With a high body temperature, extremely good insulation, and limited ways to dissipate heat, one of the biggest risks for birds in hot weather is simply overheating. Maintaining a normal activity level in hundred-degree heat is potentially fatal for a bird, and some of the strategies birds use to keep cool can dramatically change their overall appearance.
The activity patterns birds employ to survive the heat are generally what we would call “common sense,” and your strategies for finding birds in hot weather are straightforward. Birds are most active in the cooler temperatures of very early morning, so the earlier you can start birding, the better. As the day warms up, birds slow down and seek shade — especially shade with water. A small pond or stream (or a bird bath) shaded by trees and shrubs will attract birds throughout the day, and if you can find a shady place to sit where you can see the birds without disturbing them, you’ll have a really pleasant time.
Some birds remain active in the open during the heat of the day — often they’re adults with young in the nest and have no choice but to continue gathering food and carrying it back to their growing offspring. And their strategies for dissipating heat can change their appearance.
Birds do not sweat, so the only option for evaporative cooling is to open their bill and flutter their throat to allow moisture to evaporate out of the mouth. Other options for cooling off include reducing insulation by compressing feathers tightly against the body, which makes the legs look longer, and holding the wings away from the body to expose bare skin.
Watching how common birds deal with heat can help you understand the range of appearances shown by all birds, and it will give you a greater appreciation of the challenges they face every day.
This article from David Sibley’s “ID Toolkit” column appeared in the July/August 2017 issue of BirdWatching.