Cognitive behaviour in Asian elephants: use and modification of branches for fly switching

Asian elephants, Elephus maximus, have the greatest volume of cerebral cortex available for cognitive processing of all extant terrestrial animal species. A manifestation of cognitive behaviour is tool use and tool manufacture. Fly switching with branches is a type of tool use previously shown in captive Asian elephants to be effective in repelling flies and to vary in frequency with the intensity of flies, In the first part of the present study we report on observations of one juvenile and 33 adult wild elephants comprising 26.7 h of cumulative observations in Nagarhole National Park, Karnataka, India. Eight of these elephants were observed using branches presumably to repel flies. In the second part of the study, conducted also in Nagarhole Park, we presented to 13 captive elephants, maintained under a naturalistic system, branches that were too long or bushy to be effectively used as switches. The long branches were presented in two trials to each elephant and they were given 5 min to either attempt switching with the long branch, or modify the branch and switch with the altered branch. Eight of these elephants modified the branch on at least one trial to a smaller branch and switched with the altered branch. There were different styles of modification of the branches, the most common of which was holding the main stem with the front foot and pulling off a side branch or distal end with the trunk. We propose that fly switching with branches is a common form of tool use in wild Asian elephants when fly intensity is high. Our documentation of the manufacture of a tool by elephants, together with the fact that these animals have a volume of cerebral cortex available for cognitive processing that exceeds that of any primate species, would appear to place this animal in the category of great apes in terms of cognitive abilities for tool use and tool manufacture. (C) 2001 The Association for the Study of Animal Behaviour.