Microhabitat evaluation and utilization by a foraging predator

Abstract

Sit-and-wait foraging is a distinct strategy that involves significant investments prior to prey encounters. However, the complexity of decisions involved in selecting, maintaining and abandoning ambush sites provides considerable opportunity for learning and flexibility, particularly for trap-building predators, such as web-building spiders. Most research into the behaviour of trap-building predators has focused on the initiation and completion of foraging bouts (site selection and site abandonment, respectively), and less consideration has been given to the ecological significance of behaviours that occur between these end points. In this study, we sought to determine whether an interim behaviour, flexible trap-construction, is a means of real-time decision making during foraging, and test a new hypothesis that site selection is not a single decision, but a cumulative series of several, distinct decisions based on evaluation of relevant site characteristics. In a laboratory assay, web-building spiders were allowed to choose between microhabitats with and without prey, and site utilization and web construction behaviours were evaluated over a foraging period, to determine how prey cues impact the evaluation and selection of foraging sites by predators. Spiders responded to prey availability across successive phases of site searching and web construction, demonstrating that multiple, distinct decision-making steps are involved in foraging site selection. These results indicate that site maintenance behaviours, such as multiple phases of trap construction, are an integral part of the decision-making framework of foraging predators.