Most species-specific conservation efforts require estimates of population size to establish priorities and to monitor management activities. Yet obtaining reliable estimates of animal populations is often difficult, especially given time and funding limitations experienced by many research programmes. Consequently, there is a great need for practical methods to provide indices of animal density. Ideally, accurate estimates of populations would be obtained through mark-recapture data collected from recognizable individuals over multiple censuses that cover the entire population range. Such data are rarely available, so conservation biologists have no alternative but to resort to analyses of less perfect data, ranging from permanent-point censuses from cameras through to transect data on sightings and spoor encounters. The importance of census and monitoring data makes the development, and validation, of new techniques a priority. Because we do not live in a perfect world, there is a need to develop methods that can give an estimate of population sizes. It would be naïve to assume that these will give hugely accurate estimates of population size, but these techniques can prove useful in identifying areas that are likely to benefit from conservation action.