Birdlife exists in some of the hottest places on the planet, including arid, shadeless deserts in Africa and North America, where little other life is able to thrive. But how do birds cope with the intense heat? Do all – or any – birds sweat, and if not, how do they keep cool in extremely hot temperatures? Read on, as we investigate how different birds stay cool.
Unlike mammals, birds do not sweat. Instead, they rely on other adaptations to cool off on the hottest days of the year; these include finding shade and water, seeking breeze and using their feathers, wings and even bodily functions to expel excess heat from their bodies.
In warmer weather, it is not uncommon for birds to find shelter or shade in which to rest during the hottest parts of the day, only resuming activity in the evenings once the temperatures have begun to drop off. Birds of prey fly at higher altitudes in search of cooler air currents, and kingfishers and bee-eaters dive more frequently into water to cool off.
Keep reading to find out more about adaptations used by different bird species to regulate their body temperatures and expel excess heat in the height of summer.
Often, birds will utilise the shade on warm days to keep cool
Birds have developed a variety of clever techniques that enable them to lose or reflect excess heat on the hottest days of the year.
Many birds use water to cool down, with standing in water being a popular method of quickly lowering the body temperature for wading birds. Swallows cool down by skimming the surfaces of lakes or pools on hot days. Backyard bird baths have the dual purpose of providing drinking water – vital for staying hydrated – and a place to splash around and let some of the excess body heat escape.
Birds use bird baths to keep cool
Other adaptations are not universal, but particular to individual species. Where possible, birds with white feathers turn these towards the sun, which in turn reflects the most intense heat away from their bodies. When the mercury rises, birds may be observed to stand with their beaks wide open and wings spread, panting, and cooling themselves off by maximizing their surface area to allow heat to escape faster.
Less common, but perhaps equally as effective is the phenomenon of urohydrosis practiced by some birds, such as storks and gannets. This involves defecating on their own legs and feet to cool themselves down, increasing heat loss by evaporation.
Other adaptations that reflect the modern world and changing urban landscapes have been seen in Phoenix, Arizona, where temperatures regularly exceed 110 degrees. Feral Rosy-faced lovebirds are regularly spotted cooling off, perched on air-conditioning units on buildings at the heart of the city.
Rosy-faced Lovebirds can often be seen cooling off in cities on air conditioning units
Juvenile and adult birds are warm-blooded (endothermic) and have an average body temperature of around 40 degrees C (105 degrees F). They can thermoregulate their own temperature to stay between 39 and 42 degrees C (102 to 107 degrees F), so it remains at a stable level both in cold weather and in extreme heat.
When they hatch, baby birds have not yet developed the ability to regulate their body temperatures, and rely on parent birds brooding them to keep them warm for the initial few days, up to three weeks in some bird species.
Different birds have developed a number of adaptations to help them regulate their body temperatures when they begin to overheat, and what works to cool down one bird may not be as effective or practical in other species.
When it’s cold, birds eat more to create the increased amount of energy needed to raise their body temperatures. In winter, groups of birds may be seen huddled together to collectively raise their temperatures and stop heat from escaping. Storks, emus, and flamingos stand on one leg to limit heat loss from their legs.
A small flock of quail huddling to keep warm in the winter
Birds do not have sweat glands and do not perspire, so need to find other ways of evaporating excess heat from their bodies. They do lose a certain amount of heat and moisture through their skin, but not enough to maintain a stable body temperature in extremely hot weather.
Birds, particularly passerines, can be observed to engage in a behavior similar to panting when temperatures get too high, standing with their beaks open and breathing rapidly. This “panting” in birds is often accompanied by other movements, including spreading and quickly flapping their wings as a way to release heat and to cool the air immediately around them.
Some bird species are able to flutter their neck feathers in such a way that enables their throat membranes to expand and vibrate, which allows excess moisture to leave their body. Known as “gular fluttering,” this is seen in mourning doves, herons, double-crested cormorants, and some owl species.
Great Blue Heron panting in the hot summer
Birds have typically higher body temperatures than humans, around 40 degrees C (105 degrees F), but are still sensitive to extreme heat, as well as extreme cold. Having a higher average body temperature means that although a bird may be able to cope with more intense heat than humans can, they will potentially quickly overheat on extremely hot days.
When a bird is unable to maintain a stable body temperature, it can quickly cause dehydration, and affects its neural system, balance, and flight abilities.
For smaller birds, with a lower bodyweight, perhaps a more serious challenge is staying warm when temperatures drop extremely low rather than cooling down in hotter weather.
A house sparrow taking a drink of water to keep cool
Birds have no feathers on their feet and (usually their legs), and large amounts of heat can escape from these bare parts. Birds’ feet do not have many pain receptors and are not especially fleshy, so are not generally affected by extreme temperatures, either heat or cold.
An anatomical system known as a countercurrent heat exchange exists between the veins and arteries in a birds’ legs. Warm blood from the bird’s body is carried by the arteries to its feet, passing close to cold blood returning from the feet to the body via the veins.
This causes the arterial blood to cool down while the blood in the veins is warmed, regulating the bird’s body temperature to the required 40 degrees .
As well as explaining why birds do not feel excessive heat in their feet, this also shows us how birds such as gulls, ducks and geese are able to walk on icy pond surfaces without their feet freezing.
A dove taking a walk in the desert
Birds do not sweat at all, even through their feet. However birds’ legs and feet do play an important role in both conserving heat in cold weather and reducing their body heat in extremely hot weather. The bare skin on a bird’s feet and legs allows heat loss.
Long-legged birds, such as whooping cranes have been observed to wade into deeper water than usual when attempting to cool off, to maximize the portion of limbs that are submerged, radiating as much heat as possible away from their bodies.
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