Lateralization in trunk and forefoot movements in a population of free-ranging Asian elephants (Elephas maximus).

Abstract

We examined side preferences in trunk and forefoot movement during feeding in a wild population of Asian elephants. Trunk sweeping movements to pluck/uproot/gather vegetation and forefoot scuffing movements to uproot vegetation were scored in 206 individuals. We found a much stronger side preference in trunk use than in forefoot use, supporting a modified task complexity hypothesis. The forefoot and trunk appeared to be coordinated while feeding and, among individuals that had significant forefoot preferences, the proportion of right forefoot use was higher among right trunkers than left trunkers. Trunk and forefoot preferences were not dependent on individuals' social associates, and trunk preferences were also not dependent on feeding associates. There was a significant effect of individual identity on forefoot preference strength but no population-level side preference in trunk or forefoot movement, suggesting no dominant eye control over the task, which might be true of feeding-related foot movement in other herbivores also. There was no effect of age or sex on trunk or forefoot side preference or strength. The onset of trunk side preference, however, was very early compared with that observed in other species studied and calls for a comparison of the ontogeny of side preferences in precocial and altricial species. Based on 57 mother-offspring pairs, we found that offspring trunk side preferences were independent of their mothers' preferences, suggesting that these preferences are not maternally inherited.