Book 31, Question 60
How do birds keep their eggs from getting too hot or too cold?
Parent birds are like living thermometers.
On cool days they sit tight and warm the eggs with their brood patches. On hot days they stand over the eggs and shade them with their bodies or wings. Some birds, such as certain plovers, even soak their belly feathers in water to cool their eggs. Even a few degrees can make a difference for a growing chick.