The captive environment is often barren, predictable and under-stimulating so that the behavioural needs of animals in captivity may be thwarted. The welfare of animals may be compromised, which can result in the expression of abnormal behaviours. Stereotypic behaviours, such as the circling or pacing behaviour observed in captive pinnipeds, may become apparent. A simple, cheap and effective method of adding complexity to a captive environment is the use of environmental enrichment techniques. A number of enrichment devices were used in this study, focusing primarily on occupying more time in feeding/foraging behaviours of common seals, Phoca vitulina. The performance of stereotypic circling behaviour was significantly reduced during the enrichment period, suggesting it had improved the welfare of all the animals in this study.

Common seals Phoca vitulina give birth in the Wadden Sea area during the summer months. We provide evidence that the pupping season has advanced in date in this region. Analysis of stranding dates of recently-born, orphaned pups admitted for rehabilitation, revealed a shift of, on average, 0.88 days per year over the period 1974–2008, yielding a total advance of 26 days. Although the pupping season has become progressively earlier, there were no indications of any negative impact on the weight of the pups, nor was there an increase in the proportion of seals with a lanugo coat. These observations suggest that the most likely explanation for the change in phenology of the pupping season is a corresponding change in the timing of cessation of the period of delayed implantation. It is suggested that shifts in phenology could reflect an adaptive response of the animals to altered local circumstances. The latter may in turn be induced by larger scale phenomena such as food availability or climate change.