Frugivory and seed dispersal by woolly monkeys at Tinigua National Park, Colombia

Conservation programs should be based on the knowledge of ecosystem function, but especially in the complex and diverse tropical forests there are still many gaps to fully understand the patterns of plant regeneration. The ultimate purpose of this project was to determine the role of woolly monkeys ( Lagothrix lagothricha) as seed dispersers in a pristine forest in Tinigua National Park (Colombia), and to assess their potential role in forest regeneration.; Over a period of three and a half years of focal follows (2624 h), I have observed the woolly monkeys consuming fruits of about 200 different species. The results of regression analyses indicated a preference to spend more time consuming fruits with large community-wide production, displaying large crops, with high pulp/seed ratios, low lipid contents, and high sugar and water contents, and a trend to reject astringent fruits.; A total of 1562 depositions were collected during the study. They consistently act as seed predators for about 7% of plant species consumed, a behavior that is negatively correlated with fruit production in the forest. However, a significant positive slope (0.7) for the regression line predicting the number of dispersed seeds from the estimated number of manipulated seeds, indicated that the woolly monkeys dispersed the majority of the seeds that were manipulated. I concluded that in terms of dispersal quantity woolly monkeys at Tinigua Park are very efficient seed dispersers being responsible for about a third of the mass of dispersed seeds in this diverse frugivore community.; In terms of seed dispersal quality, woolly monkeys, like many other primates, are effective seed dispersers in terms of their effects on the seeds they swallow, because the germination rates of dispersed seeds are usually higher or similar to that of non-dispersed seeds. Furthermore, less than 8% of these depositions landed in close proximity (<15 m) to parental trees. It was very common that the droppings were deposited between 100 and 500 m from the parent tree. This pattern of dispersal appears to be advantageous to plant fitness, given that transition probabilities between seedling and sapling stages for the majority of the plant species studied was lower near parental plants. The transplant experiments gave little evidence supporting the escape hypothesis for the majority of species studied, but it is likely that negative density dependent effects are affecting the plants at later life stages. Small differences in the fate of seeds in different density treatments and the effects of different animals on germination rates, emphasize the importance of seed dispersal quantity in this community.; Although, none of 74 plant species observed during fruiting periods were exclusively dispersed by woolly monkeys, two lines of evidence (fruit traps and dispersal estimates, frugivory observations) suggest that they disperse about one third of the seeds in the community. In terms of seed quantity this species plays a role comparable to that of the whole bird community, and it is very likely that its disappearance from the community will have dramatic changes in the regeneration of the forest. (Abstract shortened by UMI.)...