In 2011, the 837 ISIS zoos held a total of 3,955 exotic terrestrial vertebrate species. What that means is that the zoos that participate in the International Species Information System collectively housed 455,317 individual birds, mammals, reptiles, and amphibians in that year. A number that precise is available because zoos are excellent record-keepers, especially when it comes to the identity and parentage of the animals in their collections. Those are impressive numbers, but how do they speak to zoos’ potential role in wildlife conservation, something so often featured in their marketing and advertising campaigns?

Wildlife conservation requires a diversity of approaches, ranging from habitat protection and restoration for wild self-sustaining populations to managing other populations with at least some amount of consistent human intervention. Captive breeding programs have become an increasingly necessary component to wildlife conservation for many species. Such programs have often been criticized for their high costs, high time investment, possible genetic consequences related to inbreeding or hybridization, and for diverting resources from so-called in situ efforts, such as habitat protection. Still, several breeding programs have been enormously successful in recent years, such as for the Kihansi spray toad, or the whooping crane, both of which have resulted in release programs. “Differentiating between in situ and ex situ management is becoming irrelevant,” write biologist and demographer Dalia A. Conde and colleagues, since more and more captive breeding programs are instituted with the eventual goal of releasing a viable population of animals back into a suitable habitat.

There’s just one problem. Last week in the journal PLoS ONE, the researchers noted that zoo conservation efforts are too random. By investigating which endangered or threatened species are housed at each individual ISIS zoo, they found no discernable pattern or strategy. For example, threatened species were under-represented for some taxonomic orders, and over-represented for others. While birds represent more than half of all the species held in zoos, only 8% of those species are classified as threatened on the IUCN red list. On the other hand, the order Dasyuromorphia, which includes Australian carnivorous mammals like the Tasmanian devil, are over-represented among mammalian orders, with zoos housing individuals from half of the world’s threatened Dasyuromorph species.

Taken together, just under a quarter of all 3,955 species housed in ISIS zoos are classified as vulnerable, endangered, or critically endangered. As Conde writes, “for most of the taxonomic orders, our results show that representation of threatened species is not different from what would be expected if species were selected at random.” What this means is that zoos – as a group – are not necessarily implementing captive breeding programs in a strategic way.

One could argue that this phenomenon is the result of zoos designing their collections to bring the most visitors through the front gates; polar bears and African lions naturally draw larger crowds than “yet another hoofed brown creature with some kind of horns,” regardless of the conservation benefit derived from keeping those less charismatic species. But the problem actually goes deeper than that. There are legal barriers, for example, to the import and export of certain bird species, especially since awareness of the SARS epidemic has grown. And some species are notoriously difficult to breed in captive settings; everybody has heard of the panda problem, but seabirds are also known for this. Finally, not all zoos are equipped to provide for the highly specialized dietary requirements of some species, and it would therefore be unethical to include them in their collections.

Another problem is that those zoos that do run high-quality controlled breeding programs for any particular species are scattered across the globe, making oversight and movement of individual animals for breeding purposes more costly and time consuming, even when it isn’t made impossible by import/export restrictions. On that point, Conde says “zoos within a particular region can most efficiently increase their conservation contribution by developing collectively managed [captive breeding programs] devoted towards a smaller number of focal species.”

To that end, the researchers recommend that zoos, together with conservation NGOs and academic and governmental institutions, work to identify geographically linked “clusters” to focus on prioritized species. That would allow a single region to hold more individuals of a given species, creating larger, sustainable breeding populations. They also recommend redundancy: multiple breeding populations of a single focal species should be created within multiple clusters, to “minimize the potential impact of catastrophic events.”

Finally, they suggest that certain restrictions regarding the movement of animals across borders be loosened for conservation or breeding purposes, while not losing vigilance against the illegal wildlife trade or ignoring potential public health issues. As an example, they say that the Convention on International Trade in Endangered Species (CITES) could offer special permits to better facilitate the movement of individual animals across international borders.

Conde and colleagues are certainly not the first to identify the structural problems that face the global implementation of captive breeding programs in zoos. Organizations like the Association of Zoos and Aquariums (AZA) already administer programs like the Species Survival Plans and Taxon Advisory Groups, which begin to address some of those issues. It is perhaps easy to blame zoos for appealing to the bottom line by focusing their efforts on charismatic pandas and giraffes at the expense of making perhaps a bigger difference for few dozen endangered kinds of salamander. But as a group, members of the World Association of Zoos and Aquariums (WAZA) are the third largest financial supporters of in situ wildlife conservation, to the tune of $350 million each year. And that is only possible thanks to the throngs of visitors streaming past the ticket office to see the tigers and elephants.

Contrary to the rhetoric espoused by those who would see them shutter their gates, zoos have already successfully saved a number of species from extinction, “but it has been mostly opportunistic rather than strategic.” As our planet’s climate changes and even more species become imperiled, an increasingly strategic effort is warranted. Given their extensive specialized knowledge of the husbandry, behavior, and veterinary requirements of threatened species, zoos will continue to play a vital role in wildlife conservation. – Jason G. Goldman | 22 January 2014

Source: Conde D.A., Colchero F., Gusset M., Pearce-Kelly P., Byers O., Flesness N., Browne R.K. & Jones O.R. (2013). Zoos through the Lens of the IUCN Red List: A Global Metapopulation Approach to Support Conservation Breeding Programs., PLoS ONE, PMID: 24348999

Photo: Giant panda (Ailuropoda melanoleuca) photographed at the San Diego Zoo on November 20, 2011. Copyright Jason G. Goldman.