Official journal of the Netherlands Ornithologists' Union
|Suter W. & Van Eerden M.R. (1992) Simultaneous mass starvation of wintering diving ducks in Switzerland and The Netherlands a wrong decision in the right strategy? ARDEA 80 (2): 229-242
|On an important wintering site for waterfowl along the river Rhine, Switzerland, between 2700 and 6200 diving ducks died from starvation in March 1986. At the same time, mass starvation occurred in the western part of the Dutch Waddenzee with at least 18,000 waterbirds involved of which over 14,000 were diving ducks. In Switzerland, only Pochard and Tufted Duck were affected. Both species are dependent on the Zebra Mussels Dreissena polymorpha. Mussels stocks are annually depleted by the birds towards late winter, around the onset of home migration. In 1986 however, when the available mussels biomass was probably below average, a month-long cold spell occurred in February. In The Netherlands the diving ducks faced equally harsh weather conditions when available Mytilus edulis food stocks were low. In both areas, many birds remained and starved, instead of moving away. The inadequate reaction may be explained by a waterfowl migration strategy which does not account for extremely long cold spells in late winter, since the probability of such events is very low.