In search of the optimal enrichment program for zoo-housed animals

Zoo-housed animals are regularly exposed to new forms of environmental enrichment to make their lives less predictable. However, providing new enrichment can have unpredictable effects. We evaluated the effectiveness of two enrichment regimes: (1) providing only new enrichments - "Novelty" and (2) only familiar enrichments - "Familiar." In this case study, enrichment efficacy was assessed using activity budget analysis and novel object tests. The subjects were two focal animals: the golden jackal (Canis aureus) and the European badger (Meles meles). Our results suggest that both assessment methods provided similar conclusions about the animal's welfare. The "Familiar" treatment significantly increased activity and decreased abnormal behavior in the jackal's activity budget, who avoided novel objects in her baseline novel object test. The Novelty treatment resulted in the growth of time the jackal spent in the moat instead of the main enclosure, and an increase in avoidance and abnormal behaviors. In contrast, the badger demonstrated a high intensity of exploratory behavior in the baseline novel object test, and both regimes led to an increase in the activity budget of the badger. We propose that a stable, but complex enrichment can be an effective robust tool to increase animal welfare, but its efficacy depends on the novelty preference of individual animals. A novel object test can be a rapid tool to assess individual animals' novelty preferences, and this information may help to choose optimal enrichment regimes for individual animals.