The use of photographic rates to estimate densities of tigers and other cryptic mammals

The monitoring and management of species depends on reliable population est imates, and this can be both difficult and very costly for cryptic large ve rtebrates that live in forested habitats. Recently developed camera trappin g techniques have already been shown to be an effective means of making mar k-recapture estimates of individually identifiable animals (e.g. tigers). C amera traps also provide a new method for surveying animal abundance. Throu gh computer simulations, and an analysis of the rates of camera trap captur e from 19 studies of tigers across the species' range, we show that the num ber of camera days/tiger photograph correlates with independent estimates o f tiger density. This statistic does not rely on individual identity and is particularly useful for estimating the population density of species that are not individually identifiable. Finally, we used the comparison between observed trapping rates and the computer simulations to estimate the minimu m effort required to determine that tigers. or other species, do not exist in an area, a measure that is critical for conservation planning.