Black Skimmer
Rynchops niger

 Content and photos by James Giroux – except where indicated

There are many ways that birds obtain food, but the beak always plays an important role. With the exception of raptors, who grab prey with their talons, the beak is the primary tool for acquiring food.  Ducks dabble, seed-eaters peck, shorebirds probe, terns dive, hummingbirds sip, and flycatchers catch on the wing. But there is one strange North American bird that has a unique way of catching food: the Black Skimmer.  This bird flies over the water, dragging its lower mandible just below the surface. When the bill hits a fish, a reflex action causes the head and bill to snap upward, and the fish is caught.

Their ability to maintain a position with the lower beak just below the surface, while they fly over undulating water with variable ocean winds is truly remarkable.

But wait, there’s more that makes this a strange bird. The Black Skimmer is thought to be the only bird in the world that has a slit-shaped pupil. In other words, it has a cat eye.  Why would this bird have a cat eye? Most nocturnal animals have a slit-shaped pupil. If you have a large pupil – for letting in more light – a slit-shaped pupil is more efficient for blocking light in bright conditions.  The Black Skimmer is often a nocturnal or crepuscular (dawn and dusk) feeder. That explains the large pupil. But, it also feeds during the day along the surface of the water, where there is a lot of glare. The slit pupil helps reduce that glare, and functions somewhat like our sunglasses.

And if you are still not convinced that this is a strange bird, consider how they sometimes rest on the sand. The Black Skimmer will often lay out flat on its belly – dog-like – with its head forward. This posture makes them look like they are dead on the beach, but they are just resting their neck muscles, or trying to stay cool.

Photo by Greg Lasley

In the U.S. we think of the Black Skimmer as a coastal bird, but the populations in South America are both coastal and inland birds. It makes one wonder why we don’t have skimmers on our inland rivers in North America. Is it the different fish species? Fish abundance? Has population encroachment driven them out of inland areas?

In the U.S., Black Skimmers occasionally stray into the interior, but your best bet for finding one is along the Texas coast. They are usually seen resting in flocks along the shoreline, but if you are lucky enough, you might catch one skimming. It is a sight to behold!

Sources:

https://allaboutbirds.org
https://www.wikipedia.org/
On the Slit Pupil of the Black Skimmer: Journal of Field Ornithology