Dispersal between Nest-Sites by Stonechats Saxicola torquata in Relation to Previous Breeding Success

Abstract

Distances between nest-sites used successively within a breeding season were measured in a population of Stonechats. The frequencies and consequences of dispersing different distances were examined in relation to previous nesting success. Nestpredation tended to be greatest after moving far from the previous nest site, and was no higher after predation on the previous nest, but was low if many young had fledged. Nestling growth was significantly better at greater distances from the previous nest, if young had fledged from it. Birds moved farther, and were more likely to use different vegetation in which to nest, after previous predation than if success had been low for other reasons. After escaping predators, they moved farther, and were more likely to change vegetation, if more young had fledged from the previous nest. These results imply that birds adjust the placement of nests according to previous success, though great variation in dispersal distance remained unexplained by these tactics.