Are birds faster in spring than in autumn?

In "Towards a new understanding of migration timing: slower spring than autumn migration in geese reflects different decision rules for stopover use and departure” we reveal how some birds differ from migration theory. By analyzing 65 GPS migration tracks, we showed that white-fronted geese use different strategies in their two migrations: In spring they spread out and progress slowly to acquire extra energy by feeding in many successive stopover sites en route, whereas in autumn they fill their energy stores close to the breeding grounds and wait for supportive winds to quickly move to their wintering grounds. Then, they can cover up to 2000 km in one single day, non-stop flying with the wind.

Andrea Kölzsch

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