Factors Affecting Post-Breeding Moult in the Savi's WarblerLocustella luscinioidesin Northern Poland

Abstract

A majority of Eurasian short-distance migrants moult after breeding and before autumn migration, while most long-distance migrants perform a winter moult in the tropics after autumn migration. Another strategy among long-distance migrants is a partial moult on the breeding grounds, suspended moult and then completion of moult on the wintering grounds. The Savi's Warbler Locustella luscinioides is a small passerine adopting such a ‘suspended moulting’ strategy. Here, we investigate the sequence and extent of the post-breeding moult in Savi's Warblers breeding in and migrating through northern Poland in relation to sex, body mass and date. We analysed 65 molecularly sexed adult Savi's Warblers (32 females and 33 males) caught during autumn migration in 2010–2011. Adult Savi's Warblers from the studied populations were found to suspend moult. Exchange of wing feathers started at the third primary (P3) and progressed in both directions. The onset of secondary moult began with S1 and occurred when P6 was shed....