Bird Watcher's General Store

Black Skimmers
07/17/20


Dear Bird Folks,

I didnít realize that we had Black Skimmers around here, but someone has recently posted seeing four of them on West Dennis Beach. Are they nesting there?

ĖTony, Centerville, MA

Itís a surprising place, Tony,

West Dennis Beach is one of the most popular swimming beaches on Cape Cod. The water is typically warm and calm, so it doesnít surprise me that so many people go there. Whatís surprising is that lots of birds go there as well. With Nantucket Sound on one side and a huge parking lot on the other, there is very little room for birds. Yet, as we speak, Least Terns, Piping Plovers, Willets and at least one pair of Horned Larks are all raising families there. And now you say there are Black Skimmers as well? This begs the question: How can all of these birds possibly afford the town beach stickers? Have you seen what they charge?

Here in North America, Black Skimmers are pretty much confined to the coastal areas of our Mid-Atlantic and Southern states. Folks who have spent time walking the beaches of Florida (back when it was safe to do so), very likely have seen skimmers resting on the sand along with gulls and terns. But Cape Cod is a long way from Florida and only occasionally do these odd birds breed this far north. A few years ago (it was probably more like twenty years ago, but you knowÖ), skimmers nested on Chathamís Monomoy Wildlife Refuge. In more recent times, the birds have moved over to the Vineyard, perhaps in an effort to be closer to the celebrities. Skimmers love the celebs.

Fishing-eating birds use a variety of methods to catch food. Ospreys dive for fish from high above the water, while loons pursue fish below the surface, and herons simply stand and wait for fish to come to them. While all these birds have different hunting techniques, they have one thing in common: they use their keen vision to locate prey. This is not the case with skimmers. Like fishing Jedi Masters, skimmers are somehow able to snatch fish without ever seeing them. It seems impossible, but after you read my explanationÖit will still seem impossible.

At first glance, a skimmerís beak appears deformed; the bottom half is 30% longer than the top. They look like one of those freaky dogs with a serious underbite, but even more so. When a skimmer wants food, it must first take to the air and fly an inch or so above the nearest body of water. It will then dip its extra-long bottom beak into the water and keep it there while it continues flying. This in itself is pretty amazing (or weird, depending on your perception of the event), but the next part is amazing by any standard. If the birdís beak comes in contract with a small fish, the beak will instantly snap shut and dinner is served. The process is a crapshoot, though. The skimmer never sees the fish ahead of time. It just flies low, with its beak dragging through the water, hoping that it might stumble onto a fish that just happens to be swimming close to the surface. How random is that? It would be like driving down the road, with your arm out the window of the car, hoping that an egg salad sandwich might land in your hand. My analogy might sound silly (and messy), but itís not far off.

This kind of fishing is a little haphazard, but the birds know how to improve their odds. They generally feed at low tide or in shallow water. Also, because the birds donít depend on their vision to find prey, they can forage at night when the wind tends to be calmer and the water less choppy. A few years ago (or twenty), I watched skimmers feeding in a nearby marsh. The water at this one location was only ankle deep (I know because I was standing in the middle of it). It seemed too shallow to support fish, but the skimmers thought otherwise. One bird repeatedly ďskimmedĒ back and forth, right in front of me, cutting the water with its freak beak. It was pretty cool. I attempted to take a video recording of the action, but the bird was a much better flier than I was a videographer. My video mostly consists of a blurry bird, empty sky and the back of the guy standing next to me.

When it comes to breeding, skimmers are often found in the company of terns. Even though skimmers are large birds, weighing three times more than Common Terns, it is thought the bigger birds use the smaller birds for protection. How does that work, you ask? Itís because terns are crazyÖcrazy aggressive. Terns love to scream, and mob, and scream, and will even physically attack predators. By nesting within a tern colony, the skimmers get free protection. Well, itís free as long as they can live with all the screaming.

Skimmers tend to use the same breeding areas year after year, Tony, but if they arenít successful, they will search for a new location. Itís hard to know for sure if the West Dennis birds are just visiting or are scouting for future breeding grounds. Itís now late in the season, so we probably wonít know what they have in mind until next year. Iíd write more on this topic, but suddenly Iím in the mood for an egg salad sandwich. But given that my favorite deli is only offering limited service, I might be forced to use an alternative method to get a sandwich, like driving around with my hand out the window. Iíll let you know if it works.




Artwork by Catherine Clark


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