Fruit foraging and seed dispersal by land crabs in a temperate coastal forest

Abstract

Land crabs are involved in seed dispersal and seed predation in certain tropical vegetation. However, only a few studies have examined this ecological role of land crabs in temperate regions. This study evaluated the preference of land crabs for fruit and assessed their ability to act as seed dispersers and seed predators. The study included three species of land crab, Chiromantes haematocheir, Sesarmops intermedium, and C. dehaani, that are widely distributed in Japan. Individuals from these crab species exhibited preferences for fruits of 11 plant species. C. dehaani crabs were observed only in wet vegetation; they fed on fruit near the nest and frequently destroyed seeds. Therefore, C. dehaani seems to be a seed predator rather than a seed disperser. C. haematocheir crabs were observed near different kinds of vegetation; they often carried fruit away from the nest and destroyed seeds only to a limited extent. This suggests that C. haematocheir contributes to the seed dispersal of many species. In comparison with the other two species, S. intermedium crabs were found to exhibit intermediate traits. In temperate coastal forests, each species of land crab may affect seed survival and dispersal in a different manner.