Winter Activity and Dormancy of Snails: Freezing and Food Shortage Avoidance Strategy Facing Snow-Cover Shortage

Cold tolerance is a key factor shaping the survival and geographic distribution of terrestrial snails, especially in regions with harsh winters. Understanding how these organisms cope with freezing temperatures is crucial for predicting their responses to changing climates. This study focused on two microsnail species, Vertigo antivertigo and V. moulinsiana, to assess their winter activity, cold tolerance strategies, and whether their body size varies with latitude. Activity patterns were observed under controlled temperatures (0 °C, 2 °C, and 5 °C), while supercooling points (SCP) were measured to evaluate freezing avoidance. Shell morphology was analyzed across populations from various sites in Poland to explore local adaptations. The results showed that snail activity decreases as temperatures drop, with the lowest activity observed at 0 °C. Both species displayed a freezing-avoidant strategy, with V. moulinsiana having slightly higher SCP values, reflecting its adaptation to milder climates. Morphological differences in shell dimensions across sites suggest potential local adaptations to environmental conditions. These findings highlight temperature as a critical driver of activity, survival, and morphological variation in terrestrial snails. Limited winter activity may allow foraging or shelter-seeking but poses risks for overwintering. As climate change leads to snow-free winters, these species may face significant challenges in maintaining their populations and distributions.