Environment
2:36 pm
Tue March 11, 2014

Wolves Stress Cows Out

It may not come as a surprise to hear that wolves make cows nervous. Unlike bovine that haven’t ever had a run-in with a wolf pack, ones that have can experience stress-related illnesses. KLCC’s Tiffany Eckert reports researchers with Oregon State University have found a way to measure the stress of a wolf attack on beef cows.

Wolf
Credit Oregon Department of Fish and Wildlife

Since wolves were re-introduced in the northwest, ranchers have complained that wolf attacks in livestock grazing areas meant a decrease in their profits. They claim cows that have contact with wolves are sickly and have fewer calves. But there was no quantitative proof.

Enter Oregon Beef Council. They funded the Wolf-Cow Simulated Encounter study and OSU’s David Bohnert (Bone-ert) co-authored it.

“We’ve come up with a model that allows us to evaluate stress in cattle. That entails some blood parameters that we can measure, some hormones. As well as changes in their behavioral response.”   

The study involved mixing an Idaho herd that had experienced wolf predation with a herd in eastern Oregon that had not. After a couple months, they exposed the blended herds to “pseudo wolves.”

“We had some German Sheppards that we walked around. But in that same area we had wolf scent and wolf urine. So that it would simulate the smell that they might have been used to. Then we had vocalizations of wolves that we played, howling and just normal pack behavior.”

Researchers found that the stress hormone cortisol increased by 30 percent in cows that had previously been exposed to wolves. Yet, the cows unfamiliar with wolves were unaffected.

Bohnert says the findings establish a link between cow stress and poor performance traits. They may help ranchers establish the economic impact of wolves. And strengthen their arguments for more aggressive wolf management.