Do Predator Culls Really Save Livestock?

Every year — over the bodies of dead mountain lions, wolves, coyotes and bears — officials assure the public that “culls” are necessary for livestock protection. They often frame this euphemistically phrased ”predator control” as an unfortunate decision, but one backed with science and a thorough understanding of predator dynamics.

It turns out, though, that those officials may be full of baloney.

A new study published in “Frontiers in Ecology and the Environment“ suggests that the research they’re relying on isn’t actually all that great. Lead researcher Adrian Treves of the University of Wisconsin, Madison, has some questions about how those studies were conducted — and whether their results are really all that applicable.

You’ve probably heard the logic: Ranchers keeping sheep, cattle and other livestock begin losing members of their herds to “problem” predators, so officials step in to kill some of the offenders in order to protect the financial interests of the agricultural community.

As is often the case, humans win out. In September, for example, Norway announced a dramatic wolf cull to protect its extremely large sheep population.

Earlier this month, predators in Nevada actually got a reprieve as a result of a lawsuit challenging the methodology of science used by Wildlife Services, a division of the U.S. Department of Agriculture — not to be confused with the Fish and Wildlife Service.

So is it true?

To know the answer to that question, we need research — and a lot of it. But it’s not enough to simply conduct a study, argues Treves, who performed a meta-analysis of over 100 studies on the subject.

Treves was particularly concerned about the lack of randomization. While the it can be challenging to implement such a process in the field, it provides vitally necessary information.

In this case, the question is whether removing predators really has a substantive impact on livestock losses, or whether leaving predators intact yields a similar result.

Treves refers to this as a “gold standard,” and it’s one of the underlying tenets of a huge variety of research methodologies. After all, if doing nothing has the same result, it’s pretty clear that there’s another cause for the problem that researchers are trying to solve.

But the flaws Treves raises aren’t just about randomization.

He also found issues with how studies were constructed, from the number of animals in the pastures selected for research to a lack of pre-cull research and subsequent follow-up monitoring.

Treves is not alone in questioning whether culls really work, as researchers have raised concerns about increases in predator numbers following culls, as well as a spike in predation.

As humans expand their territory, these are dilemmas that will arise even more frequently, making it critical to use robust scientific methods to examine the interactions between predators and livestock.

Critics of Treves’ findings – including some of the researchers he challenged – argued that his own work had flaws, such as a failure to consult with outside experts and misleading evaluations of some of the studies involved.

This sort of peer discussion only makes scientific research stronger. It highlights the fact that multiple studies — including literature reviews like this one — are necessary to explore and verify information.

Treves’ work isn’t designed to be a definitive study, but hopefully it will open the door to more thoughtful study construction in the future, as well as promote more careful examination of previous research on the topic.

Just because certain research superficially confirms assumptions — “killing predators reduces livestock losses” — doesn’t mean that those findings are the correct or final conclusion.

Photo credit: brainfreezer

87 comments

Robert N.
Rob Chloe Sam N12 months ago

I agree Kathryn Mitchell.

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Kathryn Mitchell
Kathryn Mitchellabout a year ago

Leave the predators alone! It's the ranchers' faults if they can't keep track of their livestock!!!

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Marie W.
Marie Wabout a year ago

NO

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Peggy B.
Peggy Babout a year ago

TYFS

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Peggy B.
Peggy Babout a year ago

I agree with Jetana Allison.

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Pablo B.
.about a year ago

tyfs

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Jetana Allison
Jetana Aabout a year ago

Stop public lands grazing, which is truly welfare ranching, and harmful to Western ecosystems. Predators are essential for the health of wildlife populations! And no one needs trophies--a disgusting practice!

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Philippa Powers
Philippa Pabout a year ago

I don't think culling does anything good.

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sandy Gardner
sandy Gardnerabout a year ago

Thanks!

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Elaine W.
Elaine Wabout a year ago

Noted.

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