Preliminary Study On Geophagy In Taihangshan Macaques (Macaca Mulatta Tcheliensis)

Activity pattern and time budget include all activities performed by animals and the time allocation for each activity type,which interact with environment and self-physiological status.Many factors,including environmental changes,food resources,social structure,and morphological and physiological traits could affect animal's activity pattern and time budget.Understanding the animal activity pattern and time budget is the cornerstone for further study of behavioral ecology,and the key to understanding of how animal behaviorally adapt their habitat.Geophagy or soil-eating behavior is defined as the intentional consumption of earth materials,and could be observed in many mammalian species,including human and non-human primates.However,the function of geophagy is poorly understood.Who,when,where and how would perform the geophagy are the key questions to answer in order to understand its function and significance.During July 2017 and September 2018,I observed and investigated the geophagy in free-ranging Taihangshan macaques?Macaca mulatta tcheliensis?in Wulongkou area within the Taihangshan Macaque National Nature Reserve in Henan Province.The contents mainly included:1)the activity pattern and time budget was investigated using scan sampling method combined with instantaneous recording method,2)the characteristics of geophagy were investigated by focal sampling method combined with continuous recording method,3)the chemical and physical characteristics of eaten soil and un-eaten soil by Taihangshan macaques were investigated to test the“Iron Supplementation Hypothesis”representing the“Supplementation Hypothesis”,and the“Buffering Stomach pH Hypothesis”representing the“Proctective Hypothesis”.The main results and conclusion of this study were as follows:1.Activity pattern and time budget of free-ranging Taihangshan macaquesFrom October 2017 to September 2018,the activity pattern and time budget of 4groups?WLK-1A,WLK-1B,WLK-2 and WLK-3?of Taihangshan macaques were investigated using scan sampling method combined with instantaneous recording method.The recorded activity types were mainly classified as resting,grooming,moving,feeding,geophagy,and others.The main findings were:1)the time budget of the 6 activity types changed monthly,and the highest and lowest months for resting,grooming,moving,feeding,and geophagy were January?47.86±21.88%?and April?31.51±19.07%?,October?38.07±19.36%?and June?8.50±11.86%?,August?25.34±20.97%?and September?12.72±15.08%?,June?24.51±21.87%?and October?3.46±5.06%?,and September?0.66±2.85%?and February?0.10±0.84%?,respectively;2)the time budget also showed seasonal changes;and the highest and lowest seasons for resting,grooming,moving,feeding,and geophagy were winter?44.29±21.89%?and spring?38.19±19.95%?,autumn?31.66±19.51%?and summer?10.88±14.58%?,summer?23.47±18.70%?and autumn?13.74±14.55%?,summer?15.10±17.18%?and autumn?7.18±9.55%?,and summer?0.39±1.64%?and winter?0.13±0.86%?.The activity pattern and time budget of Taihangshan macaques showed monthly and seasonal changes,and dominated by resting and followed by grooming or moving and feeding,but geophagy was low-frequency behavior.2.Characteristics of geophagy in Taihangshan macaquesBased on the previous section,the geophagy was re-analyzed monthly in details,and its relation with climatic factors were also tested.The main findings included:1)the geophagy of Taihangshan macaques varied monthly,and showed relatively higher frequency in June?6.02±19.36‰?,July?5.00±17.82‰?and September?6.63±28.49‰?;2)the occurrence of geophagy was significantly positively correlated with precipitation?population level:R=0.82,t=4.59,P=0.001;adult female:R=0.78,t=3.94,P=0.003?,averaged maximum temperature?population level:R=0.61,t=2.41,P=0.037;adult female:R=0.66,t=2.81,P=0.018?,averaged minimum temperature?population level:R=0.61,t=2.38,P=0.038;adult female:R=0.61,t=2.43,P=0.035?,and averaged temperature?population level:R=0.61,t=2.44,P=0.035;adult female:R=0.64,t=2.64,P=0.025?;3)the occurrence of geophagy displayed relatively more frequent at 2-3 months after birthing peak and 1 month before the mating peak.The occurrence of geophagy in Taihangshan macaques varied monthly and showed weak relation with climatic factors and the reproductive status.3.Effect of age and sex on geophagy in Taihangshan macaquesFrom July 2017 to September 2018,focal animal sampling combined with continuous recording method were adopted to investigate the effect of age and sex on the geophagy of free-ranging WLK-1A Taihangshan macaques in Jiyuan Wulongkou area,Henan,China.The main findings included:1)Taihangshan macaques showed preferred soil-eating sites,and preference for feeding sites from highest to lowest was D?144 times,34.04%?,B?120 times,28.37%?,C?67 times,15.84%?,E?62 times,14.66%?,A?16 times,3.78%?,Z?12 times,2.84%?and F?2 times,0.47%?;2)the standardized frequencies of geophagy?times/10h*30d?for adult females,adult males,sub-adults,juveniles,and infants were 10.37,8.25,17.15,8.96 and 7.26,respectively,but there were no significant differences amongst these groups?Chi-squared test,?²=6.16,P>0.05?;3)the standardized amount of soil intake?g/10h*30d?for adult females,adult males,sub-adults,juveniles,and infants were 19.38,11.29,27.77,13.76 and 4.77respectively,and there were significant differences?Chi-squared test,?²=19.56,P<0.01?;4)the average time per bout?s?of geophagy for adult females,adult males,sub-adults,juveniles,and infants were 64.16±61.12 s,57.56±79.44 s,55.46±50.59 s,65.64±85.31 s,and 24.52±16.79 s,and there were significant differences?Chi-squared test,?²=20.55,P<0.01?.The findings demonstrated that there were significant effects of age and sex on geophagy in Taihangshan macaques,and the adult females and sub-adult individuals showed higher amounts of soil intake and longer soil-eating duration.4.Chemical and physical characteristics of eaten and un-eaten soil by Taihangshan macaquesIn order to test the function and significance of geophagy in Taihangshan macaques,the chemical and physical characteristics of the eaten and un-eaten soil were detected.During July 9-10^th and October 9-10^th,2018,20 soil samples were collected for each month.Specifically,there were 10 soil samples collected from soil-eating sites by Taihangshan macaques,and 10 un-eaten soil samples collected from 2-4 m away but next to the soil-eating sites.The pH of the soil samples was measured directly with ZD Smart pH Detecter.The water content?%?was measured using vacuum freeze drier,and YF-3000 Soil and Fertilizer Nutrient Measurement Apparatus was adopted to measure the main concentration of selected elements.The results showed:1)the concentration of available potassium?K⁺?for eaten soil?July:242.6±53.01 mg/kg;October:269.97±39.71 mg/kg?was significantly lower than that of the un-eaten soil?July:499.90±203.06 mg/kg;October:667.10±158.30 mg/kg?,and ammonium nitrogen for eaten soil in July?39.50±24.24 mg/kg?was significantly lower than that of the un-eaten soil in July?50.52±12.93 mg/kg?,but there were no significant differences in water content,available phosphorus,available iron and copper?all P>0.05?between eaten and un-eaten soil,which was not consistent with the“Iron Supplementation Hypothesis”representing the“Supplementation Hypothesis”;2)the pH for eaten soil?July:6.26±0.38;October:6.72±0.29?was significantly lower that that of the un-eaten soil?July:6.74±0.41;October:7.45±0.57?,which was not consistent with the“Buffering Stomach pH Hypothesis”.Based on these findings,“Acid Supplement Hypothesis”was proposed to explain the function and significance of geophagy by rhesus macaques,which meant that rhesus macaques would eat acidic soil to alleviate the stomach distress or related function.In summary,Taihangshan macaques could adapt to the change of environment by adjusting the activity pattern and time budget.The geophagy of Taihangshan macaques varied monthly and could be affected by climatic factors and the reproductive status.The geophagy of Taihangshan macaques was not consistent with the“Iron Supplementation Hypothesis”representing the“Supplementation Hypothesis”and the“Buffering Stomach pH Hypothesis”;however,I proposed a new hypothesis,“Acid Supplement Hypothesis”,which may explain geophagy in rhesus macaques.While,more evidences would be needed to test this hypothesis and,if supported,then the mechanism would be needed to be investigated.