A “monkey huddle” refers to the behavior in which Japanese macaques press their bodies together to share warmth during cold conditions. This phenomenon is especially observed on cloudy days or at night, when basking in sunlight is not possible.
Dominant individuals and their close associates tend to occupy the warm center of the cluster, while younger or lower-ranking monkeys stay near the outer layer. The way individuals connect—belly to back, side to side, or back to back—varies depending on temperature and group size.
In snowy environments, macaques gather tightly with frost accumulating on their fur, creating a striking winter scene that is well known across regions. This behavior provides insight into their social structure and thermoregulation strategies, making it valuable from an ethological perspective.