The “ecology of fear” isn’t limited to wild animals. Livestock that have encountered wolves experience stress that may affect their health and productivity.
In experiments at Oregon State’s Eastern Oregon Agricultural Research Center (EOARC) in Burns, cows were exposed to the sounds of howling wolves and to German shepherds prowling outside an enclosure. Those cows that had previously encountered wolves on the range showed higher levels of stress than those that had not had such encounters.
“When wolves kill or injure livestock, ranchers can document the financial loss,” says Reinaldo Cooke, an animal scientist in OSU’s College of Agricultural Sciences. “But wolf attacks also create bad memories in the herd and cause a stress response known to result in decreased pregnancy rates, lighter calves and a greater likelihood of getting sick. It’s much like post-traumatic stress disorder – PTSD – for cows.”
David Bohnert, an expert in animal nutrition at the EOARC, says that stress affects ranchers’ bottom line. “In a herd, if you are not raising calves, your cows are not making you money,” he says. “A wolf attack can have negative financial ripple effects for some time.” (For more on livestock well-being, see “Caring for Cows,” Terra, winter 2013.)