Saturday, March 21, 2009

Whales and Dolphins, Oh My

In addition to Humpback Whales, we sometimes see pods of small (~4 ft) Spotted Dolphins here on the Silver Bank (in the Dominican Republic). The two species sometimes interact: the dolphins "tease" the whales, often mothers with calves. The dolphins dart in and out, and the humpbacks typically respond by slapping the water with their long pectoral fins along with other apparently agitated behaviours, seemingly trying to get the dolphins to leave them alone. This week we observed a completely different and suprising interaction.

We found a male juvenile whale (~20 feet long, perhaps 3 years old) logging on the surface. We put people in the water and he swam right up to everyone several times, very nice and easy. At some point 20 spotted dolphins appeared and the juvenile started slashing away at them, behaviour we normally expect to see. But after a few minutes Lorenzo Martinez - a Dominican whale expert and National Park official -remarked that the juvy (whale) was actually following the dolphins. The young whale followed the dolphins for perhaps 4-5 miles. Whenever we couldn't find the juvy, we would just look for dolphins, go to them and the juvy would show up. Toward the end, Captain Denise Lawrence put us in the water just as the the pod of dolphins was approaching our tender. I saw 10-15 scattered dolphins go by, then five dolphins in a tight pack, followed immediately by the juvenile humpback whale.

Shortly afterwards, this remarkable inter-species interaction ended. A mother, calf and their adult male escort swam nearby. Our juvenile whale attempted to join the group, but the escort manuvered between the juvenile and the mother and calf, rolled onto his side and repeatedly slammed the water with his tremendous pectoral fin, warning the juvenile to stay away.

Tom Conlin, whale naturalist and our host on the Silver Bank, has been observing the humpbacks and dolphins here for nineteen years. He told us that we had been very lucky to see this dolphin-whale encounter which, from his experiences with cetaceans, is probably quite rare.

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