Sunday, June 17, 2012

Re-wilding captive animals is a risky endeavour

I just read about Damien Aspinall's plans to reintroduce many of the Aspinall Zoo's animals, including gorillas, langurs, and gibbons, as well as Mark Bekoff recent blog post praising these efforts.

Quite honestly, I have some serious concerns about these reintroductions, and am appalled that a prominent ethologist is so uncritically supportive of these efforts.  The motivation is one I understand, although I do not agree with either Aspinall or Bekoff's perspective on the efficacy and ethics of zoos (both have a very negative view on zoos efficacy and ethics).

In theory, re-introductions sounds like a wonderful, beautiful idea.  Take animals whose ancestors were wrongly taken from their kin and native environment, and return them so that they can be wild again.  This is an idea that has inspired me from the very first time I watched Born Free, and when I became interested in primatology, the Golden Lion Tamarin project was my inspiration.

Because of my passion for reintroductions, I audited a course on Wildlife Reintroductions with Dr. Benjamin Beck, one of the foremost experts on the subject.  I read the literature on primate re-introductions, focusing on ape reintroductions, and eventually co-authored Best Practice Guidelines for Ape reintroduction.

And honestly, while I absolutely would love to see re-introduction programs succeed, they have very low success rates, and in many cases will be scary and traumatizing to the animals involved.  Re-introduction of birds and reptiles have higher success rates than mammals, and highly social mammals such as primates have some of the greatest obstacles and lowest chances of success.  The best candidates for re-introduction are usually wild-born sanctuary animals (who may have some memory and experience of the wild).  Individuals who have spent their whole lives in captivity, particularly those that are very human-oriented, are poor candidates for reintroduction.  Most re-introduced animals have short lifespans, are at risk for starvation, predation, and attack by wild members of their own species.  Furthermore, particularly with primates, and especially with great apes, there is a risk of spreading human-contracted diseases to wild populations.

Ultimately, while I do believe that carefully planned reintroductions can be successful, and in particular have value for increasing wild populations numbers if the introduced animals are able to live long enough to reproduce, I do not think it is a solution for individual animal welfare.  While the idea assuages the guilt that humans may have for the past atrocities of capturing wild animals, and of keeping their descendants caged/confined for human purposes, it may not be in the animals' best interests.  Particularly for human-oriented animals who have formed bonds with human caretakers, release into the wild, even in a soft release (a soft release is when animals are given post-release support and monitoring), is traumatizing, and in my opinion, may be downright cruel.

If you are further interested in this topic, I highly suggest reading the following:

Beck B, Walkup, K, Rodrigues, M, Unwin,, S, Travis, D, Stoinski T. 2007. Best Practice Guidelines for the Re-introduction of Great Apes. IUCN/SSC Primate Specialist Group, Gland, Switzerland.
Full PDF available at

IUCN (1998). Guidelines for Reintroductions. Prepared by the IUCN/SSC Reintroduction Specialist Group, IUCN, Gland, Switzerland and Campbridge, UK.

Also, if you are interested in my perspective on zoo goals and their efficacy, check out these previous posts:
Do Zoos Accomplish their Goals?
Zoo Goals: Conservation, Education, and Research
The Efficacy of Zoo Education: Empirical Evidence 


  1. from marc bekoff: as i mentioned in my post i realize they are risky but it's about time we try to free some animals from a life in captivity - like other reintroduction projects such as moving wolves back into Yellowstone there are risks (some wolves did die for the good of their species and some were injured) and we can only hope that these projects will be done with great care and that we'll learn from them for future endeavors ... we're always weighing relative harms and being in captivity is rather a large harm - many thanks for your comment ...

  2. I do think that in some case, re-introductions can be successfully done. However, I believe that they should be carefully planned and evaluated. My opinions here are largely the reaction to the idea of introducing zoo-born gorillas that have close-bonds with humans--that's just bad idea! However, I think if we are interested in improving the welfare of captive animals, there's a lot more we can do in improving the captive environment, and in some cases, this has far greatly potential to improve the lives of individual animals than re-introducing animals that are poor candidates for re-introduction.

    Furthermore, especially with primates, we need to consider the potential risks of introducing disease to wild individuals, and the dangers to humans living in release areas--great apes that aren't afraid of humans can be very dangerous!

  3. Great information! Thanks for sharing such informative post.