Testing the efficacy of a thermal camera as a search tool for locating wild bumble bee nests

Research into how bumble bee colonies respond to the stressors affecting their populations are currently studied in the laboratory using commercially reared <i>Bombus terrestris</i> colonies. Understanding how these stressors affect wild bumble bee colonies in the field would be a crucial step forward for the conservation of bumble bee species. Currently, visual cues are used to locate bumble bee nests, using human searchers looking for the worker nest traffic, but the limitations of this method mean that low numbers of nests are found and so a new method that looks to tackle these limitations is needed. Thermal cameras have been considered as a potential nest searching tool because they reduce the visual complexity of the environment by displaying a homogenized thermal landscape to the searcher. In this study, we compare the use of a thermal camera to human searches using two trials: (<i>i</i>) using inexperienced volunteers to search along the transect for a known bumble bee nest and (<i>ii</i>) using an experienced individual to search across a number of novel locations. We found thermal cameras are not a better nest detection technique than human searches, having low success rates across both trials. We discuss the limitations of thermal cameras as a technique and propose how the technology could be improved for future studies.