Into the wild

Abstract

Staying true to her wild nature was Tatiana's downfall. In a story that made national news this past winter, police shot and killed a Siberian tiger after it escaped from its San Francisco Zoo enclosure, killed a teenaged boy, and then stalked and mauled two others. The tiger was allegedly taunted before she scrambled up a 12.5-foot-tall moat wall to pursue her tormenters. As it turns out, however, the problem for many captive-bred carnivores may not be too much wildness, but too little. A University of Exeter (UK), study has found that animals raised by humans and then released into the wild all too frequently fail to survive because they have grown too accustomed to sharing space with humans. More than 30 years after the movie Born free dramatized the efforts of a Kenyan couple, George and Joy Adamson, to teach a tame lioness to survive in the wild, zoos and other captive-breeding programs are wrestling with similar issues. But in contrast to the Adamson's success, most efforts seem to be failing. On average, only one in three captive-born carnivores survives for more than 6 months in the wild, says Kristen Jule, a doctoral candidate in psychology with a background in zoology, and the lead author of a review published online in the journal Biological Conservation (doi:10.1016/j.biocon.2007.11.007). Humans were responsible for most of the deaths in the 45 case studies reviewed, involving 17 carnivore species released since 1990. Most of the animals ended up being shot or hit by cars. Wild-caught, reintroduced animals were more likely to endure beyond the 3 to 6 months over which the animals were monitored. “The research isn't telling us anything that we didn't already suspect”, Jule wrote to me in an e-mail. “Individual projects have reported low survival rates of captive-born animals for decades, but there hasn't been a recent review that compiles this data and confirms it quantifiably.” To be sure, some human efforts to manage wildness have succeeded, despite great odds. A study last year in the journal Oryx (2007; 41: 205–14) gave high marks to recent introductions of lions and African wild dogs in South Africa. And, apart from carnivores, there are those famous, inspiring cases of the American bison and bald eagle, rescued from the brink of extinction and now reproducing in the wild. Zoologist John Aiken, director of conservation at the San Francisco Zoo, feels that the trend is more positive than Jule implied. “In the past 10 years, we've seen an increase in success in reintroduction programs, and I'm optimistic that we will develop good techniques for reintroducing most species.” Furthermore, Aiken cautions that reintroduction hasn't historically been the zoologist's primary goal; preserving genetic diversity has come first, especially as life in the wild becomes more precarious for many species, with humans crowding in on their territory. Even so, Aiken agrees with Jule's assessment that zoos and other captive-breeding programs clearly still need to work on their reintroduction strategies when it comes to large carnivores. If zoos are indeed serious about their pledges to support conservation, Jule advises, they should first make some hard decisions about the kinds of animals that are put on display. There's a raging debate about polar bears, for instance, since they seem to have a much harder time with confinement than other animals, pacing nervously back and forth in their grottos and sometimes butting their heads against stone or metal. (That debate reached its improbable peak last year, when an animal rights activist in Berlin reportedly called for the killing of a bear cub named Knut, which was rejected by its mother, on the grounds that raising it by hand would “humanize” it. The report led to a huge popular backlash, which the press dubbed “Knutmania”.) Apart from that, what would a good captive-breeding program look like? Jule says a recipe for success would include releasing animals before they spend more than three generations in captivity. Other guidelines center around minimal human contact –including keeping human scent off of food – and raising the animals in conditions as close to those of their natural environment as possible, with an option of surrogate parenting for rejected offspring like poor Knut. Ideally, the animals should also have opportunities to interact with other species, she recommends, to learn how to hunt and avoid conflict with predators. In the meantime, conservation idealists keep up the good fight. The Tigris Foundation is supporting programs in Russia and China to maintain the Amur leopard (estimated at just 40 survivors) in its natural environment. And the actors who played the Adamsons in Born free created a foundation that, among other things, is funding research on how to help lions survive in the wild.