title: Barrier crossing in small avian migrants: individual tracking reveals prolonged nocturnal flights into the day as a common migratory strategy.
abstract: Over decades it has been unclear how individual migratory songbirds cross large ecological barriers such as seas or deserts. By deploying light-level geolocators on four songbird species weighing only about 12 g, we found that these otherwise mainly nocturnal migrants seem to regularly extend their nocturnal flights into the day when crossing the Sahara Desert and the Mediterranean Sea. The proportion of the proposed diurnally flying birds gradually declined over the day with similar landing patterns in autumn and spring. The prolonged flights were slightly more frequent in spring than in autumn, suggesting tighter migratory schedules when returning to breeding sites. Often we found several patterns for barrier crossing for the same individual in autumn compared to the spring journey. As only a small proportion of the birds flew strictly during the night and even some individuals might have flown non-stop, we suggest that prolonged endurance flights are not an exception even in small migratory species. We emphasise an individual's ability to perform both diurnal and nocturnal migration when facing the challenge of crossing a large ecological barrier to successfully complete a migratory journey.
authors.affiliation: Department of Zoology, Palacký University, tř. 17. listopadu 50, CZ-771 46 Olomouc, Czech Republic.|Museum of Natural History, nám. Republiky 5, CZ-771 73 Olomouc, Czech Republic.
authors.forename: Peter
authors.initials: P
authors.lastname: Adamík
authors.affiliation: Department of Bird Migration, Swiss Ornithological Institute, Seerose 1, CH-6204 Sempach, Switzerland.
authors.forename: Tamara
authors.initials: T
authors.lastname: Emmenegger
authors.affiliation: Department of Zoology, Palacký University, tř. 17. listopadu 50, CZ-771 46 Olomouc, Czech Republic.
authors.forename: Martins
authors.initials: M
authors.lastname: Briedis
authors.affiliation: Department of Animal Ecology/Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Gustafsson
authors.affiliation: Department of Animal Ecology/Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
authors.forename: Ian
authors.initials: I
authors.lastname: Henshaw
authors.affiliation: Department of Zoology, Palacký University, tř. 17. listopadu 50, CZ-771 46 Olomouc, Czech Republic.|Museum of Natural History, nám. Republiky 5, CZ-771 73 Olomouc, Czech Republic.
authors.forename: Miloš
authors.initials: M
authors.lastname: Krist
authors.affiliation: Section of Ecology, Department of Biology, University of Turku, FI-20014, Turku, Finland.
authors.forename: Toni
authors.initials: T
authors.lastname: Laaksonen
authors.affiliation: Department of Bird Migration, Swiss Ornithological Institute, Seerose 1, CH-6204 Sempach, Switzerland.
authors.forename: Felix
authors.initials: F
authors.lastname: Liechti
authors.affiliation: Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Květná 8, CZ-603 65 Brno, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Procházka
authors.affiliation: Michael-Otto-Institut im NABU, Goosstroot 1, D-24861 Bergenhusen, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Salewski
authors.affiliation: Department of Bird Migration, Swiss Ornithological Institute, Seerose 1, CH-6204 Sempach, Switzerland.
authors.forename: Steffen
authors.initials: S
authors.lastname: Hahn
mesh_terms: D000352:Africa, Northern; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001947:Breeding; D005426:Flight, Animal / Q000502:physiology*; D040362:Geographic Information Systems; D008522:Mediterranean Sea; D020308:Songbirds / Q000502:physiology*