Diet-related factors strongly shaped the gut microbiota of Japanese macaques.

Although knowledge of the functions of the gut microbiome has increased greatly over the past few decades, our understanding of the mechanisms governing its ecology and evolution remains obscure. While host genetic distance is a strong predictor of the gut microbiome in large-scale studies and captive settings, its influence has not always been evident at finer taxonomic scales, especially when considering among the recently diverged animals in natural settings. Comparing the gut microbiome of 19 populations of Japanese macaques Macaca fuscata across the Japanese archipelago, we assessed the relative roles of host genetic distance, geographic distance and dietary factors in influencing the macaque gut microbiome. Our results suggested that the macaques may maintain a core gut microbiome, while each population may have acquired some microbes from its specific habitat/diet. Diet-related factors such as season, forest, and reliance on anthropogenic foods played a stronger role in shaping the macaque gut microbiome. Among closely related mammalian hosts, host genetics may have limited effects on the gut microbiome since the hosts generally have smaller physiological differences. This study contributes to our understanding of the relative roles of host phylogeography and dietary factors in shaping the gut microbiome of closely related mammalian hosts.

Feeding ecology of free-ranging long-tailed macaques in East Java, Indonesia: Relationship with human food availability.

Food availability is an important factor affecting the feeding strategies of animals. Primate species living in habitats with high human activity have the potential to employ unique strategies to utilize human food resources. This study describes the feeding ecology of provisioned free-ranging long-tailed macaques (Macaca fascicularis) inhabiting Alas Purwo National Park, East Java, Indonesia. The activity budgets, dietary compositions, vertical usage, and ranging patterns of macaques were recorded between October 2021 and March 2022, and their relationships with the number of visitors (a proxy of human food availability) were examined. The macaques consumed more human food (mean ± SD: 53.9 ± 25.6%) than natural food (43.8 ± 25.5%), followed by unidentified food (2.3 ± 6.3%). Human food has several effects on the behavioral ecology of macaques, including reduced movement and increased social activity in response to the number of visitors, decreased consumption of natural food, frequent use of the ground and subcanopy strata, and decreased home range when the number of visitors increases. Thus, the relative importance of human food has substantially changed the essential behavioral ecology of provisioned macaque troops. Understanding the behavioral plasticity of macaques, particularly their responses to anthropogenic effects, could guide and contribute to the formulation of conservation policies and management plans.

Why do people visit primate tourism sites? Investigating macaque tourism in Japan and Indonesia.

Primates are popular species in wildlife tourism contexts and provide economic benefits to habitat countries where primate-based tourism activities are a part of the country's tourism economy. Primate tourism runs a broad gamut from safari-like expeditions within remote primate habitats to designated monkey parks and incidental primate tourism. In most forms of primate tourism, primate ecology and behaviour are directly influenced by humans, making these interfaces particularly relevant for examination using the lens of ethnoprimatology. While several studies have assessed the impact of tourism on primates, little is known about people's motivations for observing monkeys for recreational purposes. Here we present two case studies-the Jigokudani Monkey Park, Japan, and the Telaga Warna Nature Recreational Park, Indonesia-where we provide quantitative assessments of people's motivations for visiting managed (monkey parks) and unmanaged (incidental) monkey tourism sites. We further show that management regimes, socio-demographic attributes, previous experience of interactions with macaques, and feeding them play a role in people's desire to visit macaque tourism sites. In Japan, those who had interacted with macaques before were more likely to visit the park to observe macaques clearly and at close quarters. In contrast, respondents in Indonesia were more interested in the recreational opportunities offered by the nature reserve rather than in macaques. However, here too, people who had interacted with macaques earlier were more likely to visit incidental macaque tourist sites for the sole purpose of viewing or interacting with macaques. Almost 50% of the Japanese respondents visited the monkey park due to personal inclinations, while less than 14% of people in Indonesia visited the park of their own volition. Also, over 57% of the Japanese respondents said that visiting monkey parks helped them gain a better understanding of macaque behaviour, whereas only about 26% respondents said likewise in Indonesia. Unlike the Japanese respondents, most of the Indonesian respondents engaged in feeding macaques. These findings suggest that management regimes as well as socio-demographic attributes may influence people's motivations to visit macaque tourism sites.

Interspecific Difference in Seed Dispersal Characteristics between Japanese Macaques (Macaca fuscata) and Sympatric Japanese Martens (Martes melampus).

We compared the characteristics of seeds within faeces between semi-terrestrial Japanese macaques (Macaca fuscata) and sympatric arboreal Japanese martens (Martes melampus) in Shiga Heights, central Japan. We collected faecal samples of the two mammalian species for 1 year (n = 229 for macaques and n = 22 for martens). We then compared the proportion of seed occurrence, life-form composition, number of seeds and species richness within single faecal samples, and the seed intact ratio between the two mammalian species. We detected seeds from 20 and 7 species from macaque and marten faeces, respectively. Macaque faeces contained seeds of multiple strata, while marten faeces contained no herbaceous plant seeds. Seed sizes within faeces showed no interspecific difference. For macaques, seeds were found within faecal samples collected in late spring to late fall, while for martens, seeds were found between summer and winter. The proportion of seed occurrence was greater in summer (both species) and fall (macaques), which implied that the seed dispersal roles of macaques and martens was greater in these seasons. The mean seed number (across species), intact ratio of seeds (high for both species) and seed species richness within single faecal samples of macaques and martens showed no significant differences, but for several species, martens defecated more seeds than macaques and showed higher intact ratio. Our study indicates that sympatric mammals in the temperate regions of Japan contribute differently to seed dispersal in forest ecosystems.

Primates Can Be a Rallying Symbol to Promote Tropical Forest Restoration.

With 60% of all primate species now threatened with extinction and many species only persisting in small populations in forest fragments, conservation action is urgently needed. But what type of action? Here we argue that restoration of primate habitat will be an essential component of strategies aimed at conserving primates and preventing the extinctions that may occur before the end of the century and propose that primates can act as flagship species for restoration efforts. To do this we gathered a team of academics from around the world with experience in restoration so that we could provide examples of why primate restoration ecology is needed, outline how primates can act as flagship species for restoration efforts of tropical forest, review what little is known about how primate populations respond to restoration efforts, and make specific recommendations of the next steps needed to make restoration of primate populations successful. We set four priorities: (1) academics must effectively communicate both the value of primates and the need for restoration; (2) more research is needed on how primates contribute to forest restoration; (3) more effort must be put into Masters and PhD level training for tropical country nationals; and finally (4) more emphasis is needed to monitor the responses of regenerating forest and primate populations where restoration efforts are initiated. We are optimistic that populations of many threatened species can recover, and extinctions can be prevented, but only if concerted large-scale efforts are made soon and if these efforts include primate habitat restoration.

Reliability of macaques as seed dispersers.

Seed dispersal is an ecological process crucial for forest regeneration and recruitment. To date, most studies on frugivore seed dispersal have used the seed dispersal effectiveness framework and have documented seed-handling mechanisms, dispersal distances and the effect of seed handling on germination. In contrast, there has been no exploration of "disperser reliability" which is essential to determine if a frugivore is an effective disperser only in particular regions/years/seasons or across a range of spatio-temporal scales. In this paper, we propose a practical framework to assess the spatial reliability of frugivores as seed dispersers. We suggest that a frugivore genus would be a reliable disperser of certain plant families/genera if: (a) fruits of these plant families/genera are represented in the diets of most of the species of that frugivore, (b) these are consumed by the frugivore genus across different kinds of habitats, and (c) these fruits feature among the yearly staples and preferred fruits in the diets of the frugivore genus. Using this framework, we reviewed frugivory by the genus Macaca across Asia to assess its spatial reliability as seed dispersers. We found that the macaques dispersed the seeds of 11 plant families and five plant genera including at least 82 species across habitats. Differences in fruit consumption/preference between different groups of macaques were driven by variation in plant community composition across habitats. We posit that it is essential to maintain viable populations of macaques across their range and keep human interventions at a minimum to ensure that they continue to reliably disperse the seeds of a broad range of plant species in the Anthropocene. We further suggest that this framework be used for assessing the spatial reliability of other taxonomic groups as seed dispersers.

Intraspecific differences in seed dispersal caused by differences in social rank and mediated by food availability.

We use individual-based information on the behavior of wild female Japanese macaques in two consecutive years with different food availability (nut-rich vs. nut-poor) to test effects of dominance rank and nut fruiting on seed dispersal parameters. We predicted that social rank would affect dispersal (1) quantity, (2) quality, (3) species richness, and (4) percentage of berries in the diet in the nut-poor year, while these differences would disappear in the nut-rich year. We found seeds of nine fleshy-fruited plant species in the feces of the monkeys. The frequency of seed occurrence for two plant species (Viburnum dilatatum and Rosa multiflora) showed an interaction between dominance ranks and years; in the nut-poor year V. dilatatum seeds were more abundant among dominant females and R. multiflora among subordinates, while such inter-rank differences disappeared in the nut-rich year. Similarly, the intact ratio of V. dilatatum seeds was lower for dominants in the nut-poor year, while inter-rank variations disappeared in the nut-rich year. Finally, percentage of berries in diet and seed richness showed no inter-annual nor inter-rank variations. Our study highlights that differences in individuals' social rank lead to within-group variation in seed dispersal services and that these differences are dependent on nut availability.

Functional decline of sweet taste sensitivity of colobine monkeys.

For many primates, sweet taste is palatable and is an indicator that the food contains carbohydrates, such as sugars and starches, as energy sources. However, we have found that Asian colobine monkeys (lutungs and langurs) have low sensitivity to various natural sugars. Sweet tastes are recognized when compounds bind to the sweet taste receptor TAS1R2/TAS1R3 in the oral cavity; accordingly, we conducted a functional assay using a heterologous expression system to evaluate the responses of Javan lutung (Trachypithecus auratus) TAS1R2/TAS1R3 to various natural sugars. We found that Javan lutung TAS1R2/TAS1R3 did not respond to natural sugars such as sucrose and maltose. We also conducted a behavioral experiment using the silvery lutung (Trachypithecus cristatus) and Hanuman langur (Semnopithecus entellus) by measuring the consumption of sugar-flavored jellies. Consistent with the functional assay results for TAS1R2/TAS1R3, these Asian colobine monkeys showed no preference for sucrose or maltose jellies. These results demonstrate that sweet taste sensitivity to natural sugars is low in Asian colobine monkeys, and this may be related to the specific feeding habits of colobine monkeys.

Effect of Provisioning on the Temporal Variation in the Activity Budget of Urban Long-Tailed Macaques (Macaca fascicularis) in West Sumatra, Indonesia.

We studied the behavioral ecology of provisioned long-tailed macaques (Macaca fascicularis) in Padang, West Sumatra, Indonesia, to examine how temporal changes in food provisioning within a day affect macaque activity. We conducted a field survey from October 2015 to January 2016 at two different sites: Gunung Meru (GM) and Gunung Padang (GP), where macaques receive high and low provisioning, respectively. The time budgets of macaques significantly differed between study groups. At GM, macaques spent more time resting, feeding, acting out agonistic behaviors, and less time moving and searching for food, than the macaques at GP. Diurnal activity patterns significantly changed within a day. The short-term change in activity of the macaques was closely related to the number of tourists: they spent a greater time feeding and searching when more tourists came to feed the monkeys, while time for grooming decreased. Our result showed that the ability of the macaques to adjust their activity in response to the number of tourists (that is, provisioning patterns) indicated their behavioral flexibility. Our result may aid the management strategies to reduce human-macaque conflicts, which has become a major problem in Padang.

Seasonal variation of energy expenditure in Japanese macaques (Macaca fuscata).

Animals living in seasonal environments must adapt to a wide variation of temperature changes which requires flexible adjustments of time budget and metabolic processes for efficient thermoregulation. The Japanese macaque (Macaca fuscata) is one of only a handful of nonhuman primate species that experience seasonal climates over a wide temperature range. We used behavior observations, accelerometer sensors and the doubly-labelled water (DLW) method to measure activity and total daily energy expenditure (TDEE) of M. fuscata housed in captivity but exposed to natural seasonal variations at day lengths ranging from 10 to 12 h and temperature ranging from 0° to 32°C. Although overall activity was significantly lower in winter compared to summer and autumn, we found no effect of temperature on day-time activity. However nocturnal inactivity and mean length of sleeping bouts significantly increased along a gradient of decreasing temperatures from summer through winter, suggesting the importance of adaptive behavioral thermoregulation in this species. Energy expenditure that was unaccounted for by Basal Metabolic Rate (BMR) and physical activity i.e. expended through diet-induced thermogenesis or thermoregulation was between 14% and 32%. This residual energy expenditure differed between summer/autumn and winter and was relatively consistent across individuals (approximately 5-8% higher in winter). The percentage of body fat and residual energy expenditure were negatively correlated, supporting that fat storage was higher when less energy was required for thermoregulation. Our results suggest that physiological mechanisms like behavioral and autonomic thermoregulation enable M. fuscata to adapt to wide fluctuations in environmental conditions which provide insights into the evolutionary adaptations of nonhuman primates in seasonal climate.

Status of urban populations of the long-tailed macaque (Macaca fascicularis) in West Sumatra, Indonesia.

We studied long-tailed macaque (Macaca fascicularis) populations in Padang, West Sumatra, Indonesia, focusing on the effect of human provisioning on their demography and dietary composition. We conducted a field survey at three sites in the city: Gunung Meru, Gunung Padang, and Gunung Panggilun. Mean troop size (range 28-68) and infant ratio (range 0.38-1.00) were greater in Gunung Meru, where the macaques have been highly provisioned, than at the other two study sites (troop size 10-15; infant ratio 0.00-0.33). The macaques at all sites consumed both natural and human foods, but dependence on the latter differed among sites: three-quarters of the diet of macaques in Gunung Meru consisted of human foods, while human foods comprised less than 5% of the macaque diet at the other sites. The ability of macaques to modify the proportion of human food is a behavioral flexibility that facilitates the survival of the long-tailed macaque in urban habitats. Without restrictions on provisioning, the degree of dependence of macaques on human foods and population size could increase, especially in Gunung Meru, and human-macaque conflict could escalate. In order to create an effective management policy for urbanized monkeys, long-term quantitative data on macaque behavior and monitoring of population parameters are required.

Estimated Seed Shadow Generated by Japanese Martens(Martes melampus): Comparison with Forest-Dwelling Animals in Japan.

To evaluate the seed shadow generated by wild Japanese martens (Martes melampus), we combined data on their ranging behavior from the northern foot of Mt. Fuji, central Japan (seven males and three females) with data on gut passage time obtained from martens in Toyama Municipal Family Park Zoo (three males and one female). The movement distances varied, and mean distances for 0-1, 2-3, and 4-5 h intervals were 152.4, 734.7, and 1,162.4 m, respectively, with no significant sex difference. The mean gut passage time of ingested seeds was 7.4 h (range: 0.6-51.7 h), and two-thirds were defecated within 12 h. Seeds of fleshy fruits was frequently transported to 501-1,000 m, and 20% of ingested seeds were transported > 1,000 m from feeding sites. We found positive correlations between body size and home range of the animals in Japan and their seed dispersal distances. We conclude that Japanese martens are medium-range dispersers that can transport seeds from the source to open habitats conducive for germination and/or growth, partly due to scent marking behaviors.

Report on the observed response of Javan lutungs (Trachypithecus auratus mauritius) upon encountering a reticulated python (Python reticulatus).

We observed an encounter between a reticulated python (Python reticulatus) and a group of wild Javan lutungs (Trachypithecus auratus mauritius) at the Pangandaran Nature Reserve, West Java, Indonesia. A python (about 2 m in length) moved toward a group of lutungs in the trees. Upon seeing the python, an adult male and several adult female lutungs began to emit alarm calls. As the python approached, two adult and one sub-adult female jumped onto a branch near the python and began mobbing the python by shaking the branch. During the mobbing, other individuals in the group (including an adult lutung male) remained nearby but did not participate. The python then rolled into a ball-like shape and stopped moving, at which point the lutungs moved away. The total duration of the encounter was about 40 min, during which time the lutungs stopped feeding and grooming. Group cohesiveness during and after the encounter was greater than that before the encounter, indicating that lutungs adjust their daily activity in response to potential predation risk.

Endozoochorous seed dispersal by Japanese macaques (Macaca fuscata): Effects of temporal variation in ranging and seed characteristics on seed shadows.

Variation in seed shadows generated by frugivores is caused by daily, seasonal, and inter-annual variation in ranging, as well as inter-specific variability in gut passage times according to seed characteristics. We studied the extent to which seed weight, specific gravity, and daily (morning, afternoon, and evening) and inter-annual (2004 vs. 2005) variation in ranging affected seed shadows generated by wild Japanese macaques (Macaca fuscata) in northern Japan. The macaques ingested fleshy fruits of 11 species during the two year study period; Viburnum dilatatum (Caprifoliaceae: heavier seeds with higher specific gravity) and Rosa multiflora (Rosaceae: lighter seeds with lower specific gravity) were eaten frequently in both years. The travel distances of macaques after feeding on V. dilatatum and R. multiflora fruits were estimated by combining feeding locations and ranging patterns measured in the field with gut passage times of model seeds in captive animals. Median travel distances after fruit feeding were 431 (quantile range: 277-654) and 478 m (265-646), respectively, with a maximum of 1,261 m. Neither year nor time of day affected travel distances. The gut passage time of model V. dilatatum seeds was longer than that of model R. multiflora seed, but this did not affect dispersal distances. Seed shadows for both species over 2 years showed unimodal distribution (peak: 101-500 m) and more than 90%, 20%, and 3% of ingested seeds were estimated to be dispersed >100, >500, and >1000 m, respectively, the longest known distances among macaque species. R. multiflora seeds tended to be dispersed further in 2004 than 2005, but V. dilatatum seeds were not, implying that inter-annual variations in ranging pattern due to the distribution and abundance of nut fruiting could affect dispersal distance.

Effects of seasonal changes in dietary energy on body weight of captive Japanese macaques (Macaca fuscata).

Food availability varies seasonally for wild animals, and body weight fluctuates accordingly in the wild. In contrast, controlling availability of diet under captive condition is difficult from keepers' standpoint, and monotonous diet often causes health problems in captive animals. We evaluated the effects of a seasonally controlled diet on body weight of captive Japanese macaques (Macaca fuscata) in an outside enclosure at Ueno Zoo, Tokyo, Japan. We fed a high-energy diet in spring and fall, and a more restricted diet in summer and winter for 3 years (2011-2013). Seasonal changes in body weight were similar to those that occur in wild macaques: for both sexes, body weight was higher in spring and fall and lower in winter. A decrease in body weight between fall and winter occurred only in adults, which implied that reducing dietary intake in winter had a more severe effect on adults than on juveniles. Different from wild populations, the body weight of captive macaques did not decrease between spring and summer, which we attributed to a lack of movement within the enclosure and to excess energy intake in summer. In addition to controlling dietary composition, providing large enclosure with complex structure and making efforts of giving unpredictability in feeding are necessary to motivate the captive animals to be more active, which would cause the macaques to show seasonal change in body weight, which is found in wild.

Inter-annual variation in characteristics of endozoochory by wild Japanese macaques.

Endozoochory is important to the dynamics and regeneration of forest ecosystems. Despite the universality of inter-annual variation in fruit production, few studies have addressed the sign (seed predation versus seed dispersal) and strength (frequency and quantity) of fruit-frugivore interaction and the effectiveness of endozoochory in response to the long-term temporal context. In this study I evaluated the characteristics of endozoochorous dispersal by wild Japanese macaques Macaca fuscata inhabiting deciduous forest in northern Japan for five different years. I collected 378 fecal samples from the macaques in fall (September to November) and quantified the proportion of feces containing seeds, number of seeds per fecal sample, ratio of intact seeds, and seed diversity. The proportion of feces containing seeds of any species (five-year mean: 85.9%, range: 78-97%) did not show significant inter-annual variation, while species-level proportions did. The intact ratio of seeds (mean: 83%, range: 61-98%) varied significantly both between years and between months, and this varied among dominant plant species. The number of seeds per fecal sample (mean: 78, range: 32-102) varied monthly but did not between years, and the seed diversity (mean: 0.66, range: 0.57-0.81) did not show significant inter-annual variation, both of which were attributed to longer duration of macaques' gastro-intestinal passage time of seeds exceed their feeding bouts. This study demonstrated that frequency and success of seed dispersal over seed predation of macaque endozoochory showed inter-annual variation, indicating low specificity across the seed-macaque network. The temporal variability in the quality of seed dispersal may provide evidence of high resilience in response to fluctuating environmental conditions in the temperate forests.

Feeding strategies of primates in temperate and alpine forests: comparison of Asian macaques and colobines.

We analyzed regional variation in the diets of two primate clades, Asian macaques and colobines, whose distributions include temperate-alpine forests. We addressed feeding strategies that enabled them to adapt to harsh environments characterized by relatively low mean temperatures and strong seasonality in both temperature and food availability. Macaques in tropical-lowland forests feed mainly on fruit and animal matter whereas populations in temperate-alpine forests feed more on foliage and on such items as bark and fungi. In comparison, colobines in tropical-lowland forests feed more on fruit and foliage whereas populations in temperate-alpine forests feed less on flowers and more on lichens. Annual precipitation and mean temperature, both of which reflect primary production, had the most significant effects on the feeding behavior of the macaques, whereas only mean temperature had a significant effect on that of colobines. We found two behavioral strategies used by both clades to cope with severe environmental conditions in temperate-alpine forests--shifting to other food items and adjusting feeding plasticity for fruit and foliage. Macaques responded to latitudinal changes by use of both strategies whereas the colobines adapted by using the latter only. By contrast, changes in altitude resulted in the macaques' using the latter strategy and colobines' using both. The different current distributions of Asian macaques and colobines could be attributed to differences in their feeding strategies originating in their digestive systems.

Ranging and foraging of Himalayan grey langurs (Semnopithecus ajax) in Machiara National Park, Pakistan.

Grey langurs (Semnopithecus spp.) occupy a variety of habitats, ranging from lowland forests and semi-desert to alpine forests. Little is known about their foraging and ranging in alpine forests, which appear to contain less food than lowland forests. We conducted a 1-year study of Himalayan grey langurs (Semnopithecus ajax) in Machiara National Park, Pakistan, where they occur at relatively high altitudes (range 2000-4733 m). We followed three groups of different sizes and compositions and examined the effects of ecological and social factors on ranging and feeding. The home-range sizes of a small bisexual group (SBG), a large bisexual group (LBG), and an all-male group (AMG) were 2.35 ± 0.92 (mean ± SD; average of four seasons), 3.28 ± 0.55, and 3.52 ± 1.00 km(2), respectively, and were largest in winter for all groups. The daily path lengths of the SBG, LBG, and AMG were 1.23 ± 0.28 (mean ± SD; average of four seasons), 1.75 ± 0.34, and 1.84 ± 0.70 km, respectively; that of the LBG was longer in winter, while that of the AMG was shorter in summer. Both the home-range size and daily path length of the AMG were larger than those of the other groups, even after partialling out the effect of group size differences. The mean altitude used by the langurs and the proportion of animals seen feeding did not differ among seasons or group types. As the mean temperature increased, the altitude used by langurs significantly increased for the SBG and LBG, but not for the AMG. On the other hand, as the temperature increased, the home-range sizes significantly decreased for the SBG and AMG, but not for the LBG. Rainfall did not show any correlation with ranging or feeding in any of the groups. Our results suggested that grey langurs in Machiara National Park employ a high-cost, high-return foraging strategy in winter, and that the ranging of the AMG also reflects its reproductive strategy.

Fruiting and flushing phenology in Asian tropical and temperate forests: implications for primate ecology.

In order to understand the ecological adaptations of primates to survive in temperate forests, we need to know the general patterns of plant phenology in temperate and tropical forests. Comparative analyses have been employed to investigate general trends in the seasonality and abundance of fruit and young leaves in tropical and temperate forests. Previous studies have shown that (1) fruit fall biomass in temperate forest is lower than in tropical forest, (2) non-fleshy species, in particular acorns, comprise the majority of the fruit biomass in temperate forest, (3) the duration of the fruiting season is shorter in temperate forest, and (4) the fruiting peak occurs in autumn in most temperate forests. Through our comparative analyses of the fruiting and flushing phenology between Asian temperate and tropical forests, we revealed that (1) fruiting is more annually periodic (the pattern in one year is similar to that seen in the next year) in temperate forest in terms of the number of fruiting species or trees, (2) there is no consistent difference in interannual variations in fruiting between temperate and tropical forests, although some oak-dominated temperate forests exhibit extremely large interannual variations in fruiting, (3) the timing of the flushing peak is predictable (in spring and early summer), and (4) the duration of the flushing season is shorter. The flushing season in temperate forests (17-28 % of that in tropical forests) was quite limited, even compared to the fruiting season (68 %). These results imply that temperate primates need to survive a long period of scarcity of young leaves and fruits, but the timing is predictable. Therefore, a dependence on low-quality foods, such as mature leaves, buds, bark, and lichens, would be indispensable for temperate primates. Due to the high predictability of the timing of fruiting and flushing in temperate forests, fat accumulation during the fruit-abundant period and fat metabolization during the subsequent fruit-scarce period can be an effective strategy to survive the lean period (winter).