What's in this issue?
How do wild birds deal with the rough weather in winter? How can you help them?
BIRD SURVIVAL IN WINTER
By Suzanne McCarthy
How do birds manage to survive the winter? We have several species that stay in South Jersey for the winter, rather than migrating away. Others arrive for the winter, such as Dark-eyed Juncos. Some are tiny, such as chickadees and kinglets, and it’s hard to understand how they can keep their body temperatures at a high enough level to make it through snowstorms and low-temperature nights..
This article focuses on the physiological and behavioral adaptations that birds use in winter. A recent article by Tony Klock for the newsletter of Citizens United to Protect the Maurice River that also appeared in South Jersey News, provides an excellent overview of the species that stay or migrate into South Jersey for the winter. See that at https://cumauriceriver.org/wp-content/uploads/2025/01/Bird-Story-Tony-Klock-with-SNJ-web-sm-2.pdf.
There are several mechanisms that birds utilize in winter. The most important is to maintain their body temperature by fueling it with food. The second is to prevent any excess heat loss, which they do via feathers, one of nature’s most effective insulators.
Calories enable birds to generate the most body heat and foods containing fats and carbohydrates are the best sources for these. That’s why birds are attracted to the sunflower seeds and suet at your bird feeders. Those pack the most punch for the item consumed. But food is still difficult to find in the winter. Birds, especially smaller birds, spend nearly all the hours of the day hunting for food. Chickadees are known to eat more than 35% of their body weight each day.
Smaller birds never sit still. Their constant movement also helps them to retain their body heat.
According to the American Bird Conservancy (ABC), different birds rely on a variety of foods in winter:
• Sapsuckers tap into the sweet sap flowing under tree bark, leaving sap wells for other birds to feed from.
• Chickadees, nuthatches, and other birds are able to locate and eat dormant and larval insects by carefully inspecting crevices and cracks in tree bark.
• Blue Jays, waxwings, Hermit Thrushes, Yellow-rumped Warblers, and American Robins feed on the berries of junipers, honeysuckle, holly, and other plants.
• Jays, titmice, finches, and other birds feast upon fallen acorns and pine nuts.
• Seeds, grain, carrion, and small mammals provide additional cold-weather food sources for a variety of bird species.
Birds often appear larger in winter than in warm weather because they fluff up their feathers to maximize the insulation effect. Their downy feathers trap pockets of air next to their bodies. Birds can also shiver, which generates more heat. But despite their super-warm covering, many birds still depend on communal roosts at night, huddling together and sharing their warmth. This is especially true for smaller birds such as finches, nuthatches, wrens, bluebirds, and others.
Blue Jays and Northern Cardinals take refuge in dense evergreen foliage; finches roost together on coniferous trees but will sometimes burrow and create short-term sleeping hollows in snow; woodpeckers, titmice, and nuthatches prefer to roost in tree cavities. Roosting in protected areas has the added benefit of providing security from predators like owls and foxes.
Interestingly, woodpeckers can make an “overnighting” shelter for themselves that is different from the normal nesting cavity they create. It is usually in a rotting snag rather than more solid wood and much lower to the ground than their nesting hole. They may use it nightly for the entire winter or only spend a few days there.
Ruffed Grouse are another species with a special winter technique – spending their nights and much of their day under soft fluffy snow. Grouse feed on tree buds and can store what they eat quickly in their crop, to digest later. Thus, they don’t depend on the feed-all-day strategy of other birds and can afford to hide beneath snow cover. Because they do not turn white in winter and are plump and visible, they are easy prey for a Great-horned Owl or other large predator. So, their snow-roosting strategy is an advantage. They are also large enough not to get iced in overnight under the snow, as smaller birds could be.
The best winter strategy I know about is that used by the White-breasted Nuthatch: it caches food for later. That is, it stores extra seeds, one at a time, under the loose bark of a tree and covers them with a piece of bark, a lichen, some moss, or even snow to hide them. White-breasted Nuthatches join foraging flocks of chickadees and Tufted Titmice but tend to act in a solitary manner at feeders, flying off in an opposite direction, so as to avoid leading any other bird to their secret stash of seeds.
One additional method for winter that some birds use is torpor – letting the body temperature drop into hypothermia in order to conserve energy. One bird that uses this is the Pygmy Nuthatch, found climbing up and down Ponderosa Pines in the West. They are highly social and use their sociability to get them through the winter. The American Bird Conservancy says that during the cold months, they pile into a hole in a tree and roost communally; as many as 100 may share a roost. Pygmy Nuthatches survive cold nights by huddling together and going into torpor. They are the only bird in North America that combines the three energy-saving mechanisms – roosting in tree cavities, huddling together, and torpor – into one winter-survival strategy.
Sources:
The Aldo Leopold Foundation Blog. “How Do Small Birds Survive Winter?” n.d.
Heinrich, Bernd; Illustrations by Megan Bishop. “How Do Birds Survive the Winter?” Cornell Lab of Ornithology All About Birds. December 19, 2018.
Lowe, Joe. “At Home in the Cold: An Intro to the World of Winter Birds.”
American Bird Conservancy Newsroom, Bird Calls Blog. February 04, 2021.
FEED THE BIRDS FEBRUARY
By Jody Carrara
Forty years ago, I startled my mother by yelling “There’s a Yellow-crowned Night Heron!!” My awakening on a back bay boat ride was the beginning of paying attention to birds and becoming a birdwatcher. You too can enjoy our native birds by taking the small step of adding a bird feeder to your property. You won’t believe the types of birds you will see.
In the US, one-in-three households feed wild birds. To get started, let’s talk about the basics: Follow the 5-7-9 Rule. Install a bird feeder that is at least 5 feet off the ground, 7 feet away from trees and has a 9-foot clearance overhead. This helps keep birds safe and squirrels away. Stop feeding during summer months…especially if there are local bears.
Provide a water source or heated birdbath if you have space. Clean it regularly. I have a pond that has water circulating over rocks; one winter an entire flock of bluebirds came to drink from the pond. That certainly was a reward!
Provide the shelter of evergreen trees and shrubs for those very cold windy days. Titmice, juncos, cardinals, jays, woodpeckers, house finches, nuthatches and more will thank you by hanging out in your yard. Native species like Red Cedar, holly and winterberry are the best.
Each songbird has a seed they like the best because of their beak shape and size. Think of a sparrow and their little beaks…they eat little seeds. Bluejays on the other hand will crack open a peanut shell and eat the peanuts. Good foods for songbirds are sunflower seeds, black oil sunflower seeds, thistle, cracked corn, nuts suet, and white millet. Make sure your mix has a high percentage of black oil sunflower seeds for the best nutrition.
Finally, grow native trees, shrubs and plants. Wild birds, butterflies and moths will flock to your yard in the summer and the berries will sustain wintering birds. Black Cherry, Arrowwood, Bayberry, Holly, Red Cedar, Sassafras, Black Gum, and White Oaks are but a few of the exceptional native plants that benefit wildlife in our state. Enjoy the rest of the winter and thanks for your interest in wildlife.
For more information:
Comments