Behavioural and reproductive ecology of the dog-faced fruit bats, Cynopterus brachyotis and C. horsfieldi, in a Malaysian rainforest.

Abstract

Roosting, foraging and reproductive aspects of two species of dog-faced fruit bats, Cynopterus brachyotis and C. horsfieldi, were examined in Ulu Gombak, Selangor, West Malaysia. The day roosts of C. horsfieldi were sparsely distributed and were found mainly in palms, whereas roosts of C. brachyotis were abundant, and mostly found in non-palm tree species. Males of both species frequently changed their roosts. The nocturnal activity patterns of the two species were different. The initial peak of flight activity of C. brachyotis was two hours sooner after sunset than that of C. horsfieldi, and its flight activity gradually declined during the night. In C. horsfieldi flight activity decreased around midnight then increased again three hours before sunrise. The home ranges of C. horsfieldi were larger than those of C. brachyotis, however these were non-exclusive ranges with individual home ranges of both species overlapping extensively. In association with their greater home range size, C. horsfieldi also tended to move further than C. brachyotis (when comparing means of greatest distances moved). The diets of the two species also differed, with C. brachyotis eating fruits, flowers and leaves, whereas C. horsfieldi ate Ficus fruits virtually throughout the year. The wet weight of figs carried by C. brachyotis per feeding bout averaged 7.9 g, while C. horsfieldi carried on average 17.8 g of figs. The average distances between feeding roost sites and fruiting Ficus variegata trees were 50-78 m. Cynopterus brachyotis probably produces two or three litters per year whereas C. horsfieldi has two litters.