Documenting Aggression, Dominance and the Impacts of Visitor Interaction on Galápagos Tortoises (Chelonoidis nigra) in a Zoo Setting

SIMPLE SUMMARY: Understanding the mechanisms by which welfare can be optimised in zoos is essential for improving standards of animal care. Using scan-sampling methods, assessments of group hierarchy and direct observations, the behaviour of Galápagos tortoises (Chelonoidis nigra) was assessed in relation to public interaction. We observed that head movements and height were of importance in aggressive interactions. We found that the presence of, and type of, visitors (keepers, vets or public) within the enclosure influenced behaviour in this species, with increasing levels of aggression and activity. We suggest that when visitors initiate finching, a behaviour in which a tortoise will stretch its body upwards to allow birds to remove ectoparasite in the wild, they negatively influence tortoise welfare. We suggest that careful management of public interaction with this species can improve welfare. ABSTRACT: Ensuring high levels of welfare is imperative for modern zoos, but such organisations must also engage visitors in order to successfully spread awareness and raise conservation funds. It is therefore important to understand the responses of animals to visitor interaction to optimise welfare. Often, the opportunity to interact with humans may be enriching for animals, but in other contexts, this interaction may have negative welfare effects. We observed captive female Galápagos giant tortoises (Chelonoidis nigra) to describe aggressive interactions, characterize hierarchy using Elo ratings and assess the impact of visitor interactions. Elo ratings indicated that one individual was dominant over two equally ranked subordinates; aggressive interactions are discussed in this context. We detected significant effects of the presence of visitors and visitor type (keepers, vets or public) within the enclosure on aggression and activity. We suggest that previous miscategorisation of a natural behaviour (the finch response) as an operantly conditioned behaviour, rather than a fixed action pattern, may have triggered aggression. We then document changes made to the management of the animals to mitigate the impacts discovered. This work highlights the importance of empirical evidence in determining optimal management strategies for zoo animals with regards to public interactions and animal welfare.