If you've seen a robin standing on snow or a chickadee sitting on an ice-covered branch, you might find yourself asking: how don't their feet get cold? That's a common question winter bird watchers ask, and the most simple question usually has the most interesting answer. Birds have developed extraordinary adaptations to keep their bodies warm and comfortable in extreme winter conditions that would make us really want to put on a pair of wool socks. But, along with real curiosity, there are many myths about birds surviving the winter and we will put those to rest.
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Why Birds Do Not Get Cold Feet (And How The Legs Of Birds Function)
Here’s the wonderful truth: though birds do experience cold feet, they’re built to cope with it. Birds legs and feet are controlled by a completely different system than us, and it is a masterclass in efficient biology.
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It’s called countercurrent heat exchange. Arteries that carry warm blood from the body run next to veins that carry cold blood to the body from the feet. While the warm blood goes down, it gives heat to the cold blood going up. Venous blood then return to the body from the feet and arterial blood has been significantly cooled, so less heat is lost to the environment. The body’s core will then have warm blood that is returning venous blood that has been prewarmed.
This system keeps a bird's feet just above freezing—cold enough to keep the bird's heat from being lost due to heat loss. The point is, birds don't need warm feet to grip branches or walk through snow, Their feet are designed to handle temperatures that would result in frostbite for a mammal. Some birds are even able to stand on ice for hours at a time while their body temperature is a comfortable 105°F and their feet are right at or below 32°F.
Birds have an amazing adaptation that allows them to survive through cold winters. They are capable of adjusting the blood flow to their feet by increasing circulation to their feet when it’s needed, and decreasing circulation to their feet when heat conservation is needed.
Myth: Birds Survive Winter With Heated Birdbaths
If you visit a bird supply store in November, you’ll notice a lot of heated birdbaths for sale. They can be beneficial to birds, but let’s be honest about what birds really need.
Birds do need water in winter, both for drinking and bathing. Clean feathers help with insulation, so even when it is freezing, birds will look for water to keep their plumage clean. In areas where natural water sources freeze for a long time, a heated birdbath becomes a very important resource that helps birds save energy that they would spend looking for open water.
"Valuable" and "essential for survival" do not have the same meaning. Birds have various ways to get water. They can obtain water from snow and ice, streams that stay thawed, and even gutters that drip water and puddles that form during daytime thaws. Birds have been surviving well without heated bird baths and use their resources very effectively.
Having clean, ice-free water is a great way to help birds visiting your backyard. However, if this isn't something you can do, don't feel bad. You can get a simple, unheated birdbath that will work in most climates up to a certain point. Simply refill it with warm water once or twice a day as needed. Just remember that you don't have to provide water so that birds depend on your bird bath for all their water, it is important to make sure that they can easily get quick access to water.
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Myth: You Should Stop Feeding The Birds To Encourage Migration
This myth causes good-hearted bird-loving people to pull their feeders every fall and worry about trapping birds in perilous winter conditions. Here's the truth: bird feeders do not stop birds from migrating. End of story.
The first signal for migration is the change in the amount of daylight. When fall approaches and days get shorter, birds begin to change physiologically. This change prompts them to migrate no matter if food resources are readily available, and no matter if feeders are stocked. Evolution does not allow for skipped migrations, so birds will not alter instinctive migration patterns for feeders. Hummingbirds will not skip their journey to Central America to stop at a feeder, and warblers will not stay for suet.
Feeders do provide support to the birds that are in your area during the winter. Chickadees, cardinals, woodpeckers, nuthatches, and other year-round residents gain a lot from extra food when natural food sources are buried under snow or depleted from severe weather. During the toughest months of winter, feeders can really help these birds survive.
Some species adapt by wintering farther north if feeders are plentiful. For instance, in recent decades, House Finches have expanded their range across North America. This is an example of range expansion and is not a concerning alteration to migratory behaviors. Feel free to keep your feeders filled. You are helping, not harming.
Myth: Birds Freeze to Trees Overnight
Every winter, social media is full of concerned posts about birds freezing to branches while they sleep. The thought of a chickadee frozen in place until morning is quite disturbing. Luckily, that is not how bird anatomy works.
Birds have an automatic locking mechanism in their feet that is controlled by their flexor tendons. When a bird lands and crouches, their body weight tightens the flexor tendons and causes the toes to curl around the perch. The grip is completely passive meaning that no muscular effort is needed. This means that a bird can have an uninterrupted sleep. Birds can sleep even in high winds while sleeping deeply without the danger of falling off the perch.
With this system, birds are able to manage low temperatures. Birds feet remain unfrozen due to circulation restriction in their toes combined with the countercurrent exchange system. It is cold, but the toes are not frozen stiff. When morning arrives, the bird just stands up, relaxes the tendons, and normal grip is released.
Healthy birds do not face the risk of freezing to their perches, and during extreme and life-threatening cold temperatures, a healthy bird would rarely, if not never, suffer frostbite on their toes, and in fact, frostbite is more common in birds that have been injured, or in birds that have become ill and cannot sustain their body temperatures.
What Birds Need From Your Backyard This Winter
We cleared up the myths, so let's discuss the ways you can realistically support winter birds.
Having high quality foods are top of the line when attracting birds. A good options are black oiled sunflower seeds, animal fat, peanuts, and nyjer for finch birds. These foods give birds the energy they need to keep warm because they keep the birds body warm. On top of this, make sure your feeders are constantly stocked, as the birds will alter the course of there daily feeding and visiting your yard as a constant food source.
Like food, shelter is also essential. Evergreen trees and thick shrubs are great for shelter as the provide places to roost where birds can block the wind and keep their body heat. If you do not have any natural shelter, you can also put up roosting boxes meant for winter use. Even a basic brush pile can form sheltered spaces that are used by small birds to shelter from the storm.
We appreciate you mentioning that not every bird bath is heated. Water is helpful when you can supply it. It's the thought that counts. Water helps with feather maintenance and energy saving basin or bird bath that you refresh regularly.
Please keep the leaves and seed heads! Native plants with seeds that stay through the winter, like coneflowers, sunflowers, and various grasses, provide a natural food source. Leaf litter has insects that winter over, and birds `pick` them up on milder days. Do not clean everything up in fall!
Birds that survive the winter are incredibly tough, and they have special skills to help them survive the most frigid of conditions. You don't have to go overboard with your support for backyard birds. Just be consistent and provide birds with what they really need instead of what myths tell us they need. Happy birding!
