The Little Red Spot On A Gull's Bill
In the mid-20th Century, Dutch scientist NikoTinbergen studied nesting Herring Gulls. He noticed that newly hatched chicks were fed by their parents only after they pecked at the adults' bills. Tinbergen devised experiments that varied the shape and coloration of the adult's bill. It became clear that the red spot on the adult gull's bill was a crucial visual cue in a chick's demands to be fed, and thus its survival. Learn more about Herring Gulls and about Tinbergen's research.