Why do bird eggs have different colors

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October 30, 2019, 19:09 | Animals

Pigments that determine the color of the shell help maintain the temperature of the developing embryo in the egg.

Why do bird eggs have different colors< /p>

Eggshell calcium carbonate is white. However, bird eggs show a wide variety of shades, due to the presence of two enzymes – brown-red protoporphyrin and blue-green biliverdin. Details of coloring depend on their number, distribution, and so on. Such a relatively simple mechanism allows various birds to lay eggs of many colors, and they often use this, achieving a camouflage coloration that hides the clutch from predators, informs Ukr.Media.

But not infrequently there are completely non-masking shades, the role of which still remains unclear. It is hypothesized that a certain distribution of pigments can protect embryos from UV rays, help parents distinguish their clutches from neighboring ones, etc. However, Daniel Hanley and his colleagues showed that the key factor determining the color of the shell is temperature. They write about this in an article published in the journal Nature Ecology and Evolution.

Biologists conducted a detailed analysis of egg coloring in 634 species of birds from all corners of the Earth. By mapping the characteristic brightnesses and colors on the map, the scientists found that the inhabitants of colder regions have a generally darker shell than those of birds that raise chicks in areas where the sun shines warmly and brightly. If the coloring was connected precisely with the need to protect against UV radiation, one would expect the opposite picture: in the southern regions with a bright sun, it is maximum, so more pigment would be needed for shielding.

The authors associate the existing distribution of pigments and colors with the temperature characteristic of the place where the chicks were hatched. In the cold, darker eggs can absorb more radiation and additionally heat the embryos maturing inside. Conversely, light shades in hot regions help save future chicks from overheating.

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