Flip to Page 32 of September’s Birding magazine, and you’ll find some familiar names discussing “How Birds’ Bills Help Them See.”
Ohio Wesleyan University senior Sean Williams is the lead author of the article, written in collaboration with faculty-mentor and OWU zoology professor, Jed Burtt, Ph.D. The seven-page article, a preview of Williams’ senior honors thesis, also includes pen-and-ink drawings by OWU alumna Kate Ball ’10 and photographs by Burtt’s wife, Pam.
“Not only is Sean the lead author,” Burtt says, “but he has been a wonderful collaborator and colleague.”
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Burtt says he and Williams also are working to prepare their extensive data for publication in a scientific journal. Williams, a pre-professional zoology major from Boston, has made several oral and poster presentations at national conferences of the American Ornithologists’ Union and the Wilson Ornithological Society.
In the Birding magazine article, Williams and Burtt conclude that the color of birds’ bills is influenced by where the birds live and how they forage for food. Their hypothesis is that birds which spend a lot of time in sunlight or perform other visually demanding tasks have darker bills to minimize sun glare and help ensure their survival.
“To date we have observed the foraging behavior and light environment of more than 400 species of North and Central American birds,” Williams and Burtt write. “The data show that birds that spent more than half their time in sunlight have darker bills than those that spent most of their time in shade. Those that forage only in shade have the lightest bills.”
As part of his honors thesis, Williams is expanding this research to include more species of birds. With financial assistance from an OWU Theory-to-Practice grant, he spent most of the summer in three different habitats in Costa Rica studying “Glare as a Selection Pressure on Bill Color in Temperate and Neotropical Birds.” And Williams will spend his mid-semester break at the Harvard Museum of Comparative Zoology collecting data on bill color for species observed during the summer.
His Costa Rican research also supports the hypothesis that the color of birds’ bills is influenced by the brightness of their environments, but the research continues.
“We need a lot more data on color variation of the bill and a lot more field data on the light environment and foraging of different species,” Williams and Burtt tell Birding magazine readers. “You can help. …”
“If you are interested in contributing to our study, we would love to have your observations of passerines or non-passerines anywhere in the world as they forage,” they state. “Find a bird, identify it, follow it for ten seconds, and then record whether the head is in sunlight, shade, or mixed lighting, and what behavior occupied most of the ten seconds you observed.”
Though Williams and Burtt’s full article is not available online, it is reprinted here (PDF*) with permission from Birding magazine. Supplemental information written by both authors is also available (PDF*).