Sources of Eustress in Captivity

Historically, zoo welfare research has centered on identifying and mitigating sources of distress. Increasing recognition of the importance of positive welfare, however, has prompted a re-evaluation of how managed environments can also create beneficial experiences that enhance wellbeing. "Eustress"-stress that arises from biologically relevant and manageable challenge-can emerge from cognitive, social, environmental, and husbandry-related opportunities that foster curiosity, agency, and positive behavioral diversity. Drawing on parallels between naturally occurring challenges in the wild and their managed counterparts, this article considers how zoos and aquariums might intentionally design environments and husbandry practices to promote eustress through enrichment, training, environmental novelty, and social opportunities. The article discusses both the potential and the limitations of this approach, acknowledging the methodological and ethical challenges of distinguishing eustress from frustration, and the importance of species-specific evaluation and individual understanding. Rather than presenting a definitive catalog of all possible methods, the ideas outlined are intended to spark reflection and debate on how eustress may be identified, facilitated, and evidenced in captivity. By moving beyond paradigms of simply reducing negative stressors, I suggest that zoos can shift toward actively promoting positive experiences as a cornerstone of contemporary animal management. In doing so, well-designed environments and species-appropriate, evidence-based husbandry will not only prevent suffering but also maximize the opportunities available for animals to thrive.