Michigan DNR biologists discuss effects of milder winter on wildlife

(Source: Michigan DNR) 

Looking out your window, do you find yourself saying, “This winter is different?”

Remembering last winter, areas of Michigan had not inches, but feet of snow on the ground by mid-November. In stark contrast, this winter, many parts of Michigan didn’t receive any significant snowfall that stayed on the ground, until after Christmas.

With the effects of one of the strongest El Nino weather patterns on record – warmer Pacific Ocean waters producing atmospheric changes in weather thousands of miles away – this winter certainly is different.

As a result, weather forecasters are predicting above-average temperatures and drier than normal winter conditions across the northern tier of the country, including Michigan.

Michigan Department of Natural Resources wildlife biologists have been fielding inquiries about how the milder conditions might be affecting wildlife this winter.

“The 2014-2015 Michigan winter had record low temperatures for numerous days,” DNR Wildlife Division Chief Russ Mason said. “Along with those cold temps, winter brought snow depths that challenged even the most adapted wildlife.”

Waterfowl

Several mallards and Canada geese are shown in a stretch of open water.Less than a year ago, waterfowl were being negatively affected across Michigan by lakes, rivers and streams freezing completely, or more extensively than usual, leaving smaller areas of open water for ducks and swans to feed. After the last two hard winters, this winter is providing many open water locations.

“Instead of ducks being concentrated in small areas, ducks and swans have good amounts of open water in a mild winter, giving them room to forage and find the food they need,” said Barbara Avers, a DNR waterfowl and wetlands specialist.

The last two winters resulted in some malnourished or dead waterfowl being trapped on the ice, unable to fly. Not this winter.

Smaller mammals

Squirrels never take a break. They are active all year long, and this mild winter provides an easier hunt for food. Less snow to get through equals less energy needed to find food and stay warm.

With a milder winter, snowshoe hares are likely to be under a bit more pressure from predators. Their fur is light brown in the fall and molts to white as the amount of daylight changes. Until snow is on the ground, the white fur stands out, allowing hawks, owls and other predators better opportunities to benefit.

Alternatively, hares this winter should have plenty of food they can easily access.

Skunks and raccoons go into an inactive or dormant state in the winter. This is something they are naturally wired to do to conserve energy. This won’t change with the mild winter. Their late winter mating seasons, won’t be affected. As usual, they will be out and more visible for brief periods of time looking for a mate.

Large mammals

Black bear have this same instinct; their internal clock is telling them they need to conserve energy, regardless of temperature, find a place to den and go into a deep sleep.

What is frequently referred to as a bear hibernating is really a bear in a very deep sleep. Even with the warm fall and warm December, a bear will still den. Black bears also den in southern states, where temperatures and snow levels are much more moderate compared to even a mild Michigan winter.

Bears are triggered to enter their dens by a combination of things, with the amount of daylight being an important main factor. Bears are able to survive the denning period because they bulk up during the fall, gaining 1-2 pounds per day.

Not all animals will benefit from this mild winter.

“Moose are a species that are just built for the cold,” said DNR wildlife research biologist Dean Beyer. “Moose are at their southern extent of their range in the Upper Peninsula.”A moose cow with calf are shown photographed in Marquette County.

Moose, with their long legs and thick winter coat, are built for deep snow and cold temperatures. When moose have their winter coat, and temperatures are warmer than 23 degrees, they become stressed and need to take action to cool down.

“When an animal is stressed, its heart and respiration rates will increase, in turn increasing the amount of energy they are using,” Beyer said. “This December was probably stressful on Michigan moose, as temps were warmer than they normally experience.”

Deer, on the other hand, will find some relief with a mild winter.

For winter survival, deer reduce their movements by about 50 percent and their food intake by about 30 percent. Mild temperatures allow deer to survive on the layer of fat they’ve built up the previous fall.

Just like with moose, the more deer move in the wintertime, the more energy they use. However, deer, with their shorter legs, should be able to find the little food they need in the winter accessible, above and below the snow.

In the Upper Peninsula, the effects of three consecutive harsh winters, combined with the contributions of predators, have been tough on deer populations. Though wildlife biologists caution that one mild winter will not be enough to allow the herd to quickly rebound, the moderation in conditions is beneficial and welcomed.

Birds

Wild turkeys will also have an easier time in a mild winter. Typically at higher snow depths or when a hard snow crust is formed, turkeys rely solely on fruits, nuts and catkins on trees and shrubs – food found above the snow.

When possible, turkeys will continue to scratch through the snow in farmed fields, getting the valuable crumbs left behind by farming equipment, and can even find acorns and beech nuts in the woods.

Ruffed grouse may be more susceptible to predators, without several feet of snowy insulation. These birds can almost dive into the snow and burrow, staying warm and concealed. They typically do well during those hard winters.

Migrating birds generally started leaving and heading south months ago. Therefore, this unseasonably warm winter is something they’ll realize only when they return in the spring.

Some migrating birds that leave relatively late, like sandhill cranes, may stay behind as long as they can find the food they need to make it through the winter, but will continue south if temperatures drop.

Birds like American robins, eastern bluebirds and hermit thrushes may remain in the state in small numbers, because of the mild weather and availability of berries and seeds.

Resident backyard birds, like blue jays, American goldfinches, northern cardinals and black-capped chickadees will use less energy keeping warm during a mild winter, which can result in better body conditions and larger egg clutches or broods of chicks in the spring.

Outlook

So far, the milder winter we’ve experienced has been a welcome break for many people and some wildlife that have had a hard go the last few winters. Although we may think this relative lack of snow and warmer temperatures make this winter different or easier, the winter is certainly not over.

For many animals, the next couple months could still be challenging. However, animals have habits or instincts and are hard-wired to survive. They will adapt.

For more information, visit the DNR’s webpage at www.michigan.gov/wildlifeactionplan.