Models for predicting extinction times: shall we dance (or walk or jump)?

Measures of the risk of extinction, such as the expected time to extinction, are often used in population viability analysis (PVA) and in subsequent decision-making procedures, to gauge the impact of various management actions. Since PVA results are often used in the allocation of conservation funding, which in turn has a major impact on the future persistence of populations, the calculation of quantities such as the expected time to extinction is of great importance. These quantities are typically calculated by assuming a specific model for changes in the population over time. In particular, diffusion models are often used because they are simple to analyse and often give rise to explicit formulæ for most quantities of interest. However, while the