The drivers and functions of rock juggling in otters

This is the final version. Available on open access from the Royal Society via the DOI in this recordData accessibility: Data and code for rock juggling frequency, hunger and food puzzles can be accessed through the Dryad Digital Repository: https://doi.org/10.5061/dryad.rn8pk0p64. Tables of post hoc test results for puzzle order have been uploaded as part of the electronic supplementary material.Object play refers to the seemingly non-functional manipulation of inanimate items when in a relaxed state. In juveniles, object play may help develop skills to aid survival. However, why adults show object play remains poorly understood. We studied potential drivers and functions of the well-known object play behaviour of rock juggling in Asian small-clawed (Aonyx cinereus) and smooth-coated (Lutrogale perspicillata) otters. These are closely related species, but Asian small-clawed otters perform extractive foraging movements to exploit crabs and shellfish while smooth-coated otters forage on fish. We thus predicted that frequent rock jugglers might be better at solving extractive foraging puzzles in the first species, but not the latter. We also assessed whether species, age, sex and hunger correlated with rock juggling frequency. We found that juvenile and senior otters juggled more than adults. However, rock juggling frequency did not differ between species or sexes. Otters juggled more when ‘hungry’, but frequent jugglers did not solve food puzzles faster. Our results suggest that rock juggling may be a misdirected behaviour when hungry and may facilitate juveniles’ motor development, but it appears unrelated to foraging skills. We suggest future studies to reveal the ontogeny, evolution and welfare implications of this object play behaviour.Royal Societ

Effect of visitors on the behaviour of three Asian small‐clawed otters Aonyx cinereus

The Asian small‐clawed otter Aonyx cinereus is classified as Vulnerable by the International Union for Conservation of Nature Red List. The aim of this study was to evaluate the effects of the presence of visitors on the behavioural repertoire of three Asian small‐clawed otters at Cattolica Aquarium, Italy. Observational data sampling took place over two periods of 11 days each. The first period was in August when the Aquarium was open and there were visitors present (open period = OP). The second period was between September and October, on days when the Aquarium was closed to visitors (closed period = CP). Focal sampling was integrated with behaviour sampling during data collection. To evaluate the significant differences in frequency and duration of behaviours during the OP and CP periods, a Wilcoxon Signed Rank test was performed. The results of this study showed that the absence of visitors stimulated significant differences in frequency and duration of activity (such as ‘locomotion’ and ‘waiting’) and social behaviours (such as ‘play’). The otters also spent significantly more time visible than ‘out of sight’ when there were no visitors present. This preliminary research provides information that may influence the way zoos and aquatic parks manage their otters, and contributes to the improvement of the welfare of animals in human care