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Assessing the welfare of captive male giraffes in a bachelor herd using behavioural and hormonal analysis

As biodiversity continues to decline, zoos play an essential role in ex-situ species conservation. An animal’s ability to feel pain and pleasure drives the need to ensure zoos maintain high animal welfare standards. This thesis aimed to assess the welfare of four male giraffes housed in a bachelor herd at Hamilton Zoo due to concerns about some individuals’ social and stereotypical behaviour. This aim was achieved using non-invasive behavioural observations and faecal cortisol metabolite (FCM) analysis. Behavioural observations and the collection of faecal samples occurred over 12 weeks. Behavioural analysis investigated the giraffes’ social dynamic, stereotypical behaviour, and enrichment engagement. Faecal cortisol metabolite analysis investigated how each giraffe’s behaviour correlated to their stress levels. Faecal cortisol metabolite analysis also included three giraffes housed in another bachelor herd at Gibbs Farm to identify if the giraffes at each institution experienced similar welfare concerns. At Hamilton Zoo, the giraffes’ social dynamic was influenced by a hierarchy. The hierarchy was similar to that displayed by wild males and likely reduced social conflict. The expression of same-sex sexual behaviour such as following and investigating also influenced the giraffes’ social dynamic. All four giraffes expressed oral stereotypes with the underlying cause likely feeding motivation. One giraffe displayed pacing stereotypes more frequently than the others. Pacing occurred more regularly before movement to the day enclosure, and there was a positive correlation between pacing and being followed by another giraffe. Therefore, pacing likely occurred due to anticipation or social stress associated with being followed. Foraging enrichment had little impact on the giraffes’ behaviour. In the wild, subordinate males often experience higher FCM levels. However, the subordinate males at Hamilton Zoo did not experience the highest FCM levels. In comparison, the subordinate male at Gibbs Farm did exhibit the highest FCM levels. These variations may be due to the different herd and enclosure sizes at each institution. The expression of pacing stereotypes did not correlate with elevated FCM levels suggesting that stress may not be the underlying cause of that behaviour. Interestingly, the dominant male at Hamilton Zoo displayed the highest FCM levels. These FCM levels were likely due to pain associated with his hoof-related health issues. Foraging enrichment did reduce one giraffe’s FCM levels, but additional data would be needed to draw more definite conclusions about this. Behavioural observations and FCM analysis often provided contrasting results about the giraffes’ welfare at Hamilton Zoo. Contrasting results are not uncommon and they often spark conflict over what defines optimal welfare and what assessment methods are valid. Perhaps the best welfare assessments will be achieved when scientists consider all views and use multiple assessment methods in conjunction. Hamilton Zoo can use the findings from this thesis to guide its husbandry routines to ensure they support each giraffe’s welfare needs. High welfare standards will enable zoos to act as ethical arks that spark a passion for conservation in their community.
Type of thesis
The University of Waikato
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