Diet, ecological role and potential ecosystem services of the fruit bat, Cynopterus brachyotis, in a tropical city

Abstract

Urbanisation is happening at an unprecedented pace, affecting ecological interactions between frugivores and plants by altering the species composition of plant communities. Cynopterus brachyotis, a bat common in cities, is known to provide important ecosystem services, such as seed dispersal. Studying its diet offers insights into how ecological roles of bats in tropical landscapes could be affected by urbanisation. We documented the diet of C. brachyotis in Singapore, and tested the hypothesis that urbanisation decreases dietary breadth and proportion of native plants in its diet. We collected droppings of C. brachyotis at nine sites, and used morphological and molecular methods to identify plant species they contained. We evaluated whether species richness, proportion of native species and composition of plants in diet varied according to various urbanisation metrics. We recorded 33 plant species belonging to 25 genera and 21 families. Ten are native, 17 are exotic, and six are indeterminate. Twelve have never been reported in diets of C. brachyotis anywhere. Contrary to our hypotheses, urbanisation was not associated with reduced dietary breadth or declining reliance on native plants. Our results suggest urban C. brachyotis have a generalist approach to foraging and can readily exploit exotic plants as food. Because urbanisation does not affect dietary breadth or the proportion of native species they eat, these bats potentially continue to play important ecological roles by dispersing seeds of native plants even in the most urbanised sites, which is important in aiding succession in degraded landscapes. However, they may equally disperse exotic species they have exploited.