The ecology of fruit bats (Chiroptera: Pteropodidae) in a Malaysian lowland dipterocarp forest, with particular reference to the spotted-winged fruit bat (Balionycteris maculata, Thomas)
The aim of this project was to investigate the ecology of fruit bats within an area of old growth lowland dipterocarp forest in Peninsular Malaysia, with particular reference to Balionycteris maculata. Food particle size and crop size were two important factors that influenced diet choice and the partitioning of food resources throughout the fruit bat community at Kuala Lompat (Krau Wildlife Reserve, Pahang). Balionycteris maculata was the only species that fed regularly on the small, low-density fruits of understorey trees. Because they exploit food resources that are locally available throughout the year, male B. maculata are able to divide their nightly activity time between foraging and roost defence. Hence this species has developed a harem-based polygynous mating system, in which the roost cavity represents a critical resource for the recruitment of females. The roost cavities occupied by B. maculata were found within a variety of forest structures, including ant nests, termite nests, and epiphyte root masses. The consistent shape and positioning of these roost cavities, along with a single observation of cavity enlargement, indicate that B. maculata plays an active role in their creation. Balionycteris maculata has a polyoestrous reproductive cycle and gives birth to up to two litters per year. Although lactating females were captured throughout the year, the highest incidence of lactation was recorded between May and November. This period coincided approximately with the fruiting season of a number of large-seeded non-pioneer food plant species. Hence the reproductive timing of this species may have evolved in response to seasonal variation in the quantity and/or nutritional quality of available food resources. A botanical survey of one hectare of old growth forest revealed that 14% of trees (> 15 cm g.b.h.) were at least partially dependent upon fruit bats for pollination and/or seed dispersal. Hence fruit bats are likely to play a significant role in maintaining the biological diversity of Malaysian forests. Since several fruit bat species are strongly associated with old growth forest, the greatest threat to their survival comes from habitat destruction and agricultural expansion. The Krau Wildlife Reserve, and other protected areas in Malaysia, are therefore of critical importance for the long-term conservation of these species.