Sedge Warblers trapped in the Eastern Baltic in spring carry substantial fat loads. 23 to 32% of individuals were 'heavy' (i.e. their mass exceeded 13.0 g), thus a considerable proportion of birds making stopover at the Courish Spit are ready for long migration hops. Rybachy spring masses are obviously higher than in the west Europe probably due to the fact that many birds from the Eastern Baltic have a longer migratory journey ahead. Another possible explanation is that some SedgeWarblers may cross Baltic Sea during their spring migration, though no ringing recoveries supporting this suggestion are available. Autumn masses and fat loads of adult Sedge Warblers are similar to spring ones. Juveniles are significantly lighter than adults. Baltic Sedge Warblers seem not to gain large fat loads near their breeding grounds but probably move to some fattening areas in Central Europe. It remains to be discovered whether this pattern is explained by the shortage in the preferred food or by the necessity to split the long journey from the Baltic area to Sahel zone.