Iredale, S. K., Nevill, C. H., Lutz, C. K. 2008. The influence of observer presence on the behavior of singly housed baboons (Papio sp.) and rhesus macaques (Macaca mulatta). American Journal of Primatology 70(S1), 29. (31st Meeting of the American Society of Primatologists Scientific Program, Abstract #28)

Live, direct observations are often used to collect behavioral data. However, the presence of an observer may affect the behavior of unhabituated subjects. This study was conducted to determine the effect of an observer’s presence on the behavior of singly-housed baboons and rhesus macaques. Twenty baboons (10 males, 10 females) and 20 macaques (10 males, 10 females) were videotaped during four 30-minute periods. Half of the observations were collected with an unfamiliar observer present, and half were collected with no observer present. Video was scored using a 30-second point sampling method. Scorers were blind to observer presence. Data were analyzed using a repeated measures ANOVA with condition, sex, and species as the independent variables. The presence of an observer resulted in an increase in rest [F(1,36)=7.04, p<0.05] and a decrease in appetitive [F(1,36)=8.52, p<0.01] and manipulative [F(1,36)=4.34, p<0.05] behaviors. There were also condition by species and condition by sex interactions for rest and manipulative behaviors. With an observer present, macaques showed an increase in rest [F(1,36)=11.41, p<0.01] and a decrease in manipulative behaviors [F(1,36)=8.58, p<0.01] while baboons showed no change. Similarly, females rested more [F(1,36)=6.85, p<0.05] and manipulated less [F(1,36)=4.86, p<0.05], while males showed no change. This study shows that unhabituated animals are affected by observer presence, but the degree and direction of these effects vary by species and sex. Supported by NCRR grant #RR013986.