Problems associated with the seed-trap method when measuring seed dispersal in forests inhabited by Japanese macaques

Despite the widespread use of seed/litter traps in seed dispersal ecology, several problems have arisen when using this method in forests inhabited by semi-terrestrial monkeys. The first issue is the height of the trap relative to the location where macaques spit seeds and/or defecate. For Japanese macaques in the lowland forests of Yakushima Island, southern Japan, 30-50% of the seeds emitted from cheek pouches and faeces will not be caught by seed traps, leading to underestimation of seed fall. The second issue is the attractiveness of seed traps. Macaques sometimes play with the traps, potentially affecting the results of the seed-trap method in complex ways, including both negative and positive effects. To obtain reasonable estimates of total seed dispersal, we recommend that researchers conduct the seed-trap method concurrently with monkey observations, and that they should affix traps more securely to prevent macaques from destroying the traps.