However, their survival as a species is ultimately tied to habitat: food, water, and cover. For the Rocky Mountain mule deer that inhabit the western interior of the continent, access to adequate winter range is crucial.

Characteristics of a Survivor

Mule deer have evolved unique strategies to cope with winter. First and foremost, they are migratory, moving from higher elevations to lower winter ranges at the onset of cold weather and winter snows. However, even before they begin migrating, their bodies are undergoing remarkable changes. Probably the most obvious change to the eye is a change in pelage color from reddish-brown to gray-brown. This change typically begins in August.

Pelage is the coat of hair that functions primarily as insulation, regulation of heat loss from the skin surface, and absorption of heat from the environment. The fall molt is triggered by changing light levels. The winter pelage is characterized by a dense woolly under fur which also gives the grayish overall color. The pelage also contains long guard hairs. During extreme cold, the guard hairs can be raised to create air spaces that provide additional insulation to maintain core body temperatures that range from 96-104 degrees Fahrenheit. In winter, a mule deer may curl up, fluff its hair, shiver and constrict its muscles around blood vessels. This actions limits the blood supply to the skin thereby reducing heat loss.

Well before any of these changes are visible, mule deer are preparing their bodies for winter. Mule deer energy demands and food intake vary drastically by season. During the spring and summer, mule deer energy intake is the highest, while energy demands are the lowest. This results in the animal building energy reserves in the form of fat. During winter, the reverse happens.

To cope with the increased energy demands to maintain body temperatures when forage is reduced, mule deer alter their activity patterns to take advantage of what is offered them. Deer will feed where the snow is soft and the depth shallow. They will avoid moving or foraging in deep snow because the high energy costs. In early winter they can be found feeding on hillsides, under trees, and other areas clear of snow. When snow depths exceed 17 inches mule deer will leave these areas.

Mule deer will paw in soft snow to obtain food but resort to feeding on plant parts that protrude above it when the snow is hard. They also will climb snow banks to feed on low hanging branches. However, they will avoid moving around on hard-crusted snow. This is why they tend to be more active late in the day later in winter. Late winter activity peaks occur around noon and the early afternoon. On cold winter nights, with clear skies, mule deer will seek out thermal pockets that radiate heat. These pockets include sun-warmed hillsides or inversion layers.

Probably one of the most unique adaptations to reduced food availability is the ability to lower their metabolic rate by over 70 percent. Mule deer have demonstrated an ability to reduce food intake and metabolic rates (fast) for several months and withstand weight loss in excess of 40 pounds. During these periods, when energy intake may be below the fasting metabolic rate, activities such as dog or snowmobile chases quickly deplete energy reserves and greatly increase mortality.

What about this winter?

There is no question that severe winters can have a significant impact on local mule deer herds. The combination of early, heavy snows coupled with prolonged cold can result in large-scale die-offs. Extensive mule deer die-offs also can occur in winters of deep snow when little forage is available regardless of temperature. Whereas little mortality may occur in cold, dry winters when forage is readily available. In addition to direct morality caused by starvation, the effects of severe malnutrition on the survivors can impact reproduction. Hence, herd recovery for several years is reduced.

Can supplemental feeding help?

In efforts to avoid these undesirable consequences, many people believe that supplemental feeding is the answer. There is no doubt that deer will do as well or even better on artificial feeds than natural forages. This fact alone makes it reasonable to assume that supplemental feeding can prevent deer starvation. Thus, in theory, supplemental or emergency feeding should reduce the annual variation in mule deer numbers by mitigating the effects of server winters. In practice however, supplemental feeding has generally failed to prevent starvation of mule deer in the Rocky Mountain range.

Arguments against feeding?

There are several arguments against the use of supplemental feeding. First and foremost is that many artificial feeding programs are started too late in winter. At this time, mule deer rumen microorganisms have already adjusted to the poor diet. A sudden change in the diet can cause severe physiological complications that could kill the very animals that were intended to be saved. Other concerns include increased incidence of disease transmission and impacts on natural habitat when animals concentrate in feeding areas. Of particular concern is chronic wasting disease.

In addition, there is the chance that animals will develop a dependency on the handouts. If the feeding is done along roads or near human habitation, the deer also may experience increased mortality because of collisions with vehicles. And last, but not least, is the cost. Once feeding is started, it must be continued until natural food become available.

Winter feeding guidelines

Recognizing that supplemental feeding may be needed under certain circumstances, some mule deer states have adopted policies to govern the practice. For more information on these policies visit the web site www.muledeernet.org. In some states, private supplemental big game feeding programs are against the law.

For those determined to feed, here are some guidelines to consider.

1. Start feeding early - By starting in early December you may be able to help those animals that came into winter with low energy (fat) reserves. Delaying feeding until late winter with not help these animals.

2. Avoid commercial livestock feeds - Using commercial feeds developed for livestock could kill deer rumen microorganisms and ultimately the deer. Use feed processed for big game. Start slowly to allow the animals to adjust to the feed.

3. Feed often- Use smaller amounts and feed during the morning and night. Increase the amount you feed during colder weather.

4. Be careful where you feed - Locate feeding areas where animals do not have to cross roads, fences, or other obstacles. Feed on hillsides or near ridge tops. Move your feeding areas frequently. Try to select areas that offer both thermal and escape cover nearby. Feed along established trails. This will avoid impacts on natural vegetation.

5. Avoid competition - Do not feed deer and elk together. Elk are more aggressive than deer. If elk move into the area that you are using to feed deer, move it!!

6. Monitor the operation - Keep track of the amount fed and the number of animals using the site. If you notice more animals using nearby hillsides than the feeding sites, reduce the amount of feed.

7. Maintain the site - Once you start, be ready to finish. This means you need to be willing to continue the operation until the animals stop visiting the site.

Save the deer - Focus on the Future

Many wildlife biologists consider winter range as being the weakest link in the big game management cycle. Thus, the key to sustaining mule deer populations in the west is not supplemental feeding, but in the protection and enhancement of important winter ranges. This task will be made more difficult as human populations increase. Until sportsman and sportswomen are ready to unite and make a concerted effort to restore winter ranges in the west, the fate of mule deer will hinge in the balance.
The decision is in your hands. The Score Sheet