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Fuel deposition patterns in soaring migrants

Predictions about costs and benefits in fly-and-forage migration compared with the traditional stopover strategy have been preliminarily illuminated by field as well as satellite tracking studies of migrating ospreys (Pandion haliaetus). These studies indicate that the fly-and-forage migration strategy may be more widespread among migratory bird species than hereto assumed, with important implications for the effect of landscape on speed and daily timing of migration.

We plan to investigate this further by analysing fuel deposition patterns of soaring migrants, like the osprey and marsh harrier (Circus aeruginosus), in relation to their migration performance and foraging in different landscapes. Fuel deposition strategies are expected to differ greatly between birds that use thermal soaring migration and those that travel by flapping flight but there are no empirical studies that allow a critical evaluation of the fuel deposition habits among soaring migrants.

Automatic balance stations

Raptor chicks in nest
Photo: Raymond Klaassen

We are developing an automatic balance station for recording and storing data about weight and identity of free-living raptors. Such stations will be arranged close to breeding, foraging and stopover sites to record for the first time the pre-migratory fattening as well as the fuelling dynamics along the route for thermal soaring migrants. Three young Ospreys have hatched in the nest that is monitored with an automatic weighing system. One of these young was captured upon fledging and got a satellite transmitter. We now hope to follow every movement of its life.

Detailed GPS tracking data

Young osprey in nest
Photo: Raymond Klaassen

A primary focus will be on individuals that are tracked by satellite GPS transmitters allowing detailed analyses of positions and behaviour on an hourly basis throughout their migratory journeys. Our project is presently obtaining year-round detailed GPS tracking data from several individuals of osprey and marsh harrier which have already been tracked for two or more years. Here, a young Osprey just before tagging on its nest near Grimsö.

Page Manager:

Centre for Animal Movement Research
Evolutionary Ecology, Department of Biology
Ecology building S-223 62 Lund Sweden