Bird eggs come in lots of different colors: white, brown, green, lavender, pink, and more. Splotches and speckles abound, too. If you’re in North America, maybe you’ve seen tiny bright blue robin’s eggs in a springtime nest. But did you ever wonder what makes that blue color? And why are robin’s eggs blue in the first place? We talked to biologist Bob Montgomerie about the reason for the hue. 

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