“Having wolves and cows collared enables us to match up their location and time, and determine where and when wolf-cattle interactions are occurring,” Clark says. Data on wolf presence and activity are augmented by wolf scat sampling along forest roads, and use of trail cameras.

Though only one wolf was collared in 2009, the results proved interesting. “We found interactions between all 10 of the collared cows and that single GPS-collared wolf within a very extensive study area [over 50,000 acres]. The 10 collared cows were part of the larger herd of 450 cow-calf pairs, yet the data showed this wolf was within 500 yards of every one of the 10 collared cows many times throughout the summer [for a total of 783 contacts],” Clark reports.

In fact, the collared wolf’s area was 210 square miles, with a 55-mile perimeter. The least distance he traveled was six miles/day, and the most was close to 29 miles/day. “On a day of confirmed predation, we could look back to the data and see that the wolf was in the immediate area at that same time,” he says.

This wolf was part of an 11-animal pack. There were three different packs, totaling 34 wolves, roaming that study area during 2009. The producer in that area suffered more than 40 confirmed or probable wolf depredations.

wolf-cattle interaction

The collared cow with the least number of interactions with the collared wolf had 23 interactions within 500 yards during that grazing season. One cow encountered that wolf 140 times (at less than 500 yards) over the course of 137 days (mid-June through early November 2009). All 10 collared cows had interactions within 250 yards, and nine cows had interactions at 100 yards or less.

Envision 450 cows with more than 30 wolves moving among them. If one wolf had 783 encounters with just 10 of those cows, how many encounters might there have been with 30 wolves among the 450 cows? In other words, the cattle were constantly being affected by the presence of wolves. Two of the collared cows’ calves disappeared that summer.

“We wondered how many of these GPS-detected wolf-cattle interactions resulted in predations. We looked at the wolf GPS data and compared the tracking logs with locations of known 2009 predation sites. We could see tight spiral patterns in the wolf movements that occurred at those sites. These circling activities may illustrate prey-appraisal or pursuit events,” Clark says.

The following spring (2010), the researchers hiked into sites where spiral patterns occurred in the 2009 wolf track log. Inspecting the sites for signs of predation, they found fresh cattle bones at one of those sites.