A comparison of the effectiveness of methods of deterring pteropodid bats from feeding on commercial fruit in Madagascar

We compared the effectiveness of methods of deterring Pteropus rufus from feeding on commercial fruit in east central and southeastern Madagascar in 2012–2013 during the Litchi chinensis harvest. Two of the three methods used, installing plastic flags and ringing bells in the trees, were derived from those used by litchi growers in the southeast.  We improved and standardized these methods and compared their effectiveness with an organic product made from dried blood and vegetable oil (Plantskydd®) with a taste and odour aimed at deterring mammal feeding.  The bats damaged from 440–7,040 g of litchi fruits per tree and two of the three methods reduced the fruit lost to bats: the plastic flags and the organic deterrent.  There were significant differences in the damage levels between the study sites and between our three methods of deterrence.  The plastic flags and bell ringing methods were significantly less effective in reducing the fruit bat damage compared to the taste deterrent.  The latter was most effective when it had enough time to dry and adhere to the fruits after spraying and before rain.  Its effectiveness was further demonstrated in flight cage experiments during which Rousettus madagascariensis avoided litchis treated with Plantskydd®.  Analysis of bat faecal samples revealed no feeding preference but the collected samples contained large numbers of Ficus seeds, suggesting that the bats feed extensively on Ficus fruits rather than on fruit of economic importance.  Apart from fruit ripeness, tree productivity or other phenological factors did not affect the amount of fruit eaten by the bats.   More fruits were damaged by birds than bats at both study sites. </div