May unpredictable events affect monkey welfare under human care?

This study aimed at evaluating the effects of unpredictability on behavioral and clinical aspects of Geoffroy's woolly monkey (Lagothrix cana cana) - a frugivorous Amazonian primate species - under human care. We studied seven individuals subjected to five conditions: two control conditions (PRE and POST; 10 days each), and three experimental conditions in which unpredictability was associated to food presentation. Each experimental condition had three intensities (stages): spatial unpredictability (food offer in unusual, changing places; S1, S2, S3), temporal unpredictability (food offer in unusual, changing times; T1, T2, T3), and spatial and temporal unpredictability combined (C1, C2, C3). Each stage lasted 10 days. Behaviors were collected using scan sampling in 24 five-minute daily sessions, with records taken every 20 s. A Behavioral Diversity Index (BDI) was also calculated daily, and welfare assessment was performed at each stage, with the use of the Five Domains Model. Condition T promoted an increase in exploration, and reductions in behaviors indicative of dysfunction, surveillance, maintenance, and in affiliative interactions. In condition S, we found an increase in foraging, and reductions in maintenance behaviors and agonistic interactions. Finally, in condition C, we recorded increases in exploration, and reductions in behaviors indicative of dysfunction, surveillance, maintenance, affiliative and agonistic interactions. Most of these effects have been correlated to improved welfare. The Five Domains Model evaluation also supported an improvement in welfare levels in all experimental stages, compared to PRE condition. Our behavioral and welfare assessment results pointed that unpredictability promoted an improvement in the welfare levels for the animals studied, and is recommended for the maintenance of the species under human care.