RESUMO
Zoo-housed bears are prone to exhibiting stereotypic behaviors, generally considered indicators of negative welfare. We explored the effects of a variable-time feeding enrichment schedule on behavioral indicators of welfare in four bear species at Cleveland Metroparks Zoo. We distributed the diets of eight bears in one of five enrichment items, for two consecutive days each, and monitored behavior throughout the day. In Experiment 1, we compared variable-time to fixed-time presentation of enrichment over two, 10-day periods. Overall, bears performed more exploratory behavior when enriched (p < 0.0001). Furthermore, variable-time enrichment was associated with a greater increase in exploratory behavior than fixed-time enrichment when compared to baseline (p < 0.001). Both fixed-time (punadjusted <0.05, padjusted = 0.07) and variable-schedule (punadjusted <0.05, padjusted = 0.09) enrichment were also associated with similar decreases in abnormal behavior compared to baseline. For Experiment 2, we tested habituation to enrichment over 30 days using multiple items and a semi-variable presentation schedule. Again during the enrichment period, bears exhibited increased exploratory behavior (p < 0.0001) and decreased abnormal behaviors compared to baseline (punadjusted = 0.05, padjusted = 0.09). We observed no habituation during the 30-day sustained enrichment period for these behaviors. Collectively, these results suggest that daily, variable-schedule feeding enrichment, with intermittent presentation of unique enrichment items, increases behavioral indicators of positive welfare and decreases behavioral indicators of negative welfare.