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Monday
Apr082019

Deer yards: Shelter from the storm

It’s not easy being a whitetail deer in Maine in the winter, especially northern Maine. The snow piles deep, the frozen winds howl down out of Canada and food is scarce, especially foods that provide the necessary calories to help you cope with the harsh weather.

Enter the deer wintering area. Or deer yard” as it’s commonly called.

White tail DeerFor Maine deer, in a bad winter, these stands of mature softwoods — cedar, hemlock, spruce or fir — can literally be a matter of life and death.

They hold up in these areas to reduce the energy use required for them to stay alive. It’s all about conserving energy. The better the shelter, the less energy they use,” said Ryan Robicheau, the wildlife section supervisor for the Maine Department of Inland Fisheries and Wildlife, and a man who has seen his share of deer yards.

And while those mature softwood forests are important for wintering deer, dozens of other species of birds, mammals and amphibians live there as well.

Though some deer wintering areas can be wiped from the landscape by clearcutting or degraded by development, some judicious timber harvesting can actually provide food for wintering deer while helping regenerate the softwood trees that will shelter deer decades into the future.

Young spruce and fir forests are often thick with trees — too thick to easily walk through in most cases. Older forests are more open. In a mature softwood grove their needle-covered branches shade the ground and intercept a significant amount of snow, reducing the snow depth on the ground. Those same branches buffer the effects of the cold wind. Young hardwoods between the mature trees provide some much needed food and occasionally the winds bring down branches and break out tree tops that will be eaten as well.

Some deer yards in Maine have been used by generations of whitetails. Deer begin migrating into them in the fall. We look at 12 inches of snow to indicate that yarding conditions exist,” said Robicheau. With 16 inches we used to consider deer restricted. It’s directly tied to snow conditions. Sometimes if you get snow in the fall, deer can get pinched out of deer yards, or have a harder time getting to those yards.”

So what’s it like in a deer yard in the winter?

Entering one, you would notice, said Robicheau, that the snow isn’t as deep. There are packed trailsNorthern Maine Deer Yard everywhere. For a good reason: It’s easier to travel on a packed trail. You’ve probably experienced this yourself, it’s the difference between snowshoeing by yourself or in a group where everyone takes turn breaking trail. You would notice that a lot of the understory hardwood branches have been nipped. Deer have to eat and in a harsh winter with deep snow the best they’re likely to get is the relatively tender branch tips, and perhaps some lichens that fall from above.

Deer scat would be everywhere. Some of it might be old:  a deer’s coarse winter diet means their pellets take longer to decompose. You might see dead deer, usually the young or the old. Not everyone makes it through the winter, particularly a hard one, said Robicheau. No matter how good the winter shelter quality is, no matter how good the food source, there’s going to be deer that don’t make it.” You would also see spots where deer have bedded down for the night. And, you might see deer themselves.

In northern Maine the whitetail deer is getting to the northern limit of its range, where snow conditions make it harder to live and the longer-legged, more powerful moose thrives. But thanks to these deer yards, the whitetail deer continues to exist. 

Mature Spruce ForestBiologists figure that, in southern Maine, deer rely on winter shelter from 20 to 60 days, said Robicheau.This winter is going to shake out a little more severe than average.” In northern Maine deer can spend between 90 to 125 days in a yard. You can see the potential difference in mortality.”

In northern Maine deer won’t leave those yards until sometime between mid-March and the end of April, depending on how long wintering conditions persist. That’s a long time to be confined. It would be like your extended family hunkering down in the house for four to six months, rationing your meager supplies of food, husbanding a tiny stock of firewood for the stove and huddling together through frigid nights hoping you’ll make it to one day see the daffodils come up. Stomachs would growl, tempers would flare and everyone would shed weight like they were competitors on a reality TV show.

While deer winter in mature softwood stands, not all softwood stands are created equal. Maine state wildlife biologists recognize two major categories of deer wintering areas, known by the abbreviation DWAs:  A stand is considered “primary winter shelter” when it has 70 percent crown closure and its trees are at least 35 feet tall; “secondary winter shelter” would have 50 to 70 percent crown closure with trees 35 feet tall. The deer, of course, aren’t making such fine distinctions. In the end, the deer will use what is available to them,” Robicheau said.

In the unorganized territories — mainly in northern and eastern Maine —that are under the jurisdiction of the state’s Land Use Planning Commission, there are some 170,000 acres of mapped deer yards. Biologists have confirmed the use of these yards through the decades, though each of them may not be used every year. In the Commission’s jurisdiction they are afforded a level of zoning protection. State biologists have input when it comes to development proposals or timber harvesting plans. If state biologists and the landowner can agree on the details of a harvesting plan, that streamlines the permit review process, said Robicheau.

Basically, biologists look for balance, he said, recognizing that a timberland owner wants to make money onBobcat hunting a logging operation. The overall goal, he said, is to keep 50 percent of a deer wintering area in those primary and secondary classifications, with at least 25 percent in the primary category at any one time. We need at least 25 percent of it to be functioning primary shelter and 25 percent in secondary winter shelter,” he said.

Biologists do consider the condition of the softwood stand itself. Silviculture is a mix of art and science,” he said. If, say, the spruce and fir trees in the stand are nearing 80 years — getting close to the end of their natural lives, they could look at a harvest as an opportunity to rejuvenate the stand. A winter timber cutting operation in a portion of a deer yard has some short-term benefits for deer — the slash serves as food. Some deer respond to the sound of logging machinery like a dinner bell,” he said.

There are fewer protections in most central and southern Maine municipalities, where zoning is handled on a town-by-town level, though if a large development project triggers a site review by the state Department of Environmental Protection, Inland Fisheries and Wildlife biologists could have input.

Biologists take every opportunity to talk to landowners in central and southern Maine about deer yards:  reaching out when a Maine Forest Service timber harvesting permit is sought, or when someone is preparing a forest management plan and asks for information about deer yards on their property.

In central and southern Maine there could be as many as 640,000 acres of appropriate deer wintering habitat, but that’s based on computer surveys, not on the ground confirmation and the reality is likely a fraction of that, Robicheau said.

Downy Woodpecker, Photo courtesy of Maine AudubonIn central and southern Maine, deer depend less on deer wintering areas. They can functionally use smaller and smaller areas,” Robicheau said. In extreme southern Maine 10 to 20 deer could shelter in a small stand of mature softwoods because it wouldn’t be long before they could get out on the landscape again. The difference in climate is a major reason there are far more deer in the southern part of the state.

The whitetail deer is probably one of the most studied mammals in North America, but research continues.

Maine has partnered with the Cooperative Forestry Research Unit at the University of Maine, the state’s native American tribes and the province of New Brunswick in a five-year study to learn more about deer movements and how they survive. The project, now in its third year, involves outfitting some 200 to 300 deer, mainly mature does, with GPS trackers.

Robicheau said the study, which may be extended beyond the initial five-year time frame, is attempting to get information about winter survival, how it compares in different areas of the state, how it’s affected by the practice of feeding deer, how winter severity affects survival, and how deer move around the landscape with the seasons.

One thing that is known about deer and deer yards, is that, if a deer yard disappears, say through clearcutting or development, deer won’t just move down the road like you might move to another apartment if your place gets sold. It’s not an easy thing for deer to find ‘the next deer yard,’ “ said Robicheau.

Deer learn about their” deer wintering area by going there with their mothers. If they start to move to their winter range and the shelter they expected to find is gone, they likely won’t have the energy reserves to plow through deep snow, even if they knew where another deer yard was. They would try to find the best shelter they could, but mortality would likely be high. Over the years the deer that used that disappeared yard could find their way to another yard historically used by deer, but it takes time. What we see is more incremental movement of deer across the landscape,” Robicheau said.

While deer hunters, particularly in northern Maine, know how critical these old softwood forests are for deer, one thing that Robicheau says often gets lost in the conversation is the benefit of these older softwood stands for other species.

Almost three dozen species of birds, 13 species of mammals, and two types of amphibians use the cedar-Yellow Rumped Warbler, Photo courtesy of Maine Audubonspruce-fir-hemlock forests where deer shelter in the winter, according to a list compiled by state biologists.

They range from the boreal and black-capped chickadees to three types of owls and four types of woodpeckers, including the pileated, North America’s largest wood pecker. It prefers mature forests with large dying trees to nest and feed in. Seven types of warblers live in those forests, including the Canada warbler, which likes cool, moist conditions and mature stands, and the Blackburnian warbler, which likes deep forests with swampy areas and bearded lichens.

When it comes to mammals, the fisher, the pine marten, the long-tailed shrew, the bobcat and the northern flying squirrel use deer wintering areas, as well as the common red squirrel, coyote and black bear.

 

Joe Rankin writes on forestry, nature and sustainability for websites and magazines.