1. Why Hot Weather Is Hard for a Bird
People cool down mostly by sweating: water on the skin evaporates and carries heat away. Birds do not have that option. The Smithsonian’s National Zoo notes that birds are warm-blooded, which means they make their own body heat, and that some common backyard birds, such as robins and blue jays, normally run as hot as 42°C (109°F) [1]. That leaves little room for getting hotter.
Birds also cannot always hide. A research paper on birds’ heat tolerance points out that most birds are active in the daytime, so they may have to put up with “operative temperatures” sometimes above 50°C [2]. Operative temperature is a measure that combines air temperature with sunshine and wind, to describe how hot a body really feels. This is why birds have several ways to lose heat, which the rest of this page follows.
2. Panting and Throat Fluttering: Cooling by Breath and Moisture
The zoo article lists panting among the ways birds cope: a bird opens its beak and lets heat and moisture escape with its breath [1]. Some birds do something that looks a bit different. Cormorants, pelicans, owls, and ravens quickly flutter their neck muscles, which, the zoo explains, lets heat leave the body and exposes skin to cooler air [1].
Scientists group the ways birds cool by evaporating water into three kinds. The research paper on desert birds names throat fluttering (its example is nightjars), evaporation through the skin (its example is doves), and panting (its example is the songbird group called passerines) [2]. So “every bird just opens its beak” is not the whole story. Which method is the main one depends on the kind of bird.
Panting looks like the easy option, but the same paper says its efficiency is “substantially lower” than throat fluttering or skin evaporation. One reason it gives is that the big chest and belly muscles used for fast breathing make heat of their own [2]. Any method that depends on evaporation also uses up water, so evaporation alone cannot solve every hot day. That raises a question: can a bird lose heat without spending water at all?
3. How a Toucan’s Huge Beak Works Like a Radiator
One answer comes from the toco toucan, a bird of the Brazilian cerrado (a savanna-like grassland) with a beak almost as big as the rest of its body. In a study published in Science in 2009, a team led by Augusto Abe in Brazil, together with Glenn Tattersall in Canada, found that the toucan changes how much blood flows to its beak. When it is hot, more blood flows there and extra heat escapes. When it is cold, the flow is cut back to hold warmth in [3]. The researchers compared this to a car radiator, or to opening and closing a window.
The toucan does not change blood flow to its beak instantly. In one experiment, the surroundings were cooled from 25°C to 10°C, and the toucan took about 10 minutes to adjust [3]. The magazine reports that, depending on conditions, the beak gave off between 25% and 400% of the heat the bird makes while resting [3]. That is a very wide range, and it comes from a magazine summary rather than the original paper, so treat it as a rough picture of how much the beak can matter, not a fixed number.
Bare, blood-rich body parts can serve as radiators in other birds too. The zoo article says flamingos and ibises have long, thin, featherless legs that let heat escape through the skin, and that standing in cool water helps even more [1].
4. Why Storks Put Their Droppings on Their Legs
Now for the odd one. Storks sometimes excrete onto their own legs. As the wet droppings evaporate, the legs cool. Scientists call this urohidrosis (say “yoor-oh-HY-dro-sis”) [4]. The zoo article mentions it too, saying storks and herons do it [1].
A 2021 study in Scientific Reports asked when storks do this. The team used photos and videos from the Macaulay Library, a large archive run by the Cornell Lab of Ornithology, and found 6,112 usable records covering all 19 living stork species. They matched each record to the weather at that place and time [4]. Storks used urohidrosis more when it was hotter, sunnier, and more humid, and when the wind was weaker [4].
The temperature threshold for urohidrosis that the study’s models estimated differed between species: 27.68°C for the white stork and 33.49°C for the woolly-necked stork [4]. These are numbers for two stork species, not a rule for all birds. The authors say such differences may show which species are more at risk from high temperatures [4].
It is also rare. The paper says it requires regular access to drinking water, and lists storks, New World vultures, condors, gannets, and boobies as birds that do it [4]. This links back to the earlier question: when a bird spends water to cool down, it has to be able to get more water.
5. Resting in the Shade and Other Ways Birds Avoid the Heat
Birds do not rely only on their bodies. The zoo article describes birds that avoid heat by being active in the cooler parts of the day and taking naps when the sun is strongest, and others that bathe so that wet feathers let heat escape quickly [1]. It also says people can help wild birds with clean water, such as a birdbath or fountain [1].
Putting the four sections together, a reasonable summary is that a bird keeps cool with a mix of tools: evaporation from breath, throat, or skin; extra blood flow to bare parts such as beaks and legs; evaporation from droppings in a few species; and simply choosing a cooler place or time. Which tool comes first differs from one bird to the next.
6. A Careful Way to Watch Birds on a Hot Day
On a hot day, look for birds at a park or by a river. Watch from a distance, and do not touch them or feed them. Go with an adult, choose a cooler time of day, bring a hat and water, and stop and find shade if you feel too hot.
Write down what you see: the kind of bird if you know it, the time, whether it is in sun or shade, whether its beak is open, and whether there is water nearby. Then you can ask questions like “Is the bird with its beak open a small songbird?” or “What does a big wading bird do with its legs?” Your notes can be compared with the sources below. The toucan paper in Science (2009) is a good place to start if you want the original numbers.