Foraging Modes of Predators and Behaviors of Prey Determine the Outcome of Multiple Predator Interactions

Abstract

Interactions with multiple predator species may differ among prey with different antipredator defenses. The interactions between largemouth bass Micropterus salmoides (a cruising predator) and muskellunge Esox masquinongy (an ambush predator) and prey with different antipredator behaviors, bluegill Lepomis macrochirus and fathead minnow Pimephales promelas, was examined in mesocosms. In the combined predator treatment, no differences were found in the foraging sequence for the cruising predator, whereas the ambush predator increased the number of follows and pursuits. Bluegills altered their behavior across predator treatments by changing their activity levels and habitat use. Ultimately, the ambush predator benefited from the combined predators because of a greater encounter frequency with bluegills that led to more captures and a risk-enhanced effect on bluegills. The high vulnerability of fathead minnow to individual ambush and cruising predators led to a neutral effect from combined predators. Predator foraging modes and prey behavior must be taken into account to understand natural food webs.

ACKNOWLEDGMENTS

We thank the staff at the Kaskaskia Biological Station, Illinois Natural History Survey, especially L. Einfalt and M. Diana for help with conducting experimental trials and field collections. Numerous undergraduate students especially M. Goshen, J. O’Brein, C. Steger, A. Goldberg, N. Leagnavar, I. Carney, and A. Romero from the University of Illinois at Urbana-Champaign assisted with gathering the behavioral data. All procedures conformed to the University of Illinois Institutional Animal Care and Use Committee, and compliance with the current laws of the U.S. Support was provided by the Illinois Natural History Survey.