Last summer, Washington ranchers welcomed a call to kill members of a wolf pack that had killed dozens of sheep. But a WSU researcher says killing wolves actually increases livestock deaths.
Rob Wielgus, is director of Washington State University’s Large-Carnivore Conservation Lab. He says after analyzing data over a 25 year period he found that killing wolves to reduce livestock predation actually led to more dead sheep and cows the following year, because of a change to the wolf pack structure.
Wielgus: “Let’s say you kill some members of the pack, particularly the dominant animals, they suppress reduction, so if they are removed you end up with more breeding pairs, and breeding pairs are linked to livestock depredations.”
His research shows that for every wolf you kill, you increase the probability of a new breeding pair by 5 percent, the same odds as for increased livestock depredation. But the number of depredations begins to decline if more than 25 percent of a pack of wolves is killed. Even so, Wielgus says that is not an option in Washington State to slow the killing of sheep or cattle.
Wielgus: “We're trying to recover wolves here, so if you killed more than 25 percent you would driving the few wolves that we had down, so you would never reach recovery , you’d probably extirpate them.”
Wielgus says in a state like Idaho where the populations are high enough that they have been removed from the endangered listing, one plan might be to have an annual kill level of 25 percent of the wolves to try to keep that at that level.
Wielgus: “Knowing that you will have livestock predation associated with that. The idea is to find a sweet spot where everyone is happy, the ranching community, the hunting community the wildlife advocates and the wolves themselves.”
Wielgus' research for WSU also includes non-lethal methods to reduce wildlife depredation by wolves, a project funded by the state legislature.