PARENT SESSION
Contributed Oral Session 104: Predator - Prey Ecology: Communities; Defenses
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 521 A, Level 5, Palais des congrès de Montréal
Predator-prey space use as the emergent outcome of a behavioral response race.
Hammond, John*,1, Luttbeg, Barney1, Sih, Andrew1, 1 University of California Davis, Davis, CA, USA
ABSTRACT- How predators and prey distribute themselves across space can have large population and community level consequences by affecting the frequency and potential strength of interactions between and within trophic levels. The general pattern that emerges from numerous studies is for predators to seek areas with higher prey densities and for prey to avoid areas with higher predation risk. Almost all of these studies, however, have focused either on predators or prey and have spatially fixed the distribution of the other species. In nature, many systems feature mobile predators and prey that freely interact. Spatial patterns thus reflect a space race involving conflicting predator and prey responses. We examined the behavior and space use of mixed groups of small and large Pacific tree frog tadpoles, Hyla regilla, as prey and tiger salamander larvae, Ambystoma tigrinum, as predators in small pools consisting of four patches (two levels of algal abundance crossed with two levels of structure). Groups of predators and prey were first assayed in isolation and then together. The predators and both size classes of prey significantly shifted their space use in response to the presence of the other. Interestingly when together, larger tadpoles significantly increased their use of low resource areas, despite the fact that predators followed the same pattern. Smaller tadpoles responded to predators by tending to increase their use of patches with more structure. Overall predator-prey spatial overlap and experienced densities were lower than the null expectation based on their behaviors in isolation. A significant survival difference was also observed over 14 hours with larger tadpoles have an increased chance of survival. Results support some predictions of extant game models, but contradict others.
Key words: behavior, predator-prey, space use