It was the first day of my first conference, and I was flitting somewhat aimlessly from session to session, really going wherever the wind blew me. It just so happened to blow me into a meeting of the ungulate working group (ungulates being hoofed mammals), when a speaker came up the podium and made an announcement. Earlier that day, a small herd of scimitar-horned oryx, a beautiful desert antelope once found across northern Africa, was transferred from a breeding facility in the Middle East to a compound in Chad. There, they would eventually be transitioned into larger and larger paddocks, until finally they were truly wild. The species is currently classified as Extinct in the Wild. That designation may be able to change someday.
The room went nuts.
Zoos and aquariums like to think of themselves as "the modern arks", sheltering animals from the ravages of a human-dominated world - habitat loss, invasive species, overhunting, pollution, etc. The thing is, an ark-ride isn't supposed to last forever. For some of our animals, it looks like an existence in captivity might be permanent. Sometimes, however, we can snatch one species back from the reaper and actually restore it to its true habitat - the wild.
Sometimes wild animals are moved from one location to another. This is what happened in Yellowstone National Park in the US, where wild grey wolves were captured in one habitat and released in another. It's easy, in a way, because the wolves in question already knew how to survive in the wild because they were, in fact, wild. This is not always possible, however, because it depends on their already being an existing wild population that is large enough for you to siphon off animals to release somewhere else without compromising the first population. A second option is headstarting, which has been discussed earlier this month. The third option - the most controversial, the most challenging, and in general the last-ditch effort - is the release of captive-bred animals back into the wild.
Horse Querida, born in Prague Zoo in 2012, jumped out of her transport crate upon arrival at the nature reserve. Read more about the Mongolian wild horse reintroduction program - and see more pictures - here.
Reintroduction into the wild is one of the greatest ambitions of zookeeping. Like any great ambition, it is easier said that done. First of all, you have to have a sustainable captive populations, large enough and genetically healthy enough to serve as an engine that produces the offspring you will use for reintroduction. This is essential. It does no good to put your entire breeding stock out in the wild and loose them all - then you have nothing to start over again with. The Sumatran rhino is teetering on the edge of extinction. Before any reintroduction can even be contemplated, the first step is trying to build a breeding population. So far, success has been very limited.
Secondly, you must have a place suitable for reintroductions to occur. "The Wild" isn't that wild anymore, and there are very few places where animals can live in a landscape that isn't completely shaped by humans. Ideally, you would know and understand what factors lead to your species becoming imperiled and then correct those before reintroducing. Reintroducing zoo-born Guam rails into the middle of Guam, for instance, is basically a form of very-expensive, government-subsidized feeding of brown tree snakes. Until the invasive snakes are under control, there's no reason to release the birds there. The same would be the case in the face of excessive hunting, or if there is no remaining habitat to reintroduce animals to.
Thirdly, animals must be prepared for a life back in the wild... usually. Some species, especially reptiles, amphibians, fish, and invertebrates, have a lot of behavior hard-wired as instinct. Many reintroduction programs are carried out with these species for that reason. Mammals and birds, however, often undergo lots of learning and social development. Thick-billed parrots, for example, were bred in captivity and released in the Sky Islands of the Southwestern US. That program proved unsuccessful. Some birds failed to learn how to utilize wild food sources. Others became easy prey for goshawks, having failed to learn adequate predator evasion skills from parents.
Fourthly, the program must be monitored carefully and evaluated, especially as to the survivorship of the released animals. Program leaders need to how many individuals are surviving, what animals are dying of (and there is always a steep mortality rate), and what factors can be used to improve future success. Sometimes, that means knowing when to pull the plug of a reintroduction program. You can release one million Panamanian golden frogs in the cloud forests of Panama, but if every single one succumbs to disease one week later, you might as well have euthanized them yourself and saved yourself the trouble.
Fifthly and finally, a program can only last if it is sustainable. Some reintroduction programs, such as that of the black-footed ferret and that of the California condor, are starting to get there, as the wild population is growing, though augmented still with the releases of captive-born animals. Sustainability isn't just an issue of population genetics and demographics - it's also about people. The most successful programs are those that have the support of the local people behind them. The red wolf reintroduction program in North Carolina was doing fine at first, largely because biologists cultivated positive relationships with the local people to build goodwill towards the program. In recent years, hostility has broken out towards the wolves, and now the future of that program is in serious doubt.
There are a lot easier ways to save an endangered species than captive breeding for reintroduction. Easiest of all is don't let the species become endangered in the first place. Or you can protect the habitat. Or stop poaching, or the spread of invasive species. You could translocate wild animals from one population to start a new one. In some cases, you can headstart.
Release of captive-born animals into the wild is a major challenge. It's one of those things that makes me bang my head on the wall whenever I hear snooty animal rights activists demand that animals be released into the wild. It's not just opening a cage door and letting the animal be "free." To do so often subjects the unlucky animal to a life of hunger, anguish, and terror in an unfamiliar world - the good news, of course, is that life is apt to be very short. Don't take my word for it, ask Keiko.
Reintroduction takes lots of patience, organization, training, and, in many cases, sacrifice. It can stress animals almost to the breaking point, and there is no guarantee of success. The animal welfare implications are enormous, and as such, it should only be employed as a strategy when the conservation benefit outweighs the cost of the hardship the animals will have to undergo. It's not pretty to see an animal that's been cared for all of its life have to make it on its own. In some cases, though, it's the only way to save a species.
As more and more species fade away in the wild, it may become an option that we have to rely upon more and more in the years to come.