Winter diet of Japanese macaques from Chubu Sangaku National Park, Japan incorporates freshwater biota

Abstract

The Japanese macaque (Macaca fuscata) is native to the main islands of Japan, except Hokkaido, and is the most northerly living non-human primate. In the Chubu Sangaku National Park of the Japanese Alps, macaques live in one of the coldest areas of the world, with snow cover limiting the availability of preferred food sources. Winter is typically a bottleneck for food availability potentially resulting in marked energy deficits, and mortality may result from famine. However, streams with groundwater upwelling flow during the winter with a constant water temperature of about 5 °C are easily accessible for Japanese macaques to search for riverine biota. We used metabarcoding (Cytochrome c oxidase I) of fecal samples from Japanese macaques to determine their wintertime diet. Here we provide the first robust evidence that Japanese macaques feed on freshwater biota, including brown trout, riverine insects and molluscs, in Chubu Sangaku National Park. These additional food sources likely aid their winter survival.

Behavior of snow monkeys hunting fish to survive winter

“…However, the fish-eating behavior of Japanese macaques are not an opportunistic or accidental because we observed Japanese macaques catching swimming fish fourteen times in three troops in this study. In addition our earlier study showed that brown trout DNA was detected in about 20% of the fecal samples (7/38 samples) over three winter seasons 12 . In such situation, we suggest that fishing by Japanese macaques only occurs in winter and only in the Kamikochi area of Japan.…”

“…1 B). There have been a few reports of Japanese macaques potentially consuming aquatic insects during winter in deep snow areas, including Kamikochi 17 before our research 12 . However, this study firstly provided a detailed understanding of the techniques by which they feed on the aquatic insect species.…”

“…Japanese macaques ( Macaca fuscata ) of the Japanese Islands are distributed at the highest latitudes in the world among non-human primates. In addition, the subalpine zone (elevation 1500–1600 m) of the Japanese Alps, which the macaques inhabit, is one of the coldest and harshest winter environments at high latitudes inhabited by non-human primates 10 – 12 . Some animals (e.g., brown bear, Ursus arctos ) survive the harsh winter season by seasonal migration and/or hibernation, but hibernation is not known in primates, with a few exceptions for small primates 13 and Japanese macaques in Kamikochi are known to remain in the subalpine zone during the winter 10 , 14 .…”

“…Regarding the behavior of Japanese macaques in Kamikochi during the winter, more than 70% of foraging has targeted the bark of woody plants and bamboo leaves protruding from the snow 14 , 18 . Our previous study 12 using DNA metabarcoding on Japanese macaque’s fecal samples over a three-year period during winter (2017–2019), revealed that they frequently feed on freshwater biota, including aquatic insects and fish (brown trout, Salmo trutta ) in groundwater streams. Although these are a high quality food resource in terms of nutrition, fish are difficult to catch.…”

Diet of a threatened rattlesnake (eastern massasauga) revealed by DNA metabarcoding

“…To identify all potential prey, we selected the universal metazoan forward mlCOIintF (Leray et al, 2013 ) and reverse jgHCO2198 (Geller et al, 2013 ) primer set, targeting a 313 bp fragment of the cytochrome oxidase subunit 1 (CO1 region; see Table 2 for the list of primers used in this study). This primer pair is designed to amplify all metazoan taxa and is commonly used in DNA metabarcoding dietary assessments (e.g., Bohmann et al, 2018 ; Milner et al, 2021 ; Robeson et al, 2018 ). The reverse primer jgHCO2198 is a redesign of the Folmer reverse primer HCO2198 (Folmer et al, 1994 ), corrected for mismatches and with increased degeneracy to allow for broader taxonomic amplification (Geller et al, 2013 ).…”