Thursday, August 24, 2006

Can dolphin watching tours interfere with females' parenting?

Who doesn’t have a story about their mother? Mothers are either the balm or bain of their children’s existence, sometimes both in the same day. I study how animal mothers raise their children. They neither neglect their children nor relentlessly ‘parent’ them with a constant stream of instructions. There is little punishment. Yet animals grow into functioning members of their societies. Indeed, most animal societies don’t have criminals.

Think about that.Like people, there are good and bad animal mothers. Bad animal mothers tend to be more preoccupied with their own lives then the needs of their children. Such children (especially monkeys) must make a lot of noise to get their needs met. Good animal mothers are attentive and responsive to their kids. They quickly provide what their youngster needs. Like people, the kind of attention animal children get makes a difference in how they grow up.

So what kind of mothers are dolphins? And how can you tell at sea?I spent some time today watching a mother named E and her calf Easter. E is a difficult dolphin to study. She is, to put it mildly, not interested in boats. Anytime we get remotely near her, she gathers up little Easter and rushes off. The data display her disinterest: We take pictures of dolphin dorsal fins as data. Most of E’s pictures are at a great [blurry] distance.

Luckily, her fin is distinct enough to recognize.Around noon, I found a small dolphin, too little to be by itself. It was messing around the waters of a big bay in the southern part of our study area. I saw another, bigger, fin far in the distance. It would have taken me three minutes to get over to it (we drive slowly around dolphins) so I had no idea who it was or if it was this little tyke’s mother.

Mothers with older calves (1 to 2 years old) often feed while their calf amuses itself some distance away. The older the calf, the greater the distance. Nonetheless, the two are in contact. Mother is no further from baby than she can monitor.This may be why. Calves are curious. They love to investigate. As I slowly approached, the calf zoomed by the boat a couple of times. That was all it took. Next thing you know, I see its little fin speeding towards that big fin in the distance. That big distant fin is speeding toward it.

As I pondered the dazzling dolphin communication system, E and Easter surfaced together. I sighed, throttle in neutral.When you study animal behavior, you don’t want change the behavior. Since it was E, I also expected them to rush off. Instead, they surfaced together near the boat. In turn, they arched up and glanced over at me. I was grateful and relieved. They were beginning to trust us.But that was it. I waited.

The waters remained empty. The next time they surfaced, they were far in the distance again, puffing out visible breaths from their sprint. As I watched them leave, I thought about the critical world of distance between living beings. Every creature has a specific distance it likes to keep between itself and others of its kind. This is called personal distance. Even corals and anemones have a personal distance.

Every living being also keeps a specific distance between itself and potential enemies, its flight distance. If someone steps inside this critical distance, the animal flees.To study wild animals, you first have to figure out their flight distance. You can study them when you stay outside their flight distance. E has a huge flight distance from moving boats. What happened to her that she avoids them so tirelessly?

Quick "Facts about Dolphins"