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Patterns of nest predation contribute to polygyny in the Great Reed Warbler

Author:
  • Bengt Hansson
  • Staffan Bensch
  • Dennis Hasselquist
Publishing year: 2000
Language: English
Pages: 319-328
Publication/Series: Ecology
Volume: 81
Issue: 2
Document type: Journal article
Publisher: Ecological Society of America

Abstract english

According to the polygyny threshold model, females are compensated for the cost of sharing a territory with other females by breeding in territories of higher quality than those of monogamously mated females. In the polygynous Great Reed Warbler (Acrocephalus arundinaceus), the variation in territory quality may be associated with nest site characteristics or food supply. In this study, we examined the probability of nest predation in Great Reed Warblers in relation to an indirect measure of territory quality (territory attractiveness rank as indexed by settlement order) and to several variables of nest site structure. Artificial nests with attached soft plasticine model eggs were placed in Great Reed Warbler territories of different attractiveness; Marks in the soft model eggs were compared to marks from possible predator species. Both inter- and intraspecific predators were found to prey upon eggs in artificial nests. Marsh Harriers (Circus aeruginosus) predominantly preyed upon artificial nests located in territories of low attractiveness, in low-density reed beds, and early in the season. Bitterns (Botaurus stellaris) and Water Rails (Rallus aquaticus) showed a preference for artificial nests located inside the reeds. When all types of predators of artificial nests were pooled, the probability of nest predation was lower in more attractive territories. This pattern was corroborated in an analysis of predation on real nests. In general, polygyny occurred in territories with a low rate of nest predation, whereas unmated males held territories where the risk of predation was high. The low rate of nest predation in attractive territories on average compensated secondary females for the cost associated with sharing a male (i.e., reduced male assistance when feeding nestlings). The polygyny threshold model has been around for several decades, however, only few studies have identified the factors that may compensate secondary females for the cost of sharing a mate. In the present study we were able to show that the patterns of nest predation can be an important territory quality parameter that compensate secondary females, and, hence, contribute to the occurrence of avian polygyny.

Keywords

  • Biological Sciences

Other

Published
  • Long-term study of great reed warblers
  • Molecular Ecology and Evolution Lab
  • ISSN: 0012-9658
Staffan Bensch
E-mail: staffan [dot] bensch [at] biol [dot] lu [dot] se

Professor

MEMEG

+46 46 222 42 92

E-C213

Sölvegatan 37, Lund

50

Head of unit

MEMEG

+46 46 222 42 92

E-C213

Sölvegatan 37, Lund

50

Research group

Molecular Ecology and Evolution Lab

Projects

Doctoral students and postdocs

PhD students, main supervisor

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