Killing Wildlife: The Pros and Cons of Culling Animals

Is targeting species like badgers, swans, and deer effective? And is it ethical?

Last fall, the U.K.'s Department for Environment, Food and Rural Affairs targeted badgers for culling—the selective killing of a species as a population control measure.

Badgers reportedly transmit bovine tuberculosis, a disease with a profound economic impact on farmers whose cows test positive. But a recent report by an independent panel leaked by the BBC said the culls failed in efficacy and humaneness. (Related: "Mr. Badger Should Be Worried: Britain Ponders a Cull.")

Proposed culls have made headlines in the United States as well. Wildlife managers have targeted bison in Montana and swans, geese, and deer in New York.

What's driving these high-profile culling programs? Are they necessary? Can they be done ethically? And what's at the heart of the debate between their proponents and their detractors?

We explored the controversy over culling with Mary Pearl, a conservationist with the City University of New York who formerly served as president of the Wildlife Trust, a nonprofit organization now called EcoHealth Alliance.

Wildlife culls have been in the news a lot lately. Is this a new practice?

I would say nature has been a culler, in the past, of wildlife species. It still is. If an animal becomes superabundant in a limited habitat, they're going to have either a die-off from starvation or some pathogen that will take advantage of their vulnerabilities. Then there's hunting by predators, including humans.

Today's culling is an artifact of our transition from having a lot of open, interconnected wilderness to having islands of wildlife habitat that then become almost like gigantic zoos. You have a finite exhibit area, and you can't let the population abundance go unmonitored.

There's also the effect of rapid global travel of wildlife, which is either intentionally introduced to new places or hitches a ride on an airplane or ship and moves from one part of the world to another. Newly arrived species can become superabundant in the absence of natural predators.

Bison were hunted nearly to extinction before conservation efforts began. Now they're being culled in Yellowstone National Park. Is culling a sign of the conservation movement's success?

Yes. You could also say that about the Canada geese, which were under protection and now are superabundant. And the white-tailed deer that was almost hunted to extinction as well.

Animals can be brought back. That's a wonderful thing about conservation. Often, if they're left in good habitats, populations will rebound. The problem is that they can become victims of their own success and become so abundant that they then become a threat to the survival of other species and to their own populations.

Last year, an excerpt of a book by Jim Sterba published in the Wall Street Journal said, "It is very likely that in the eastern United States today more people live in closer proximity to more wildlife than anywhere on Earth at any time in history." To what extent is culling the result of increasing interaction between humans and wild animals?

Well, you could say, "It's very likely that in the eastern United States today more people have toothaches than ever before," and that's because there are more people.

The more interesting question would be about the relative abundance of wildlife per person, and I'm not sure that that's different. There have always been people who have lived with and followed masses of animals, such as the Native American groups traveling with the bison or the indigenous people in the Arctic Circle following reindeer herds.

The northeastern U.S. landscape has changed dramatically. In the 1800s, New England and the mid-Atlantic forests were mostly converted to agricultural land, which eliminated a lot of forest species. Now it's reversed and we have 80 percent forest and 20 percent open land, and that's resulted in a big wildlife return.

But it has been selective. There are more white-tailed deer, but there are probably not more lynx. Deer do very well in the mosaic habitat of forested and open lands that we have created in suburbs. Animals that are human commensals also have become abundant, like raccoons and skunks.

In New York, where you live, the New York State Department of Environmental Conservation recently proposed culling mute swans, but a public outcry forced the agency to reconsider. What factors went into the cull proposal?

First of all, they're an exotic invasive species. They're native to Europe. The introduced birds were rare before the 1960s. More recently, their populations have grown dramatically in some areas.

The problem is, beyond their numbers, that they are huge birds with seven-foot [two-meter] wingspans and a big impact on the ecosystem. They eat between five and eight pounds [2.3 and 3.6 kilograms] of aquatic vegetation per day. And they're very aggressive. This means they'll chase away native, endangered birds. They can clear a five-acre pond so that other birds can't nest there.

What factors contributed to the public opposition?

They're big and beautiful and they're not afraid of people, so people can feed them and develop an emotional attachment. It's kind of comical and romantic to see a big male swan chasing everyone away so his mate can sit on the nest.

People connect with the romance of the mated pair of birds, and the little cygnets are so cute. They're charming.

A recent report in the United Kingdom concluded that a pilot culling program did not kill badgers humanely in many cases. What would you call an ethical cull?

It may be surprising to most people, but most animal ethicists consider the avoidance of suffering to be more important than the avoidance of death. For example, a sharpshooter immediately removing an unwitting animal is in most cases preferable to a protracted and disruptive capture, with the attendant fear and pain.

Any contact with wildlife should be minimal and humane. And there must be an evidence-based rationale for removal—not wishful thinking, but a sound plan where risks are anticipated and avoided, and the intended goal of disease reduction or achieving a sustainable population level highly likely and constantly monitored.

When bats are culled in South America to prevent rabies, for example, care must be taken to remove overabundant vampire bats, rather than insectivorous bats that typically do not interact with humans but play a positive role in reducing crop pests.

When West Nile virus first appeared in New York, the city sprayed pesticide at dusk, when those pesky mosquitoes that prefer humans come out. It turned out that the major transmitter of the virus was a daytime mosquito that feeds primarily on birds, so the spraying targeted the wrong species.

Wildlife managers have portrayed culling as a balancing mechanism for ecosystems. Some wildlife advocates have portrayed the practice as disruptive to ecosystems. Is this a debate about the definition of "natural"?

I think there are two strong strains here that get confused in our society. There are people who are really committed to wildlife conservation. That refers to maintaining the health of the most biodiverse habitats possible. And then there are animal rights advocates, who believe that every animal is ethically considerable and should have the right to live.

I think these two camps sometimes overlap in that wildlife conservationists want to find the most humane ways of managing ecosystems, but believe that the genie is out of the bottle—we live in an artificial set of habitats that must be managed or we will lose biodiversity. And then there are the animal rights people who say we'll deal with that as we come to it, but we have to find a way to make room for every animal to fit into the ark.

That's really not my perspective. If wildlife managers don't cull, then nature culls, and we will see animals starving [and] habitat types that used to be vibrant and beautiful consisting of highly reduced numbers of species. That's the specter that frightens wildlife conservationists, whereas I think those with the animal rights perspective feel that, ethically, we lose our souls if we cannot respect the divine spark in every individual animal.

The sad thing is I think both sides really love nature. But they have a very different view of looking at the future of nature on a planet that is overpopulated by humans.

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