Long-term, climate-change-related shifts in feeding frequencies of a Mediterranean snake population

In a context of climate change, ecological and physiological adaptations of organisms are of central importance for determining the outcome of niche challenges (e.g., with potential competitors) and species persistence. Typically, long-term data on free-ranging populations are needed to investigate such phenomena. Here, long-term data on a free-ranging population of western whip snakes (Hierophis viridiflavus: Colubridae) from central Italy were used in order to test the hypothesis that snake feeding frequencies should increase in relation to climate warming, thus positively affecting individual performance because of longer annual activity period, increased daily activity and larger prey base. Data from 231 ‘female snake-years’ of records (including inter-annual recaptures) were collected were collected between 1990 and 2014. The frequency of fed snakes varied remarkably across the study period with a significant increase over the years. There was a significant positive effect of the mean annual temperature on the percentage of fed animals, whereas there was a non-significant relationship between yearly rainfall and percentage of fed animals. There was a positive relationship between mean annual temperature and yearly diversity-of-prey index. No other climatic variables were significantly correlated with yearly diversity-of-prey index. This study supported the hypothesis that global warming may be favorable for thermophilic species (such as H. viridiflavus), as it enhances their foraging performances and hence their feeding frequencies. The same may not be necessarily true for other species which have colder preferenda (e.g., Zamenis longissimus).