ABOVE: Out of the 21 species of pigeons found in Borneo, 5 species of Treron Green Pigeons are common in forested areas. Green Pigeons feed largely on ripe figs, some more than others. The Thick-billed Green Pigeon and the Large Green Pigeon feed almost exclusively on the figs of canopy level stranglers and for that reason are highly nomadic.
The 5 doves found in Borneo are all seed rather than fruit eaters. They will eat fig seeds opportunistically but only as a small part of their diet. This means that they are not serious fig seed predators
Summary: Of the 21 pigeons that live in Borneo only 5 species (3 Ducula Imperial Pigeons and 2 Ptilinopus fruit doves) are fig seed dispersers which enhance or “farm” their habitat. The other 17 species are seed predators which effectively destroy their preferred habitat by predating the seeds of their most favored fruit.
Overall Borneo’s 21 pigeons probably have a negative effect on fig populations.
The effect of this “pest pressure” on figs has led to a number of evolutionary adaptations by fig fruits to avoid seed predation;
- Many fig fruits are too large for Treron Green Pigeons to swallow. See Ficus drupacea at Signal Hill
- Most fig seeds are too small for most doves to bother eating. See Ficus racemosa and Zebra Dove
All illustrations are by Karen Phillipps copied from the Phillipps’ Field Guide to the Birds of Borneo Third edition (2014)