Critical time for wildlife, fish
GRAND FORKS -- As winter continues its grip, natural resources managers in North Dakota and Minnesota say the eventual impact on wildlife and fish won't be known until the snow finally melts.
For the time being, it's so far, so good. Probably.
"At this point, I simply don't know, and it would be silly to try and predict," said Bill Jensen, big game biologist for the North Dakota Game and Fish Department in Bismarck. "The most critical part of the winter is still ahead."
According to Jensen, the harshest winter conditions in the state appear to be in the Langdon area and the northern tier of counties across the state. There hasn't been significant deer mortality, he said, but die-offs usually occur in phases, starting in December and January with old bucks stressed from breeding and small fawns through February.
The real concern is when mature does begin dying, and so far, that hasn't happened, Jensen said. Also, areas farther west and south in the state have little to no snow, Jensen said; the ground in Bismarck is about 70 percent bare.
"It's like anything else," he said. "It depends on where you are in the world."
Randy Prachar, manager of Roseau River Wildlife Management Area in northwest Minnesota, said the lack of snow early in the winter provided a "cushion" for deer to better withstand the cold and snow that blasted the region in February and March. The Winter Severity Index, a measure of days with temperatures below zero and snow deeper than 15 inches, hit 100 last week, Prachar said.
Generally, winter conditions start to take a toll on deer when the index surpasses 100.
"Deer movements are restricted somewhat by the snow depths," Prachar said. "So long as spring works its way toward us in the next few weeks, I think the influence of winter on deer will be relatively minor."
Gretchen Mehmel, manager of Red Lake Wildlife Management Area at Norris Camp south of Roosevelt, Minn., said she hasn't heard of any deer mortality, and the whitetails she's seen looked fine. There's not much crust on the snow, though, she said, so larger animals such as deer and wolves are falling through, which makes access more difficult.
Grouse, which burrow in the snow, are loving the conditions, she said; owls, not so much. Several dead boreal owls have been reported across northwest Minnesota, Mehmel said.
The Winter Severity Index at Norris Camp also hit 100 last week, she said.
"WSI points are adding up," Mehmel said. "That's going to start taking a toll on deer if it lasts much longer."
Perhaps the biggest danger this time of year, managers say, is prolonged spring rain followed by a cold snap. That combination can be deadly not only to deer, but pheasants, as well.
"We had some freezing rain go through a few days ago, and that can be more detrimental than heavy snows this time of year," said Stan Kohn, upland game biologist for the Game and Fish Department in Bismarck.
Kohn said pheasants in the southeast, central and northwest parts of the state probably face the greatest dangers from the extended winter because there's not much snow anywhere else in pheasant range. But so far, at least, Kohn said he hasn't received any reports of dead birds from department staff.
"If they've got a food source and get some heavier cover, some cattail sloughs or shrubby cover to get out of the environment, they're going to do OK," Kohn said. "A lot of times when we get these tough winters, we don't see repercussions until snow starts dissipating a little bit."
Native game birds such as sharp-tailed grouse rarely experience winter die-offs because they're adapted to the extreme weather conditions, Kohn said.
"It's pretty much the same thing with Huns," Kohn said, referring to gray partridges. "They're pretty tough little birds, and because of the way they rosette (group) up during the cold temperatures and burrow into those snow bowls, very seldom do we run across winter mortality on Huns."
The outcome could be less favorable for fish in some shallow lakes across northeast North Dakota. Randy Hiltner, northeast district fisheries supervisor for Game and Fish in Devils Lake, said Lake Juanita east of Carrington already has experienced winterkill. Hiltner said fisheries crews also are keeping tabs on about a dozen small lakes in the northern part of his district where dissolved oxygen levels are declining.
Winterkill occurs when deep snow atop the ice blocks out light and prevents plants from producing oxygen. Recent storms have resulted in upward of 15 inches of snow on several lakes, Hiltner said.
Lakes of concern, he said, include Armourdale Dam and Bisbee Dam in Towner County and Island Lake in Rolette County.
"We've done several oxygen checks on some lakes that had shown lower oxygen levels, and they continue to go down from our February readings, which is to be expected," Hiltner said. "The snow that's on the ice doesn't appear to be going anywhere soon. Oxygen levels are just going to continue to go down and likely winterkill on those lakes.
"There'll be some surprises, too, as the ice goes off," Hiltner said. "Maybe we'll get some later winter mortality and people see fish come floating in on a shoreline. I hope they report it to us; we'll go ahead and check those, too."