Wild species, and the natural and modified ecosystems of which they are a part, are increasingly at risk. Ecosystems are being fragmented and degraded and their biodiversity reduced. Use of wild species can help slow or even halt this process (at least locally) when they give value to wild habitats and help to protect them from conversion to agriculture and settlements. But many uses do the opposite: depleting populations, damaging habitats, or both. Determining and enhancing the sustainability of wild species is difficult and controversial. This volume tries to tackle the major problems surrounding the issue, to clarify the debate, and begin the process for laying down effective and sustainable guidelines for future conservation strategies.