Nutritional Ecology Of The Golden Snub-nosed Monkey (Rhinopithecus Roxellana) And Its Adaption To Cold Environment

Climate and food resource are two main substantial ecological factors that influence survivability and development of the animals.Primates living in temperate region have to face dual stresses of seasonal fluctuation of food availability and cold winter.The Golden snub-nosed monkey(Rhinopithecus roxellana),the northern-most distributed colobine in the world,has fragmented habitats and severely interfered by anthropogenic activities and climate change.This is a case study focusing on the monkeys' populations in Zhouzhi National Nature Reserve,Qinling Mountains,China,in order to understand their nutritional ecology and evaluate their behavioral,physiological,nutritional,and energetic strategies used to deal with this twofold challenge,particularly regarding its prolonged cold environment accompanied by with food shortages.To reach the purposes we completed the following procedures:1).We used instantaneous scan samples to record seasonal variation of dietary composition and surveyed its food availability.The results indicated that the monkeys living in deciduous forests showed seasonal diets in line with the seasonal change of food availability,leaves were the dominated food between April and November,while buds and bark comprised its majority of the diet during leaf-scare period from December to March.Such phenomenon was different from the situation of the southern populations that turn to predominately eat lichens during winter.This could be related to the fact of less availability of lichens in Zhouzhi.We also analyzed macronutrients of the foods and some uneaten items.The related results showed that while leaves dominated dietary resources,monkeys preferentially selected leaves with higher level of the protein but lower level of the lignin;while leaves less available,monkeys adaptably selected barks with higher non-structural carbohydrates and energy,and low level of acid detergent fiber.The study also indicated that carbohydrate and energy-rich foods appear to be the critical resources required for the persistence of this endangered species in temperate habitat,The dietary flexibility of these monkeys likely contributes to their wide distribution over a range of habitats and environments.2).We first quantified the full-day macronutrients and energy intake by the R.roxellana in the wild,and use nutritional geometry to analyze individual-based nutrients data.The results showed that the species has adopted “protein prioritization” pattern,maintaina striking consistent of protein intake across the seasons,while allowed the non-protein(carbohydrates and lipids)energy to vary seasonally.Such “protein prioritization” pattern,which was reported on Homo sapiens,Ateles chamek,and Lepilemur leucopus,is first reported in this colobine species.3).This study combined multiple thermoregulatory strategies,behavioral,physiological,nutritional,and energetic,to unravel the adaptive responses to food shortage and energetic crisis in cold environment,including the increased feeding time and food patches,a rising feeding investment in winter;shorten moving time and daily path length,and increasing resting time to reduce energy expenditure.The monkeys increased non-protein energy intake(326 kJ/mbm)was quantitatively match the additional thermoregulatory costs(329 kJ/mbm)in winter compared to spring.Aside from the increased energy intake in winter,R.roxellana adopted some feeding strategies prior to winter;including increased feeding time,visited more feeding patches,and increased non-protein energy intake in autumn.This study also quantitatively reported that the average daily caloric value of losing fat(102 kJ/mbm)was almost identical to daily energy deficit(101 kJ/mbm,the difference between energy expenditure and energy intake)in winter.This indicated that the animals were able to rationally consumed the deposited fatty tissue(14% of body mass loss during winter),preserved prior to winter.In addition,the monkeys were also capable of reducing body temperature(facial maximum temperature)in cold winter,allowing them to reduce energy expenditure and heat loss.4).The characterized multi-level social structure of large group and significant sexual dimorphism in body mass(male is about 1.9-fold than female)were responsible for energy expenditure(kJ)in adult males were higher than adult females.Because of lengthy periods of reproduction and lactation,energy expenditure of lactating females were higher than adult male,non-lactating females and juveniles,once metabolic body mass was accounted for.