FRUIT FINDING BY MANGABEYS (LOPHOCEBUS-ALBIGENA) - ARE MONITORING OF FIG TREES AND USE OF SYMPATRIC FRUGIVORE CALLS POSSIBLE STRATEGIES

Frugivorous forest primates face a continual challenge ro locate ripe fruit due to the poor visibility characterizing a heavily vegetated ha bitat and the spatial and temporal unpredictability of their fruit sou rces. We present two hypotheses regarding fruit finding in gray-cheeke d mangabeys (Lophocebus albigena). The first hypothesis is that mangab eys monitor nonfruiting fig trees by visiting and checking them for fr uit at a higher rate than control trees that do not produce preferred fruit. We test this hypothesis by comparing rates of visitation to foc al Jig trees and control trees. The second hypothesis is that mangabey s use sympatric frugivore loud calls to locate fruit sources. We test this hypothesis (1) observationally, by comparing the rates at which m angabeys visit calling sires of sympatric frugivores and matched contr ol areas; and (2) experimentally, by following mangabey responses to p laybacks of tape-recorded calls: the black-and-white-casqued hornbill (Bycanistes subcylindricus) long call, the great blue turaco (Corythae ola cristata) rattling kok, the adult male mangabey whoopgobble, and t he chimpanzee (Pan troglodytes) pant hoof. We rested the hypotheses vi a data from a single group of mangabeys in the Kibale National Park, U ganda. There is no evidence that mangabeys monitor fig trees for the p resence of fruit, but they may use the calls of hornbills to locate fr uit. Statistical evidence that mangabeys use conspecific whoopgobbles and chimpanzee pant hoots in fruit finding is lacking, though anecdota l observations suggest this possibility. There is no evidence for use of turaco calls in fruit finding.