Age-specific foraging performance and reproduction in tool-using wild bottlenose dolphins

Abstract

Effective foraging is necessary for nearly all animals, but most animals are not born with adult-like foraging performance. Instead, foraging skills are developed during an individual’s lifetime. Life-history theory predicts that adult-level foraging performance should be reached prior to the start of reproduction, but for most species, we know little about age-specific foraging in the wild. Here, we examine lifetime changes in foraging performance for a group of female wild bottlenose dolphins that use marine sponge tools to forage. After controlling for ecological effects and developmental changes in activity budgets, we show that females continue to improve in 3 aspects of foraging until a peak at around midlife, well after dolphins reach physical and sexual maturity. The factors that lead to this improved performance are unknown, but likely include learning and increasing physical ability. Dolphins’ peak in foraging performance also coincided with a peak in reproduction, with middle-aged females maximizing foraging efficiency and having the highest probability of lactating. Thus, inadequate mastery of foraging behaviors, such as tool use in bottlenose dolphins, does not limit the onset of reproduction, but improvement in foraging skill may help maximize age-specific reproduction and lifetime fitness.