Habitat quality and breeding parameters in relation to female mating status in the polygynous Eurasian Bittern Botaurus stellaris

Zbigniew Kasprzykowski,Marcin Polak

doi:10.1007/s10336-012-0904-5

Abstract

The Eurasian Bittern Botaurus stellaris has a polygynous mating system where the nests of solitary and clumped females are located within a male territory. However, the factors that may favour the formation of nest clusters remain unknown. The focus was on the clustering effect in the Eurasian Bittern population on fishpond complexes in eastern Poland in order to test whether clumped nesting is dependent on habitat quality. Breeding parameters were also assessed in order to investigate the advantages accruing to females of nesting close together in clusters. During the breeding periods between 2003 and 2009, we found 144 active nests of the Eurasian Bittern: most of them (55.5 %) were in clusters of two to four nests. The mean distance between adjacent nests in a cluster was 23.5 m. The proportion of open water to emergent vegetation and the category of fish stock have significant effects on cluster nesting in the Eurasian Bittern. There were differences between single and clumped nests with respect to the first-egg laying date and male presence. The environmental and ecological factors that may determine the Eurasian Bittern female’s nest-site choice are discussed.

Highlights

The Eurasian Bittern Botaurus stellaris differs from other herons (Ardeidae) in many aspects of its ecologyJ Ornithol (2013) 154:403–409(Voisin 1991; Kushlan and Hafner 2000)
Of the 127 combinations of variables investigated, the model containing the number of green reed stems, the proportion of open water to emergent vegetation and the category of the fish stock best explained clustered nesting in the Eurasian Bittern (Table 2)
The proportion of open water to emergent vegetation had a significant influence on the probability of nesting in clusters: clumped females preferred a more even proportion of these two habitats than

Summary

Introduction

The Eurasian Bittern Botaurus stellaris differs from other herons (Ardeidae) in many aspects of its ecologyJ Ornithol (2013) 154:403–409(Voisin 1991; Kushlan and Hafner 2000). Eurasian Bitterns are reported to nest on wet vegetation stands with rich food resources such as fish, crustaceans, amphibians and insects (Gilbert et al 2003; Poulin et al 2005; Puglisi and Bretagnolle 2005), and in related open habitats, especially highly productive marshlands, which can be monopolised by certain males; these attract additional females to their high quality territories (Verner and Willson 1966). In Eurasian Bitterns, some female nest sites may not coincide with the locations of male booming territories (Gauckler and Kraus 1965; Adamo et al 2004; Gilbert et al 2005a; White et al 2006). The factors that may influence female nest grouping in Eurasian Bitterns remain unknown

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