Snowy Showoff: Bill-vibrating behavior
I recently had the pleasure of attending the 39th Western Field Ornithologists Conference in San Diego, California. Among the wonderful places I birded was the San Dieguito River Estuary in Del Mar. Its banks and mud bars hosted a pleasing variety of shorebirds (Pacific Golden-Plover, anyone?), and landscaped properties bordering the river teemed with bird life. But my personal highlight of the stop involved a Snowy Egret engaged in a behavior I’d never seen before. It was out in shallow water, facing in the direction of a light current moving inland with the rising tide. The bird was crouched horizontally, holding its bill in the surface of the water and burbling away like a kid about to be rebuked for blowing bubbles in his chocolate milk.
Thinking this was pretty brilliant, I grabbed a few digiscoped stills and filmed the behavior with my Leica APO-Televid 65mm + iPhone 5s via PhoneSkope adapter. In the 5 or so minutes I watched this happening I was fortunate to witness the bird capturing a fish, which was apparently attracted by the ripples and small splashes the Snowy had created.
After putting the rough footage up on Facebook, my fellow Leica Birding Team member Rafael Galvez chimed in that this behavior is known as “bill-vibrating”, citing Jim Kushlan’s nice article addressing The Terminology of Courtship, Nesting, Feeding, and Maintenance in Herons. I was also able to find a 1973 article by Wolfe & Dawson addressing this behavior entitled Bill-vibrating: A Prey-attracting Behavior of the Snowy Egret that nicely describes what I saw.