Long Winter Hurts Big Game Survival

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ELKFlies buzz around the elk carcass as the research biologist examines the marrow in a leg bone, looking for clues to whether the starving calf was killed by a mountain lion or wolves.

“It’s a dark red; it’s gelatin,” Fish and Game biologist Craig White said as he pointed to the bloody cross section of a leg bone. “That indicates it wasn’t in great condition. Really poor marrow.”

It is a sharp contrast to the solid, white, healthy marrow found in the bones of another elk carcass earlier in the day. Both are part of an ongoing study in the Garden Valley area designed to determine elk mortality.

This year’s extended winter took a toll on the elk calves being monitored in Garden Valley as well as deer and moose young throughout the state.

“This has been an unusual year. The winter was not especially tough,” said Dale Toweill, Fish and Game wildlife manager. “The problem with over-winter survival is more how long the winter lasts.”

Deer, elk and moose have adapted over centuries for long periods of starvation. They live off their body fat. But this past year, winter came early and lasted a long time causing the animals to steadily keep losing energy.

In eastern Idaho and in the Panhandle, the cumulative snows attracted moose to roads and railway beds where they were killed by cars and trains.

“Even more unusual, moose calves were utilizing all the marrow in their bones, where the fat’s stored, and breaking their legs when they get into tough snow,” Toweill said. “That’s an indication of very poor condition.”

For more than 20 years, moose numbers in Idaho have been growing steadily. But with this season’s winter kill and animals coming into summer still in poor condition, moose hunting permits will need to be reduced to keep the population healthy, Toweill said.

“Moose should come back very quickly. I anticipate if we have a normal year and good production that the surviving cows will have good survival next year,” Toweill said. “They’ll enter the fall fit and healthy, and if we don’t have another long cold winter, we should have good calf survival. With fewer animals feeding on available plants this spring and summer, they should provide additional food for animals in the coming fall and winter.”

Most adult female mule deer monitored by Idaho Fish and Game biologists survived, but less than one third of fawns survived. Elk fared better in some areas and more poorly in others depending on habitat conditions.

“I think it’s important for people to realize that although we focus on hunting as a main source of mortality on wildlife, it’s really habitat and habitat is influenced by weather,” Toweill said. “So, if habitat is good in any given area, they’ll concentrate there. But as the months go by, the amount of food there gets depleted very quickly. That’s why it’s so essential that we have good habitat well distributed across the landscape.”

Good habitat includes places where animals can get out of the wind so they’re not losing body heat; places to avoid people and predators so they’re not wasting valuable energy; and places to find something to fill their stomachs.

“Don’t expect to see as many young animals after a tough winter like this,” Toweill said. “But on the other hand, with good management the animals will bounce back. And we’ll be back to abundant hunting seasons here very shortly.”