predators of natural and artificial nests were birds, and to a lesser extent, also mammals. I found wide variation level of predation of both types of nests in different years. Nest survival rate of artificial nests was significantly lower in the farmland than in the river valley and in natural nests I observed reverse pattern. According to the predictions of the predator protection hypothesis the survival rates of the natural and artificial nests were significantly higher in territories of individuals breeding in the protective nesting association. This type of interspecific positive interaction between two associate species can be classified as facultative mutualism.

Highlights

The pressure of predators may significantly affects the distribution pattern of nesting birds
Artificial nests situated within the territories of both RBS and BW were subject to the lowest level of predation (24 %; n = 136)
Losses were higher in nests located exclusively in RBS (28 %; n = 71) or BW (35 %; n = 46) territories and were the highest in the control nests sited outside the breeding territories of either species (51 %; n = 109)

Summary

Introduction

The pressure of predators may significantly affects the distribution pattern of nesting birds. According to the predictions of the predator protection hypothesis the survival rates of the natural and artificial nests were significantly higher in territories of individuals breeding in the protective nesting association This type of interspecific positive interaction between two associate species can be classified as facultative mutualism. Other authors point out that, in accordance with the predator protection hypothesis, birds actively choose the neighbourhood in which they are to breed, because they benefit from this through better protection from predators and a higher reproductive success (Cramp 1992; Cramp and Perrins 1993; Isenmann and Fradet 1995) This was recently confirmed by Goławski (2007), who provided evidence that RBSs nesting in close proximity to BWs achieved greater breeding success, and by Neuschulz (1988), who demonstrated that BWs inhabiting territories occupied by RBSs were reproductively more successful. This enabled to compare the reproductive success of birds nesting within the territories of the associate species and outside them

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