Influence Of Seasonal And Social Factors On Fecal Testosterone And Cortisol Levels In Wild Male Tibetan Macaques Macaca Thibetana

Primates in natural environments face different social challenges,such as reproductive competition,which usually increase testosterone and cortisol levels in the body to address them.For Tibetan macaques(Macaca thibetana),the male monkeys have strict social hierarchy and fierce competition in mating season.So how to deal with these challenges by changing the endocrine level of male Tibetan macaques(Macaca thibetana)has not been studied in depth.The study was conducted from July 2019 to January 2020(mating season)and April2020 to June 2020(non mating season)based on Tibetan macaques(Macaca thibetana),which inhabits Huangshan,Anhui Province.Based on the individual identification,the behavior data of male macaque under different seasons were collected by the method of focal animal sampling and behavior sampling.The results of the analysis of the effects of seasons(mating season,non mating season),social(social grade,social behavior),ecological factors(monthly rainfall and monthly average temperature)on the hormone level in feces were analyzed to explore how male individuals in wild macaque population can change their levels of testosterone and cortisol by changing their own hormone level of body is used to deal with the corresponding social challenges.The results showed that:(1)the testosterone(Mean-Whitney U test: Z=-6.64,N=315,P< 0.01)and cortisol(Mean-Whitney U test: Z =-3.94,N=315,P< 0.01)were seasonal,and the levels of testosterone and cortisol in mating season were significantly higher than that in non mating season.(2)The testosterone levels of male macaques showed significant individual differences(mating season: Kruskal Wallis test,H = 75.76,df = 12,p < 0.01;non-mating season:Kruskal Wallis test,H = 26.56,df = 9,p = 0.02).(3)There were significant individual differences in cortisol levels in both mating and non mating seasons(mating season: Kruskal Wallis test,H = 83.22,df = 12,P <0.01;non-mating:Kruskal Wallis test,H = 26.57,df = 9,P = 0.02).(4)In mating season,the testosterone levels of high rank males were significantly higher than those in the middle rank(Mann-Whitney U test,Z =-3.59,N=130,P <0.01)and low rank(Mann-Whitney U test,Z =-4.67,N=131,P < 0.01),while there was no significant difference in testosterone content between male individuals of three types in non mating period(Kruskal Wallis H test,H = 1.23,N=112,df = 2,P =0.54).(5)In mating season,the cortisol levels of middle rank males were significantly higher than high rank(Mann-Whitney U test,Z =-3.43,P < 0.01)and low rank(MannWhitney U test,Z =-1.36,P = 0.17),the cortisol levels of high rank and low rank no difference(Mann-Whitney U test,Z =-1.36,P = 0.17).(6)The testosterone content of male in mating period was correlated with the attack frequency of each month(Spearman correlation analysis: r = 0.27,P = 0.02),but there was no correlation between testosterone content and monthly attack frequency in males in non mating period.(Spearman correlation analysis: r = 0.21,P = 0.27),the testosterone content in males was positively correlated with the mating frequency of each month(Spearman correlation analysis: r = 0.46,P < 0.01).(7)There was no correlation between the cortisol content and the rank order of male in mating period(Spearman correlation analysis: r =-0.34,P=0.25),and there was no correlation between the cortisol hormone content and grade sequence in the non mating period.(Spearman correlation analysis: r =-0.07,P=0.86),the cortisol content of male and the time of individual hair management were not correlated(Spearman correlation analysis: r = 0.53,P = 0.06),while the cortisol content of male and the time of individual hair treatment were not correlated(Spearman correlation analysis: r =-0.05p=0.98).(8)There was no correlation between testosterone content and average temperature of each month in male during the whole observation period(Spearman correlation analysis:r =-0.14,P=0.78).There was no correlation between testosterone content and monthly rainfall(Spearman correlation analysis: r =-0.03,P=0.96),and there was no correlation between cortisol content and average temperature of each month(Spearman correlation analysis: r = 0.19,P = 0.72),At the same time,there was no correlation between cortisol content and monthly rainfall in males(Spearman correlation analysis: r =-0.03,P=0.97).The results show that the seasonal reproduction of the Tibetan macaques(Macaca thibetana)has seasonal differences in hormone secretion.They can cope with the upcoming seasonal challenges by releasing the corresponding hormones.For example,the secretion of testosterone and cortisol is increased in mating season,and the effects of seasons,grades,social behaviors,temperature and rainfall on hormone secretion are analyzed.It can provide evidence for further understanding of the law of primate hormone secretion and provide technical support for further study on the physiological mechanism of social behavior of macaques.