Thursday, May 18, 2006

How do dolphins discipline their calves?

It isn’t easy to study dolphins at sea. They often do mysterious things. But they also do quite obvious things.One evening, we had the chance to see how mother dolphins discipline their calves at sea.We were in a small cove about half way through the survey route, when we came upon a mother dolphin and her calf. The calf was just a bit smaller than its mother, so it was probably at least a couple of years old.Mother was feeding. She searched the ocean floor for tidbits.

As a result, she wasn’t visible very often. But her calf was another story. It danced around the waves, evidently not very hungry. It hung around the vicinity of its mother. Whenever people watch animals, we tend to watch the young. There are probably lots of reasons for this. One, the kids are small and this catches the eye. Two, the kids are usually way more active than the adults (just like in humans), and their gamboling antics are very entertaining.

I am always struck to see how a group of people who come up to an animal enclosure at a zoo immediately notice any babies in the cage. So it is at sea. When we find dolphin groups that include calves, it is too easy to watch the calves to the exclusion of the adults.This particular day was the same way. The calf surfaced more often than its mom. It zoomed around, popping up here and there, in the ways that dolphins use to amuse themselves when their mothers are busy and there is no one else to play with.Ah, but we were there, a small boat hovering nearby.

After a while, it seemed to occur to the calf that we might be something entertaining to play with. Now, when we find dolphins, we hang off to one side to watch them without disturbing their behavior. Our federal permit gives us permission to get close enough to take pictures of the dolphins, which we use to identify individuals, census their population and monitor their numbers. But since we study behavior as well, we watch from a distance without getting in the middle of things.

In this respect, we act like other boaters, which is good because the Marine Mammal Protection Act makes it illegal for people without a permit to get closer than 50 yards from dolphins and manatees.The next time the calf surfaced, it was a little closer to our boat. Then we saw it surface near its mom. When it surfaced the next time, it was again closer to our boat. Then closer. Finally it swung past our bow in what we call a crisscross behavior, rolling to peer into our faces.

Dolphins seem to use the crisscross behavior to check out boats. Because dolphins crisscross, we question the ethics of designing boat hulls that are so high that the boat driver can’t see what might be under them … like, dolphins or manatees in their path.Mother dolphin had her own version of ‘unethical’. When she saw her calf crisscross our bow, she shot through the water to her calf. Next thing you know, the calf shot out of the water to avoid its mother. The calf cleared its mother’s irritated lunge and, peace restored, they swam off together into the sunset.

Quick "Facts about Dolphins"