Mammals serve as important dispersers of large-seeded plant species in many habitats. In the Neotropics, agoutis are important seed dispersers as well as seed predators and have been shown to be the only disperser of many important canopy trees. Agoutis eat seeds on site or disperse and bury them in a shallow cache as a means of storage for later consumption. However, not all cached seeds are recovered and those that are not are thought to possess a competitive advantage over uncached seeds. The red-rumped agouti, Dasyprocta leporina, is an introduced species on the Caribbean island of Dominica, where there are a number of large-seeded tree species with few other dispersers. We asked whether the presence of D. leporina on Dominica significantly alters levels of seed predation and dispersal of large-seeded canopy trees. To address how many seeds are removed from below fruiting trees by D. leporina versus other animals, we placed seeds of various large-seeded canopy trees in piles inside or outside of exclosures designed to exclude agoutis but allow all other possible seed dispersers and predators. We then tracked thread-marked seeds to determine the rate at which seeds removed by agoutis were dispersed and cached versus consumed immediately.
Results/Conclusions
The majority of secondary dispersal of large-seeded species in Dominica can be attributed to agoutis. Dispersal distances varied depending on tree species, seed size, and region of Dominica. Germination rates of cached seeds differed from seeds placed on the forest floor. These results suggest that the introduction of D. leporina to Dominica may have significantly altered dispersal patterns of large-seeded canopy species from what they were prior to the introduction of D. leporina.
