Patterns of surface temperature and link to environmental variables in Weddell seals from the western Antarctic Peninsula

Pinnipeds face challenges in maintaining a stable body temperature in two mediums with distinct characteristics: the terrestrial and aquatic environments. Water extracts heat faster than air, so pinnipeds possess adaptations to maintain thermal balance in both environments. When exiting the water, some phocid species develop thermal windows, areas on the body surface displaying higher temperatures than the rest of the body. This mechanism is thought to help in dissipating excess heat from the body. We assessed whether Weddell seals (Leptonychotes weddellii), the southernmost distributed marine mammal, had the capacity to develop thermal windows and investigated the relationship between thermal surface patterns and environmental factors. We obtained infrared images of 45 hauled-out Weddell seals within the western Antarctic Peninsula, during the summer season. Weddell seals presented uniform surface temperatures across body regions (head, torso, front flipper, and hind flipper) suggesting that all body parts have an equal role in keeping thermal balance. The main driver of surface temperature was wind speed, with higher wind speeds resulting in lower surface temperatures. Wind facilitates convective heat transfer to the environment, decreasing the insulating capability of fur. Thus, wind was a more important driver than air temperature and relative humidity. Thermal windows were identified in 49% of the Weddell seals studied and occurred more frequently at higher air temperatures. The development of thermal windows could solve the problem of overheating when seals haul out on land, which is particularly relevant under the warming scenario within the western Antarctic Peninsula.