title: Corticosterone and timing of migratory departure in a songbird.
abstract: Bird migration entails replenishing fuel stores at stopover sites. There, individuals make daily decisions whether to resume migration, and must also decide their time of departure. Variation in departure timing affects the total time required to complete a migratory journey, which in turn affects fitness through arrival time at the breeding and wintering grounds. It is well established that stopover departure decisions are based on cues from innate rhythms, intrinsic factors and extrinsic factors. Yet, virtually nothing is known about the physiological mechanism(s) linking these cues to departure decisions. Here, we show for a nocturnal migratory songbird, the northern wheatear (Oenanthe oenanthe), that baseline corticosterone levels of birds at stopover increased both over the migratory season and with wind assistance towards the migratory destination. Corticosterone in turn predicted departure probability; individuals with high baseline corticosterone levels were more likely to resume migration on a given night. Corticosterone further predicted the departure time within the night, with high baseline levels being associated with early departures. These novel findings indicate that corticosterone may be mediating between departure cues and the timing of departure from a stopover site, which is a major step towards understanding the hormonal control of animal migration.
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany cas.eikenaar@ifv-vogelwarte.de.
authors.forename: Cas
authors.identifier: 0000-0003-1049-8036
authors.initials: C
authors.lastname: Eikenaar
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Müller
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
authors.forename: Clara
authors.initials: C
authors.lastname: Leutgeb
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Hessler
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Lebus
authors.affiliation: Bird Studies Canada Chair of Ornithology, Acadia University, Wolfville, Nova Scotia, Canada.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Taylor
authors.affiliation: Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Schmaljohann
mesh_terms: D025041:Animal Migration; D000818:Animals; D003345:Corticosterone / Q000502:physiology*; D012621:Seasons; D020308:Songbirds / Q000502:physiology*
chemical_list: D003345:Corticosterone
keywords: Corticosterone; departure; migration; stopover; wheatear