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How to kill wild animals humanely for conservation

An international group offers guidance to help reduce pain and suffering in animals destined for culling.

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Friend or foe? The brushtail possum is native to Australia, but is considered a pest in New Zealand.

Every year, trained professionals kill millions of wild animals in the name of conservation, human safety and to protect agriculture and infrastructure. Commercial pest-control operators, government agents and conservationists trap beavers, poison cats, shoot wolves and gas rabbits in their warrens with varying levels of ethical oversight. Now, animal-welfare experts and conservationists are making a bid to ensure that these animals get the same consideration given to pets and even to lab animals that are killed.

People use methods such as carbon dioxide gas, drowning and painful poisons, to kill non-native or ‘pest’ animals, says Sara Dubois, chief scientific officer for the British Columbia Society for the Prevention of Cruelty to Animals in Vancouver, Canada. She considers these methods inhumane. But no one bats an eye, she says, because those animals are considered ‘bad’.

Dubois is the lead author of a set of guidelines published on 9 February in the journal Conservation Biology1. The authors — a group of animal-welfare experts, conservationists and government researchers from around the world — hope the principles will become a model for the ethical review of projects that include killing wild animals. The guidelines are the result of a 2015 workshop in Vancouver.

The document incorporates the latest findings in animal-welfare science, which tries to quantify the pain and suffering animals experience in different situations, including when they are killed. It says that control actions should only be undertaken if they support a clear, important and achievable goal. In addition, just because an animal is non-native or considered a ‘pest’ or ‘feral’, is, by itself, not reason enough to get rid of them.

Not the same

The principles are sound, says Bruce Warburton of Landcare Research, a government-owned research company in Lincoln, New Zealand. He was not involved in creating the guidelines, but has studied the animal-welfare impacts of pest control for two decades. Warburton adds that the principles would reduce the number of available animal-control tools and would be likely to incur a cost, at least initially.

Matt Heydon, a species-protection expert at Natural England, a government advisory group based in York, UK, says the principles tend to favour animal welfare a little more than do the ones his organization uses, but are broadly similar. “We approach the issue with a slightly greater emphasis on biodiversity, although animal welfare is also very important to us,” he says.

The US Department of Agriculture’s division of Wildlife Services kills millions of animals each year to protect agriculture and address other human–animal conflicts. A spokesperson noted that it already follows “euthanasia guidelines from the American Veterinary Medical Association, whenever practicable.” And Australia’s Department of the Environment and Energy says it follows similar versions of the principles reported in the new paper.

No good option

No set of guidelines can provide easy answers to the toughest calls. Brushtail possums (Trichosurus vulpecula) are a native Australian species regarded as an invasive pest in New Zealand. They are often killed using anticoagulants, which are the worst poisons in terms of welfare, says Ngaio Beausoleil, an animal-welfare researcher at Massey University in Palmerston North, New Zealand and an author on the paper.

Animals that ingest anticoagulants bleed to death over the course of days or weeks. But the poison’s use is safer for pets and children because it takes so long to kill. If a child accidentally eats bait laced with an anticoagulant, there is still time to get them to a hospital and administer the antidote. With faster-acting and more humane poisons such as cyanide, a family pet that inadvertently ate it could die before anyone could do anything about it. A third option, Beausoleil says, is to re-evaluate the need for killing the possums at all.

Island Conservation, a non-profit organization based in Santa Cruz, California, also uses anticoagulants when eradicating rodents in order to save endangered seabirds and other vulnerable island species, says Gregg Howald, the organization’s North American regional director and an author on the paper.

But the organization is actively working on replacing or refining their method for a more humane approach. The new guidelines are a call to innovators around the world, he says. “Bring us something that will work; we will be the first to adopt it.”

Journal name:
Nature
Volume:
543,
Pages:
18–19
Date published:
()
DOI:
doi:10.1038/nature.2017.21536

Corrections

Corrected:

This article originally stated that Sara Dubois was with the British Columbia Royal Society for the Protection of Animals. She is with the British Columbia Society for the Prevention of Cruelty to Animals. The article has been changed to reflect this.

References

  1. Dubois, S. et al. Conserv. Biol. http://dx.doi.org/10.1111/cobi.12896 (2017).

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