The air space of an egg: an embryonic “cold nose”?



Experiments have been performed to measure the cooling rates of air space and equatorial regions of the incubated egg. The air space has a low specific heat so that it cools faster than the rest of the egg when an incubating bird leaves the nest. This rapid cooling of the air space reduces the water loss that would occur when a bird leaves the nest by 50% when compared with the water loss from an equivalent area of the rest of the shell. The overall influence of the air space is probably to reduce water losses during incubation by 10–15%.