“Washington State University researchers have found that it is counter-productive to kill wolves to keep them from preying on livestock. Shooting and trapping lead to more dead sheep and cattle the following year, not fewer.”
“…Their study is the largest of its kind, analyzing 25 years of lethal control data from U.S. Fish and Wildlife Services Interagency Annual Wolf Reports in Montana, Wyoming and Idaho. They found that killing one wolf increases the odds of depredations 4 percent for sheep and 5 to 6 percent for cattle the following year. If 20 wolves are killed, livestock deaths double.”
According to Wielgus: “..the wolf killings likely disrupt the social cohesion of the pack. While an intact breeding pair will keep young offspring from mating, disruption can set sexually mature wolves free to breed, leading to an increase in breeding pairs. As they have pups, they become bound to one place and can’t hunt deer and elk as freely. Occasionally, they turn to livestock.”
It is also important to remember, that according to USDA National Agricultural Statistics Service losses of cattle from wolves accounts to only about 0.2% of all cattle losses — a minor threat compared to losses from health issues, weather and even other predators.
Data source: “Cattle Death Loss,” a report by the USDA National Agricultural Statistics Service (see chart on pg. 5)
Meanwhile, non-lethal control have shown to be exceptionally effective. According to Phys.Org:
“In an ongoing study of non-lethal wolf control, Wielgus’s Large Carnivore Lab this summer monitored 300 radio-tagged sheep and cattle in Eastern Washington wolf country. None were killed by wolves.”