Bat cave vulnerability index (BCVI): A holistic rapid assessment tool to identify priorities for effective cave conservation in the tropics

Abstract

The identification of important habitats for wildlife is essential in order to plan and promote strategies for long-term effective conservation. Caves and subterranean habitats are frequently overlooked habitats with diverse communities, which are frequently endemic to a region, karst outcrop or even a single cave. These cave species include a wide range of taxa adapted to cave environments. Within cave systems, bats are key providers of energy for other cave-dependent species. However, identifying caves for conservation prioritisation requires an understanding of cave-dwelling species diversity, patterns of endemism, and conservation status, in addition to a standard mechanism to evaluate risk. In this paper, we present the ‘Bat Cave Vulnerability Index’ (BCVI) as a standard index for evaluating bat caves for conservation prioritisation by determining Biotic Potential (BP) and Biotic Vulnerability (BV) of caves. The Biotic Potential is represented by various species diversity and rarity measurements. The Biotic Vulnerability is represented by the cave geophysical characteristics and human-induced disturbance present. Pilot testing in the southern Philippines has demonstrated that the index is an effective and practicable method to identify bat caves for conservation prioritisation. The biotic potential variables assess the presence of endemic, rare, and threatened bat species and assays the priority level based on an equation. Relative risk and vulnerability were assayed using landscape vulnerability variables, which showed anthropogenic activities were important factors in conservation prioritisation. The application and mechanism of the index potentially provides a valuable, rapid and simple assessment tool in cave conservation with special relevance to bat diversity and vulnerability. Furthermore, the multiple and holistic criteria of the BCVI, and the accessible information for both biotic and landscape features can be adapted to prioritise caves in a wider scale in the tropics, and in other regions with diverse cave ecosystems.