It was only recently that an Arctic Clipper laden with a full cargo of frigid weather sailed into the Peach State this winter. Of course, when cold dominates our weather we have the luxury of taking refuge in cozy abodes. When we do venture outside, we don heavy winter coats, hats and gloves to ward off the cold.
Such is not the case with our bird neighbors. To them, dealing with extremely cold weather is a life and death struggle. Fortunately, many birds are well adapted to deal with the cold.
One way they keep warm is by fluffing out their feathers to trap body heat. The air found between the fluffed-out feathers acts as an excellent insulation. A Carolina chickadee, for example, uses an intricate network of tiny muscles to fluff some of the 2,000 feathers that cloak its body.
Other birds, like the American goldfinch, grow more feathers as winter approaches. The additional feathers provide added insulation.
Birds also keep warm by shivering. Since small birds are affected by the cold more than larger birds, it is not surprising that they shiver almost continuously when temperatures drop below freezing. In fact, some birds such as the black-capped chickadee (a close northern relative of our Carolina chickadee) can sleep while they shiver.
Shivering can keep an American goldfinch five times warmer than it would be if it was not shivering.
Keeping warm in cold weather also requires more energy just to survive. Hummingbirds can literally starve to death trying to stay warm on a bitter cold night, especially if they have not eaten enough food to fuel their high metabolism. Birds such as turkey vultures and mourning doves are capable of reducing their body temperatures on cold nights, allowing them to conserve precious energy.
A few birds such as hummingbirds and black-capped chickadees carry this to the extreme. These feathered mites will go into torpor to survive the cold. In this condition, the birds remain motionless and their body temperature and respiratory and heart rates plummet. A hummingbirds body temperature may drop from the usual 107 degrees Fahrenheit to the mid-80s or so when the bird is in torpor.
You would think that since a birds feet are not protected with feathers they would be vulnerable to frost bite. Actually, they are not. First of all, a birds foot has little muscle tissue tissue that would be highly susceptible to the cold. Additionally, birds will often stand on one foot while keeping the other tucked close to their warm bodies. When the exposed foot gets too cold or tired, the bird stands on the other foot and nestles the foot on which it had been standing among its soft feathers.
Have you wondered how ducks and geese swim about in ice-cold water without damaging their legs and feet? The answer to this perplexing question is simple: They can constrict the veins found along the outsides of their legs and feet. This forces blood closer to warmer blood flowing through arteries from the heart, warming the cooler blood and preventing damage to legs and feet.
Quail will keep warm at night by roosting in a tight circle with their wings slightly elevated. Each bird faces out. The arrangement allows quail to more easily detect predators approaching from any direction and enables the birds to share their body heat, keeping them warmer than if they roosted alone.
Birds will also roost in thick cover, tree cavities or manmade nesting or roosting cavities to ward off cold. Chipping sparrows, northern cardinals, blue jays and mourning doves, for example, will roost in dense conifers and other thick cover on frigid nights.
Meanwhile, woodpeckers, titmice and bluebirds will spend the night in nesting and roosting houses, as well as natural cavities. Interestingly, during extremely cold weather birds often retire to roosts earlier in the afternoon than they would during warmer weather.
There are a number of things you can do to help your bird neighbors survive frigid temperatures. First, provide them with high- quality roost sites such as brush piles, dense shrubs, vines and trees that retain their foliage throughout the winter. When possible, leave standing any dead trees that contain cavities.
Also, erect nesting and roosting boxes in your yard. A variety of boxes featuring different sized holes will benefit a wider variety of wildlife than a number of boxes with entrance holes of the same diameter. When the weather turns cold, safe, warm nighttime roosting sites are just as important as food.
Last, but not least, stock your feeders with high energy foods such as suet and black oil sunflower seeds.
As you can see, wild birds are well adapted to surviving freezing weather. However, you can help them and other wildlife make it through the worst that winter can throw at them.
If you do, you will feel a warm glow during even the coldest weather, knowing that your actions may make the difference between life and death for the birds that live just outside your backdoor.
Terry W. Johnson is a former Nongame program manager with the Wildlife Resources Division, a backyard wildlife expert, and executive director of TERN, the friends group of the Nongame Conservation Section. (Permission is required to reprint this column. Contact rick.lavender@dnr.ga.gov.) Learn more about TERN, The Environmental Resources Network, at http://tern.homestead.com.
How Do Birds Survive Winter?
Birds and winter. Courtesy of Amanda Frank, Unsplash
It’s amazing birds survive the winter when the temperature drops and the ground begins to freeze. By providing food, we can assist our garden birds in gaining much-needed weight, but what about all the birds we are unable to see?
Thousands of species of birds have adapted to live in some of the strangest and most hostile environments on Earth.
storks have hollow bones in their legs to help lift their massive frames off the ground when flying, pelicans have enormous pouches in which to store so much fish, and toucans use their enormous bills to thermoregulate the intense heat of the rainforests. It makes sense that they would have mastered the winter as well.
As is well known, a large number of bird species migrate south or west for the winter in search of warmer climates. Certain species will travel to areas that we might consider to be fairly cold, but in comparison to their potential home, the icy estuaries of East Anglia, UK, are tropical paradises.
However, some birds are referred to as resident birds because they never leave their homes. These birds have exchanged the dangers of migrationlike being blown into the ocean by a storm, being hunted by humans or animals on the way, or simply becoming exhaustedfor a whole new kind of strugglethe bitter coldin order to maintain their hard-won territories throughout the year.
While many wild mammals hibernate or grow thicker coats, humans dress more, adjust the thermostat a few degrees, and do other things, resident birds remain in the same outdoor locations, wear the same feathers, and perform daily tasks. Therefore, birds must find solutions to two issues in order to survive winter: finding enough food and staying warm enough.
Since most wild birds naturally have body temperatures around 105?°F, or 40?°C, which is considerably higher than ours, any drop in temperature outside seems even colder to them than it does to us.
When you consider that their food supplies are sadly depleted just when they are most needed, the fact that they can endure a single winter, let alone several, is an incredible testament to their tenacity.
Courtesy of Buntysmum, Pixabay
Birds must use a variety of strategies and specialized adaptations to get past these barriers and reach the warmth of spring. To begin with, their feathers serve a much more useful purpose than just being attractive or aiding in flight; they are excellent heat traps.
The majority of a bird’s body is covered in a thick layer of down, a unique type of feather that is highly valued in our pillows, sleeping bags, jackets, and the envy of technical outdoor clothing manufacturers worldwide. Down is found underneath the longer exterior feathers of birds.
Through a process called ptiloerection, birds can “puff these up,” giving the impression that they are larger than they actually are. Instead, they have simply pushed the finer filaments out of their bodies and spread them out, allowing the heat from their interior to escape.
This fluffy barrier captures air pockets near the body, which are then heated by the bird’s internal radiation of warmth, astonishingly holding on to 90% of its core temperature. While down feathers are present in most birds, we are more likely to see them in waterfowl that are raised for our manufactured comfort and warmth because ducks and geese produce large amounts of down to keep their skin warm in freezing water.
Many birds do not have feathers on their legs or feet; instead, they let their feet cool down to nearly the same temperature as the surface they are standing on. By using their tiny feet, birds are able to avoid freezing to death thanks to a process called counter-current exchange.
Instead, birds’ feet have evolved to consist primarily of bones, tendons, and extremely thin-walled blood vessels in the skin that pass incredibly close to each other. This is because any heat lost from the body to the extremities would need to be instantly replaced, which would be impossible to maintain throughout the winter.
The warm blood that leaves the body through the blood vessels that supply the legs and feet merely warms the cool blood that is being transported away from the feet, returning heat to the feet.
Courtesy of Blalonde, Wikimedia Commons
Huddling together is another method that birds, especially smaller ones like long-tailed tits, sparrows, and chickadees, preserve their heat, especially at night.
They group together to form a line or a ball in order to decrease their surface area to volume ratio. Throughout the night, they will compete for position because the ones at the outer edges of the line lose more heat than the ones in the middle.
After spending the majority of the year by themselves or in pairs for breeding, wrens will gather in groups of five or more during the winter to share heat, occasionally reaching sixty.
Many birds, including owls, treecreepers, most of the tit family, woodpeckers, and thrushes, will also seek out cavities in trees, rock faces or quarries, or snags and rotten holes in logs to spend the night in.
It’s possible that you’ve noticed a lot of woodlandbirds disappearing during the winter. This is because they’ve moved farther inside to avoid the chilly winds at the exposed edges, but it’s also more likely that food has survived in the warmer, darker, deeper interior.
If there is no food, then none of the strategies used are meaningful. Planting trees and flowers that can supply those necessary ingredients in the form of seeds, nuts, or even insects in the autumn and through to the winter is crucial because birds require a steady supply of fatty and high-protein foods to survive the winter.
Many birds, including woodpeckers, nuthatches, juncos, and jays, will cache this food during the summer and fall, usually remembering most, if not all, of the hiding spots.
Sharp-billed birds, such as starlings, can still burrow into tree bark to find lifeforms that have buried themselves there to stay warm. Some birds also migrate from summer fruit to winter seeds that are high in oil.
In the winter, birds essentially exist day to day because it is so counterproductive for them to use energy to find food when night falls and temperatures drop even lower. Nevertheless, many of them will shiver to create heat and stay warm, just like humans do.
Almost all of the calories gained during the day are used up by this alone, so the cycle starts over at dawn.
You can make a huge difference in their ability to survive this winter by making sure they have access to plenty of food and fresh water.
The more of us that take that action, the less strain we put on all other “non-garden” birds. As self-serving as it may sound, you will also enjoy some fantastic birdwatching in the winter from the cozy (smug?) comfort of your own house.
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About the author: Our writer and researcher for the Bird Buddy blog is Sim Wood. She is currently remodeling her Slovenian property with her spouse and making do without a plan. She is also proficient in 72 bird species’ calls and songs. Favorite bird: shoebill.
You would think that a bird’s feet, lacking feather protection, would be more susceptible to frostbite. Actually, they are not. A bird’s foot, to begin with, has very little muscle tissue, which makes it extremely vulnerable to the cold. Furthermore, birds frequently balance on one foot with the other tucked against their warm bodies. The bird stands on the other foot and nestles the foot it was standing on among its soft feathers when the exposed foot becomes too cold or tired.
An American goldfinch that is shivering can stay five times warmer than it would be otherwise.
Terry W. Johnson is the executive director of TERN, the Nongame Conservation Section’s friends group, and a backyard wildlife expert. He was previously the Wildlife Resources Division’s manager of the Nongame program. (Permission is required to reprint this column. Contact rick. lavender@dnr. ga. gov. Visit http://tern to find out more about TERN, The Environmental Resources Network. homestead. com.
This winter, an Arctic Clipper loaded with a full cargo of bitter cold has just recently sailed into the Peach State. Of course, we have the luxury of retreating to warm homes when the weather turns chilly. To protect ourselves from the cold, we dress in bulky winter coats, hats, and gloves whenever we go outside.
Insects like hummingbirds, butterflies, and honeybees immediately spring to mind when we consider pollinators. In actuality, though, a wide range of other pollinators are also actively engaged in the process of pollinating flowering plants. These creatures consist of native bees, hoverflies, beetles, flies, moths, and wasps, among others.
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