Knowledge, management and optimization: the use of live traps in control of non-native squirrels.
This study identifies techniques to maximize trap efficiency and minimize trapping effort when using live traps to capture the invasive alien Pallas's squirrel (Callosciurus erythraeus), which was introduced in Italy near the Swiss borders. We explored the effects of time of day, season, number of checks in the capture session and type of live trap (single or multi-capture). Moreover, the vegetation around traps (characteristics of the tree supporting the trap, vegetation growth, vegetation cover, vegetation richness and similarity index) was tested. Squirrels were caught more frequently in the morning, but trapping success was not affected by the type of trap used. Squirrel trap response varied significantly in relation to the season, and a higher trapping success in the first days of the trapping session suggests the importance of prebaiting. We reject the hypothesis that vegetation around traps affected the capture success of Pallas's squirrel in deciduous forests. Thus, recommendations to improve the trapping efficiency of this species are to (1) use single capture live traps with at least one week of prebaiting, (2) increase the capture effort in winter and (3) set traps where access is easy and where there are signs of high activity of individuals of the alien species.