Most discussions about the impact of wolves on livestock producers focus on depredation losses, both confirmed and unconfirmed. The rule of thumb is that for every confirmed kill there are probably eight more unconfirmed losses.
This is a significant impact, but ranchers who have been dealing with wolves have reported additional costs and losses when wolves are present. These costs include weight loss, lower pregnancy rates, reduced gain for calves, more sickness, and an increase in management costs.
David Bohnert, beef extension specialist and ruminant nutritionist at Oregon State University (Eastern Oregon Agricultural Research Center, at Burns, OR) and coworkers decided to do studies looking at these issues. After wolf introduction into Wyoming and Idaho, and expanding wolf population into Washington and Oregon, there was a growing perception and anecdotal reports by beef producers that the damages they were seeing went far beyond actual death losses.
“The Oregon Beef Council helped fund some research that Renaldo Cooke and I proposed. John Williams, Wallowa County Extension agent (now retired) was part of this work as well. Our first study used cattle from Idaho that had been exposed to wolves for several years, with numerous verified cases of wolf depredation. In contrast, cattle here at our Research Station at Burns, OR, had never experienced wolves, so we decided to compare the two groups of cattle,” he told WLJ.
“We brought in 50 cows from the Idaho operation and used 50 of our cows, running them together as a common herd. We managed them all the same and ran them through our working facility weekly for two months so they would get used to it. This gave the Idaho cows time to settle in and become comfortable here. We wanted to look at stress effects, so we gave them time to become familiar with our facilities, handling, and people—to remove that potential source of stress,” he explains.
Initially, the cattle were sorted by temperament (flighty or not) and their identity blocked so the data could be analyzed scientifically and statistically.
“We had five groups of 10 cows from each herd. We thus had five groups from the wolf-exposed cows and five groups of the non-wolf-exposed cows. This allowed us to compare two groups (one group from each herd) at a time, to evaluate differences in stress and behavioral responses,” he says.
At that point, the preliminary data was collected, looking at temperament, body temperature, and the levels of cortisol (a stress hormone) in the blood.
“Then we exposed them to a mock wolf encounter. This consisted of a howl box—emitting the sound of wolves howling—cotton swabs soaked with wolf urine placed near the cattle, and we brought in pseudo wolves (German shepherd dogs).”
The dogs were walked past the corral, to create the presence of a large canine.
“We did this for about 20 minutes with each group. Then we brought the cattle to the chute and re-evaluated all of the variables we’d looked at earlier. At that point we saw that the nervousness (temperament score) rose much higher on the cattle that had been exposed to wolves in the past. Blood cortisol levels also went up at a greater rate than in the naïve cattle. Body temperature went up in both groups of cows because we were handling them and moving them around, but it went up much higher in the cows that had previously been exposed to wolves.”
In short, the cattle with wolf experience became visibly stressed and agitated.
The lasting impact of wolves on cattle in pictures
A series of photos documenting the initial Oregon State University wolf experiment. Cattle that had never experienced a wolf attack were curious about the experiment's "mock wolves" while experienced cattle showed dramatic fear and defensive behavior, as well as dramatically higher levels of stress hormone in their blood.
“We took photos, but I wish we’d taken videos, to really show their nervousness. The cows that had been exposed to wolves in the past formed a tight bunch like musk-ox in a protective circle, mobbed up and agitated. By contrast, our Oregon cows were just standing back quietly, wondering what was going on—more curious than frightened,” says Bohnert.
“It was very obvious that there was a definite stress response, and the data indicated this as well. We published that study in the Journal of Animal Science in 2013. We have conducted other work that looked at these same variables, and we know that when we see the same things we saw in those wolf-exposed cows, there are greater incidences of sickness, and lower pregnancy rates/conception rates. This suggests that the ranchers’ observations are more than just anecdotal.”
John Williams, who was an Oregon Extension agent at that time, did some economic comparisons, plugging in numbers based on depredation, sickness, potential losses, pregnancy rates, etc. and his preliminary estimate was something between $250-300 per head as the actual additional cost for a cattle operation that has to deal with wolves, compared with when they did not have to contend with wolves in the past.
“We wanted to do another study, so we got more cattle from the same ranch in Idaho, a herd that was still exposed to wolves. We used 10 of those cows and 10 of our cows (that had not been exposed to wolves) and did the same scenario; we sampled cows at the beginning of this study, then we exposed them to the howl boxes, wolf urine, and pseudo wolves and measured everything again. This time we actually harvested the cows, either before they were exposed to the wolf stimuli or after, and evaluated the differences, using blood and brain biomarkers for stress,” says Bohnert.
“We saw an indication that the cows that were earlier exposed to wolves had a fear that was greater than what we saw in our cows that had not been exposed to wolves in the past. This suggests that the cattle were suffering from PTSD (post-traumatic stress disorder).
“The blood and brain biomarkers we looked at were the same as those shown to be affected by stress and fear in rodents. Our data showed that cattle exposed to wolves, or simulated wolf encounters, seem to be negatively impacted psychologically by the predatory activities of the wolves,” he says. Results of this study were published in 2017.
This suggests that injury wolves can cause to cattle definitely goes beyond the simple loss of an animal.
“There is some fear-related, psychological disorder affecting the cattle that can not only hinder productivity but also negatively impact their welfare.” This becomes an animal welfare issue as well as an economic issue.
Production, management impacts
Harassment of cattle by wolves also makes them much harder to handle and manage. Most livestock producers try to use low-stress handling methods to have docile cattle that are easy to manage and highly productive. The presence of wolves negates all this and makes cattle more fearful and flighty, harder to manage or keep in the proper pastures, and sometimes they become dangerous to handle.
For example, cattle that were traditionally easy to move and work with dogs become so upset and agitated at the presence of dogs that in many instances this is no longer an option.
“Cattle that used to be able to be worked with dogs are now impossible or extremely difficult to work with dogs. The cows are on the fight and attacking the dogs,” Bohnert says.
“It would be interesting to redo this type of study 10 years from now, to see if—over time—the cattle might adapt to the presence of wolves. This is something we don’t know,” he continued. In the wild, cattle (like any other prey animal) were defensive and flighty, in order to survive.
“It would be interesting to see, however, in the regions where cattle have had interaction with wolves over a long time, if the stress response moderates to a point, or if the cattle producer just has to live with a certain element of lower production.”
Exposing cattle to wolves (cattle that have not been exposed in the past) definitely has a negative effect from a stress standpoint.
“We can’t really quantify it right now, but I am confident that there is an economic effect in decreased pregnancy rates and decreased production; the wolves are having a negative effect on cattle production.” — Heather Smith Thomas, WLJ correspondent