ABOVE: Rajah maxomys (Maxomys rajah), a common forest rat in Borneo about to feed on a ripe female Ficus cereicarpa fig. In a 3 year (1995-1998) study at Lambir in Sarawak, Rhett Harrison found that female Ficus cereicarpa fig fruits which are produced at the base of the tree trunk, were eaten by rats. Note that other potential dispersers such as Bearded Pigs, Sumatran Rhinos and deer were already locally extinct at Lambir during Harrison’s study. Illustration by Karen Phillipps.
In a Sabah study Wells et al (2009) found that although Rajah maxomys rats are known seed predators, they passed seeds up to 1.5 mm wide unharmed in their feces. Thus Rajah maxomys is most likely to be a disperser of Ficus cereicarpa and most other earth figs because their seeds are less than 1.5 mm in width.
In a Hawaiian study Shiels (2010) found that three invasive species of rats Rattus rattus,R. exulans and Mus musculus were dispersers of the seeds of Ficus microcarpa which measure 0.9 x 0.7 mm. Only seeds larger than 1.5 mm width are likely to be predated by rats. Thus on the Hawaiian islands invasive rats disperse invasive figs, and the same is probably true in Borneo.
CONCLUSION: Borneo hosts some 30 species of rat type rodents. The majority of species are likely to be important dispersers of fig seeds. The exception are the 5 species of aboreal tree mice which are believed to predate fig seeds.