Habitat loss is one of the main threats to bats worldwide. In Southeast Asia, where as much as 74% of forests may be lost by the end of the century, it is a critical issue. A substantial proportion of the bat fauna appears to be highly dependent on intact stands of forests for foraging and roosting. Many species, particularly those in the families Hipposideridae, Rhinolophidae and the vespertilionid subfamilies Murininae and Kerivoulinae, combine wing morphologies and echolocation signal designs that confer efficient foraging in densely vegetated habitats, but are less effective in the more open habitats typical of deforested landscapes. The availability of appropriate cavity roosts in both standing and fallen trees is likely to further restrict species to forest habitats.
Similarly, although a number of Old World fruit bats (Pteropodidae) are readily captured in villages, secondary habitats, and small agricultural holdings (e.g., Cynopterus spp.), others are found primarily in forests and are highly vulnerable to habitat loss.
The most dramatic illustration of the consequences of forest loss to bat diversity comes from Singapore, which has lost 95% of its primary forest since European colonization began in the 1800s. Of the 30 species documented for the island, only 20 have been recorded in recent surveys, and this is likely a gross underestimate of true species losses because extensive land-use change was already underway before bat inventories began. Estimates of percentage species lost based on the likely presence of species before colonization fall between 67 and 72%, and it is the forest-dependent species that show the greatest declines. The surviving species are generally either insectivorous species that forage in open and edge habitats or plant-visiting species able to forage in agricultural and secondary habitats.
Little is known of the ecological requirements and population dynamics of forest-dependent bats in undisturbed forest, nor the response of forest assemblages to different land uses. Long-term monitoring of forest-dependent insectivorous bats is being conducted at five large study plots at Krau Wildlife Reserve, Peninsular Malaysia with studies in the surrounding landscape investigating the persistence of species in forest fragments and oil palm plantations. However, there is a general lack of data in dramatic contrast to the growing number of bat assemblage disturbance studies from the Neotropics.
Thus, the SEABCRU resolutions for forest-dependent bats identify the need for:
- A network of long-term study sites to elucidate the dynamics of bat assemblages in undisturbed forest.
- Studies focused on the response of forest-dependent bat species to land-use change, allowing for identification of both priority sites for protection and species most adversely affected by anthropogenic disturbance.
