Enrichment reduces stereotypical behaviors and improves foraging development in rehabilitating Eastern Pacific Harbor Seals (Phoca vitulina richardii)

There is empirical support for the efficacy of enrichment in decreasing stereotypical behaviors and increasing naturalistic behaviors in laboratory, agricultural, and zoological settings. However, little research has been done on the possible value of enrichment in facilitating appropriate behavioral development of rescued wildlife in rehabilitative captivity. Eastern Pacific harbor seal pups (Phoca vitulina richardii) often strand on the west coast of California due to maternal separation or malnutrition and need to develop skills essential for reintroduction success while in rehabilitation. In the current study, we designated four enclosures at The Marine Mammal Center in Sausalito, CA, as enrichment or control. Behavioral data were collected on 32 pups in these enclosures throughout the 2016 stranding season (April – July). In three enrichment sessions per day, pups were exposed to stimuli that elicited behaviors related to foraging and exploration (e.g., diving, tactile investigation, locomotor coordination). Stereotypical behaviors (e.g., flipper-chewing, suckling) were recorded daily when no enrichment was present. Extent of interaction with enrichment, number of stereotypical behaviors, and number of days to independently forage (free-feed) were used to determine the efficacy of enrichment for stereotypy reduction and development of foraging skills. We found a positive relationship between number of stereotypical behaviors and days to free-feed such that the more stereotypical behaviors were expressed, the more days it took the pups to free-feed (p = 0.06). When exposed to enrichment, pups displayed a trend toward fewer stereotypical behaviors than pups in a standard (unenriched) environment (p = 0.09). There were no differences in number of days it took to free-feed between enrichment and control pups but there was a negative relationship between the extent of engagement with enrichment and number of days to free-feed that approached significance (p = 0.07). This pattern of strong statistical trends suggests that enrichment can be used to reduce stereotypical behaviors and encourage naturalistic behaviors in wildlife rehabilitation settings, promoting the likelihood that rehabilitated animals will succeed when reintroduced to the wild.