Learning strategies and long-term memory in Asian short-clawed otters (Aonyx cinereus)

Abstract

Social learning, where information is acquired from others, is taxonomically widespread. There is growing evidence that animals selectively employ ‘social learning strategies', which determine e.g. when to copy others instead of learning asocially and whom to copy. Furthermore, once animals have acquired new information, e.g. regarding profitable resources, it is beneficial for them to commit it to long-term memory (LTM), especially if it allows access to profitable resources in the future. Research into social learning strategies and LTM has covered a wide range of taxa. However, otters (subfamily Lutrinae), popular in zoos due to their social nature and playfulness, remained neglected until a recent study provided evidence of social learning in captive smooth-coated otters ( Lutrogale perspicillata ), but not in Asian short-clawed otters ( Aonyx cinereus ). We investigated Asian short-clawed otters' learning strategies and LTM performance in a foraging context. We presented novel extractive foraging tasks twice to captive family groups and used network-based diffusion analysis to provide evidence of a capacity for social learning and LTM in this species. A major cause of wild Asian short-clawed otter declines is prey scarcity. Furthering our understanding of how they learn about and remember novel food sources could inform key conservation strategies.

Captive Asian short-clawed otters ( Aonyx cinereus ) learn to exploit unfamiliar natural prey

“…Due to a reduction in their wild prey brought about by overfishing, pollution and habitat loss [ 52 , 55 , 56 ], Asian short-clawed otter populations are decreasing in the wild, and they are classified as ‘Vulnerable’ on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species [ 52 ]. Furthering our understanding of otter foraging behaviour may help inform conservation action in the future [ 57 ]. In particular, detailed information on how otters learn extractive foraging skills vital for their survival in the wild could be used to develop pre-release training procedures as part of species reintroduction programmes [ 57 – 59 ].…”

“…Here, we investigated how two groups of captive Asian short-clawed otters, which had little to no prior experience of their natural prey, learned to recognize and overcome the extractive foraging challenges presented by three different unfamiliar natural prey types. We then combined these data with data collected when we previously presented the same otters with novel artificial food puzzles that were baited with their regular food [ 57 ]. This allowed us to compare the time it took these otters to overcome mechanistically novel extractive foraging challenges, when the food within was familiar (i.e.…”

“…asocial) learning, and learning by observing the behaviours of others (i.e. social learning; [ 57 ]). We therefore predicted that (i) they would do the same here when learning to both interact with, and extract meat from, the natural prey items.…”

“…Our previous study also indicated that otters relied more on social information when learning to interact with puzzles than when extracting the food rewards. These results suggest that otters' unfamiliarity with the puzzle boxes may have led them to look for guidance from their group mates when deciding to interact with them [ 57 ]. Then, once they had started to interact with the puzzle boxes, they recognized the food rewards inside and learned to extract them mainly asocially [ 57 ].…”

“…These results suggest that otters' unfamiliarity with the puzzle boxes may have led them to look for guidance from their group mates when deciding to interact with them [ 57 ]. Then, once they had started to interact with the puzzle boxes, they recognized the food rewards inside and learned to extract them mainly asocially [ 57 ]. Due to their unfamiliarity with both the palatability and the physical protective measures of the natural prey presented here, we predicted that (ii) the captive otters would rely on social learning to a similar extent when learning to interact with, and extract meat from, natural prey items.…”