title: Avian migration: temporal multitasking and a case study of melatonin cycles in waders.
abstract: Timing "in the real world" must cope with the temporal complexity of natural environments. Extreme examples for the resultant "multitasking" are migratory birds, which precisely time movements to remote areas. New field technologies highlight temporal accuracy, while captivity studies emphasize underlying programs and plasticity of schedules. After reviewing these findings, we focus on waders, which undertake spectacular long-distance migrations, have robust circannual clocks, and cope with diel, tidal, and polar environments. To explore features that may facilitate such multitasking, we speculated that melatonin amplitudes are low and damped during seasons when entrainment to subtle Zeitgebers occurs. We measured melatonin profiles under European daylength in two species with different ecologies and found low-amplitude melatonin cycles that changed over the year. Annual patterns neither fully supported our hypothesis, nor simply reflected daylight availability. While migratory birds are inspiring models for chronobiology, mechanistic understanding of their multitasking is still poor.
authors.affiliation: Max-Planck-Institut für Ornithologie, Andechs, Germany; Fachbereich Biologie, Universität Konstanz, Konstanz, Germany; Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom. Electronic address: helm@orn.mpg.de.
authors.forename: Barbara
authors.initials: B
authors.lastname: Helm
authors.affiliation: Max-Planck-Institut für Ornithologie, Andechs, Germany.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Gwinner
authors.affiliation: Department of Marine Ecology, Royal Netherlands Institute for Sea Research (NIOZ), Den Burg, Texel, The Netherlands.
authors.forename: Anita
authors.initials: A
authors.lastname: Koolhaas
authors.affiliation: Ecology Group, Institute of Natural Resources, Massey University, Private Bag, Palmerston North, New Zealand.
authors.forename: Phil
authors.initials: P
authors.lastname: Battley
authors.affiliation: Max-Planck-Institut für Ornithologie, Andechs, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Schwabl
authors.affiliation: Department of Marine Ecology, Royal Netherlands Institute for Sea Research (NIOZ), Den Burg, Texel, The Netherlands.
authors.forename: Anne
authors.initials: A
authors.lastname: Dekinga
authors.affiliation: Department of Marine Ecology, Royal Netherlands Institute for Sea Research (NIOZ), Den Burg, Texel, The Netherlands.
authors.forename: Theunis
authors.initials: T
authors.lastname: Piersma
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001717:Birds / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D004777:Environment; D008550:Melatonin / Q000378:metabolism*; D017440:Photoperiod; D012621:Seasons
chemical_list: D008550:Melatonin