March 14 (UPI) -- A new study of moose behavior found the mammals become more tolerant of the presence of wolves late in winter.
The findings, published this week in the journal Ecology, further complicate scientists' understanding of predator-prey relationships between wolves and big-game species. The research also makes it more difficult to determine the role fear plays in shaping ecosystem dynamics.
"We have known for some time that hungry animals will tolerate the presence of predators in order to forage and avoid starvation, and that phenomenon, called the 'starvation-predation hypothesis,' is supported by our research," Brendan Oates, now working with the Idaho Department of Fish and Game, said in a news release. "In this case, close proximity of wolves does cause moose to move, but not enough to drive them from their preferred habitats -- especially late in the winter."
Oates conducted the study while a graduate student at the University of Washington.
Over a period of five years, Oates and his research partners used GPS collars to track the movements of moose and wolves in Grand Teton National Park and the Bridger-Teton National Forest. The survey identified 125 unique interactions between six wolf packs and 25 individual moose.
In early winter, the researchers found moose relocated when wolves came within 550 yards. Despite relocating, the moose remained in their preferred habitat near streams and marshes. In late winter, when moose were presumed to be hungrier, the mammals were more reluctant to relocate.
The research findings contrast with surveys of elk behavior. When wolves come within 1,000 yards, elk move away, and they continue to do so throughout the winter.
Researchers hypothesize that the moose's larger size gives it the confidence to stand its ground. It's also possible, scientists suggest, that the moose's preferred habitat offers protective benefits in addition to food resources.
Still, authors of the new study acknowledged that moose aren't fearless, and that moose-wolf interactions need to be more precisely measured to properly model predator-prey dynamics.
"Although moose may be generally less responsive to predation risk from wolves, our detection of a heightened behavioral response during early winter suggests that anti-predator behavior is dynamic within and among species of ungulates," the researchers wrote in their paper.