by Greg Mayer
A few days ago, in my post on the ducks of San Diego, I noted that mergansers were my favorite ducks, in part because of their tooth-like bill serrations, and that I knew of no other birds (except sort of in geese) that had such modifications of the bill. Well, of course, as soon as I said it in public, I’m proved wrong*. Look at these frighteningly fierce serrations on a hummingbird!
As explained by James Gorman of the New York Times, explicating a recent paper by Alejandro Rico-Guevara and colleagues, this “toothsome” smile arises from the struggle for controlling nectar resources. The short version: hummingbirds’ bills are long for getting nectar out of flowers, and they are hooked and serrated to keep other hummingbirds away from the flowers.
*Being shown to be mistaken, promptly after announcing my generalization, is an example of what Ernest E. Williams called the Principle of Unsympathetic Magic. He recounted his recognition of the Principle in a very short paper in 1977.
Rico-Guevara, A., M. A. Rubega, K. J. Hurme and R. Dudley. 2019. Shifting paradigms in the mechanics of nectar extraction and hummingbird bill morphology. Integrative Organismal Biology, Volume 1, Issue 1. pdf
Williams, E.E. 1977. An anecdote. Anolis Newsletter III: iv. pdf