Non-native species can significantly impact novel environments. Ecological studies that include a species' movements in its habitat can inform management and policy decisions for the control of introduced species. Information learned can be used to identify movement pathways and habitat preferences to predict dispersal routes and limitations for range expansion. Understanding which environmental features influence movement can lead to more successful control and targeted removal. Native to southern and central mainland Europe, the Aesculapian snake (Zamenis longissimus) was introduced into the UK twice; during the 1960s in North Wales then later in the 1980s in London. The population in Colwyn Bay, North Wales is the northernmost extant of their range. Previous studies of northern populations in their native range have identified preferences for anthropogenic features and woodland, but we know very little about which habitat features are selected during movement. However, few studies investigating snake movement ecology include habitat selection during movement but rather focus on where a snake starts moving and then the location and habitat in which it settles. This study used radiotelemetry to locate adult male snakes between May and August 2022 in a largely suburban and agricultural landscape. We radio-tracked a total of seven snakes five times each day over this period to identify habitat preferences along movement pathways. Locating focal snakes enabled us to observe individual behaviour to gain insight into the distances moved but also into how snakes exploited habitat features available to them. Using Integrated Step Select Functions (ISSF), we analysed how habitat features influenced movement.
Habitat features had no influence on the step characteristics (step length and turning angles of observed locations) but were affected by the distance of an observed step towards a habitat feature. We found at the population level snakes were positively associated with hedgerows, buildings, and scrub. High levels of variability toward habitat selection between individuals show a level of habitat generalism. Similar to other reptile species, Z. longissimus also exhibits a high degree of individual heterogeneity, further complicating predictions for movement.
However, linear features including hedgerows were frequently used as pathways through the fragmented landscape. The findings of this study highlight the importance of understanding movement ecology in non-native snake species. Using preferences for habitat features, especially along pathways can inform decisions on where is best to focus for targeted searches or to place traps for future removal if necessary. This will increase the probability of snake detection and capture rates, also aiding in reducing the associated costs and labour requirements. With increased global connectivity and climate change, this population should continue to be monitored into the future to respond quickly to any changes including range expansion.