Boon Allwin, Nishit S Gokarn, Serma S Pandian, Stalin Vedamanickam, Sathish Gopal, Manoj K and Bharath Jothi S
The faecal glucocorticoid metabolites of a free-ranging small Nilgiri tahr population of Western Ghats, Tamil Nadu was studied to investigate contributing confounding influences of season, ambient temperature, rainfall and water level on the annual secretion pattern. The was done for a period of one year Oct 2013-Sep 2014. Individuals may cope with environmental challenges through the secretion of stress hormones (glucocorticoids) which allows the integration of environmental change as essential life events such as predator stress, food and water availability, resting cover, influence of tourists and life history events such as birth, death, maintenance of an essential population size by means of an adaptive feedback mechanism. Adaptation and eventually acclimatization to cyclic day-to-day activities, short-term environmental stressors or long-term ecological pressures have been observed with these animals. However, being a highly limited population the animals maintained an effective population size. A clear cut seasonal pattern of glucocorticoid metabolites excretion was detected, with increasing levels in summer and winter. The confounding factors such temperature, rainfall, relative humidity, solar radiation, soil temperature were recorded throughout the study period and did not have any correlation with the stress the animals exhibited. The observed pattern might be due to lack of feed availability both during summer and winter, a declining nutritional intake and reduction of metabolism during winter, clearly the animals were not in their “Thermo comfort Zone”. However, broad retrospective studies are essential to identify potential contingent environmental stressors. This study reports the baseline cortisol level in Nilgiri Tahrs, with the relevant confounding factors correlating with their annual variation level.