In this study we used the daily activity pattern and use of space as indicators of change in the program of structural enrichment, implemented with 2 subjects of the species Ursus arctos in the Barcelona Zoo. We collected 930 sampling points in each study phase for each of the individuals: The samples were taken in a balanced way at different times of day. We observed a wider range of behavior in the male than the female. With respect to the indicators, we observed statistically significant differences in behavior in both individuals in the 2 study phases. Both individuals showed an increase in vigilance, maintenance, and inactivity when their enclosure was changed. In terms of the subjects' well-being, we considered the percentage of stereotyped behavior within acceptable limits. The percentage of activity observed in the male was very similar to that of individuals of this species in the wild. In terms of the use of space, we observed homogeneity only in the male during the enrichment program. The 2 individuals responded in different ways to the structural enrichment.

We studied the behavioral responses of three brown bears (Ursus arctos) to different types of enrichment devices to assess the predominant pattern of animal–enrichment interaction (PAI) to each type of enrichment. We assessed the bears' responses to feeding, sensory, and occupational enrichments over nine sessions. Using Pearson's correlation (r) and the coefficient of variation (CV)—we describe four models of PAIs: habituation, increasing, continuous, and fluctuating. The habituation model (r < 0 and p < 0.05; CV (%) > 0) consists of a loss of interest in the device over time and it occurred with the occupational device. The increasing model (r > 0 and p < 0.05; CV (%) > 0) consists of a sustained interest in the device over time and it was not observed for any device of this study. The continuous model (0 > r > 0 and p > 0.05; CV (%) < 100) consists of a consistent and unchanging interaction over time and it occurred with the feeding enrichments used in this study. The fluctuating PAI (0 > r > 0 and p > 0.05; CV (%) ≥ 100) consists of wide oscillations in the degree of interaction over time and we observed this pattern with sensory devices. Review of previous literature supports these classes of PAI, and suggests similar relationships between PAIs and the type of enrichment as we observed in this study.