Wednesday, 26 June 2013

More than life and death, part I: using measures of animal stress to monitor the success of reintroductions

As a plant ecologist, I find some of animal-specific issues in conservation translocations are particularly interesting and relevant to my current work writing a code and best practice guidance for undertaking conservation translocations in Scotland.  The implications of moving animals can affect their welfare and ultimately make or break a reintroduction (or other translocation) attempt.  In a paper I've recently read, David Jachowski and his co-authors (2013) look at elephant stress indicators (fecal glucocorticoid metabolites concentrations) in South Africa and demonstrate that an elevated physiological state, indicative of high stress, can take up to 25 years ameliorate. What was striking was the decrease in the coefficient of variation in this relationship which reduced by about half in a reintroduction that had taken place 24 years prior compared to one that had been undertaken the year before the study commenced. Effectively, this tells us that elephants might be subject to very high levels of stress immediately after release, whilst other individuals show levels of stress which are not so different to elephants that have not been moved.  Elephants are complex animals - behavioural, social and physiological cues can all contribute to whether an individual shows signs of stress, so it isn't surprising to see a big range of stress responses in a study such as this one which looks retrospectively at reintroductions in five separate locations.  The authors suggest that some causes of stress such as seasonal pressures from lack of food and higher temperatures, are out of the control of reserve managers, however human interaction, principally with tourists, can be reduced by providing refuge areas away from roads and developments and from which tourists are prevented from entering.

Given that elephants are such long-lived animals, we might expect that physical acclimatization will take a long time post-release. But what about other animals? A systematic review of animal reintroductions* by Lauren Harrington and her co-authors categorised the reported results according to measures that could be interpreted as welfare indicators, either directly or indirectly. The projects reviewed were mainly focused on mammals and birds (89% of 199 studies). Unsurprisingly, more than 70% reported survival rates, and reproduction was reported in 52%, dispersal in 42% home range establishment in 39% and population size in 36% of the projects reviewed. But to me, these measures give a very limited insight into the welfare implications of translocating animals. For example, Jachowski et al (2013) report that high stress in elephants causes incredibly aggressive behaviouir which can affect the survival of other species including humans. Harrington et al 's review revealed that only three studies (2%) incorporated physiological measures of stress similar to that used by Jachowski et al (2013). The review also showed that animal welfare during translocation was more than closely monitored than similar welfare indicators post-release (26% versus 14% respectively).

So when I'm recommending monitoring of animals post-release, what should this plant ecologist say? I'm very aware that it's easy to make demands on translocation practitioners from the comfort of my office but in reality, would stringent requirements to monitor stress indicators put people off undertaking conservation translocations? My current feeling is that all proposals for future animal translocations should incorporate plans to monitor stress indicators. The example of elephants killing people and other large animals (in one case >100 white rhinoceroses) may be an extreme one but effectively illustrates that just because translocated animals have survived, doesn't mean we can call the reintroduction a success.

* Although the authors refer to reintroductions in the title, the review actually encompasses various types of conservation translocation.

Harrington, L. A., Moehrenschlager, A., Gelling, M., Atkinson, R. P. D., Hughes, J., & Macdonald, D. W. (2013). Conflicting and Complementary Ethics of Animal Welfare Considerations in Reintroductions. Conservation Biology, n/a–n/a. doi:10.1111/cobi.12021

Jachowski, D. S., Slotow, R., & Millspaugh, J. J. (2013). Delayed physiological acclimatization by African elephants following reintroduction. Animal Conservation, n/a–n/a. doi:10.1111/acv.12031

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