The foraging ecology of the short-nosed fruit bat, Cynopterus brachyotis (Muller, 1838), in lowland dry evergreen rain forest, southeast Thailand
The feeding ecology of the short-nosed fruit bat, Cynopterus brachyotis, was investigated in selectively-logged lowland dry evergreen forest in south east Thailand between March 1998-April 2000. C. brachyotis consumes fruit of 14 plant species, pollen/nectar of four and leaves of nine species. Faecal analysis revealed that fruit comprises more than 95% of the diet, and nectar and pollen supplements the diet during the dry season. Fruits of successional plants contribute two-thirds of the diet. The diet of C. brachyotis varies significantly with the age and sex of the bats. Juvenile and immature bats ingest more fruits from plants producing large crops over a relatively short period, while mature bats consume more fruits from plants producing a few fruits nightly over a long period. Females, especially reproductive ones, consume disproportionately more fruits from selectively logged dry evergreen forest species than males. Different study techniques reveal a significant variation in the diet of fruit bats. Leaves are prominently represented in the diet deduced from pellets collected below day roosts than from faeces of captured bats. Radiotracking carried out on 18 individuals for 18-149 days revealed that home range of mature C. brachyotis is between 30-365 ha with the average maximum width of 2,545m. Females have marginally significantly larger home range than males. The roost area contributes an average of five percent of the home range, and there was no incidence of overlap of roost area between any solitary roosting bats. Male C. brachyotis has a high fidelity to its home range and roost area both between seasons and years. Radio-tagged bats visit 1-6 feeding areas each night and spend an average of 1 h 38 minutes in each feeding area. In feeding areas, they undertake 2-10 feeding bouts at fruiting trees each hour. During each night, individual bats commute an average of 7.14 km and up to 14.5 km between day roosts and feeding areas. Mature bats spend 17.9 % of their nightly foraging activity at day roosts. Moonlight inhibits foraging activity of C. brachyotis. During bright nights, it visits fewer feeding areas, reduces its rate of movement between feeding areas and the number of feeding bouts.