Varanus olivaceus feeding in a Microcos tree – Polillo,
May 2005. From video by Simon Normanton/ Steel Spyda.
Daniel Bennett (2014) used camera traps and direct observation to investigate the foraging behavior of the butaan, . This lizard is an obligatory frugivorous monitor lizard restricted to Luzon, Polillo and Catenduanes islands in the northern Philippines. Its diet consists almost entirely of fruit and snails. Auffenberg studied this species and stated it feeds exclusively on fallen fruit from the forest floor and rarely, if ever, took fruit from trees. However, a ten year study of the species on Polillo Island in Quezon Province found no evidence to support this assertion that the lizards typically forage on fallen fruit. Bennett gather evidence indicating that the butaan normally climbs fruiting trees of all species and picked the fruit directly from branches or syncarps. The study was carried in and around the Sibulan Watershed Reserve, Polillo Island Quezon Province in primary and secondary lowland dipterocarp forest.
Bennett found the lizards spend as little time on the ground as possible. However they never overnight in fruiting trees and suggests this is probably because the trees provide neither suitable hollows nor dense thickets in which to shelter. The lizards spent as little time as possible in fruiting trees before returning to larger trees that provide greater protection from predators, and that they appear to approach fruiting trees directly without searching for fallen fruit below the canopy makes it unlikely that they would preferentially take fruit from the ground. However, snails are probably found and consumed on the forest floor rather than in trees.
Bennett, D. (2014) The Arboreal Foraging Behavior of the Frugivorous Monitor Lizard Varanus olivaceus on Polillo Island. Biwak, 8(1), 15-18.