LOGAN – Brown bears and wolves share some territory, which means as predators, they often compete for the same food. Biologists have long thought that the presence of bears would increase wolf kill rates, but a recent study by Utah State University ecologist Aimee Tallian reveals the opposite. It actually decreases.
It was assumed that when a wolf makes its kill, and then the kill is taken away by a more dominant bear, the wolf would be quick to move on and look for more prey, leading to a higher kill rate. But that isn’t what is taking place. The study, which was conducted in both Yellowstone National Park and in Scandinavia, revealed that wolves aren’t killing more when bears are around. Tallian said the reasons aren’t completely clear, but she has a few ideas as to why.
“Instead of wolves leaving, they’ll just kind of wait on the sidelines,” she said. “That increases the amount of time it takes to handle the kill they made. That actually ends up increasing the kill interval or the amount of time it takes to make the next kill.”
The other possible explanation? There simply might not be enough food to go around. Both predators feed on ungulate newborns – usually deer or elk.
“Maybe they are depleting that resource,” Tallian said. “Less of that on the ground so it takes longer to find prey.”
According to Tallian, studying the situation in two different parts of the world has provided a better understanding than just one area would have.
“Especially with a finding like this, where we kind of have this unexpected result,” she said. “Sometimes you do studies in systems and they can be very system specific, so it was interesting to be able to compare systems and seeing what was going on in both of these systems.”
Tallian said predation affects ecosystems. As biologists begin to understand this behavior and its effects better, they will be able to understand other aspects of the ecosystem.
“Understanding how competition between these top predators which have these trickle-down effects is important for understanding how predation can affect the rest of the ecosystem,” she said. “It is just one more piece of that puzzle.”