title: Narrow-front loop migration in a population of the common cuckoo Cuculus canorus, as revealed by satellite telemetry.
abstract: Narrow migration corridors known in diurnal, social migrants such as raptors, storks and geese are thought to be caused by topographical leading line effects in combination with learning detailed routes across generations. Here, we document narrow-front migration in a nocturnal, solitary migrant, the common cuckoo Cuculus canorus, using satellite telemetry. We tracked the migration of adult cuckoos from the breeding grounds in southern Scandinavia (n = 8), to wintering sites in south-western Central Africa (n = 6) and back to the breeding grounds (n = 3). Migration patterns were very complex; in addition to the breeding and wintering sites, six different stopover sites were identified during the 16,000 km annual route that formed a large-scale clockwise loop. Despite this complexity, individuals showed surprisingly similar migration patterns, with very little variation between routes. We compared observed tracks with simulated routes based on vector orientation (with and without effects of barriers on orientation and survival). Observed distances between routes were often significantly smaller than expected if the routes were established on the basis of an innate vector orientation programme. Average distance between individuals in eastern Sahel after having migrated more than 5,000 km for example, was merely 164 km. This implies that more sophisticated inherent guiding mechanisms, possibly involving elements of intermediate goal area navigation or more elaborate external cues, are necessary to explain the complex narrow-front migration pattern observed for the cuckoos in this study.
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mikkel
authors.initials: M
authors.lastname: Willemoes
authors.affiliation: Department of Biology, Lund University, Lund, Sweden.
authors.forename: Roine
authors.initials: R
authors.lastname: Strandberg
authors.affiliation: Department of Biology, Lund University, Lund, Sweden ; Dutch Montagu's Harrier foundation and Animal Ecology Group, Centre for Ecological and Evolutionary Studies, Groningen University, Groningen, the Netherlands.
authors.forename: Raymond H G
authors.initials: RH
authors.lastname: Klaassen
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Anders P
authors.initials: AP
authors.lastname: Tøttrup
authors.affiliation: Department of Biology, Lund University, Lund, Sweden.
authors.forename: Yannis
authors.initials: Y
authors.lastname: Vardanis
authors.affiliation: Microwave Telemetry Inc, Columbia Maryland, United States of America.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Howey
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Kasper
authors.initials: K
authors.lastname: Thorup
authors.affiliation: Max Planck Institute for Ornithology, Department of Migration & Immuno-ecology, Radolfzell am Bodensee, Germany ; Department of Biology, University of Konstanz, Konstanz, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wikelski
authors.affiliation: Department of Biology, Lund University, Lund, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Alerstam
mesh_terms: D000350:Africa, Central; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001717:Birds / Q000502:physiology*; D003198:Computer Simulation; D005843:Geography; D009949:Orientation; D011157:Population Dynamics; D017215:Satellite Communications; D012621:Seasons; D013686:Telemetry / Q000379:methods*