Incorporating circadian and circannual rhythms into welfare assessments of zoo-housed animals

Abstract

Zoos must conduct thorough welfare assessments to determine how well animals in their care are faring, and also understand the many factors which affect particular welfare states, so they can make appropriate interventions if needed. However, comprehensive welfare assessments require a lot of time and resources and there is no standard welfare assessment across zoos. In addition, an overarching factor that is not thoroughly understood is the effect that zoo environments have on welfare. This is particularly important when considering circadian rhythms. Circadian rhythms are adaptive physiological and behavioural changes that follow a 24-hr cycle. They are regulated by predictable external cues like light and temperature, which may be different in a captive environment. In this thesis I aim to address these issues by first collaborating with the Royal Zoological Society of Scotland Edinburgh Zoo to make their welfare assessment tool more efficient and reliable. I addressed efficiency by analysing concordance between assessors and determining whether the number of assessors could be reduced without losing reliability. I addressed reliability further by developing an evidence-based protocol for responding to behavioural and environmental questions that incorporate the assessment of daily rhythms and enclosure use. To demonstrate the importance of incorporating full circadian and circannual rhythms into the assessment of welfare and how circadian rhythms can illuminate the effects of the zoo environment, I conducted a study on giant pandas housed in zoos around the world, observing behavioural cycles across one year. Results indicate that giant pandas have clear circadian and circannual behavioural rhythms that are associated with life stage and sex, regulated by light, temperature and zoo specific external cues, and affected by latitudinal location. Overall, this thesis provides information and evidence on how zoos can take a holistic, evidenced-based approach to understanding the needs of their animals to consequently improve welfare and conservation efforts.