Why Birds Feet Don’t Freeze? Explained In Detail

Why Don’t Birds Get Cold Feet?

When the winter cold has settled in and is seeping into your floors, even walking around your house after a comfortable night under the blanket is a pain in a** feeling. 

If you ever had to step outside barefoot for even a moment, then you will know how much it really hurts.

Yet so many birds are able to do exactly this with no problems at all. Sure, they have their feathers creating an insulating system covering their body to preserve body heat, but in most birds, their feet stay barren. 

So how do they keep their fragile little feet from freezing up in the harsh cold? 

Today, we’re going to look at the bird’s feet anatomy in detail, discuss the reason why they can do this, as well as look at some other common thermoregulatory measures undertaken by them.

Bird’s Feet Mechanism Explained

In birds, the lower leg or the tarsus is a single bone that is actually a result of fusing between the remaining metatarsals of the ankle and arch bones.

This bone then connects with another bone called tibiotarsus, which might be more familiar to us as the drumstick bone. 

As we know, the upper part of the drumstick tends to pack some muscle while the lower part stays relatively bare.

In the colder months, birds are thus put in an impossible situation, where they have to account for the heat loss that could happen through their feet. 

To truly account for it, they would have to raise their metabolic rate through eating or increase their muscular activity – both of which are not sustainable solutions for the bird to keep warm in the already harsh period. 

The main issue here is that the warm blood from the core of the body would cool down when it goes to the feet, and this cold blood is what would be returning back to the body of the bird. 

So what do they do about it? Well thankfully, nature has it all in control, and has established a specialized system for this temperature management.

Reason Why Birds Feet Don’t Freeze? Countercurrent Heat Exchange System

The legs and feet of birds are especially vulnerable in harsh and cold conditions as they do not enjoy the same protection and insulation of feathers that the rest of the body does. 

While there are birds where the feathers go all the way down to their feet, like in some Arctic birds like snowy owls and ptarmigans, the majority of birds have legs and toes that are exposed to the outside conditions.

The solution to both the concern in their thermoregulation and the bare vulnerability of their feet is the countercurrent heat exchange system they possess. 

Simply put, this is a mechanism that puts the main artery that carries warm blood down to the leg and the main large vein that carries cold blood from the bird’s foot to the body side by side. 

A little shunt or passage at the base of the bird’s toes allows the warm arterial blood to pass directly into the vein without further losing any body heat by going through the toes or webs.

So what happens when the main artery and vein sit side by side?

The venous cold blood absorbs heat from the warmer arterial blood right next to it, and so when it comes back to the body it is met with even warmer arterial blood and thus the heat exchange works out throughout. 

They also do not just simply lie side by side. The mechanism is a wonderful web of arteries and veins that surround one another to increase the surface area of contact so the cold venous blood gets more effectively warmed that much quicker.

Other General Techniques In Birds To Preserve Heat And Keep Warm

Fluffing Up And Making Use Of Their Feathers

When the cold gets especially high, birds will fluff up their feathers to increase the insulation powers by trapping heat in between them, thus creating an incredibly effective and wonderfully natural layer of insulation between them and their environment. 

Not only is this a fascinating technique, but it is also adorable to watch happen in real-time as they double in their size.

Sometimes birds also tuck their face into their body and under their scapulars, which is the term used to refer to the bunch of feathers they have on their shoulders. 

This also allows them to breathe in warm air, just like we sometimes like to do with our palms in our faces.

Bigger Is Better, As Well As More Feathers!

An effective technique for birds to stay warm is to put on some pounds.

A great adaptation for conservation is their size, as was evident in research that showed in birds of the same species, those that lived in northern regions were bigger as compared to those in temperature regions. 

Birds generally eat up quite a bit for their size already, so adding to that is not a problem for them, especially if it means better survival in the coming weeks.

Research also shows that many species of northern birds have been observed to have an increased number of feathers during the winter as opposed to the summer, and this is also a way to trap air in between the different layers and provide insulation.

In Conclusion

So that is how birds protect themselves from the harsh and cruel cold of the winter. Birds are fascinating creatures with a world of complex and intricate mechanisms at play behind the scenes. 

We hope you had fun exploring this mechanism with us today and furthermore, that you learned something new.

Thank you for reading!

Related Articles You May Like

Scroll to Top