Determinants of day-range length in the black howler monkey at Lamanai, Belize

Extract

Ranging patterns are important features of animal ecology both for evolutionary ecologists who study adaptive foraging and habitat use, and for conservationists who need information on habitat requirements and minimum resource needs. Because ranging patterns are difficult and time-consuming to measure, many researchers have sought socio-ecological variables that predict range use. For example, many studies show a correlation between daily path length (day-range length) and the number of animals in a group (Chapman et al. 1995, van Schaik et al. 1983, Waser 1977, Wrangham et al. 1993). This seems reasonable because larger groups have more mouths to feed, necessitating more travel to find adequate food supplies. Group size is far easier to measure than day range, hence the attraction of this variable. However, group size must be used cautiously as a proxy for day range because their relationship is neither strong nor straightforward.