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Non-Invasive Hormone Monitoring: Faecal Androgen and Glucocorticoid in Male Crested Macaques (Macaca nigra) in Relation to Seasonal and Social Factors

Gholib Assahad, MSc student, Bogor Agricultural University, Indonesia - 2011 completed

Non-invasive hormone monitoring using faeces has become an increasingly popular technique, but it is essential to validate before applying the technique to a new species. The aims of this study were to validate a method for measuring androgen and glucocorticoids noninvasively in feaces of crested macaques (Macaca nigra) and investigated the impact of season (climate) and social factors (copulation rates, male aggression, number of fertile females and dominance male) on male hormones. The study was carried out on two groups of crested macaques (Rambo 1 and Rambo 2)  living in the Tangkoko-Batuangus Nature reserve, North Sulawesi, Indonesia. Three established enzymeimmunoassays (EIAs) for androgens (epiandrosterone, testosterone and 5α-androstanolone) and glucocorticoids (cortisol,11-oxo-CM and 11β-dihydroxy-CM) were tested using biological validation and immunoreactivity tests. Moreover, behavioural observations,measuring rainfall and temperature, and hormone measurements were performed. A General Linier Mix Model (GLMM) test was then conducted to investigate the effect of season and social factors on male hormones. The result shown that except 5α-androstanolone, both of androgen EIAs appeared reliable in their ability to discriminate androgen levels between juvenile and adult males, although HPLC data clarified that epiandrosterone is the most abundant. On the other hand, 11-oxo-CM and 11β-dihydroxy-CM assays discriminated better between pre-stress and stress periods than the cortisol. However, HPLC results shown that 11β-dihydroxy-CM detected the most abundant glucocorticoid metabolites. Result of GLMM test shown that androgen and glucocorticoid levels were not significantly influenced by rainfall and temperature. Androgen levels were significantly influenced by copulation rate (p=0.029) and dominance rank (p=0.002).  Glucocorticoid levels were significantly influenced by number of fertile females (p=0.004) and dominance rank (p=0.02). In conclusion, biological validation can be used to validate androgen and glucocorticoid metabolites using faecal samples which epiandrosterone and 11β-dihydroxy-CM are the most realible and useful as a measure of androgen and glucocorticoid excretions respectively. Moreover, pattern of androgen and glucocorticoid levels in male crested macaques do not show a clear seasonal variation which levels of both hormones are not directly linked with enviromental factors (e.g., climate), but associated with social factors such as copulation rate, number of fertile females and dominance rank.

Keyword: crested macaques, androgen, glucocorticoid, season, social factors