The influence of phenology on double-brooding and polygyny incidence in the Sedge Warbler Acrocephalus schoenobaenus

Tadeusz Zając,Wojciech Solarz,Wojciech Bielański,Adam Ćmiel

doi:10.1007/s10336-015-1181-x

Tadeusz Zając, Wojciech Solarz + Show 2 more

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https://doi.org/10.1007/s10336-015-1181-x

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Abstract

There is growing evidence that the fitness of birds in temperate zones depends strongly on the match between the timing of breeding and local phenology. We have analysed data collected from a 15-year study on a Sedge Warbler (Acrocephalus schoenobaenus) population in its natural habitat. The highly skewed distribution of arrival dates of males indicated that they competed intensely to be the earliest arrivals. The distribution of mating dates, unlike arrival dates, was not skewed, rather it formed a bell-shaped distribution. Because females arrived much later, they could not base their mating choices on the arrival dates of males. Females, however, could use male song repertoire, a trait we found to be correlated with male arrival date. Double-brooded females mated early in the season, exactly within the peak of mating date distribution. Polygynous females, on the other hand, mated later in the season, choosing high-quality older males which had arrived significantly earlier. Male territory quality did not differ between double-brooded and polygynous females, nor did the quality of the territories occupied by an individual female change during her lifetime. Although longer lifespan and double-brooding influenced a female’s fitness over the course of her lifetime, polygyny had no significant effect. We conclude that Sedge Warbler females do not compete for territorial resources, but they do prefer to mate with high-quality early-arriving males. Polygyny is an effective strategy used by females to compensate for their late arrival and breeding onset, since they pair with high-quality males.

Highlights

For migratory birds, the timing of male arrival at the breeding territory is a key determinant of male breeding success
We have analysed data collected from a 15-year study on a Sedge Warbler (Acrocephalus schoenobaenus) population in its natural habitat
The aim of our study was to determine how reproductive decisions of the female of the Sedge Warbler Acrocephalus schoenobaenus are governed by the timing of breeding

Summary

Introduction

The timing of male arrival at the breeding territory is a key determinant of male breeding success. The earliest males occupy the best territories (Aebischer et al 1996; Petit and Petit 1996; Hasselquist 1998; Forstmeier 2002; Smith and Moore 2005; Zajac et al 2006; Sergio et al 2007) They mate more successfully (Alatalo et al 1984; Møller 1994; Aebischer et al 1996; Lozano et al 1996; Hasselquist 1998; Kokko 1999; Currie et al 2000), raise more progeny (Møller 1994; Hasselquist 1998; Currie et al 2000; Cooper et al 2011) whose survival prospects are better (Hochachka 1990; Hasselquist 1998; Currie et al 2000; Smith and Moore 2005) and improve the quality of their territories thanks to advanced arrival dates in subsequent years (Bensch and Hasselquist 1991; Zajac et al 2011). The decision to mate as a second polygynous female may result in some disadvantages in terms of fitness (Searcy and Yasukawa 1989; Bensch 1997)

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