López-Álvarez, J., Sanjorge, Y., Soloaga, S. et al. 2019. Looking for visitor's effect in sanctuaries: Implications of guided visitor groups on the behavior of the chimpanzees at Fundació Mona. Animals 9(6), 347.

The question of 'if and how captive primates are affected by visitors' has gained increasing attention over the last decades. Although the majority reported undesirable effects on behavior and wellbeing, many studies reported contradicting results. Most of these studies were conducted at zoos, typically with little or no control over visitors' actions. Yet little is known about the impact under very controlled visitor conditions. In order to fill this gap, we conducted this study at a primate sanctuary which allows public access only via a guided visit under strict supervision. We observed 14 chimpanzees, recording their behavior during, after and in the absence of guided visits over a 10-month period. Furthermore, we categorized the visitors regarding group size and composition to see if certain group types would produce a stronger impact on the chimpanzees' behavior. As expected, we found visitors at the sanctuary to produce only a neutral impact on the chimpanzees' behavior, detecting a slight increase of locomotion and decrease of inactivity during visitor activities with chimpanzees demonstrating more interest towards larger sized groups. We argue that the impact has been greatly mitigated by the strict visitor restrictions and care strategies allowing chimpanzees a certain control regarding their visibility.