DOLPHINS ARE FASCINATING CREATURES

by Whit Gibbons

March 21, 2010

Dolphins are marvelous animals, whether in the wild or in a sea park. Following is a question about dolphins I received last week.

Q: I saw a website that said dolphins have a feeding technique in which they herd fish and will actually come out of the water onto a beach after they wash the fish ashore. The site says this behavior occurs only in coastal South Carolina, and nowhere else. Is that because the behavior is genetic or because only the ones in the S.C. population have learned it?

A: The behavior you refer to is called strand feeding. I am familiar with the website that says the behavior is unique to South Carolina, but the statement is not true. Strand feeding is commonly observed in several rivers in the state, but according to Meg Hoyle who conducts Botany Bay Ecotours (www.botanybayplantation.com) on Edisto Island, S.C., the behavior has been reported throughout the range of bottlenose dolphins, from New York to Argentina. In fact, one of the first reports of strand feeding, in 1971, was not from South Carolina.

Highly social creatures with large brains, dolphins have an uncanny ability for mimicking behavior they observe in other dolphins, or even in other species. The strand feeding behavior may be learned within certain populations and passed on from one generation to the next. My first observation of strand feeding happens to have been in South Carolina, at Kiawah Island. Tony Mills, Tim Owens, and I stood waist deep in a tidal creek, setting a trammel net made of thin nylon mesh to catch diamondback terrapins, the salt marsh turtle, for a research project. We were stretching the net across the creek to catch turtles that became entangled.

As we neared the opposite shore, we saw four sets of fins circling in the open water about a hundred feet from where we stood. We stopped to watch as four bottlenose dolphins, ranging from eight to 10 feet long, began swimming faster and faster, in a smaller and smaller circle. We saw fish jumping, and then an enormous splashing wave washed over a sandbar alongside a meadow of salt marsh grass.

What happened next was amazing to behold. All four dolphins swam straight toward the sand bar and slid forward until their entire bodies were out of the water. They were turning their heads to eat fish that had washed up onto shore but appeared to be chatting with each other like four sunbathers. They stayed on land almost a minute, as the three of us yearned for the camera in our boat farther up the creek. The sight of the beached dolphins was quite a spectacle, but their next act was even more dazzling. Simultaneously, as if choreographed, all four flipped their heads and bodies to the right, turned completely around, and dove back into the water.

But the show was not over. As we watched in amazement, four dorsal fins headed toward us in single file about a dolphin length apart. They were traveling right toward us as fast as any motorboat. We looked at each other, realizing that we could not possibly get to the bank before they reached us. We stood helpless as the four leviathans sizzled past between us and the near shore. Their fins cut through the water within a couple of feet of where we stood.

We watched, still immobile, as they made a large arc in the creek and started back toward us from the opposite direction. Again, all four swished by within the span of two seconds. We were glad their sonar was working so that they missed us and the trammel net stretched across most of the creek. We were also thankful that dolphins are playful and not mean, and that their diet does not include primates. They were clearly in their element and in control. They may do clever tricks when confined to a sea aquarium, but what they can do naturally in the wild without human trainers is even more remarkable.

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