Establishment and Implementation of an Animal Welfare Decision Tree to Evaluate the Welfare of Zoo Animals

During the last few decades, zoos and aquaria have made great improvements in their exhibit designs, feeding routines, social housing conditions, mixed species presentations, and environmental enrichment, as well as in the prevention of infectious and parasitic diseases, to enhance animal welfare. To monitor the effectiveness of all these changes, animal welfare science is needed. It is important to evaluate animal response by applying welfare metrics that include behaviour and/or physiology. To get a state-of-the-art overview of animal welfare metrics, Zoo Nuremberg organized a workshop in May 2016, inviting scientists from different disciplines. The workshop dealt with the challenges we face in developing and applying animal welfare indicators for zoo and aquarium animal species and clearly emphasized the need to assess the welfare of these animals. It was shown that animal welfare is science, and many scientific methods are available to assess welfare objectively at the species level, at least for some vertebrate species. However, it remains a challenge to apply different scientific methods for assessment of the broad species collection(s) of zoological parks and the huge number of individuals. The discussion also revealed that the assessment of animal welfare is a topic of much debate due to the complexity and practical implications of the evaluation. As a result, a written report was produced, Assessment of Welfare of Marine Mammal Species in Zoological Parks (Zoo Nuremburg, 2016), and a proposal for an animal welfare Decision Tree was created. The Decision Tree includes four different steps, involving keepers, veterinarians, biologists, and animal welfare inspectors: 1st Step: Survey - including life history, health protocol and nutrition plan, physical environment, animal management, and behavioural support system 2nd Step: Theoretical Analysis - including data analysis, data correlation, data evaluation, and preliminary report 3rd Step: In Situ Inspection - including verification of protocol application, and verification of management, observations, and hormonal analysis 4th Step: Conclusive Report - about the welfare state of the animals This Decision Tree and its applicability were tested for two species at Zoo Nuremberg: (1) the bottlenose dolphin (Tursiops truncatus) and (2) the Antillean manatee (Trichechus manatus manatus). The results of the practical application of the evaluation are described in this article.