Clutch predation in relation to nest density in the Mallard and Tufted Duck.

Abstract

Many nesting studies on waterfowl report the proportion of nests destroyed by predators (Hilden 1964; Havlin 1966a. b. 1971; Bengtson 1972; Newton & Campbell 1975; Duebbert & Lokemoen 1976) but few studies have related the proportion of nests destroyed by predators to nest density. Hill (1984) showed that clutch predation was only weakly density dependent in the Mallard Anas platyrhynchos population breeding on the Sevenoaks reserve in Kent and that predator control removed this relationship.

This paper now aims to examine the evidence for between year density dependent clutch predation in the Mallard and Tufted Duck Aythya fuligula on other areas and to investigate daily changes in predation in relation to nest density. Nest success has been shown to be higher for nests in tall vegetation (Hill, in press), therefore this paper investigates whether nests are aggregated in patches of tall cover and whether this aggregation further leads to an increase in the proportion destroyed by predators.