Ecological implications of mammal feces buried in snow through dung beetle activities

In early spring, snow-buried mammal feces simultaneously emerge on the ground with the melting of the snow across regions with heavy snowfall. Here, we evaluated the ecological implications of this phenomenon for the cool-temperate forest ecosystem in terms of the resource use of dung beetles (Coleoptera: Scarabaeidae), which play key roles in secondary seed dispersal and nutrient cycling. During May 2012 and 2013, we conducted cafeteria experiments in heavy snowfall regions with different types of forest cover in northern Japan by using pitfall traps baited with the snow-buried feces of Japanese macaques (Macaca fuscata), Japanese serows (Capricornis crispus), and Japanese hares (Lepus brachyurus angustidens). From the experiments, we identified 12 dung beetle species, indicating that the snow-buried feces could act as a valuable resource for vernal beetles. Most of the beetles had obvious fecal preferences. The snow-buried feces of serows were widely available resources for most vernal species, including dwellers and tunnelers, contributing to the biomass of those species. Although dung beetles using snow-buried feces in young broadleaf forests with rich feces supplies did not always exhibit the highest species richness, tunnelers frequently emerged in those forests, and Phelotrupes preferred macaque feces. This finding could have important implications for plant regeneration, as it relates to time-lagged mammal–beetle interactions. Endozoochorous seeds dispersed by macaques in the autumn have insufficient opportunities for secondary seed dispersal by beetles as the beetles are inactive in autumn, but those seeds are protected against predation by snow during winter and are safely preserved under soil by vernal tunnelers.