Regional wind patterns likely shape a seasonal migration detour

Migrating animals should optimise time and energy use when migrating,
travelling directly to their destination. Detours from the most direct
route may arise however because of barriers and weather conditions.
Identifying how such situations arise from variable weather conditions is
crucial to understand population response in the light of increased
anthropogenic climate change. Here we used light-level geolocators to
follow Cyprus wheatears for their full annual cycle in two separate years
migrating between Cyprus, over the Mediterranean and the Sahara to winter
in north-east sub-Saharan Africa. We predicted that any route detours
would be related to wind conditions experienced during migration. We found
that spring migration for all birds included an eastern detour, whilst
autumn migrations were direct across the Sahara. The direct autumn
migration was likely a consequence of consistent tail-winds, whilst the
eastern detour in spring is likely to be more efficient given the wind
conditions which are against a direct route. Such variable migration
routes shaped by coincidence with prevailing winds are probably common
suggesting that some birds may be able to adapt to future changes in wind
conditions.