New publication on passerine migration

Photo: Aron Hejdström 

Different birds use different strategies during migration. However, at some point most of them are forced to fly out over unsuitable habitats, sometimes where it is not even possible to land. This is the case for migratory passerines leaving southern Sweden during autumn migration. 
In a new study Sissel Sjöberg with colleagues look at factors affecting route choice, and which factors that affects the flight duration for the initial flight (the first 50km) across the Baltic Sea. As expected, winds were of dominating importance, both in route choice and in flight duration. More surprisingly, they observed birds departing on a longer flight across the Baltic to depart in a time frame just after sunset and that the flight duration further were affected by both cloudiness and fuel load.

The photo shows one of the robins equipped with a radio transmitter from the study. The automatic radiotelemetry system in Falsterbo makes it possible to follow it during its stay in the area, and depending on route choice, during its departure across the Baltic Sea. This to get a better understanding of stopover and departure behaviour in migratory passerines, and how they affect the overall migratory success.

The study: "Weather and fuel reserves determine departure and flight decisions in passerines migrating across the Baltic Sea" is published in Animal Behaviour.