If projects or interventions are small however, they are less likely to have impacts on the wider economy and the latter may not be needed. Generally, the types of costs should include start-up costs, programme costs, capital costs, personnel costs and opportunity costs. All the costs should be discounted to their present value. These are expressed in terms of probability', and are therefore not discounted. The approach is based on prioritising threat management for biodiversity, following Carwardine et al. (