Relationships between Fruiting Seasons and Seed Dispersal Methods in a Neotropical Forest

The weight of fruits and seeds that fell into 75 polyethylene sheets, each 152 x 152 cm, totalling 175 m2 in area, was measured over a period of 17 months in the humid forest of Barro Colorado Island, in the Panama Canal Zone. A total of 72 species of fruits and seeds fell into the traps, and the number falling into any individual trap varied from three to 14. The number of fruiting species per month varied from 11 to 26, while the combined weight of fruits and seeds varied from a monthly average of 0.61-1.930 gm/square meter per day. Small-seeded fruits ripened rather evenly throughout the year, whereas large-seeded fruits tended to be seasonal. Although the primary determinants of fruiting times may be physical, small fruits the seeds of which pass unharmed through the guts of animals tend to be nonseasonal and thus avoid competition for dispersal. Fruits with large seeds that are destroyed by the animals eating them fruit synchronously. The agouti (Dasyprocta punctata), being unable to devour the entire synchronous crop, scatterhoards much of it and, since it fails to find many of the buried seeds, aids in the dispersal of its food species.