Cortisol reactivity and its relation to homecage behavior and personality ratings in tufted capuchin (Cebus apella) juveniles from birth to six years of age.

Rank correlations between cortisol reactivity measures (baseline, 2 h stress peak and change from baseline) at 6 months and 1 year and (1) behaviors videotaped in the home cage and (2) subjectively judged personality ratings were examined in 36 juvenile tufted capuchins from birth to 6 years of age. High cortisol reactivity was associated with both lower levels of play and exploration in the home cage, and higher levels of proximity and contact with mothers. Animals with higher baseline cortisol played by themselves more, and played with other animals less, than did those with lower baselines. High cortisol reactivity, especially at 1 year of age, was also related to higher levels of dorsal carrying by mothers in the second year, when most infants are independent of mothers. Ratings on the personality traits, Aggressive, Confident, Curious, Effective and Opportunistic, were all negatively correlated with cortisol reactivity levels, while Apprehensive, Fearful, Insecure, Submissive and Tense were positively correlated with cortisol reactivity. In summary, there was a relationship between high physiological reactivity and inhibited, fearful behavior and temperament patterns not previously described in capuchins.