Learning and individual variation in bluegill foraging: habitat-specific techniques

Abstract

Bluegill sunfish, Lepomis macrochirus, are generalist predators that feed routinely in the vegetated and open-water habitats of North American freshwater lakes. These habitats differ in physical structure and resident prey communities, each requiring different searching behaviours for effective foraging. Laboratory feeding trials were conducted in aquaria containing vegetation and open-water habitats to detail the behavioural modifications used by bluegill to improve their habitat-specific foraging rates. In general, bluegill foraging in the open-water habitat learned to increase their searching speed, whereas bluegill foraging in the vegetation learned to search more slowly. These changes are interpreted within the context of a model of bluegill searching behaviour. Although individuals modified their searching behaviour to match the requirements of particular prey types, density and habitat structure, individuals were not equally flexible and differed in their asymptotic searching tactics. These differences in searching tactics translate into differences in habitat-specific foraging efficiency.