Birds’ eggshells act as sunblock, says study

BBC : Eggshells may be even more complex than previously thought. Developing bird embryos require a certain amount of UV radiation. A recent study shows that a bird’s shell, depending on its thickness and the amount of pigment it contains, can control the amount of UV radiation an embryo receives. The discovery could shed light on the color variation in birds’ eggs. Birds that nest in the open tend to lay eggs with extra pigment, while those that lay eggs in holes and burrows tend to have white eggs. In addition, the longer the incubation period, the thicker the shell and the more pigment it contains. To determine how much light gets blocked by a given shell, the researchers used a spectrophotometer to shine light through it. They also extracted and examined the pigment. Previous studies have shown that besides acting as sunblock, the coloring of eggshells can fight infection and provide camouflage in the wild.