Birds are warm-blooded animals and can regulate their body temperature. Birds have several methods to warm themselves up when cold or cool down when too hot. In this article, we look at some of the ways that birds keep from getting too hot or cold.
Birds can regulate their temperature throughout the year to maintain a steady internal temperature. Birds do not have sweat glands but cool down using water, shade, and by finding a cool breeze. Birds that are too cold can increase their temperature by finding shelter, huddling together, and sunning themselves.
If you want to know more about how birds regulate their temperature, please read on.
How do birds thermoregulate?
Birds are warm-blooded and can regulate their temperature. They are homeothermic and keep their body temperature between 40 and 42 degrees centigrade. Birds need to warm up when cold and cool down when hot.
Birds are unlike mammals as they do not have sweat glands and cannot sweat to cool down, so they will use methods such as finding shade, drinking water, and finding cool pockets of breeze to cool down.
When cold, birds need to eat more as the food produces energy in the form of heat. They can also be seen sunning themselves, huddling together, and fluffing their feathers.
How do birds cool down?
Birds need to maintain a stable temperature, and in summer, it is harder for them to do this. Whereas mammals have sweat glands and perspire to cool down, birds don’t. Because they have no sweat glands, birds need to cool down in other ways.
A birds temperature is affected by the environment around them. On sweltering days, a birds temperature increases, as does ours. There are several methods that birds use to cool down.
Birds use water to cool down when they are hot. This can be as simple as drinking water, but they will also stand in it or bathe in it. Some birds can be seen diving into the water to cool down, while others, such as swallows, will swoop over the water to dampen their chest.
On hot days birds can be seen spreading their wings. This allows air to get under the wings to help cool them down. They will also make sure that any areas that aren’t covered with feathers are exposed and will sleek back their feathers to allow this.
Birds also use the wind to cool down. They can be seen facing away from the wind allowing the breeze to get under their feathers and reach the skin.
Birds will also use other ways to cool down with air. Some will sit on higher perches than usual to take advantage of the breeze, while large winged birds will soar to find cooler pockets of air.
Although it is not possible for all birds, staying away from the ground is a great way to stop getting too hot. Even the ground birds who can’t fly can be seen standing as tall as possible so that their bodies are away from the ground.
Another way that birds cool down is by panting. Non-passerine birds use a mechanism called gular fluttering, where the throat moves rapidly up and down. As the air moves rapidly, heat is expelled through moist membranes and blood vessels close to the surface.
As with many other animals, birds will take refuge in the shade to escape the heat. Shade from trees, bushes, or buildings can bring much-needed relief from the midday sun and help the bird cool down.
Some birds, such as gannets, storks, and turkey vultures, have a more extreme way of keeping cool when it is really hot. They will defecate down their legs to cool them down. As the waste is white, it reflects the heat from the bird’s legs.
How do birds warm up?
The quickest and easiest way for birds to warm up is to sit in the sun. Birds can often be seen sunning themselves with their wings open to expose as much of the body’s surface to the sun. They may be seen laying flat on the ground with their wings open to allow the upper body to warm up before lifting one of their wings to let the sun get underneath them.
Not all birds sun themselves while on the ground. Larger birds can often be seen high in trees with their wings open. They can often be seen facing the sun to take full advantage. Cormorants can often be seen sunning themselves with their wings open after diving to catch fish to warm up and dry themselves.
Huddling together is another technique that birds use to warm up. Many birds will sit together with their bodies touching to generate warmth. As they are sitting close together, this serves a few purposes. If there is a cold wind, this will only affect the birds at the edge, but the shared body temperature helps to protect them. Huddling, or clumping as it is sometimes called, also helps keep predators from the group, making them safer than if alone.
Whereas birds that are too hot will find shade to cool down, birds that are too cold will find shelter to keep them warm. This can be as simple as a hole in a tree or a cave to manmade structures such as the eaves of a house or barn.
Bird nests can be extremely warm, and a closed nest can be 5 – 10 degrees warmer than temperatures outside. By not having to warm up itself, the bird can save a lot of energy.
Areas such as rocks that have been exposed to the sun can be a lot warmer than other areas, and birds can often be seen sitting on them to warm up.
As bird legs do not have feathers, they are normally the coldest part of the bird. Without insulation, birds need to protect their legs from the cold. One way they do this is to bring their legs into their bodies, tucking them up so that they are not exposed. This is one reason why storks, ducks, and herons can often be seen standing on one leg.
Although birds will often rely on the techniques above, they also have internal mechanisms that stop them from freezing. If the body reaches a temperature that is too low, then the brain realises that the temperature needs to increase.
The lower critical temperature is not the same in all birds but depends on the size of the bird. If the temperature is too low, the metabolic rate will increase. Birds will shiver to warm up, with some birds can triple their metabolic rate when cold.
This does use a lot of energy, and birds need to eat soon after to regain this. If the internal temperature drops too much, the bird may get hypothermia and die.