Why Do Gulls Have a Red Spot on Their Bills?

The answer helped develop the science of animal behavior.

This story comes to you through a partnership between Audubon and BirdNote, a show that airs daily on public radio stations nationwide.


Written by Bob Sundstrom

You may have noticed--on a trip to the shore or at a waterfront restaurant where gulls gather--that many gulls have a bright red spot near the tip of their otherwise yellow bills. Behind that red spot lies a considerable tale--that's t-a-l-e!

In the mid-20th Century, Dutch scientist Niko Tinbergen studied nesting Herring Gulls. He noticed that newly hatched gull 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.

Tinbergen also made the case that the chick's attraction to the red spot on the bill was instinctive. This conclusion came at a time when there was furious debate among experts about whether such behavior was learned or innate. Tinbergen's gull research helped lay the groundwork for the science of animal behavior, and in 1973 earned him a Nobel Prize. And it all started with that little red spot.

Learn more about Tinbergen's research--and see a photo of that red spot--on our website, BirdNote.org. I'm Mary McCann.

Bird audio provided by The Macaulay Library at the Cornell Lab of Ornithology, Ithaca, New York. Calls of Glaucous-winged Gulls recorded by A.A. Allen. Begging call of Glaucous-winged Gulls recorded by E.S. Booth. Herring Gulls recorded by Martha Fischer.
Producer: John Kessler
Executive Producer: Chris Peterson
© 2013 Tune In to Nature.org      October 2013     Narrator: Mary McCann