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 (18 S, 15 degrees E). The birds migrated south or southwest to approximately 10 degrees N, where they changed to southeasterly 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 transequatorial Palaearctic-African bird migration systems.

Keywords

bird migration; Eurasian hobby Falco subbuteo; equatorial rainforest; route convergence; ecological barrier

Published in

Proceedings of the Royal Society B: Biological Sciences
2009, volume: 276, number: 1657, pages: 727-733

SLU Authors

• Hake, Mikael

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1098/rspb.2008.1202

Permanent link to this page (URI)

https://res.slu.se/id/publ/27274