Dolphin Watch
Mysterious morning
By ANN WEAVER
| Article published on Thursday, Nov. 2, 2006 |
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I'd been trailing five adult bottlenose dolphins since dawn. It was hard to stay with them. They kept scattering and disappearing like short dogs in tall grass. They were hunting.
Suddenly one leapt across the surface, a fantastic dolphin long jump. Ah, chasing a fish. It leapt again, closer this time, and vanished. Suddenly, it leapt up next to me and looked me straight in the eye.
The other four rushed over and milled around, breathing heavily. Here and there, a dolphin slugged the water with a powerful tail slap. I felt like a covered wagon surrounded by whooping Indians. I floated in neutral.
They bunched up and sprinted from whence they came ... all but one. It hovered starboard. I waited. It rolled sideways and peered at me. I edged forward. It swam alongside, peering, then sped to the others. What just happened?
Feelings are not facts. The facts fit three very different interpretations.
The first interpretation was threat. Exasperated by the engine drone hurting the hunt, the leaper was saying, "Get lost!" They'd been breathing heavily as if grousing among themselves but not chuffing, an acoustic punch that can mean anger. If angry, how impotent their growls and barks against the indifferent fiberglass hull. Tail slaps can mean anger too, but not always. The leaper's behavior was clearly about me. But was the other's? If threatening, it was a first.
A second interpretation was recognition. The leaping dolphin suddenly remembered my boat and sprinted over to say hello.
Recognition seemed plausible. Other study subjects have raced over to greet me. Once, after many months away, I returned to the zoo and my many friends who worked and lived there. One was a female pygmy chimp (bonobo) named Lana. I'd studied her extensively while investigating how chimp mothers raise their babies but never fed nor groomed her. From a distance, she picked me out of scores of zoo-goers, an impressive feat of recognition, and raced across the enclosure to greet me with wiggles, jiggles and a great happy face. Others (people and bonobos!) rushed over as well. If not for the Plexiglas barrier, I would've hugged her. And she would've hugged me back.
Like bonobos, dolphins know and need their companions. Recognition is easy for them. They learn boat engines and avoid boats that harass them. Wild dolphins befriend human swimmers or spend their lives escorting boats through passes. If the leaping dolphin rushed over to greet me, were the others caught up in the excitement?
A third interpretation was seeking shelter or protection. The other four dolphins were conspicuous for swimming in pairs. The dolphins in each pair surfaced as one in perfect synchrony.
Experts have two words for large dolphins swimming in synchrony: adult males. As far as we know, some male bottlenose find a buddy during their teens and remain devoted companions the rest of their long lives. This is curious given the mammalian penchant for male competition. However, a pair easily out-competes a single bull. Synchrony advertises male status.
Male pairs sometimes work in teams, their combined bulk compelling available females to swim with them. Did the leaper suddenly break away to seek shelter at the boat? Among themselves, especially as calves, dolphins seek shelter next to and under trusted companions. The others may have been chasing a fleeing captive, appearing to surround me when they were actually surrounding her. They may have tail slapped to get her 'back in line'.
Seeking protection isn't so far-fetched. During my bonobo studies, a frightened mother with a clinging infant sought my protection although I was on the other side of the cage bars.
Off public display in a small bedroom cage, the chimps often got bored. This day, three adults got into a chase game that became rough. The mother started screaming. She reached out to me desperately. I instinctively grabbed her hand. Her grasp crushed my knuckles. I yelped. She let go. The hubbub faded. The chimps probably recognized that humans were now involved.
To solve mysteries like this memorable morning, scientists turn interpretations into predictions we can test systematically (hypotheses). Nature is full of mysteries. Climb aboard.
Dr. Weaver studies wild dolphins under federal permit GA1088-1815, National Oceanic and Atmospheric Administration. Contact her at www.dazzlingdolphins.com.
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Article published on Thursday, Nov. 2, 2006
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