Invasion biology is the study of non-native species so to better understand the impacts that they have on their new environment. Non-native species have the potential to become invasive, causing severe negative ecological and economic impacts. Snakes in particular have shown themselves to have high invasive potential due to their life-history traits, and behaviours: high fecundity, secretive lifestyles, and generalist diets. To effectively control invasive species and mitigate their impact requires the implementation of wildlife management schemes with sound ecological understanding of the focal species is required. One such aspect of ecology which applies to invasion biology is habitat selection. Habitat selection underlies the survival and population distribution of a species. If an individual is to choose their habitat incorrectly they may find themselves without the necessary resources for survival. Snakes, as ectotherms, have intrinsic ties to their environment as they are thermally constrained, requiring specific temperature thresholds for physiological functions. Often, snakes select their habitat based upon its thermal quality, yet, prey availability has also been shown in some snake species to affect population distribution. The Aesculapian snake (Z. longissimus) is a large colubrid snake found throughout Europe, yet a population of Z. longissimus exists in the Welsh Mountain Zoo (WMZ), North Wales, at a much higher northern latitude than is found in its native European range. We investigated the WMZ Z. longissimus population to establish key habitat features, including prey availability (small mammals), to be able to predict population densities of the snake in the future. We used novel marking methods in capture-mark-recapture studies to assess the snake and small mammal population and calculated macro-habitat characteristics coverage across the grounds of the WMZ. We calculated snake encounter rates across the grounds of the WMZ from search effort and snake captures. By use of multiple regression analysis we identified significant relationships between specific habitat characteristics to generate a multiple regression equation predicting snake encounter rates. In contrast to other snake habitat selection studies, we found that the best predicting habitat feature for Z. longissimus is prey abundance. This can be explained by the fact that the climate in the WMZ is continuously cooler than the climate in the snake native range; therefore, as the snake cannot reach optimal temperatures as seen in its native range, the snakes select their habitat based on other important habitat characteristics. Alternatively, it may be that the snakes are reliant on other methods of thermoregulation i.e. use of anthropogenic sites, to overcome the cooler climate. Future studies should implement radio-telemetry to further clarify Z. longissimus habitat selection at a microscale, allowing greater insight into the impact that the non-native snake has in North Wales.