Influence of artificial refuge type on the success of a presence-absence survey for slow worms Anguis fragilis

Artificial refuges are widely used to improve detection rates when surveying for reptiles. We compared the efficacy of refuges constructed from four different materials to detect slow worms (Anguis fragilis). The refuges included two types that were flat - roofing felt (bitumen) and carpet tiles, and two types that were corrugated - one constructed of roofing felt (bitumen-soaked fibers) and the other of metal. The proportion of occupied refuges (i.e. sheltering at least one slow worm) varied greatly by month with the highest proportions in June. The effect of refuge type was not statistically significant on its own, but the interaction between the type and month was significant. The proportion of occupied refuges was most affected by refuge type in the months with intermediate slow worm occupancy rates (May, July). Flat roofing felt and the corrugated roofing felt appear to be the most different, the former higher in July and the latter higher in May and June. Using a mixture of refuge types simultaneously during surveys could potentially increase the detection rate of slow worms.