Thermal forest zone explains regional variations in the diet composition of the Japanese marten (Martes melampus)

Abstract

Examining biogeographical variations in species’ diet is important for linking key ecological traits between consumers and their environment. While the trophic ecology of the Holarctic martens has been globally synthesised, systematic information on the feeding ecology of martens (Martes spp.) in Asia is still deficient compared to species in Europe and North America. Here we conduct a meta-analysis based on literature describing regional and seasonal variation in diet composition of the Japanese marten (Martes melampus). Across nine study areas in the Japanese archipelago, annual marten diet mainly comprised fruits, invertebrates, and mammals. Cluster analysis divided these into three groups according to the similarity in composition. Dietary niche breadth and the relative frequency of occurrence of the mammalian prey was significantly higher in sub-alpine/cool-temperate than warm-temperate thermal forest zones, whereas the occurrence of fruits was significantly higher in warm-temperate than sub-alpine/cool-temperate zones. Seasonal analysis showed significant effects across all four seasons on the frequency of occurrence of mammals, invertebrates, and fruits. The Japanese marten is a flexible and opportunistic feeder with the potential to maintain its key macronutrient requirements by adapting its feeding strategy to changes in resource variability and environmental conditions. This trophic plasticity may advantage the Japanese marten in coping with human-induced rapid environmental change, as global analysis has projected for martens across other regions.