A new publication in the journal Wildfowl shows a strong coupling between Long-tailed Ducks and the density of their food, blue mussels, in the southern Baltic Sea (Hanö bight). The study shows that although Long-tailed Ducks tend to aggregate in areas of overall high food density, patchiness of the resource also plays a significant role. This suggests that the birds seek areas that optimize their feeding efficiency.
The Long-tailed Duck is the main offshore wintering seaduck species in the Baltic region, although numbers have declined steeply since the early1990s. The reasons for the decline are not well understood and information about habitat choice is scarce.
Reference: Nilsson, L., Ogonowski, M. & Staveley, T. 2016: Factors Affecting the Local Distribution of the Long-Tailed Duck Clangula Hyemalis in Baltic Offshore Waters. Wildfowl(66): 142–158.