Predation on Northe rn Lapwing Vanellus vanellus nests : the effect of population density and spatial distribution of nests.

The effects of population density, nest pattern , size of nest aggregations and position of nests within aggregations on preda ti on rates were an alysed in two Northern Lapwing Vanellus vanellus populations in agricultural l andscape in South Bohemia, Czech Republic, 1988-98 . Two sites ( Arable Land and Meadow) differed in breeding densities but their nest patterns were similarly clumped. While population density negatively correlated with nest predation rate at both sites, the nest pattern demonstrated only a weak effect. Nest predation was not influenced by dist ance to the nearest neighbouring nest while it was significantly affected by aggregation size in Meadow but not in Arable Land. Decreasing predation from edge to centre of large aggregations supports Lack’s protective umbrell a hypothesis . However, large aggregations in Arable L and experi enced high predation risk, particularly due to extensive loss of marginal nests indicating that the Northern Lapwings’ aggregating behaviour may not always reduce predation risk in the group as a whole . Habitat quality and composition of predator guilds are considered to be factors in fluencing the different predation pattern on nests at the studied sites.

Salek M. & P. Smilauer 2002, Ardea 90(1) : 51-60