Diet, behavior, and activity patterns

Abstract Ectothermic Galapagos tortoises must optimize their diet and behavioral repertoire in response to variable conditions across the Archipelago. In this chapter, data on tortoise diets, foraging behavior, social organization, and activity patterns from multiple species are summarized in the context of selection pressure on individuals that determine the evolutionary trajectories of populations and species. Galapagos tortoises are generalist foragers, with dietary preferences driven by water and nitrogen content, and phenological condition of available plant species. Food availability and foraging strategies determine in part the social organization and behavior of tortoises; tortoises are not territorial but do defend resource hotspots, competition for which may establish and reinforce dominance hierarchies, most pronounced in saddleback tortoises that occupy resource-poor islands. Activity patterns are constrained by the thermal environment, in particular by high temperatures that inhibit activity. Behavioral flexibility will determine in part tortoises’ persistence in a rapidly changing world.