Born Free Foundation - Keep Wildlife in the Wild

Do Zoos Help Conservation?

Does captive breeding in zoos have a viable part to play in conservation? Chris Draper and David Jay investigate the science vs the ark principle.

Tigers in captivity: all about publicity, nothing about conservation - Photo © www.balkanpix.com
Tigers in captivity: all about publicity, nothing about conservation - Photo © www.balkanpix.com

One lauded justification for the keeping of wild animals in captivity is to ensure a secure population that could be used to return a species to the wild, should it ever become extinct. A few celebrated captive breeding and release projects are regularly cited to demonstrate the success of this kind of intervention, such as the Arabian oryx and the black-footed ferret of the plains of North America. However, closer inspection reveals that the effectiveness of these and many other captive breeding programmes is, at best, limited.

Relying on captive populations lulls us into a false sense of security, drawing attention away from threats to wild populations and habitats which, if not protected, could be destroyed leaving no viable location for return. The substantial costs of captive breeding could be used more effectively to protect these wild species and habitats. Many high-profile captive breeding and release projects were only initiated when wild populations were very low – if in situ1 protection had been prioritised they would not have been necessary. Indeed the ‘Rio’ Convention on Biological Diversity states captive breeding should be ‘predominantly for the purpose of complementing in situ measures’.

Captive breeding is only attempted with relatively few individuals, leading to potential issues with inbreeding – the development of hereditary problems due to a limited gene pool. In addition, such breeding removes the challenges animals face in the wild, quickly leading to genetic changes that may make individuals less able to survive in the wild. For example, captive populations of red junglefowl (wild ancestors of chickens) differ significantly in response to predators after just a handful of generations in captivity. Animals that respond badly to captivity may be less likely to breed, even though they may be best adapted for wild conditions.

Photo (c) US Fish and Wildlife Service
Most reintroduced black-footed ferrets were bred in dedicated facilities not zoos - Photo (c) US Fish and Wildlife Service

The best release successes have been with wild-born animals. A recent review of 45 carnivore reintroductions found wild-caught individuals were more likely to survive than those born in captivity. The closest captive breeding can come to this is to breed in genuine natural habitat enclosures within natural range. Even so, geographical knowledge of the best places to find food, water or shelter, shown to be critical to the survival of elephant families, for example, cannot be transferred in captivity. Pre-release training, where individuals are exposed to simulated predators, food sources or other stimuli, is a poor substitute for growing up in
the wild.

Oryx reintroductions have not achieved long term success - Photo Wikimedia Commons

Many disease-related problems can also arise. Animals not exposed for generations to diseases found in the wild may have reduced resistance to them. Released animals can also carry diseases into the wild population, as recently discovered following a release of Mallorcan midwife toads. Many captive Arabian oryx were found to have tuberculosis which could have proved disastrous if they had been released to the wild. Hundreds of captive-bred black-footed ferrets died from disease after release.

Looking at the conservation science of captive breeding a clear picture emerges. The best animals for restocking wild populations are those from highly endangered species born in the wild (or, failing that, to wild-born parents), and kept in their natural habitat and social groups. The worst candidates are those species not in immediate threat of extinction, bred for generations in captivity, in environmental conditions very different from their natural habitat, especially those subjected to frequent relocation (which disrupts social grouping). Unfortunately these are precisely the animals produced in the main by the international zoo community – the alleged ‘ark’ for the preservation of species.

Many of the high-profile ‘successes’ of captive breeding and reintroduction have involved animals bred at specialised centres not open to the public, rather than in zoos. Is one of the main reasons zoos undertake captive breeding programmes actually nothing to do with conservation? Do they simply provide more animals for the zoo industry?

Conservation in action?

Some captive-bred species ‘successfully’ reintroduced to the wild by UK zoos:

  • Partula snail
  • British field cricket
  • Przewalski horse

Some captive-bred species never successfully reintroduced to the wild by UK zoos:

  • Tiger
  • Elephant
  • Chimpanzee

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