A risky business or a safe BET? A Fuzzy Set Event Tree for estimating hazard in biotelemetry studies

The use of biotelemetry methods can provide information on animal behaviour, movement ecology and energetics. However, deployment of biotelemetry equipment on free-living animals incurs risk of damage or loss, which can result in high cost and low sample sizes. To facilitate the uptake of these methods, we have recognized the need for a prescribed procedure for assessing failure risk in biotelemetry studies. Here, we have adapted a commonly used technique in industry and engineering, Event Tree analysis, to facilitate risk estimation and deployment procedure critique. This method can incorporate the use of fuzzy logic to accommodate the uncertainty and scarcity of technical data that are often associated with animal biotelemetry equipment and techniques. Alternatively, probabilistic data may be used for procedures where appropriate models have been established. To encourage the adoption of this method by the scientific community, we have developed a freeware program, Biotelemetry Event Tree (BET). We advocate the use of this method, in the interests of scientific robustness and animal welfare.