SEEN - SE European Bird Migration Network
Weighting and fat scoring - simple measurements or a composed problem?
Przemysław Busse
Bird Migration Research Station, University of Gdansk, Poland

Apparently simple diploma work on relations between a body mass and a fat load, as defined by a standard fat scoring, gave a very surprising result. Average body mass of Robins migrating through Polish Baltic coast declined within 18 years of study by around 0.2 g. In the same period the fat level did not changed at all. More deep study shown that the average body mass is negatively correlated with a number of migrating birds. During last years number of Robins grown in average, so decline in the body mass is explained. However, stability of fatness forces a conclusion that the fat-free body mass was influenced already at the breeding grounds, far out of the migration period. The migratory fuel load is defined at different level and depends probably on a migration strategy.
Created by Pronetix 2006