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The Black Skimmer: A Scissor-beaked Night Hunter

Bear with me for a brief thought experiment: What if humans had to eat the same way Black Skimmers eat? What would that even look like?

First you need to know how Black Skimmers feed, of course. It works like this: Flying a few inches above calm water, the skimmer drops its elongated lower mandible under the surface and moves over the water until its bill comes into contact with a fish, at which point it reflexively snaps shut and the skimmer has its meal. To reiterate, in case I'm not making this clear: Every time this bird feels a pang of hunger, it flies around over the surface of the water, half of its bill submerged, hoping to blunder into a fish that it does not know is there. 

Okay, back to my opening question. Let’s think about how this would work for humans. Imagine yourself walking around your apartment with your mouth open, in the dark, just hoping to bump into some food. Go ahead and try it. See if you can manage to fill your belly with anything more than drywall and doorknobs. I’ll wait.

Well, if you’re still reading this and aren’t off to the dentist for emergency surgery I’m guessing you failed. But skimmers succeed! So much so, in fact, that their capture rates for fish are about the same as their nearest relatives, the terns.  

Black Skimmers, a.k.a. Rynchops niger, which skim along North America’s southern coasts and throughout eastern South America, are striking birds—jet black on the back and snow white below, with long wings that help them flap and glide smoothly over the water. But their bills are by far their most distinctive feature, with an underbite that rivals Jay Leno’s. Bright orange and black, the lower mandible is long but knife-thin, making it easy to slice through the water. 

When Darwin saw the skimmers in South America he called them “scissor-beaks,” and marveled at their “extraordinary” fishing technique. He also presumed that skimmers preferred to feed at night, when small prey are more likely to be found at the water’s surface. He was correct, of course—he was a pretty smart guy—but even Darwin wasn’t aware of another special modification that helps skimmers at night: their cat-like eyes.

Skimmers have large pupils, which they need in order to forage at night. But they also need to be able to protect their retinas from bright sand and reflections off the water. To do this, skimmers’ pupils close vertically, forming thin slits that act as natural sunglasses. Skimmers are the only birds in the world with this kind of mechanism.

Could these birds get any weirder, you might be asking? Why, yes, they can! They sleep weirdly! When skimmers want a rest, they don’t sit like most birds, with their heads up. Instead, they just flop their heads right there on the ground in front of them, like Snoopy on top of his doghouse. It can be somewhat disconcerting to come across a flock of skimmers in repose, all splayed across the sand, but if you had a bill that big you’d probably want to rest it on the ground, too.

In summary, the knife-billed, cat-eyed, face-sleeping Black Skimmers are the quirkiest birds in America. Take a trip to the coast and see them for yourself, and be thankful that when you’re hungry all you need to do is walk to the refrigerator.