Impact of climate warming on the foraging behavior of northernmost distributed primates.

Climate warming has profound effects on animal behavior, ecology, as well as on human activities. As the number of extreme weather events increases with climate warming, organisms are facing unprecedented environmental challenges. In temperate regions, winter food scarcity poses a critical survival challenge for many animals. This study investigated the unique foraging behavior of the Kamikochi population of Japanese macaque, Macaca fuscata, which forage for aquatic insects during severe winters with scarce food availability. In February 2024, a thermal event with rising temperatures and rain triggered snowmelt and river flooding, which made it difficult for the macaques to access aquatic food. Comparisons of foraging behavior during periods with and without the thermal event showed that Kamikochi macaques reduced their foraging on aquatic insects inhabiting streams during the thermal event. These findings highlight the ecological impacts of heating events expected to become more frequent due to climate change. Japanese macaques in Kamikochi provide valuable insights into how wildlife behavior may change in response to these events.