Subject Species Sex Age Loss Condition Gain Condition

females and 10 males) at Lola Ya Bonobo in Kinshasa, Democratic Republic of Congo. Animal husbandry and care practices at both locations complied with the Pan-African Sanctuary Alliance (PASA) Primate Veterinary Healthcare Manual, as well as the policies of Tchimpounga Chimpanzee Sanctuary and Lola ya Bonobo Sanctuary respectively. Apes in African sanctuaries are born in the wild, and typically enter the sanctuary after being confiscated at an early age (~2-3 years old) as a result of the trade in wildlife for pets and bushmeat. Previous work indicates that sanctuary apes are psychologically healthy relative to other captive populations [1]. All apes at both sites were socially housed, and the majority free-ranged in large tracts of tropical forest during the day (5-40 hectares across groups). In the evening, all apes spent the night in indoor dormitories (12 m2-160 m2). Apes were tested individually in these familiar dormitory buildings. Following testing, most apes were released back with their larger social groups outside. Apes had ad libitum access to water and were never food deprived for testing. In addition to the food the apes could eat in their forest enclosures, they were fed a variety of fruits, vegetables, and other species-appropriate foods two to four times daily. Apes were tested on only one session per day and all tests were voluntary: if subjects stopped choosing for more than three trials, the sessio