title: Converging migration routes of Eurasian hobbies Falco subbuteo crossing the African equatorial rain forest.
abstract: Autumn migration of adult Eurasian hobbies Falco subbuteo from Europe to southern Africa was recorded by satellite telemetry and observed routes were compared with randomly simulated routes. Two non-random features of observed routes were revealed: (i) shifts to more westerly longitudes than straight paths to destinations and (ii) strong route convergence towards a restricted area close to the equator (1 degree S, 15 degrees E). The birds migrated south or southwest to approximately 10 degrees N, where they changed to south-easterly courses. The maximal spread between routes at 10 degrees N (2134 km) rapidly decreased to a minimum (67 km) close to the equator. We found a striking relationship between the route convergence and the distribution of continuous rainforest, suggesting that hobbies minimize flight distance across the forest, concentrating in a corridor where habitat may be more suitable for travelling and foraging. With rainforest forming a possible ecological barrier, many migrants may cross the equator either at 15 degrees E, similar to the hobbies, or at 30-40 degrees E, east of the rainforest where large-scale migration is well documented. Much remains to be understood about the role of the rainforest for the evolution and future of the trans-equatorial Palaearctic-African bird migration systems.
authors.affiliation: Department of Animal Ecology, Lund University, 223 62 Lund, Sweden. roine.strandberg@zooekol.lu.se
authors.forename: Roine
authors.initials: R
authors.lastname: Strandberg
authors.forename: Raymond H G
authors.initials: RH
authors.lastname: Klaassen
authors.forename: Mikael
authors.initials: M
authors.lastname: Hake
authors.forename: Patrik
authors.initials: P
authors.lastname: Olofsson
authors.forename: Thomas
authors.initials: T
authors.lastname: Alerstam
mesh_terms: D000349:Africa; D025041:Animal Migration; D000818:Animals; D046093:Falconiformes / Q000502:physiology*; D005843:Geography; D012621:Seasons; D013548:Sweden; D013686:Telemetry; D014197:Trees; D014329:Tropical Climate