ARE FASCINATING CREATURES
March 21, 2010
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
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.
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.
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.
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
you have an environmental question or comment, email