Many of you probably live in a region where winters are cold. Sometimes bitterly cold. We don’t even like running out to the mailbox without bundling up in hats and scarves. Do birds get cold? Yes! Birds are warm-blooded creatures like us, therefore they have to keep their body at a constant temperature (for birds around 105 Fahrenheit). So how do birds stay warm? How do birds survive in the winter? Let’s look at their winter coping strategies, and talk about ways you can help birds in the winter.
A certain section of the bird population migrates to warmer climates. Sounds smart doesn’t it? Leave the frigid cold behind for a warm, tropical climate! So why don’t all birds migrate? Birds are very territorial when it comes to their nesting and feeding grounds. Birds that stick around in their territory all year round have a better chance of defending and keeping that territory than those who leave and try to return. Also, migration can pose some serious hazards. It’s not easy to fly thousands of miles to warmer grounds! It takes a lot of energy and resources. It also exposes birds to threats such as storms and predators.
Each species has evolved over time to weigh their options carefully. Risk flying hundreds maybe thousands of miles to escape the cold, or hunker down in a safe spot that will take all your energy to stay warm enough to survive.
Next, let’s look at the strategies used by the birds that choose not to migrate.
Many species cache, or store, food during the fall months to eat later when food is more scarce. Some common species that use this technique are Chickadees, nuthatches, some woodpeckers, jays, and crows. You may notice chickadees and nuthatches especially visit your feeder only for a moment to grab a seed before flying off again. Chances are they are hiding it. Common hiding spots include pushing seeds into the bark of trees, finding tree cavities, or even sometimes burying in the ground.
How do they remember where they have hidden all this food? Researchers have discovered that chickadees, for one, can actually enlarge their brain! In the autumn when it’s time to store food, they add neurons to the hippocampus region of their brains (responsible for memory), increasing brain volume by 30%. As spring approaches and food becomes available again, energy is no longer sent to creating these neurons and their brain shrinks back down again. What a fascinating adaptation!
Chickadees can grow their brain in colder months to increase their ability to remember where they hide seeds. What remarkable little birds!
Lowering Body Temperature
Keeping the body warm takes a lot of energy, therefore conserving energy in the cold weather becomes crucial. Do birds hibernate? For the most part, no. There is one species who hibernates, the common poorwill. Most birds do not hibernate however they have other, similar methods for conserving energy.
One method involves entering a state called “Torpor”. During torpor, body temperature, breathing rate, heart rate and metabolic rate are all lowered for a short period of time, such as overnight. Waking back up to normal activity rates from torpor can take about an hour and involves heavy shaking and muscle contractions. This waking-up period does expend energy, however energy is still saved by the hours spent in the torpor state. Birds such as hummingbirds, nightjars and swifts use this tactic.
Other birds don’t enter a full torpor but use what is called “regulated hypothermia”. Small birds like kinglets and chickadees will drop their body temperature up to 15-22 degrees F during the night, allowing them to save about a quarter of the energy they would be using each hour.
Just as you would head back inside your house when it gets too cold out, birds also seek shelter. Shelter can protect from cold winds that strip away heat from the body. It can also protect against wetness from snow and rain that will also result in heat loss. Tree cavities are great go-to shelter spots, however dense foliage, evergreen trees, brush piles and birdhouses can all provide a respite from the elements.
One bird that is able to create their own overnight shelter (rather than finding one), are woodpeckers. Woodpeckers will often excavate a hole specifically to use as a shelter for overnight roosting. These roosting holes differ from the the holes they would excavate for nesting in that they can be much closer to the ground (within about six feet).
A very simple but effective strategy – stay on the opposite side of the tree that the wind is blowing on. Birds can actually conserve energy by a simple enough tactic of sticking to the side of the tree that shields them from wind and rain. Or on cold but sunny days, sticking to the side of the tree that will provide them with the most sunshine.
Huddling and Insulation
Birds have many types of feathers that are designed to perform specific functions – help fly, shed water, display colors and markings – but they also have “down” feathers whose purpose is to provide warmth. Down feathers are short and closest to the body. They keep cold air away from the bird, and keep the birds warm body heat from escaping. You will often see birds looking like fluffed up poof balls. They are expanding their down and maximizing the space for heat retention.
This is why you may see comforters, sleeping bag and jackets made with goose down feathers, they are excellent at retaining heat.
Another type of insulation is body fat. Extra body fat can act as both an insulator and a source of energy. These birds will frequent your feeders not only to eat enough to maintain energy, but to keep that extra layer of fat. They need to constantly eat fatty food sources to keep on this extra bulk.
Birds may huddle close together to take maximum advantage of multiple warm bodies, sitting on their feet and lowering their head to bring all extremities as close to the body as possible, and within the warm air layers of their down feathers.
Many species of birds are able to keep warm blood circulating specifically near their vital organs while allowing their extremities to cool down. For example, seagulls can stand on ice and their feet will approach temperatures near freezing, yet the temperature at their body core will remain nice and warm.
So why don’t birds get frostbite on their feet?
We know that protecting our fingers and toes is incredibly important in cold temperatures or else we will get frostbite. So why doesn’t this happen to birds with their exposed feet? Unlike humans or other mammals, birds feet are mostly made of bone and tendons. There is very little muscle or nerve tissue, and little fluid in the cells.
Also, birds employ a countercurrent heat exchange system in their legs and feet. That is a fancy way of saying the blood vessels are quite close together, and the blood can flow into and out of the feet very quickly. Blood that is cold from being in the feet is quickly moved to the body’s core and warmed, then cycled back into the feet. Blood doesn’t remain in the feet long enough to freeze.
You may also see birds standing on one foot at a time, then alternating feet. In this strategy the foot pulled up close to the body gets the benefit of body heat and being insulated by the body feathers. Birds can also squat down when they perch so that their bodies are covering their feet and covering them with their insulating feathers.
How to help birds during the cold winter
We’ve discussed many of the strategies birds have to make it through the cold winter months. But what can you do to help birds in the winter? Water, shelter, and food!
Maintain a constant food source
Very simply, provide a constant source of fatty foods for the birds to keep their energy reserves up and put on bulk. A quality bird seed mix, such as Wagners Greatest Variety Blend will work just fine. The most important thing when it comes to food is to keep the feeders consistently filled.
Suet, which is predominantly made of fat, is also a great food to put out for birds in the winter. High fat, high energy. Suet can come in blocks that can be put in special suet cage feeders, or in nuggets which can be sprinkled into open platform feeders. Suet is enjoyed by many birds such as woodpeckers, nuthatches, Carolina wrens and titmice. Two products I think are great quality, and the birds have loved in my yard are the C&S Hot Pepper Suet blocks, and the C&S Bluebird Nuggets (good for all birds not just bluebirds!)
You can also find a number of different types of seed and suet at good prices on Chewy.com.
Give birds a source of fresh water
Dehydration is a big threat to birds in the winter when most freshwater sources are frozen over. Providing a bird bath or dish of water with a heater in it can give birds a much needed source of fresh water to drink. A great option is this Songbird Essentials Songbird Spa, which is a heated birdbath that can attach right to your deck. If you already have a birdbath consider adding a heater like the K&H Ice Eliminator Birdbath Deicer.
Provide shelter from the elements
Provide a place for birds to get out of the wind and snow. If you already have a birdhouse, just clean it out at the end of the nesting season and it will make a good shelter.
Brush piles can also provide great shelter. Simply collect twigs, branches, and evergreen clippings and arrange in a loose pile. Brush piles, evergreen bushes or woody shrubs located near feeders will give the birds a place to cozy up between feedings.
Roosting Houses are a certain type of birdhouse specifically made for providing shelter. Unlike birdhouses made for nesting, these roost houses are designed with a lower entrance hole and usually a “ladder” or perches inside for multiple birds to be able to roost together. Simple wooden roostboxes or larger, recycled plastic roost houses are both good options.