Factors affecting the winter distribution of wildfowl in the valley of the Ticino River (northern Italy)

Abstract

Abstract From 1981 to 1988 the wintering wildfowl population in the valley of the Ticino River varied from a minimum of 6 100 individuals in 1988 to a maximum of 20 910 individuals in 1982. Seventeen species were recorded; the mallard (Anas platyrhynchos) was the most common bird and on average represented 81.1% of the total population. Most of the waterbirds were observed in oxbow lakes, and these areas were positively selected by all species. Canals and streams were preferred by ducks. The river was avoided by all species, and reservoirs were only used by teals (Anas crecca) and, to a lesser extent, by mallards. Riparian vegetation cover and disturbance were the main factors affecting the distribution of water‐birds. Most of the wildfowl used the wetlands only for roosting. A reduction in the movement of birds from roosting to feeding sites (mainly maize and wheat stubbles), and hence a reduction in the mortality caused by hunting, could be achieved by management practices aimed at increasing aquatic vegetation in the wetlands.