Wildlife in Winter

Nov. 27, 2017
Canada Lynx

From frozen lakes to 24-inch snowfalls, New England’s powerful winters bring dramatic changes to landscapes and ecosystems across the region.

Wild animals have three main options in the face of these winters: migrate to more hospitable climes, find a cozy place to hibernate, or endure the season’s often punishing conditions. Those that stay and withstand winter have adapted to deep snow, darker days, and extreme cold in fascinating and wondrous ways.

This post explores the seasonal adaptations and behaviors of four species found in New England’s winter forests: the Eastern Moose, Canada Lynx, Great Gray Owl and Northern Hawk Owl.

Each winter, these species navigate forest ecosystems very different from summer’s peaceful and sun-dappled landscape. Tasks like finding a tree to shelter under are impacted by the season, as deciduous forests in winter are often colder than nearby coniferous ones. Wind and snow howl through leafless deciduous trees, while evergreens’ dark needles and snow-covered boughs combine to form an insulating blanket.

All four animals grapple with challenges like finding food in these transformed and snow-ridden forests, but they go about the business of enduring the season in very different ways.

Keep reading to learn how the three predators—with their thick fur and feathers, their silent feet and wings—are well equipped for the coldest months of the year, while the herbivorous moose has a harder time coping with winter conditions.

Eastern Moose

Eastern Moose, photo by Larry Master

Eastern Moose

Scientific name: Alces alces americana

Aquatic plants, or the lack thereof, lie at the heart of the Eastern Moose’s winter struggles.

New England-based moose rely heavily on sodium-rich aquatic vegetation and other high-quality forage during warmer months. These resources disappear in winter, and so moose undertake a season-long battle to provide their immense bodies with sufficient energy when only lower quality, woody browse is available.

In the fall, moose gear up for the lean days ahead by growing a thick winter coat and accumulating as much fat as possible. They metabolize this stored fat throughout the winter—and lose a great deal of weight in the process—to compensate for seasonal malnutrition.

Bull moose also save energy in winter by shedding their antlers, which can weigh up to 40 pounds. Carrying that much extra weight would be a poor use of already taxed energy reserves.

Moose have one more trick up their sleeve: Read about their winter diet below to see how moose’s unusual leg movements help them find food in snowy weather.

A Moose’s Winter Diet

Northern New England’s woods in winter form a moose cafeteria. Our largest regional herbivore eats the twigs, buds and small branches of almost any shrub it can reach. One study in Maine that examined oven-dried moose dung found that moose consumed balsam fir, beech, hawthorn, poplar, maple and even poison ivy. Another study about what captive moose would eat when placed in wild settings found they consumed more than 100 different species of plants.

And no matter what is on the menu, moose eat a lot of it. They are estimated to consume anywhere from 20 to 60 pounds of twigs a day in winter. As a result, moose browse can have a major influence on how quickly forests regrow.

In landscapes where moose and North American Beaver are both abundant, moose will often browse extensively in open “beaver meadows,” the grassy areas left behind when beavers temporarily abandon a dam after exhausting the food around it. Moose browsing can keep these meadows open for additional years, spacing out the return of beavers to their former pond, and perhaps even limiting beaver populations at a landscape scale.

To consume such vast amounts of food, moose rely on their ability to move around in deep snow. Unique joint construction allows moose to lift their legs straight up out of snow banks, which helps them move swiftly and efficiently even in deep snow. While this ability makes snow less of an obstacle to moose than to deer, they still prefer hard-packed surfaces like snowmobile trails when they can find them.

So, look out for nature’s winter lawnmower when you’re in the backwoods of northern New England.

Canada Lynx

Canada Lynx, photo by Larry Master

Canada Lynx

Scientific name: Lynx canadensis

Facing a fierce New England winter as a kitten is surely a daunting task, so it’s a good thing Canada Lynx spend their first 9-10 months with their mothers.

This means that when kittens take their long, lanky legs and enormous feet out onto snow banks and slippery ice for the first time, they do so under parental supervision. This is what the youngsters were born to do, even if their steps are initially a little ungainly—lynx are true winter specialists.

In New England, the federally threatened Canada Lynx is found in the northern forests of Maine, New Hampshire and Vermont. This mid-sized cat primarily hunts Snowshoe Hare, so much so that lynx will only settle in territories that have established hare populations. They stalk and ambush hare and other prey from the ground even when there’s deep snow cover; this is also a skill set passed onto juveniles by their mothers.

Several adaptations allow lynx to live in the harshest of conditions, including a dense winter coat and excellent night vision that serves them well when days grow short, but their feet are what really set the cats apart.

Their snowshoe-like paws have an unusually large surface area relative to the lynx’s weight, and they become even broader when the cat is on the move thanks to easily spread toes. Add in some thick fur between the toes, and you’ve got feet that move smoothly over soft, deep snow.

Balancing Lynx and Marten Habitat

Snowshoe Hares’ preferred habitat is young and dense softwood forests, and where Snowshoe Hares go, Canada Lynx follow. In northern New England, this type of forest forms primarily as regeneration following harvests or large-scale natural disturbances. Young forests, with their abundant sunshine and generally higher summer temperatures, also provide foraging habitat for some insect-eating birds, including some that prefer to nest in mature closed-canopy forests.

These young forests and the harvesting that often precedes them are not ideal for all species, however. In an effort to protect habitat for a broad array of wildlife, NEFF and other regional organizations are focusing on developing a prescription for Exemplary Forestry. Exemplary Forestry will continue to deliver the wood products society needs, while also providing a balance of forest management strategies to support the very different habitat needs of two key species: the Canada Lynx and the American Marten.

In contrast to lynx, marten need large tracts of mature forest and a latticework of tree cover, and their preferred habitat combined with that of the lynx represents a wide range of forest ecosystems. Forests that are managed to protect the habitat of both species will collectively benefit more than 75 percent of other forest mammals, birds, reptiles, and amphibians.

Great Gray Owl

Great Gray Owl, photo by Larry Master

Owls of the Far North

Imagine walking at night on a solid crust of snow—one of those “bulletproof” crusts that will hold full-grown adults. Suddenly your flashlight catches a hint of movement, and a huge owl plunges down from above and punches through the crust to grab a mouse.

The Great Gray Owl, which employs this powerful hunting technique, and the Northern Hawk Owl are both adept at surviving incredibly harsh winters.

They live year-round in the boreal forests of Canada and Alaska, and their ranges extend as far north as the tree line—the very top of the forested world. They also have populations in the forests of Northern Eurasia, and in the case of the Great Gray Owl, the Pacific Northwest.

While they don’t migrate to escape winter weather, they are known to wander and will sometimes relocate within their usual ranges in search of food.

Periodically, groups of these raptors go even further afield into the northern United States in wintertime movements known as irruptions or invasions that are triggered by food shortages. New England is a common touchdown point in these years, and what a remarkable sight Great Gray Owls and Northern Hawk Owls make when they spend the winter in local forests.

Great Gray Owl

Great Gray Owl, photo by Larry Master

Great Gray Owl

Scientific name: Strix nebulosa

Great Gray Owls are one of North America’s tallest owls, reaching nearly three feet in height, but a great deal of their bulk is made up of feathers and they weigh less than the shorter but less-feathered Great Horned Owl. This added insulation, which can stand up to bitter cold, is just one of their several seasonal adaptations.

These birds’ asymmetrical ear openings—the left is higher on the head than the right—help them hunt by sound alone, even if their prey is scurrying around under a thick layer of crusted snow.

When they make their move to grab prey with needle-sharp talons, they can reach rodents and other small mammals more than 15 inches below the snow.

Great Gray Owls have one other interesting way of interacting with hard snow. While they rarely walk on bare ground, they walk and even run easily on solid snow crusts.

Northern Hawk Owl

Northern Hawk Owl, photo by Maxime Légaré-Vézina

Northern Hawk Owl

Scientific name: Surnia ulula

Northern Hawk Owls illustrate one of the realities of researching species well suited to harsh conditions and remote wilderness: Scientists sometimes struggle to reach the animals in question, let alone study them.

Northern Hawk Owls’ low population density in their usual range provides an additional challenge, and very few studies have been conducted about their breeding biology in the spring and summer in the far north. This means their southward irruptions provide a useful opportunity to observe the birds, though many questions remain.

One aspect of the species that is well documented is the reason for its name. Their behavior, flight profile and body structure are unusual for North American owls, and resemble those of some hawk species like the Cooper’s Hawk—another forest raptor.

For example, Northern Hawk Owls have similar diets and hunting habitat to Great Gray Owls, but they depend more on eyesight than hearing for hunting, and hunt primarily in daylight. Their ability to spot prey up to half a mile away is beneficial in any season.

Their reliance on eyesight doesn’t hold them back in winter. Their hearing is still sharp, and Northern Hawk Owls are able to locate and catch prey hidden up to about 10 inches under snow.

One major concern for wild animals that remain in winter-bound habitat is the absence of liquid water, and this is another area where Northern Hawk Owls have demonstrated season-specific skills. They have been observed eating snow after consuming prey and taking snow baths, two useful workarounds.

Writing by Tinsley Hunsdorfer. Top Great Gray Owl photo by Judd Patterson.