The role of environmental enrichment in the behaviour and welfare of rehabilitating harbour seal (Phoca vitulina) pups

Environmental enrichment is widely used to promote animal welfare in captive animals. However, research on this application in marine mammals, particularly during rehabilitation, remains limited. This study investigated behavioural responses to environmental enrichment in rehabilitating harbour seals (Phoca vitulina) admitted as pups for rehabilitation at the Wadden Sea World Heritage Centre (WEC). Behavioural observations were conducted using 20-minute video recordings under enrichment and control conditions. Four harbour seals were included in the analysis, three group-housed and one individually housed, with three control and three enrichment observations analysed for each individual. Behavioural time budgets were calculated and grouped into Active, Inactive and Enrichment categories. Swimming pattern and the social context of enrichment interaction were also examined. Behavioural responses varied considerably between individuals and observations. Low or absent enrichment interaction was frequently observed when inactive behaviour, particularly resting in water, predominated. However, this pattern was not consistent across all individuals. One individual showed high activity during enrichment observations despite relatively limited direct enrichment interaction and was the only seal in which patterned swimming was recorded. Enrichment interaction also varied between repeated observations and did not show a consistent increase over time. Overall, these results highlight individual variation in behavioural responses to enrichment, suggest that social context may be relevant to enrichment engagement and indicate that direct interaction alone may not fully represent the animals’ responses to enrichment.