Estimation of Seed Shadows Generated by Andean Woolly Monkeys (Lagothrix lagothricha lugens)

Abstract

Seed dispersal is known to play an important role in the ecology and evolution of plant communities, and there is ample evidence that seed dispersal by primates influences plant population dynamics in tropical forests directly. We used nonparametric statistical methods to estimate the dispersal kernels, i.e., the probability that a seed is moved a particular distance, generated by woolly monkeys (Lagothrix lagothricha lugens) at a sub-Andean forest in Colombia and test the hypothesis that the time of feeding influences dispersal distances. We collected data on monkey ranging patterns with the aid of global positioning system (GPS) units and obtained information on gut retention times from behavioral follows to build a model based on the kernel density estimator. Woolly monkeys drop most seeds hundreds of meters from parent trees and only a small proportion of seeds within close proximity. The time of seed ingestion had a significant effect on dispersal kernels, with seeds from fruits consumed early in the day having a greater chance of landing farther away from the tree than seeds swallowed in the late afternoon. The results of this study build on previous findings suggesting that woolly monkeys have a positive effect on the fitness of plants, which may be exacerbated in mountain forests where the diversity of large frugivores is low.