Biodiversity faces a crisis, with extinction rates approximately three orders of magnitude higher than those typical of the Earth's history (Pimm et al. 1995). This crisis has numerous negative consequences for humanity, including to economies, health, environmental services, and moral and spiritual well-being (Wilson 2002). The biodiversity crisis is particularly serious in Southeast Asia (Sodhi et al. 2004; Sodhi & Brook 2006), where wholesale extinctions are already in the process of unfolding (Brook et al. 2003). Among a large number of causes of these extinctions, the destruction of natural habitats is the most pervasive, affecting ~90% of all threatened species (Baillie et al. 2004). Given this, it is clear that the primary tactic necessary to stem the crisis is to safeguard sites of global biodiversity significance. This has received intergovernmental mandate, with, for example, the 188 parties to the Convention on Biological Diversity agreeing on a Programme of Work on Protected Areas (http://www.biodiv.org/programmes/cross-cutting/protected) to support the establishment and maintenance ‘of comprehensive, effectively managed, and ecologically representative national and regional systems of protected areas’ (Decision VII/28). However, this raises the question of how these sites can best be identified and delineated.
This chapter addresses this question. We begin by explaining the variety of factors that require consideration in the identification of those areas requiring site safeguard. Next, we show how the approach of identifying and delineating Key Biodiversity Areas (KBAs) emerges from these considerations. Finally, we discuss the issue of how KBAs can best be delineated.