Abstract

The value of animal enrichment programs in reducing stereotypical behaviors, reducing stress, and encouraging natural behaviors in managed care settings has been demonstrated in a number of species, including marine mammals.^1–3 However, there is limited information about how these enrichment programs might be useful and successfully implemented at marine mammal wildlife rehabilitation facilities. A recent study in stranded harbor seal pups found enrichment can be used to encourage naturalistic behaviors and reduce stereotypical behaviors during rehabilitation, supporting the premise that providing enrichment to wild pinnipeds may increase post-release success in the wild.⁴

Marine mammal strandings and rehabilitation on the west coast of the United States are dominated by pinniped species, including California sea lions (Californianus zalophus) and Northern elephant seals (Mirounga angustirostrus). Most are pups or yearlings, who strand primarily due to maternal separation, malnutrition, trauma, fisheries interactions/entanglements, and/or illness. These young pinnipeds are at a crucial stage of cognitive development and can easily habituate to humans without proper precautions. Additionally, if their environment does not provide diverse opportunities to hone natural behaviors stereotypies can occur, which are adverse to the animal’s reintroduction into the wild.

During the 2021 stranding season the Pacific Marine Mammal Center incorporated and assessed an environmental enrichment program with stranded California sea lion pups (n=7) and Northern elephant seal weanlings (n=8) to determine the efficacy of environmental enrichment devices (EEDs) in reducing stereotypical behavior and decrease risk of habituation. Three enrichment devices were compared (Horse Kong, Wubba Kong, artificial kelp) as well as a control session (no enrichment). Behavioral data was recorded over the course of 9 enrichment sessions per animal, as well as 9 sessions when no enrichment was present (control). An ethogram was developed to document the amount of time interacting with enrichment, engaging in stereotypical behavior, engaging in natural behavior or how often the animals were looking at caretakers working in the area (parameter used for measuring risk of habituation) during each 30-minute session.

The most significant result was when enrichment items were present, sea lion pups and elephant seal weanlings spent significantly less time looking at caretakers. By reducing the time wild patients are looking at caretakers, the risk of habituation during rehabilitation may decrease. Next, three of the sea lions that displayed stereotypical behaviors, including suckling on self or others, circle/pattern swimming, sliding in and out of the water, or logging in water, had a significant reduction in these behaviors when any EED was present. Lastly, all three EEDs were safe, and both species showed a significant interest in the enrichment with a preference for the Horse Kong and Wubba Kong, followed by the artificial kelp.

These findings support that EEDs are safe and effective tools for decreasing stress and stereotypical behavior in young sea lion and elephant seal patients during their time in rehabilitation. Incorporating enrichment programs into marine mammal rehabilitation settings may not only increase animal welfare, but also could contribute to their improved success upon reintroduction to the wild.

Acknowledgements

The authors would like to thank the Pacific Marine Mammal Center Animal Care Staff and Volunteers for their continuous care of the rehabilitation patients and participation in this study. The authors would like to thank KongZoo (KongZoo.com) for their support in conducting this study and providing the EEDs employed with the animals. Last, but not least, we would like to thank our flippered friends who bravely tested the waters with, and so thoroughly enjoyed the EEDs.

Literature Cited

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2.  Shepherdson D, Lewis KD, Carlstead K, Bauman J, Perrin N. 2013. Individual and environmental factors associated with stereotypic behavior and fecal glucocorticoid metabolite levels in zoo housed polar bears. Applied Animal Behaviour Science, 147(3–4): 268–277.

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4.  Chudeau KR, Johnson SP Caine NG. 2019. Enrichment reduces stereotypical behaviors and improves foraging development in rehabilitating Eastern Pacific Harbor Seals (Phoca vitulina richardii). Appl. Anim. Behav. Sci. 219.