FORAGING STRATEGIES OF LONG-TAILED MACAQUES, MACACA-FASCICULARIS - DIRECTIONAL EXTRAPOLATION

This experiment examined whether macaques could use purely spatial characteristics of a food distribution as cues to organize their search. Five captive male long-tailed macaques were tested individually and presented with three food piles (cues) of decreasing visibility, spaced at l-m intervals along an invisible directional line. The line changed its location and orientation in space on each trial. After the macaques had found the cues, they inspected other places which were (1) on the same terrain on which they found the cues (a sandfield), (2) on the extension of the invisible line through the three cues and (3) in the direction in which the visibility of the cues decreased. The macaques appeared to extrapolate from the variation in the visibility of the cues and from the position of the cues relative to one another to new potential food sites. An ability to predict food locations based on the distribution of previously found food can be expected to improve a macaque's foraging success in natural patches. The present study indicates a close connection between foraging tendencies and event perception in macaques.