Competition over dead elk dinners can lead to unexpected outcomes for wolves and grizzly bears of Yellowstone National Park. The wolves are less likely to kill bears that steal a meal from them when they do.
Matthew Metz, a University of Montana researcher, told the Missoulian that they had broken down the wolf-foraging sequence. “We looked at their hunting time and their handling times – how long they spend eating their kills.”
Particularly in spring, when Yellowstone’s Elk herds are delivering thousands of wobbly calves across the Lamar Valley, and every predator around cruises to get fresh protein, grizzly Bears lean on wolves in ways which change the behavior of the wolves. A paired study of Scandinavian predators also showed a reduction in wolf deaths when grizzlies were around.
Aimee Tallian from the Norwegian Institute for Nature Research said that wolves provide extra food for bears. She collaborated with Metz through UM’s Yellowstone Wolf Project. But bears can be antagonistic to wolves. They take part in the supply of shared prey and they take over wolf kills. While wolves can be helpful to bears, they don’t always help wolves as much.
The Greater Yellowstone Ecosystem, which surrounds Yellowstone National Park, has the second-largest concentrations of grizzlies among the Lower 48 States. The estimated 1,000 grizzlies live in the Greater Yellowstone Ecosystem, which covers an area of approximately 100 kilometers.
Scandinavia is home to about 3,000 brown bears, the same species as American grizzly bears. They are spread at three bears per 100 km in Sweden and Norway. They eat moose which aren’t herded like elk, but they do live in similar numbers in Scandinavian forests.
Tallian stated that bear relations on the Atlantic Ocean’s far side are also controversial.
Scandinavia is home to a large wolf population. They can be found in areas with or without brown bears. This added complexity was possible because researchers were able to compare wolf behavior with and against ursine competition.
Tallian stated that patterns are being observed in many places, which suggests they exist where bears and wolves co-exist. This is a lot of their habitat.
Other complications arise when comparing American and Scandinavian meat-eaters. Yellowstone’s grizzlies and wolves have to compete against black bears in Yellowstone.
While grizzly competition can reduce the number of wolves killed, it can also have an adverse effect on mountain lions. Metz stated that bear country lions are also driven from their kills by the grizzlies and have to kill more in order to survive.
It is possible for the relationship to change from one place to another. Kodiak brown bears, which are found along Alaska salmon streams, eat only heads of spawning fish. This leaves them with plenty of meat to feed the wolves.
It remains to be determined how and why these inter-species killing rates are balanced. Metz and Tallian agreed that it was fascinating to observe several top predators on the same landscape.
Metz stated that “relatively little was known about the effects of bears on the foraging dynamics and wolves” Our work fills in the gaps by showing that dynamics can differ. It also reminds us how ecosystem complexity changes – in this instance bears – can affect the behavior of other species.
Tallian said, “One cool way of thinking about this is to consider the historical context.” This is what these systems look like over thousands of years with the dynamic interplay between competitors. It is rare to find a place that feels so untouched, and where ecosystems can flourish on their own.
