Seed dispersal by woolly monkeys (Lagothrix lagothricha) at Tinigua National Park, Colombia: dispersal distance, germination rates, and dispersal quantity.

Abstract

The purpose of this study was to describe seed dispersal patterns of woolly monkeys (Lagothrix lagothricha) in terms of dispersal quantity and two factors related to dispersal quality: germination rates of dispersed seeds and the distance of dispersal to parental trees. The possible influence of retention time, travel distance, seed size, activity patterns, and fruit abundance on dispersal distance was also analyzed. Observations on activity, diet, daily movements, and seed dispersal were made on focal individuals of a group of woolly monkeys at a tropical rain forest in Tinigua National Park (Colombia). Sixty hours of focal samples per month were completed during 1 year. A total of 753 depositions were collected during the study. Each dropping contained seeds from an average of 2.68 different species (range 0 to 9). Collected depositions contained an underestimated total of 50,168 seeds (>1 mm). Given a population density of 30 individuals/km2, the woolly monkeys in the study area disperse more than 25,000 seeds/km2/day. These seeds belong to 112 different plant species. Germination rates of dispersed seeds are usually similar or higher than those of non-swallowed seeds. It was possible to determine dispersal distance in 264 cases when the focal animal was continuously followed from ingestion at the parental tree to deposition. Only 1% of these depositions landed in close proximity (<15 m) of the parental tree. It was very common that the droppings were deposited between 100 and 500 m from the parent tree, and up to 1.5 km. Higher retention times and longer travel distances were not correlated with increased dispersal distance. Two main reasons for this result were the prolonged and variable passage rates (avg=11.2 hr+/-6.5 SD.) and the circuitous routes of monkeys in this forest.