Do wild animals that attack people need to die?

The justice meted out to animal attackers varies by jurisdiction and species. But the default is to err on the side of human safety. Photo / Washington Post

A marathon runner who was mauled by a bear in New Mexico at the weekend thought quickly, played dead and escaped injured, but alive.

The female bear, which wildlife officials said was with her cubs when she was surprised by the runner, was captured and put to death.

New Mexico officials said they were "confident" they had the right bear, which wore a radio collar, and noted with regret that state law requires them to euthanise and test for rabies any wild animal that attacks or bites a person, no matter the circumstances.

The bear's death was decried by some observers as an unjust sentence for an animal that may have been acting defensively. And it was the latest such killing to highlight the common reaction to most of the very rare attacks by wild animals on people in the United States: Capital punishment for the animal, and sometimes even for animals located nearby.

After a mountain lion pounced on a child in his Colorado yard last weekend, officials captured and killed two lions, saying it it is their policy to kill wild animals that may have been involved in an attack on humans.

Last week, after an alligator dragged a toddler into a lagoon in Orlando, wildlife authorities trapped and killed at least six of the reptiles.

Leaving them at tourist-filled Disney World certainly wouldn't make sense, and Florida says it typically doesn't relocate "nuisance alligators" - large ones "believed to pose a threat" to people, pets or property - because there are so many that killing individuals doesn't affect the species' population.

The justice system for wild animal attackers varies across jurisdictions, and sometimes by species. But there's no Innocence Project for animals, and generally no trials (though some national parks have approaches that amount to something like that). Instead, the prevailing idea, experts say, is that human safety is paramount, and if a wild animal attacks once, it might do it again.

How do we know that? There's not a lot of statistical support, but experts say the anecdotal evidence is pretty strong. To consider it, it helps to put attacking animals in two broad categories: The so-called "maneaters" that seek out humans as prey, and those that attack for other reasons, when they find themselves in the same area as people.

Alligators lie on grass near fresh water at Paynes Prairie Preserve State Park, in Gainesville, Florida. Photo / AP

History books and newspaper archives contain plenty of stories about serial "maneaters" that have gotten a "taste for blood". But there's no research to back that up, for a decent reason: To test whether an animal that preyed on a human is likely to repeat the behaviour, you'd have to wait to see if it attacks a person again.

"It wouldn't be a study we would want to do," said David Steen, a wildlife ecologist at Auburn University.

But Craig Packer, a University of Minnesota biologist who's spent decades researching big cats including maneaters, said there are credible cases of individual animals that have acquired a preference for two-legged prey, particularly in rural communities in Africa and Asia. One such serial killer was the lion of Mfuwe, Zambia, whose 1991 reign of terror ended when a California hunter killed it.

"In an undisturbed situation, they're going to eat what their mothers and grandmothers have always eaten. That does not include garbage; that does not include 2-year-old children. But when circumstances change, then they will adapt," Packer said.

When monkeys "figure out there's a trash heap at a lodge, they keep coming back, because it's there, it's easy, and it's already cooked. Certain individuals become cattle-killers, if they're lions or hyenas. And with maneaters, that seems to be the case as well."

This can happen when other prey is scarce, sometimes due to loss of habitat. Packer said that when farmers in Mozambique slept in their fields to protect crops from wild pigs, lions that followed the pigs happened upon another nutrient-dense food source.

"There's no impala. There's no wildebeest," Packer said. "But there's meat walking around in shoes."

Packer said wildlife managers work hard to mitigate these conflicts, both by teaching people to avoid them and by tracking and killing the offender. The latter can prevent indiscriminate killings, he said, which often happen after lions kill valuable cattle. But he said killing a suspected maneater, even without being absolutely sure it's the guilty party, is the right strategy.

"Oh yeah, no question. You've got to get rid of them once they start doing it," he said. "When it's people, you don't want to take chances."

There's no impala. There's no wildebeest. But there's meat walking around in shoes

Craig Packer

Wildlife officials in the United States often describe bears and other "problem" animals as "food-conditioned" - so used to getting snacks directly from people or their trash that they seek them out, increasing the likelihood of a bloody human-animal encounter. They may have lost some fear of humans, but they haven't lost their instincts.

Some studies and data, most involving bears, back that up. Biologists have studied whether food-conditioned bears inherit their taste or learn it from their mothers, but the results are mixed. In a survey of 48 North American wildlife agencies released in 2007, 70 per cent said human-bear conflicts were caused by garbage or other human food magnets. Three-quarters said they relocated "problem bears," but only 15 per cent viewed it as an effective solution. Four in 10 said they had a two- or three-strike approach - they move nuisance bears once or twice, but euthanise recidivists.

The Florida Fish and Wildlife Conservation Commission says 30 per cent of calls it received about bears from 1990 to 2015 were about garbage-eating, and it says 50 per cent of bears relocated after exhibiting "conflict behaviour" become repeat offenders.

"We don't euthanise bears just for getting in trash when that's all they're doing," Carl Lackey, a wildlife biologist for the Nevada Department of Wildlife, told AP last year, after officials at Lake Tahoe euthanised a black bear. "But that conflict behaviour escalates from tipping over trash cans to breaking into homes, and that's when we have to euthanise them."

This cycle has spawned a motto in the wildlife world: A fed bear is a dead bear. It's why wildlife officials and advocates emphasise tell you not to feed wild animals - Florida alligators are also known for getting comfortable with people-provided snacks - and why parks increasingly install bear-proof garbage cans.

But some animals, such as the Florida alligators, don't necessarily have to display a fondness for human food to be labelled nuisances and killed.

"It does seem like a relatively proactive approach to reducing human-animal conflict," Steen said.

They've preyed on something that's vulnerable, they've been successful, and they've received a reward

Chris Servheen

To some observers, it's never right to kill wild animals that attack people.

"The reason for letting these animals live, including presumed 'maneaters,' is that they were doing what comes naturally to them, as horrific and sad as the results of their tragic attacks are," Marc Bekoff, a professor emeritus of ecology and evolutionary biology at the University of Colorado, wrote in Psychology Today in 2012.

And some places do take a more nuanced position to wild animal justice, though it often requires more resources. Australian authorities didn't euthanise a crocodile that killed a 5-year-old boy in 2009. India recently sentenced a maneating lion to life in a zoo. After officials at Great Smoky Mountain National Park euthanised a bear mistakenly accused of being a human-attacker, they said they'd use DNA to confidently identify such culprits in the future (though their system failed last month).

If the New Mexico marathon had taken place in Yellowstone National Park, the bear's fate might have been different. On the very, very rare occasion of bear attacks on people, officials there carry out complicated investigations involving crime scene reconstruction and DNA, all to try to answer one question: Why did the bear do it?

Chris Servheen, the Montana-based grizzly bear recovery coordinator for the US Fish and Wildlife Service, said some bear attacks are deemed "natural" aggression. They occur when a bear is startled or defending its cubs or food. Those bears aren't euthanised, Servheen said, pointing to case of a hiker who was fatally mauled after accidentally surprising a bear and her cubs in 2011. A man-killing bear was also given a reprieve many years ago in Glacier National Park, he said, after it was determined that the victim had approached the animal to take photos.

"We actually have a record of the bear getting bigger and bigger in the view finder," he said. "In that particular case, we left the bear alone."

But if wildlife investigators determine that a bear's actions were predatory, they deem it "unnatural aggression". Evidence that a bear has eaten or "cached" human remains are also red flags. In those cases, the bears are killed, Servheen said.

"They've preyed on something that's vulnerable, they've been successful, and they've received a reward," Servheen said.

But a bear is a predator, right - isn't trying to eat a human the very definition of natural? Servheen said no: The bears that attack humans are the outliers.

Bears "have every ability to prey on us, but they're very wary of us. Ninety-nine point nine per cent of bears stay away from people, and that's how they survive," Servheen said.

"But if a bear crosses that line and begins to think that humans are attractive as a food source, then they could become very dangerous. And we don't tolerate those cases at all."