Declines amongst breeding Eider Somateria mollissima numbers in the Baltic/Wadden Sea flyway

Breeding Eider populations in the Baltic/Wadden Sea flyway have experienced a dramatic 48% decline between 2000 and 2009, following stability from 1991 to 2000. The majority of these declines occurred in Finland and Sweden, where breeding pairs halved over the same period. While wintering numbers increased in the Baltic Sea during this time, they decreased in the Wadden Sea. Analysis of Danish hunting bag data revealed a shift in population structure, with adult female proportions dropping from 45% to 25%, while first-winter birds fell from 70% to 30%. These trends suggest continued population decline unless factors reducing adult female survival are addressed. The study highlights the need for improved flyway-level monitoring and management to mitigate these declines.

Ekroos, J., Garthe, S., Meissner, W., Nilsson, L., De Boer, P., Cervencl, A., Laursen, K., Green, M., Jonsson, J. E., Kilpi, M., Petersen, I. K., Christensen, T. K., Fox, A. D., & Öst, M. (2012). Declines amongst breeding Eider Somateria mollissima numbers in the Baltic/Wadden Sea flyway. Ornis Fennica, 89(2). https://doi.org/10.51812/of.133795