Genetic variability among Long-tailed Ducks wintering in the Baltic Sea

Abstract

The majority of Long-tailed Ducks (Clangula hyemalis) breeding in the Western Palearctic winter in the Baltic Sea. Little is yet known about population structure in wintering Long-tailed Ducks or their site fidelity to certain wintering areas, issues important in their conservation and management. Accordingly, we set out to territory-specific patterns of brood reduction, more chicks were fledged from territories with higher densities of secondary prey ('forest territories') than on those where secondary prey were less abundant ('mire territories'). The number of chicks produced by goshawks is thus habitat-dependent. By simulations that set the relative proportions of territories of different quality in different combinations in the landscape, we show that such territoryspecific patterns of reproductive success largely explain earlier reports of a weakening connection between main prey availability and goshawk reproductive success nationwide.