DIETARY HABITS OF THE WORLD'S LARGEST BATS: THE PHILIPPINE FLYING FOXES, ACERODON JUBATUS AND PTEROPUS VAMPYRUS LANENSIS

The endemic and endangered golden-crowned flying fox (Acerodon jubatus) coroosts with the much more common and widespread giant Philippine fruit bat (Pteropus vampyrus lanensis) in lowland dipterocarp forests throughout the Philippine Islands. The number of these mixed-roost colonies and the populations of flying foxes in them have declined dramatically in the last century. We used fecal analysis, interviews of bat hunters, and personal observations to describe the dietary habits of both bat species at one of the largest mixed roosts remaining, near Subic Bay, west-central Luzon. Dietary items were deemed "important" if used consistently on a seasonal basis or throughout the year, ubiquitously throughout the population, and if they were of clear nutritional value. Of the 771 droppings examined over a 2.5-year period (1998-2000), seeds from Ficus were predominant in the droppings of both species and met these criteria, particularly hemiepiphytic species (41% of droppings of A. jubatus) and Ficus variegata (34% of droppings of P. v. lanensis and 22% of droppings of A. jubatus). Information from bat hunter interviews expanded our knowledge of the dietary habits of both bat species, and corroborated the fecal analyses and personal observations. Results from this study suggest that A. jubatus is a forest obligate, foraging on fruits and leaves from plant species restricted to lowland, mature natural forests, particularly using a small subset of herniepiphytic and other Ficus species throughout the year. In contrast, P. v. lanensis has a broader diet, including fruits, leaves, and flowers; forages in both natural and agroforests; and uses a wider variety of fruit than does A. jubatus in natural forest habitats. A small subset of the available Ficus species also is used heavily by P. v. lanensis throughout the year. These results provide insight into the autecology and interspecific relationship of these coroosting species, as well as suggest the prospects of both species' continued survival given changes in their habitat.