More Than Just Kibbles: Keeper Familiarity and Food Can Affect Bonobo Behavior.

The welfare of captive animals relies on numerous factors. Keepers can affect animals' welfare and this could especially apply to emotionally and cognitively complex species, such as great apes. We collected video data over three months on 17 bonobos (La Vallée des Singes, France) and extracted five behaviours (play, aggression, anxiety, gestures, sociosexual interactions) -during two-minute slots-under three conditions: keeper-present/food-unavailable; keeper-present/food-available; keeper-absent/food-unavailable. We ran generalized linear models to investigate whether behavioral frequencies were affected by food presence/quality and keeper familiarity. Anxiety-related behaviors increased when the keeper was present and in absence of food, due to food expectation. Sociosexual interactions increased in presence of more familiar keepers and in absence of food, maybe to decrease the tension around food. Gestures increased in presence of more familiar keepers and with low-quality food, which was provided in large 'catchable' pieces. Aggression levels increased with high-quality food with no effect of keeper. Play behavior was not affected by any variable. Hence, bonobos were affected not just by food but also by keeper features. Considering multiple variables in the 'welfare equation' can improve captive management and increase the well-being of bonobos, a species that is much closer to humans than to other non-human animals.