The winter of 2017-18 hasn't been too severe for deer and most other wildlife to this point, but prolonged cold spells could cause problems in some areas if they persist too late into the season, managers say.
"Some of these cold days are starting to take their toll a little bit, but it looks like we're working out of that now here for a short period of time," said Jeb Williams, wildlife chief for the North Dakota Game and Fish Department in Bismarck.
There isn't much snow on the landscape this winter, and the conditions are especially marginal in North Dakota, where the Game and Fish Department hasn't been able to conduct winter aerial white-tailed deer surveys.
Snow is essential for spotting deer from the air.
"It's a double-edged sword," Williams said. "On the one hand, you like to get that information, (but) you know deer are getting through winter in pretty good condition because of lack of snow cover, and that's a good thing, too."
In Minnesota, where the Department of Natural Resources compiles an annual Winter Severity Index based on daily snow depth and temperature, the index from Nov. 1 through Feb. 7 was 50 or lower everywhere except for a band in northeast Minnesota along the Ontario border and a couple of areas near Roseau River Wildlife Management Area and Norris Camp south of Roosevelt, Minn., in northwest Minnesota, where the index falls in the range of 51 to 79 points.
To compile the index, a point is added for each day with 15 inches or more of snow on the ground and each day the air temperature is 0 degrees or colder; sites can accumulate two points daily under the harshest conditions.
A WSI of less than 100 at the end of the season reflects a mild winter, while an index of 180 or higher indicates a severe winter.
"There's little about this winter right now that's alarming to any type of wildlife degree," said John Williams, northwest region wildlife supervisor for the DNR in Bemidji.
Based on the most recent DNR snow depth map, far northwest Minnesota has 4 to 8 inches of snow on the ground, while areas farther east have 12 to 15 inches, with small pockets of 18 to 24 inches near Voyageurs National Park and Minnesota's Arrowhead.
There was plenty of snow for the DNR to conduct its winter aerial survey of elk near Grygla, Minn., but more snow is needed before crews can survey the Kittson County herd, the DNR's Williams said.
That's especially a concern for the Kittson Central elk herd near Lancaster, Minn., where the DNR needs good data for setting hunting regulations to keep the herd within goal range, Williams said.
"I'm not ready to get real nervous yet, but I'd sure like to have (the survey) done," he said. "Typically, we like to have at least a foot of snow, but we could probably get by with 6 inches or so."
Deer complaints down
Farther south, parts of extreme western Minnesota have even less snow, a pattern that extends diagonally up into northwest North Dakota. The general lack of snow is reflected in the number of deer depredation complaints the Game and Fish Department has received this winter, Jeb Williams said.
"We've had very little, which isn't super surprising with the lack of snow, but we've also had some cold enough conditions where I'm a little bit surprised we haven't had more," he said. "It really is the combination of lots of snow and lots of cold where we really see depredation conditions, and we just have not had the snowfall in the majority of the state.
"We know certainly there's some deer out there getting into feed supplies in these cold conditions, but obviously, it must be at a fairly tolerable level for most landowners out there because we haven't heard from many."
Game and Fish personnel last year at this time were dealing with more than 100 depredation complaints just in the Bismarck area, Williams said.
"It's not uncommon for us to be dealing with hundreds of them-300-400 depredation complaints in some instances," he said. "But again, it's also probably a symptom of lower deer populations, too. We know there are some deer out there taking advantage of feed supplies, but it's probably at a more tolerable level when you're dealing with 30 or 40 deer vs. a couple hundred deer, so that makes a big difference."
No news is good news for North Dakota pheasants to this point, but wildlife managers will be keeping a close watch on the birds, which last year were hit by the double-whammy of a severe winter and a widespread spring and summer drought that decimated insects the chicks depend on to survive.
"We had a couple of big hurdles to try to get over last year, which we didn't get over as far as the winter goes and then really tough drought conditions, which led to probably the poorest pheasant season we've had in over 20 years," Williams said. "There's going to be a lot of focus on pheasants and where the pheasant population might go next year."
Unlike native birds such as sharp-tailed grouse, which burrow into the snow for shelter and have feathered legs and feet that basically function as snowshoes, pheasants struggle in severe winter conditions, Williams said.
Ruffed grouse, more common in the forested areas of Minnesota, also burrow into the snow and are well-suited to surviving harsh winter conditions; deep snow is a benefit rather than a detriment.
"One of the things that always makes me nervous about pheasants is spring blizzards," Williams said. "The snow can get them even when they're tucked into good habitat. They end up basically suffocating in those areas where they just stay tucked in."
Cold is less of a factor unless the conditions persist, Williams said.
"It really reduces their body fat, and they're just not as equipped as, say, a sharp-tailed grouse is, to get through our cold spells in North Dakota," he said. "But not having the snowfall definitely is a benefit for pheasants."
Mixed bag for fish
Lack of snowfall also reduces the potential for winter fish kills, which can occur when heavy snow blocks out the sunlight necessary for aquatic plants to produce oxygen. As the plants die and decay, they further deplete oxygen levels, and fish kills can result, especially on shallower bodies of water.
This winter's dry conditions also increase the potential for drought, which creates a whole new set of problems come spring, reducing shallow wetland habitat for waterfowl and shorebirds and depleting spawning habitat for species such as pike and perch.
"We need more snow," said Henry Drewes, northwest region fisheries supervisor for the DNR in Bemidji. "Water levels weren't that high going into the winter, and particularly as you move south, there's not much snow in the southern half of (Minnesota), so we could use some more snow.
"We're going to have thick ice come the end of the winter, but without snow on top, we're not getting winterkill in our rearing ponds, which we want. And then there's not going to be a lot of runoff, which is important for recharging lakes and creating fish runs and all of that, so the winter weather is going to be a factor if we stay dry."
Winterkill reports have been minimal but the lack of snow stands to have a negative impact on new lakes that have popped up across North Dakota during recent wet years, said Greg Power, fisheries chief for Game and Fish in Bismarck.
"We probably have known winter kills on three or four lakes, which is not unusual by any stretch," Power said. "We've lost a couple more feet of water from last year, and I'm thinking water-depth wise on a lot of these lakes, it's getting pretty marginal.
"So far, so good in the big picture, but without getting a serious drink of water in the next year, one of these winters we're going to lose a lot of lakes fast."