What happens when wild animals are provided with activities while they are recovering from illness or injury in a captive setting? Current UC Davis researcher Karli Chudeau, along with UC Davis alumni Dr. Shawn Johnson and Dr. Nancy Caine, set out to answer this question to better understand interventions that improve the welfare of seals while they are under temporary human care. Their recent paper illustrates that wild harbor seal pups (Phoca vitulina richardii) benefit from enrichment during their rehabilitation.

Enrichment is a term that describes activities or devices that aim to improve an animal’s physical and psychological health by decreasing abnormal behaviors and encouraging an animal to express their natural behaviors (e.g. hunting or nesting). Enrichment is commonly used in captive husbandry settings such as zoos and aquariums and is shown to have numerous health and behavioral benefits for both aquatic and terrestrial species. Yet, this is not a common practice in wildlife rehabilitation programs, that rescue and medically treat wild animals with the intent of release back into their wild environment. 

In the wild, animals use their sensory and problem-solving skills to navigate a dynamic environment, yet in captive environments opportunities to use those skills can be limited. Spending time in undynamic environments can lead to abnormal, repetitive behaviors and prevent the development of these important skills for wildlife. Chudeau equates this situation to being sick in a hospital room that has no books or games available. A person may become bored or anxious to be in the same room with nothing to do which may lead to developing “tics” such as biting fingernails or hair-twirling. Similar behaviors (a.k.a. stereotypical behaviors) can occur in animals in the form of repetitive pacing, scratching, or for young animals, non-nutritive suckling (which is essentially attempting to nurse on objects such as the pen floor or themselves). Understanding the effects of enrichment in harbor seal pups is especially important because these seals come into rehabilitation as young as 1-2 days old. This means that they spend a critical period of development in a foreign environment without comfort from their moms or guidance on how to hunt for fish. 

The authors were interested in whether enrichment decreased stereotypical behaviors that impede appropriate physical and behavioral development. They were also interested in whether enrichment improved the development of foraging behaviors (e.g. finding food) that will be essential for when they are released back into the wild. Harbor seal pups that lost their mothers and were malnourished were rescued from beaches along the California coast and brought to The Marine Mammal Center, the largest wildlife rehabilitation hospital in the world, for medical treatment. For the duration of their rehabilitation, they received normal veterinary and husbandry care and were either provided with different types of enrichment (enriched) or no enrichment devices (control). 

The authors observed how much each seal in the enriched or control environments expressed stereotypical behaviors and how quickly (i.e. number of days) they learned to eat fish without any assistance from rehabilitation staff. Using these data, they were able examine the relationships between stereotypical behaviors, eating fish, and interactions with enrichment. The results show that stereotypical behaviors influence how quickly the seals learned to eat fish, such that on average, the seals that expressed more stereotypical behaviors took longer to learn how to eat fish. When comparing the amount of stereotypical behaviors expressed in the enriched group and control group, results indicate that enrichment reduces those abnormal behaviors. However, it is not just the presence of enrichment that reduces stereotypical behaviors. The authors also found that the seals learned how to eat quicker the more they interacted with the enrichment. 

These results provide evidence that factors beyond physical health are important for the welfare of seals in rehabilitation. An understanding that abnormal behaviors can impede foraging development and how enrichment mitigates that issue has guided new husbandry protocols to include enrichment provisioning. Research building off of this unprecedented project aims to answer more questions about the role enrichment can play in the welfare and conservation of wild seals in order to learn how to prepare seals for release into the wild, not just physically, but behaviorally. 

For more information:

Chudeau, K.R.*, Johnson, S.P., & Caine, N.G. (2019). Enrichment reduces stereotypical behaviors and improves foraging development in rehabilitating Eastern Pacific Harbor Seals (Phoca vitulina richardii). Applied Animal Behaviour Science, 19, 104830. Link to article.

*Denotes ABGG and/or UC Davis affiliated authors.