STUDIES OF THE ECOLOGY AND BEHAVIOUR OF INSECTIVOROUS BAT SPECIES IN SINGAPORE

Abstract

Of the 22 species of Microchiroptera listed as present in Singapore in 1990, 18 were of an indeterminate status because no recent research had been done. Since the last known record of many species, the landscape of Singapore has undergone many changes. Thus the main aim of this thesis was to assess the effects of urbanization on species diversity. This was to be examined by producing a current inventory of Microchiroptera in Singapore for comparison with previous records. Reasons for any local extinctions were hoped to be determined by examining the two most important factors for a bat's survivorship: the availability of a place to forage and a place to roost. A decline of the diversity of Microchiroptera in Singapore was noted: the current status of the 22 bats previously recorded is: 9 species locally extinct; 5 endangered; 1 rare; 1 uncommon; 4 common; 1 indeterminate; and the origin of 1 record is doubtful. Excluding the doubtful record, this is a local extinction rate of 42%, and of the remaining species, 41% are endangered. However, two new bat species for Singapore were recorded - Nycteris tragata and Rhinolophus refulgens. Both species being forest dwellers, they are assumed to have been present in the past but not ‘found' by early naturalists. Of the species present, it was found that it was possible to distinguish them by their echolocation calls with the aid of a bat detector and associated computer software. Ten species were trapped to aid initial identification; two other species were detected but remained uncaught. However one of the species, Rhinolophus luctus, was identified with comparisons of recordings of bats made in Malaysia; the other species remained unidentified. Echolocation call structure and wing morphology were examined to predict foraging habits and habitats. There was a close association with foraging flight style (habit) but foraging habitat could not be accurately predicted. For locally extinct species information was gleaned from the literature. Transect surveys showed that the forest habitats had the highest diversity of bats; the highly urbanized areas had the lowest diversity. Some of the locally extinct species were found from the literature to be forest specialists, and the decrease of the forest habitat is assumed to be the cause of their decline. For other species it is suggested that the loss of suitable roosting sites due to accidental or deliberate destruction, or even just increased human activity, has led to their local extinction; especially vulnerable are species that are gregarious in their roosting habits as one catastrophic event could lead to the local demise of the entire population. This study reports the first use of bat boxes in a tropical country. It proved to be successful with one species of bat regularly using the boxes, including three nursery roosts It is suggested that further research should be conducted on the provision of artificial roosts for the preservation of Microchiroptera in Singapore, particularly as they are important in the control of insect pests.