What You Can Do to Help Deer Survive the Harsh Winter

By: John Cristinziani

There aren’t many times during the year in which deer experience a low-stress lifestyle. As winter covers Canada, deer herds are in a major nutritional decline.

In many areas, it’s extremely difficult for deer to consume the 6 pounds of food intake their bodies require each day once winter grips the landscape. As a result, deer in northern climates can often lose as much as 30 percent of their body mass by the time spring arrives and provides plentiful browse.

While spring, summer and fall present unique challenges for deer, winter is by far the hardest period of year for them. The elements are harsh and can be unforgiving, and the numerous challenges that accompany extreme temperatures, snow and ice can wage a physical battle on the condition of the herd.

Fortunately, deer are built to endure and thrive, and they have the ability to overcome the most adverse circumstances during any given season. 

A Deer’s’ Physiological Changes and Needs

Deer have the proper physiology to survive during winter, but they need food and cover to sustain it. During harsh winters, deer mortality can be devastating if they lack food and cover.

The determining factor if a deer will survive the winter or how it will fare by the end of the season depends on if its physical condition and if its nutritional needs were met during the previous fall. Studies suggest that it’s important to consider the timing of winter and spring in any given year. An early winter combined with a later spring, for instance, can add an extreme amount of additional stress that is tough for deer to overcome.

Healthy deer typically go into winter with fat reserves that provide an indirect source of energy when a deer’s habitat offers little to no food or forage. Deer need to conserve energy during winter, because if they burn more calories than they consume for a long period, death will soon follow. During stressful periods like this, a physiological change occurs that results in a decreased metabolic rate.

With little nutritious forage and browse available, deer undergo physiological changes throughout the winter. It is their internal survival mechanisms that are key to surviving the winter. Finding sources of carbohydrates, protein and essential nutrients can be really difficult, resulting in a lower caloric intake.

The only way deer can survive especially severe winters when food sources are limited is to conserve as much energy as possible to ensure their fat reserves aren’t depleted by winter’s end. The only way for them to accomplish this is to naturally and gradually decrease their activity levels.

Smaller-bodied animals lose body heat more quickly. Large body size conserves energy better because of a lower surface-to-mass ratio. This is why it’s vital that deer take advantage of the energy and carbohydrate-rich foods when they’re available which is primarily during the spring, summer and fall months. . This could mean the difference between surviving the winter and not.

Keep in mind that by the end of the rut a deer’s fat reserves have already been dramatically depleted. By the time the rut is winding down, dominant breeding bucks are often pretty lean, and, to make matters worse, they don’t really have a great recovery opportunity in a Country like Canada. By the time the rut ends, winter has already arrived and food is likely scarce in most areas.

For these reasons, bucks often head into winter depleted and stressed from the rigors of the rut, while does are growing fawns and perhaps even still nursing their previous offspring. Fawns are also especially vulnerable during the winter if their mother didn’t receive adequate nutrition while pregnant or if the fawn had a later birthdate.

Studies show that a deer’s lowest metabolic rate is during the month of February. Once does enter the last half of the gestation period, when fetal growth increases rapidly, the metabolic energy significantly increases. If does can’t get an adequate amount of nutrition in their food sources, they can become so run down they actually absorb their unborn fawn.

Externally, the role of a deer’s winter coat is to insulate against the cold. A deer’s winter coat is darker and actually absorbs solar energy. The rough, hollow guard hairs of their winter coat are longer and provide protection and insulation by trapping air, but it’s the finer hair underneath that really affords the greatest insulation value. As a result, their well-designed coat not only absorbs heat, but it also insulates against heat loss.

Enhancing Deer Survival

In addition to harsh winters, deer also face threats from predators. From hunters to coyotes to even mountain lions and wild boar in some areas of Western Canada, predators can cause a lot of stress on deer during the winter. Hunters can really help deer and other wildlife by eliminating their share of predators, and hunting and trapping predators such as coyotes is a great wintertime management effort to keep a deer herd’s stress at a minimum.

I certainly don't pretend to be a great coyote hunter but I make a concerted effort at predator control, especially during the winter. I also try to help by encouraging friends and neighbors to do the same. If they can’t hunt them then they can trap them. If they don’t have a trapper’s license, maybe they can hire the services of a professional trapper or at least allow access to their properties from a trapper. Can you imagine if only 50% of hunters in every province harvested just 1 coyote annually during the winter how many hundred of thousand less there would be roaming the country.

Hunters can also help deer during the fall months by providing additional habitat and food sources so deer can enter the winter season as healthy as possible. 

In addition to providing fat reserves, additional food sources also help sustain deer and recoup from rut stress. Let’s point out that this is another important reason why food plots are so vital to the herd. Yes, the plots do indeed provide many deer encounters throughout the hunting seasons by attracting does in estrous and hungry or rut-crazed bucks. More importantly, these quality food sources planted with “Annual” plants, really help the does, bucks and fawns to build essential fat reserves to help get them through the punishing winter months. 

I am fortunate to have the ability to plant several acres of food plots for the deer herds on the properties that I own or lease. Brassicas, radishes, sugar beets and turnips are high in carbohydrates, and carbs are what deer need to generate warmth during freezing winter conditions. I make sure that I provide several acres of these plantings ever year for my deer. I highly recommend all four for a perfect combination of late-season attraction and wintertime nutrition. Whitetail Institute provides several seed blend mixes that contain these quality high-carb plants like; Winter Greens, Winter Peas Plus, Tall Tine Tubers or Beets & Greens.

If you don’t have the ability to provide food plots, you can always put out cracked or whole corn, alfalfa bales or a quality designed commercial deer feed if and when it is legal to do so in your area. Stay away from deer-type pellet feeds as they tend to swell and mold (just like a dog food pellet does when it falls in the water) when they come in contact with water/melting snow or condensation. However, if you choose that route make sure you don’t stop, or you could cause more harm than good to your deer. Providing food sources is excellent, but remember that keeping it close to abundant cover and thermal habitat is absolutely critical.

As a deer manager, providing habitat that has everything deer need to survive winter can also truly make a difference. These areas should be protected from the elements and have thermal cover consisting of native grasses like Switchgrass or mature conifers of cedars or pine next to food sources. You want to minimize the travel distance that the deer will undertake to get from the food source to their thermal cover therefor minimizing energy for the deer.

Cedar groves, make great winter deer yards. They provide critical thermal cover, as their dark-green foliage absorbs heat from the sun, and they also provide protection from harsh winds and accumulating snow on the ground.

Good wintering areas like these also offer escape cover where deer can flee or remain hidden from predators. So, to help the herd in your hunting area, consider planting cedars or establishing a few acres of warm-season grasses this spring or summer.

Deer will search out wintering areas where they can conserve energy. They begin eating less and moving less. Their feeding patterns seem to rely heavily on temperature and weather patterns.

A very respected Deer Biologist that I know estimates that deer movement starts to slow down when temperatures dip to around - 10 degrees Celsius.

If you get below-zero temperatures or heavy snow fall and wind for extended periods of time, you can even have deer that stay bedded-up for several days. Movement can be dramatic just before or just after periods of heavy snow or blizzards, as deer feel the need to fill their stomachs and gain energy to burn.

When deer needlessly have to expend large amounts of energy it really hurts their chances of survival. So be sure to give them space and keep their stress low by reducing predators, providing food sources and adequate cover. Also, do your best to stay away during late winter, or you’ll risk causing unnecessary disturbance and stress. Try and avoid snowmobiling or ATV activities or snowshoeing in areas where you know that deer are using as winter cover.

The impact on farmers 

Farmers grow abundant food sources which deer use during the spring, summer and fall, but once the crops are harvested and covered in snow, it’s often a vast wasteland out there. As a result, what often happens during severe winter weather are seasonal relocations and sometimes migrations to winter yarding areas. In the many parts of Canada, more times than not, this means right next to or into a farmer’s livestock feed stores.

Each winter varies depending on its severity, but this crucial time can be extremely taxing on deer herds as their primary focus becomes all about surviving by exerting as little energy as possible. However, their survival instincts will often put them in direct conflict with producers.

Private landowners and farmers don’t own the deer, but they sure as heck feed the majority of them. Let’s help do our part in managing our resources and keeping tolerance levels manageable for producers.

The elements of food, water and cover are all very necessary elements to sustain wildlife. By providing food, boosting wintertime cover, and managing predators and winter stress, we can help our deer herds get through this difficult time.

Our home property holds more deer through the winter than any other time. The reasons are simple, and they’ll always be the same — food, water, cover and security. Even if you don’t own land, knowing what deer are going through and helping out when and where you can is within every hunter’s reach, and every hunter can do their part to help.

Always make it a point to respect the land, respect the landowner and respect the wildlife.