Field Guide to January 2023

“Who” Lays The First Eggs?

By Kent McFarland

Listen for Great Horned Owls advertising their territories with deep, soft hoots in a stuttering rhythm: hoo-h’HOO-hoo-hoo. It can carry a mile or more. Both sexes hoot, with the female call higher pitched and consisting of 7 or 8 syllables. Even though the female Great Horned Owl is bigger, the male has a larger voice box and a deeper voice. Pairs often call together, with audible differences in pitch.

Great Horned Owls are one of the earliest species to nest in the Northeast, often brooding eggs as early as January. For nesting sites, they use old hawk, eagle, heron, or osprey nests, squirrel nests, tree hollows, or cliffs. Check out the Vermont eBird map to see all the sightings reported in January. From the first to the second Vermont Breeding Bird Atlas, Great Horned Owls decreased by 33% (57 to 38 blocks), with the greatest decrease in Taconic Mountains.

If you hear an agitated group of cawing American Crows, they may be mobbing a Great Horned Owl. Crows may gather from near and far and harass the owl for hours. The crows have good reason because the Great Horned Owl is their most dangerous predator.

Great Horned Owls are covered in incredibly soft feathers that insulate them against the cold winter weather and help them fly quietly in pursuit of prey. Their short, broad wings allow them to maneuver in the forest while hunting prey.

Winter Lodging

By Emily Anderson

When life gives you flowing water, you dam it. At least, that’s the motto of beavers. These furry engineers are a common sight on many of Vermont’s streams, marshes, ponds, and lakes; however, they vanish when winter sets in. But they don’t hibernate. Beavers remain indoors when the weather turns cold, living out the winter on edible tree branches stored underwater near their lodge. A family of eight beavers requires about one ton of bark to make it through the winter. This means that they spend the fall busy as, well, beavers in order to amass enough wood to last them until spring arrives.

Underwater is not the only place where beavers store sustenance. Much like other animals that overwinter in the north, beavers put on a layer of body fat to stay warm and provide insurance against food shortages. In particular, a beaver’s tail is designed to store fat and shrinks as its supplies are depleted. In emergency food shortages, beavers will venture onto land. However, their ambling gait and deep snow make them easy prey for predators like coyotes.

Besides food, warmth is the other factor crucial to a beaver’s survival in winter. Luckily, beavers’ thick, waterproof fur provides excellent insulation against both cold temperatures and freezing water. Beaver lodges also trap heat reasonably well, keeping the interior above freezing even when the outdoor temperatures are below zero. The more individuals who can contribute body heat, the warmer a lodge remains. And sometimes, the beaver family is not alone in their lodge. Occasionally, muskrats and mice will join the beavers, sharing the warmth and safety provided by the lodge.

For more information on beavers in winter, listen to this episode of Outdoor Radio. If you want to learn more about beaver’s life cycle and history in Vermont, check out their VT Fish & Wildlife Department webpage.

Peeling Bark

By Kent McFarland

While snowshoeing in the high elevations of the Green Mountains of Vermont recently, I was struck by how many large White Birch (Betula papyrifera) trees there were. All of them had the telltale peeling paper-like bark. Some of them with long strips flapping in the cold wind. And then it struck me, why does birch bark peel?

On my hike back, I came up with a couple of ideas. Maybe as the tree grows, the weak bark splits and peels away, exposing new skin underneath. Sort of like a snake that sheds its skin as it grows. The bark is white for a reason, I suspected, so maybe they peel just to stay clean. But why do they need to be white and clean?

It turns out that this unique characteristic may allow birch trees to shed lichen and moss that grow on their trunks over time. The epiphytic curtain covering the trunk darkens them, causing problems for the tree in both winter and spring.

In the early spring, birch bark can photosynthesize, giving the trees a head start before any leaves are fully opened. This is an excellent advantage for a pioneer species like White Birch because it can grow before other trees have leaves closing the canopy.

The biggest advantage may be during the winter. Darkened trunks can be disastrous for birch trees. The sun is low on the horizon during the winter and its rays strike more directly on the trunk. White bark reflects the sun on bright cold days. Even in the dead of winter, the sun is quite intense. Stand with a pair of black ski pants facing the sun, and even when it is brutally cold, you can feel the sun heat your legs as the black fabric absorbs the sun’s energy. But, when a birch trunk warms from the sun on frigid days, it can lead to frost cracking as it expands and contracts quickly. Cracks in the trunk can heal with scar tissue, but more often, it leads to the trees slow demise as rot and disease attack the wood. Shedding bark keeps the tree clean and healthy.

Ruffed Grouse Warm Under a Blanket of Snow

By Kent McFarland

Where’s the warmest place for a bird to spend the night? Depending on the temperature, it might be subnivean. With the air temperature dropping well below freezing, a deep blanket of snow might be the insulation that separates life from freezing death for a Ruffed Grouse. You can find places they’ve roosted by the marks in the snow showing where they entered and where they exited their winter den. They may even burst out of the snow in front of you, frightening you into a warmer state. On a warmer night or when snow conditions are poor, grouse may settle for roosting in the branches of an evergreen tree.

Each fall, Ruffed Grouse grow comb-like rows of bristles (called pectinations) on their feet. These create a “snowshoe” effect for the grouse, allowing them to walk on the surface of the snow. Grouse also have extra feathers covering the beak’s nostrils to make the air slightly warmer as it enters their airways, like a balaclava mask you might wear on a cold winter day.

Deer Yards: Key to Winter Survival

By Kent McFarland

White-tailed Deer survive the harsh northern winters using specific winter habitats, what most of us call deer yards.” These areas have ample evergreen trees for cover on slopes that often have a southerly aspect, providing protection from deep snow, cold temperatures, and wind. Deer yards might be only a few acres to perhaps as large as 100 acres. If conditions remain the same, these yards can be used for generations. Deer may migrate from miles around in late fall to use these areas for the winter. The deer cut their metabolism in half during this time of scarcity in an effort to make it until the lush spring grasses arrive.

Deer yards are also important for other wildlife: porcupines, snowshoe hares, foxes, fishers, coyotes, bobcats, crows, ravens, crossbills, owls, and more. Human encroachment or forestry operations can have a devastating effect on these stands and the wildlife that rely on them. Deer yards make up a small percentage of the land—only 8% of the forested landscape of Vermont has been identified as deer yards.

Listen to Outdoor Radio as they visit a deer yard and talk more about these critical habitats.