When I was fifteen, I received as a Christmas present the three-volume Audubon Society Master Guide to Birding. Accompanying promotional material promised the reader something on the order of sixty never-before disclosed secrets to field ID. One that I recall was a new way to tell the waterthrushes apart–by the shape of the supercilium.
Thirty years later, that’s old hat. We “all” know–well, okay, some birders know–the difference: prominent and flared out behind the eye on the Louisiana Waterthrush vs. thin and tapering behind the eye on the Northern. But somebody had to figure out that field mark, and take it to the next level: to get that knowledge out there.
There’s something else. Even if waterthrush supercilia are old news, it’s still just as exciting as ever to learn about new field marks. I confess, I don’t refer too often these days to the Master Guide. But that three-volume set retains a special place in my heart: The Master Guide reminds me to stay alert to the possibility of new knowledge and understanding.I take it as a given that there’s new bird ID knowledge still waiting to get processed and publicized. Here at The ABA Blog, Catherine Hamilton recently described how the “gape notch” is important for distinguishing among the notoriously difficult “peeps” (the little sandpipers in the genus Calidris.) And in the January/February 2014 Birding, Nick Lethaby takes a new look at the old problem of the “Spizella trio”–the Chipping, Clay-colored, and Brewer’s sparrows. These three sparrows are especially tricky in fall and winter, and Nick encourages us to look at them from behind. Click here for a free PDF download of his article.
Here’s my question for you. Are you aware of some little-known field mark? Something that, as far as you know, isn’t depicted or discussed in the major field guides? Don’t worry if your knowledge is a bit provisional. That’s how it is as we push forward together to learn more about bird ID.