Dietary studies of Livingstone's fruit bat Pteropus livingstonii: Feeding behaviour, diet evaluation and modification

Relatively little is known about the adequacy of captive diets for Old Worl d fruit bats (Megachiroptera). The combination of reduced exercise and a pl entiful food supply results in captive bats being generally heavier than th eir wild counterparts. Livingstone's fruit bats Pteropus livingstonii were studied at Jersey Zoo. It had become apparent that young, captive-born bats were considerably heavier than wild-caught adults. This paper gives an ove rview of three dietary studies carried out to produce an improved diet. A p reliminary study was undertaken to see if weight differences could be expla ined by individual behavioural variation. Scan sampling of feeding sites sh owed considerable variation in time spent feeding, the utilisation of feedi ng sites and the extent to which individuals monopolised them. A second stu dy evaluated the current diet fed to the bats. Weights of the different foo ds presented and left over were recorded over a 10 day period. The diets va ried considerably from day to day, in amount and the number of different fo od types given. The available literature on fruit bat nutrition was used to compare known nutrient and energy requirements with the levels presented t o the captive groups. To try and minimise the effect of individual preferen ces and social status on nutrition, a new diet was proposed, with a reduced daily diversity of food items. Dietary diversity was maintained over a wee kly period and made nutritionally comparable to the former one, as no healt h problems, other than possibly obesity, had so far been linked to nutritio n. Trials of the modified diet were carried out by presenting known quantit ies of food items to two groups of bats, collecting the leftovers and deter mining the proportions remaining. This also gave a useful indication of gen eral dietary preferences: for example, acid fruits were found to be the lea st preferred foods. Consequently, the diet was then further altered to take into account these preferences, distributing the most preferred and dislik ed items more evenly throughout the week.