title: Individuality in bird migration: routes and timing.
abstract: The exploration of animal migration has entered a new era with individual-based tracking during multiple years. Here, we investigated repeated migratory journeys of a long-distance migrating bird, the marsh harrier Circus aeruginosus, in order to analyse the variation within and between individuals with respect to routes and timing. We found that there was a stronger individual repeatability in time than in space. Thus, the annual timing of migration varied much less between repeated journeys of the same individual than between different individuals, while there was considerable variation in the routes of the same individual on repeated journeys. The overall contrast in repeatability between time and space was unexpected and may be owing to strong endogenous control of timing, while short-term variation in environmental conditions (weather and habitat) might promote route flexibility. The individual variation in migration routes indicates that the birds navigate mainly by other means than detailed route recapitulation based on landmark recognition.
authors.affiliation: Department of Animal Ecology, Lund University, Ecology Building, 22362 Lund, Sweden. yannis.vardanis@gmail.com
authors.forename: Yannis
authors.initials: Y
authors.lastname: Vardanis
authors.forename: Raymond H G
authors.initials: RH
authors.lastname: Klaassen
authors.forename: Roine
authors.initials: R
authors.lastname: Strandberg
authors.forename: Thomas
authors.initials: T
authors.lastname: Alerstam
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001717:Birds / Q000502:physiology*; D013997:Time Factors