Snow hardness impacts intranivean locomotion of arctic small mammals

• Published in: Ecosphere
• Main Authors: Poirier, Mathilde, Fauteux, Dominique, Gauthier, Gilles, Dominé, Florent, Lamarre, Jean-François
• Format: Other/Unknown Material
• Language: English
• Published: Ecological Society of America 2022
• Subjects: Arctic; Burrowing behavior; Digging; Fossorial; Hardness; Lemming; Locomotion; Rain-on-snow; Rodent; Snow; Subnivean; Tunnel; Lemmings > Mœurs et comportement; Neige; Lemmings > Effets des modifications de l'habitat sur; Climate change; Dicrostonyx groenlandicus; Lemmus trimucronatus
• Online Access: https://hdl.handle.net/20.500.11794/105723; https://doi.org/10.1002/ecs2.3835

Fossorial locomotion is often considered as the most energetically costly of all terrestrial locomotion. Small arctic rodents, such as lemmings, not only dig tunnels in the soil but also through the snowpack, which is present for over 8 months of the year. Lemmings typically dig in the softest snow layer called the depth hoar but with climate change, melt-freeze and rain-on-snow (ROS) events are expected to increase in the Arctic, leading to a higher frequency of hardened snowpacks. We assessed the impacts of snow hardness on the locomotion of two lemming species showing different morphological adaptations for digging. We hypothesized that an increase in snow hardness would 1) decrease lemming performance and 2) increase their effort while digging, but those responses would differ between lemming species. We exposed 4 brown lemmings (Lemmus trimucronatus) and 3 collared lemmings (Dicrostonyx groenlandicus) to snow of different hardness (soft, hard, ROS) during 30-minute trials (n = 63 trials) in a cold room and filmed their behavior. We found that the digging speed and tunnel length of both species decreased with snow hardness and density, underlining the critical role of snow properties in affecting lemming digging performance. During the ROS trials, time spent digging by lemmings increased considerably and they also started using their incisors to help break the hard snow, validating our second hypothesis. Overall, digging performance was higher in collared lemmings, the species showing more morphological adaptations to digging, than in brown lemmings. We conclude that the digging performance of lemming is highly dependent on snowpack hardness and that the anticipated increase in ROS events may pose a critical energetic challenge for arctic rodent populations.