Do male robins play favourites when it comes to tending to their young? It appears they do, and colour has something to do with it. Bob Montgomerie, a biology professor at Queen's University in Canada, has been studying robins for 25 years. He and an assistant have been running experiments whereby they temporarily replace the eggs they find in robin nests with artificial eggs. Each study nest is given eggs of a unique intensity of the classic robin’s egg blue colour. Prior to the eggs hatching, the real eggs are put back into the nest. The research shows that male robins will pay closer attention to their young if the eggs are a bright shade of blue. “Sure enough,” says Montgomerie, “males whose nests contained the brightest blue eggs fed their newly-hatched babies twice as much.”
The blue pigment found in eggshells is caused by biliverdin, an antioxidant the female robin uses to prevent cellular damage to her own body. Some scientists note that the female is jeopardizing her own health by redirecting this valuable resource to create more appealing eggs for her mate. Another example of moms putting their offspring first.