Sharp Differences in the Timing of Male and Female Spring Arrival in the European Stonechat, Saxicola Rubicola, and the Whinchat, S. Rubetra (Passeriformes, Muscicapidae), in North-Eastern Ukraine

Abstract

Abstract Protandry, or the arrival of males prior to females to the breeding grounds is a widespread phenomenon in migratory birds though rarely examined in related species in which its manifestation can vary. European Stonechat and Whinchat are such a pair studied with use of individual marking in North-Eastern Ukraine in 1993–2008. An apparent protandry was found in Whinchat but not in European Stonechat. The difference between the arrival dates of male and female Whinchats (6 days) was significant. The mean time span between territory establishment by a male and subsequent pair formation was 10.6 days. By contrast, 38% of the first records of European Stonechats in spring were those of already paired birds and the difference between arrival dates of both sexes was non-significant. The proximate cause of protandry in Whinchat and its’ absence in European Stonechat seems to be the differences (or the lack thereof) in the onset of spring migration. The time lapse between the start of migration of male and female Whinchats originates at African wintering grounds and is maintained en route. The absence of the protandry in European Stonechat is probably a relict behaviour from the residency. The protandry in migratory populations of this species is yet to be developed.