Leaving us humans aside, Japanese macaques (Macaca fuscata) have the northernmost distribution area of all primates. In winter, they have to expect snow, especially in the mountains, to which the animals have adapted with some behaviors. Their tendency to visit hot springs in the cold to bathe for hours is well known. But even with their diet, they have become accustomed to resorting to a wider range of food so that they survive the cold season. This is reported by Alexander Milner from the University of Birmingham and his team in »Scientific Reports«.
At least in the Kamikochi region in the Chubu-Sangaku National Park, the monkeys regularly eat fresh fish, snails and aquatic insects during the winter: the region is one of the coldest areas in Japan; snow often covers the vegetation by meters in winter and blocks the macaques' access to plant food such as leaves and roots. Fast-flowing streams, which are fed from groundwater and constantly have at least five degrees Celsius, on the other hand, allow the Japanese macaques to access the wildlife of the waters.
Biologists had already observed that representatives of the species on the coast eat opportunistic fish when he is freshly stranded or dried up in the sand. In addition, related maca seed species do not spurn fresh water fish, but they usually do not form a fundamental component of food. The situation is different with the Japanese toilets also mentioned: faecal examinations showed that the monkeys eat trout regularly in winter. The menu is supplemented by shellfish and water insects.
The primates probably fished the trout from shallow areas at the edge of the streams, the working group writes. "Japanese macaques continue to roam around in winter, when food resources are scarce. But Kamikochi is located in a deep valley, where you can not cross the mountains. The population density is exceptionally high, and the macaques have to winter in an extremely harsh environment, " says Milner: "With a large number of freshwater animals in the rivers and streams, the Kamikochi area is perhaps the only region in Japan where the topographic, geological and meteorological conditions allow the macaques to supplement their winter diet in this way.«
