A male Ficus allutacea fig which has been pecked but then rejected by a hornbill at Tawau Hills Park. These bright red figs obviously look delicious to the local hornbills but after a few pecks the figs are dropped and litter the forest floor below the fruiting liana.
Of the 150 fig species found in Borneo around two thirds (103 species) are dioecious which means that each plant and each fig on that plant is either male or female.
Female fig fruits produce seeds and are sweet and succulent when ripe to attract seed dispersers such as fruit pigeons and hornbills.
Male figs produce pollen not seeds and act as brood chambers for pollinating fig wasps. When male figs are ripe the fig wasps hatch. Male wasps mate with female wasps and the now pregnant females fly off carrying male pollen to search for another fig of the same species at the right stage of ripeness. If the female wasp finds a female fig first they will move around trying but failing to lay their eggs but in the process smearing male pollen on the female flowers. Eventually they will die inside the fig and their eggs will rot. If the female wasp finds a male fig first they will lay their fertile eggs in the gall flowers inside the male fig. About 30 to 40 days later the wasps will hatch and the whole cycle will begin again.
Once the female fig wasps have exited a male fig the male figs have no further ecological function.
Some curious facts:
- Male figs are not eaten by animals at any stage of their existence and will either eventually rot either on the tree or rot on the ground.
- Fig wasps detect ripe figs by smell. Female fig wasps cannot tell the difference between male and female figs.
- With some fig species such as Ficus parietalis ripe male figs look very different from ripe female figs so although birds can tell the difference female fig wasps cannot.
- With fig species where the ripe male and female figs look the same such as with Ficus allutacea, no one knows how a hornbill can tell the difference with a single peck.