Early settling the following spring: a long‐term benefit of mate desertion by male Great Reed Warblers Acrocephalus arundinaceus

Abstract

In a population of the Great Reed Warbler Acrocephalus arundinaceus in central Japan 33 cases of mate desertion by males were recorded during eight breeding seasons. Thirty of these occurred at the end of the breeding season. The absence of the male parent during the nestling period affected neither the frequency of nestling starvation nor the return of females. Eight deserters were confirmed to have begun moulting prior to the fledging of their young. Males which had abandoned their territory relatively early in the summer tended to settle earlier and to be polygynous the following spring. As earlier settling is an important factor influencing polygyny in males, an increased chance of early settling the following season can be regarded as a long‐term benefit of mate desertion.