A global survey suggests that it might help keep them warmer
DEC 6, 2019 — 6:45 AM EST
Bird eggs come in a dizzying array of colors. But from a global perspective, that diversity follows a simple pattern, new research shows. The colder the climate, the darker the egg.
Darker eggs absorb more heat than lighter ones. This could help developing chicks stay warm while their parents forage for food. That’s the conclusion of the study. It appeared online October 28 in Nature Ecology and Evolution.
Biologists have long tried to understand why birds’ eggs come in so many shapes and colors. There could be many reasons. Color may help camouflage eggs from predators. Egg shape or color might also somehow protect eggs against bacteria or signal their quality. Shape or color might even help keep an egg warm. Scientists have turned up some evidence to support all of these hypotheses, says Phillip Wisocki. He worked on the research while studying biology at Long Island University Post in Brookville, N.Y.
Adds Daniel Hanley, scientists were never sure whether any of these factors were important to egg diversity. This biologist advised Wisocki on his research.