The exclusion of avian predators from aggregations of nesting lapwings (Vanellus vanellus)

Territorial lapwings in Aberdeenshire, Scotland, largely prevented carrion crows, (Corvus corone), their main egg predators, from approaching close to nest-sites and from entering the area within an aggregation of 11 nests. Predation rates of artifical nests were significantly lower when placed within 10 m of active lapwing nests than when>200 m from nest-sites, indicating that the presence of lapwings afforded protection from crow predation. Further artificial nest experiments showed that the amount of protection declined linearly with increasing distance from the nest-site, and some degree of protection occurred to at least 30–50 m from it. The size of this protected zone was apparently related to the number of lapwing nests present, and the survival time of eggs in artificial nests reflected the lapwings' nesting density. The defended zones around each lapwing nest overlapped appreciably in dense or large nesting aggregations, leading to the observed protection by generally excluding crows, from the nesting area.