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Wolf study probes effects on cattle
by MITCH LIES, Capital Press June 8, 2012
Oregon and Idaho ranchers are involved in a long-term study that could shed light on how wolves affect everything from cattle grazing patterns to labor costs, cattle weight gain and conception rate.
The 10-year study involves documenting the movement of cattle when they come in contact with wolves and includes ranchers recording body condition scores, labor costs and other factors compared to historic conditions.
Scientists also have data from a collared wolf.
Preliminary data in the study, initiated four years ago, shows some surprising and some not-so-surprising results, researchers found.
Cattle, for example, don't appear fearful of wolves when initially encountering the animals. After witnessing a wolf kill a cow, however, herds become skittish. Cows that have seen a wolf kill a cow bunch together and run as fast as 6 mph when a wolf is nearby.
The study is showing that calf yields in herds that graze near wolves aren't nearly as high as yields in wolf-free zones.
It is also showing labor costs are up in areas where wolves are present.
And the study is showing that contrary to some thought, wolves aren't afraid to go near houses, as the collared wolf often roamed within 330 feet of houses.
In the study, funded by USDA, Oregon State University, University of Idaho and the Oregon Beef Council, cows are fitted with GPS collars containing a secure digital, or SD, card. Scientists document animal movement after retrieving the SD card.
The idea behind the study is to provide scientific basis for wolf policy, and reduce wolf-livestock conflicts, said Doug Johnson, an OSU range scientist.
"What we'd like to do is come up with some tangible ways to reduce the impact of wolves on livestock," Johnson said. "But it's not going to be an easy problem to solve."
The original concept was to compare cows that interact with wolves with cows that don't. Scientists collared four sets of 10 cows in Oregon and four sets in Idaho, with the idea the Oregon cows weren't interacting with wolves, and the Idaho cows were.
Johnson's focus -- originally to study grazing patterns -- changed when wolves started killing cows in Oregon.
"Wolves are now the focal point of this study," he said.
Scientists received a bonus when USDA Wildlife Services agents agreed to collar an Idaho wolf that was earmarked to be killed because of its predation. The collar showed the wolf's location every 15 minutes for 200 days.
The wolf, identified as B446, was part of a pack of 13 that have since been eliminated by USDA Wildlife Services agents.
The data show B446 traveled often between his den and a highland pasture where heifers grazed, and the rancher involved in the study suffered heavy losses to depredation, even though he could prove just a fraction of the loss.
The rancher figures he lost between 40 and 45 calves to wolves, or 10 percent of the expected yield from a 450-cow herd, Johnson said.
In another herd, the rancher was able to show only an 80 percent yield on calves, Johnson said. In all, the rancher estimated he lost between 65 to 70 animals out of 800 head, but he was able to confirm the loss of just 17.
In addition to cattle lost through depredation, preliminary results show wolf presence reduces weight gain in cattle, reduces conception rates and changes a cow's body condition score, a measure of whether an animal can be rebred.
Ranchers also are reporting that cattle preyed on by wolves don't tolerate dogs, which often are vital tools in herding.
"The presence of the wolf is changing the behavior of these animals," Johnson said.
Wolves, Johnson said, are unique among the many animals he has studied over his 20 years as a range scientist.
"They're very smart animals, and they are amazing in terms of their ability to move," Johnson said.
B446 traveled an average of 11 miles a day in the 200 days he was collared and covered more than 27 miles in one day. The wolf traveled primarily at night, according to data, shuffling between his den and cow herds.
"The wolves are going where the cows are," Johnson said.
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Page Updated: Saturday June 09, 2012 11:35 PM Pacific
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