Estimation of the retention times and distances of seed dispersed by two monkey species, Alouatta seniculus and Lagothrix lagotricha, in a Colombian forest

Isolated-bout method to estimate the retention times and dispersal distance s was applied to the seed dispersal by red howler monkeys (Alouatta senicul us) and Humboldt's woolly monkeys (Lagothrix lagotricha) in a lowland tropi cal forest at La Macarena, on the border of the Macarena and Tinigua Nation al Parks, the Department of Meta, Colombia. Continuous observations were ma de on the feeding and ranging behavior of well-habituated troops of howler monkeys and woolly monkeys as well as continuous collection of monkeys' fec es. We selected out the 'isolated-bout' as a feeding bout on the specific s pecies that was only once recorded within 48 h before the seeds of that spe cies appeared in the feces of monkeys. In that case, the seeds were strongl y suggested to come from that isolated bout. Then retention times, route se ed dispersal distances and direct seed dispersal distances were estimated. Howler monkeys, which are regarded as generalist herbivores, showed longer retention times and dispersal distances along monkeys' route than did wooll y monkeys, which are specialist frugivores. However, the direct distances t hat seeds were carried from the mother tree were not significantly greater for howler monkeys than for woolly monkeys. This shows that both retention time and movement patterns by the monkeys, especially the total ranging are a, influence the direct distance that seeds are carried from the mother tre e.