The first method birds use to avoid getting hot is by fluffing their feathers. The bird will just open their winds wide and let it stand in that position for some time. They will generally be facing towards the direction of the oncoming wind. This will make the air carry away its body heat, keeping birds cool.
Another trick that birds use is panting. When a bird recognizes that it is heating up, it will start taking short, quick breaths. The aim is to let the air move through its mouth, throat, and lungs. As a result, the moisture in these regions will evaporate, which in turn will cool down the body of the bird. And by continuing panting several times, the bird succeeds in cooling itself completely.
Now, if none of the above methods work, then the bird will choose to simply rest during the day. Most of the flying and hunting will be done in the early morning when the temperature is cool. And when the sun is fired up in the afternoon, the birds will rest in their place, only to come out once again in late evenings.
When your bird starts feeling the heat, it will start doing many things that you can take as a sign of its discomfort. For one, the bird will start holding its wings wide away from its body in a bid to get as much air as it can. In some cases, the bird will also look extremely agitated. And when you look at its face, it probably will have a blank stare.
In worst cases, the bird will start panting very heavily, might fall off its support onto the surface and start convulsing aggressively. Unfortunately, this can even lead to death. So, be very watchful for the initial signs of heat like panting, spreading wings etc. This will help you take corrective measures early one and prevent the bird from being in life-threatening situations.
However, if the bird is in a critical condition, and you are unable to improve it, then you must immediately take it to the nearest veterinarian. Delaying such an action may prove fatal to your pet.
Once you understand the signs of a bird feeling the heat, you can implement some measures to keep pet birds cool in hot weather. Many bird owners attach an automatic mister very near to the birds. These devices spray a mist of water on a regular basis. As such, the bird can stand under the device and get a cool mist of water sprayed all over its body.
Another useful device is the bird cooling fans. These work just like normal cooling fans people use at home. The difference is that these fans are smaller sized ones so that they fit nicely into the birdcage. You can also add in a thermostat in the cage which can keep a tab on the temperature and can switch the cooler on and off depending on whether the temperature is hot.
And at last, just remember to keep the bird cage away from direct sunlight during the summers. That alone will cut down the heat felt by your pet bird.