PARENT SESSION
Organized Oral Session 30: Modeling movement at multiple scales
Organizer(s): J Fryxell, M Turner, and M Boyce
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 511 C, Level 5, Palais des congrès de Montréal

Movement strategies and the viability of Serengeti grazers.

Fryxell, John^*,1, ¹ University of Guelph, Guelph, Ontario, Canada

ABSTRACT- Population movement across complex ecological landscapes has been the focus of much recent work. Little attention has been placed, however, on the importance of rules by which organisms decide to leave one patch and settle in another. Using an extensive data set on foraging, grass growth, and movement by Thomson's gazelles living on the Serengeti Plains, my colleagues and I have constructed a series of simulation models of movement behaviour, ranging from simple diffusion to optimal foraging. These models suggest that gazelle populations can only persist in the face of observed levels of grassland stochasticity by making adaptive decisions to depart grassland patches with below-average rates of energy gain and preferentially moving into neighbouring patches with above-average rates of energy gain. Hence, adaptive foraging decisions are needed to survive in spatially and temporally heterogeneous grazing systems. Observed patterns of gazelle population redistribution from week to week on the Serengeti Plains was most consistent with the adaptive movement models. Perhaps most importantly, unrestricted movement over large landscapes is necessary to guarantee long-term persistence. This has important practical implications for the conservation and management of savannah ecosystems.

Key words: herbivore, model, movement, landscape