A simulation study to quantify drift fence configuration and spacing effects when sampling mobile animals

Abstract

Drift fences with traps are commonly used for ecological research and survey. Field studies have examined the effectiveness of selected fence layouts, but comprehensive field testing is impractical. We applied a simulation approach to investigate how the interaction of fence layout and animal movement type influence fence encounter rates. A range of fence layouts, varying in spacing and configuration, were chosen based on common field practices and recommendations in the literature. Animal movement patterns ranged from meandering (Brownian) to highly directional over distances of 10 to 500 m.We found that fences in short, straight, widely spaced arrangements would be encountered more frequently by highly mobile animals than the same amount of fence in complex or continuous configurations. The dispersed arrangement was encountered just as often by animals with more limited movement patterns as were closer spaced fences. Consequently, for broad-scale surveys, as opposed to studies on individuals' movements and microhabitat use, we recommend spacing trap/fence units in relation to the movement abilities of the most mobile species being sought. For studies that require intense point sampling, additional fencing should increase the total rate that animals encounter fences at a point but the increase will not be proportional to the additional fencing used. The software is provided to allow for other configurations of fences and movement patterns to be investigated. © 2014 Ellis and Bedward.