The fruits the agouti ate: Hymenaea courbaril seed fate when its disperser is absent

The neotropical canopy tree Hymenaea courbaril L. (Caesalpiniaceae) has long been hypothesized to depend on mammals for the dispersal of its seeds. Hallwachs (1986) suggested that agouti (Dasyprocta spp., Rodentia) inherited the role of disperser of H. courbaril seeds from large Pleistocene mammals (Janzen & Martin 1982). She further postulated that agouti are currently the only effective disperser of H. courbaril seeds, and predicted that they are now so critical for the regeneration of this tree that in the absence of Dasyprocta, H. courbaril would go extinct in areas where its other seed predators are present (Hallwachs 1986). Not only does this prediction have important conservation ramifications but similar predictions have been made about other neotropical tree species (Forget 1994, Leigh et al. 1993, Smythe 1989). However, these predictions have yet to be critically tested at sites with and without agouti. In this communication we test Hallwachs’ (1986) prediction on islands in Lago Guri, a 4300-km hydroelectric impoundment in east-central Venezuela. When inundation of Lago Guri was completed in 1986, scores of forested land-bridge islands were