Thanks for your interesting question! As you probably know, birds are "warm-blooded" (endotherms), which means that their internal body functions (metabolism) keeps them warm from "the inside." Most other back-boned animals that live on land--e.g., turtles, frogs, crocodiles---are cold-blood (ectotherms). This means that they rely mainly on the sun's warmth to keep themselves warm. The other kind of warm-blooded animals is the group we belong to, mammals (which have hair, produce milk for their babies, etc.).

Interestingly, we know that birds and mammals developed their warm-bloodedness independently--in other words the latest common ancestor that birds and mammals shared was cold-blooded. Over the course of their histories, warm-blooded animals developed (through the process of evolution) mechanisms for cooling themselves down. That's because these animals are already warm at rest. When they run, fly, or exert themselves physically, that makes them even warmer, since activity "burns" calories, a byproduct of which is heat. Bodies can tolerate only so much heat before bad things happen. For example, proteins, which make up our muscles and many other important components of our bodies, break down when they get too hot. Animals, including humans, can even die from overheating.

Evolution "invented" two different ways to cool down endotherms (mammals and birds). Most mammals sweat. Through this process, fluid (salty water, basically) is secreted onto the furry surface of these creatures. That moisture evaporates, thereby cooling the animal. (To convince yourself of the cooling power of evaporation, put on a wet t-shirt, or a wet towel on your bare back.)

Which takes us at long last to birds--which do NOT sweat. Flying takes a lot of energy, meaning that birds have lots of excess heat to lose when they travel. An important way they do this is through the unique way of breathing. They have air sacs, which permit a one-way flow of air through the lungs. In mammals, airflow is bi-directional (back and forth). We mammals inhale and exhale air through the same passages. Air is pulled in half of the time, and air is pushed out half of the time. In birds, however, air is constantly drawn into the mouth. As a consequence, much more air passes through an average bird than through an average mammal. Accordingly, breathing plays a much more important role in cooling birds than it does in mammals (although even in humans, heat is lost through breathing. Don't believe me? Exhale onto your open hand. Is it warm or cold?

So...sorry for rattling on so long in answering your seemingly simple but intriguing query.

PS In case you're wondering, some mammals have secondarily lost the ability to sweat--dogs, for example. They cool by panting, and through evaporation on their tongues.

Great question! Only mammals (animals that give milk and have hair) sweat. Most mammals don’t have many sweat glands. Cats and dogs, for example, have very few. They cool off by panting. Horses and some primates (like humans) do have a lot of sweat glands.

Flying creates its own breeze, so this keeps birds cool when they are exercising. When birds get too hot, they might go into the water. They can spread their wings or fluff their feathers to allow a breeze to get to their skin. They may even pant like dogs. If it’s way too hot, they may just stay quiet in the shade until things cool off.

Can you think of any problems with sweating a lot for animals with feathers or thick fur?

Sweating is an important part of temperature regulations in human. Sweat is excreted by the sweat gland, which is unique to mammals. There are two major types of sweat glands, eccrine and apocrine. Eccrine sweat gland is responsible for what we usually think as sweating. They are only found on the hairless parts of a mammal, such as the foot pads. As a result, human has far more eccrine sweat glands than any other animals.

Birds have no sweat gland and rely on different mechanisms for temperature regulation. Feather is a good insulator of heat. Therefore birds expose un-feathered parts, such as their legs, to the environment to exchange heat. Some birds can track the direction of the Sun while nesting to minimize the area receiving solar radiation. Birds can also lower their body temperature by reducing activity, just what their reptilian ancestors would do.

Great question Kenneth! Birds do not sweat like humans but have other ways that they "keep their cool". This article by the Audubon society will tell you all about them! They include finding shade, evolving a bigger beak, and a bird version of panting. How birds keep their cool.

Hi Kenneth great question! In fact, birds don't sweat like humans do. But everyone needs to keep cool! Humans sweat to lower their body temperature. Sometimes dogs pant to lower their body temperature. Some birds have their own version of panting. With its mouth open, the bird flexes their neck muscles. This lets heat flow out and cools them off. Other birds like the great blue heron open their large wings to the wind. This allows air to cool them. With their wings, herons may shade their young from the sun. Also birdbaths cool down the birds on hot days.

Great question! Birds don’t sweat like we humans do, but they do have their own ways of keeping cool. One study found that birds with bigger beaks are able to keep cool better because they can control the amount of blood that goes into the beak. So a tropical toucan that has a very large beak can keep cooler better in the hot and humid environment it lives in.

Another cool way that birds cool off is opening their wings. I’m sure you’ve seen big birds like vultures do this before. When they open their wings big and wide, they let the wind flow across more of their bodies to sweep away any excess heat.

Like humans, birds also like to cool down in the water. That’s why some people put bird baths in their backyard. Or sometimes you see birds gathering at a fountain in the park. They like to swim around and cool off their bodies like we do! Birds also like being in the shade when it’s hot.

So while they may not sweat like we do, birds have found many ways to stay cool in the hot summer sun.

I have a dove's nest on my balcony, and it can get very hot in the afternoon. One afternoon, the parent dove was breathing rapidly in and out. It looked like it was trying to cool itself.

This link says birds can pant to cool themselves off: How birds stay cool.

Here is a picture of a parent dove and its newborn baby dove, in front of it, in their nest. There are some pine needles in front of the baby dove. Both parents spend about the same amount of time sitting on the nest and taking care of the baby bird.

No. Birds open their mouths and pant, in a fashion similar to how dogs cool off. They do not sweat.

Birds do not sweat! Unlike humans, they do not have sweat glands. (Actually, dogs also do not have sweat glands.)

Humans sweat to keep cool in hot temperatures. Since birds do not sweat, they have to release body heat in different ways. One way is by panting, breathing rapidly with an open beak. Some types of birds also flutter a membrane in their neck while panting to help cool themselves.

Another way is "urohidrosis", a scientific way of saying they poop on their own legs. Their poop is actually a mix of urine and solids. As the liquid evaporates and dries, it cools the birds down too.