On Animal Abundance Estimation Based on Pitfall Traps

This paper gives a simple proof of an equation for the mean number of animals from a very large population which are trapped in a pitfall trap. This equation can be applied to estimate the abundance of epigeic animals walking on the ground such as some insects or spiders. For the estimation, knowledge on the locomotion behaviour of the animals is necessary. As an alternative, an approach is discussed that is based on the two‐dimensional Brownian motion.