National Geographic : 1988 Dec
ENTLE GIANTS" be comes a misnomer when violence erupts among humpback males competing for females during winter calving and mat ing in Hawaiian waters. As a group of males at the surface pursue a cow, one agitated suit or lashes his tail in a furious dis play (left). Another distends his throat pouch (above), perhaps to appear more formidable, and lunges toward a male in front of him. I have often watched pairs of humpbacks lashing each other with their tails, really beating the tar out of each other. Males use a variety of displays to gain dominance, including blowing a long string of bub bles, perhaps as a screen or warning to rivals. It took many years to under stand such behavior. Most cows with calves are accompanied by another adult, which scientists had long assumed to be a female "aunt" that helped the mother raise her calf. Then researcher Debbie Glockner-Ferrari began identifying the sex of the escorts and found they were all males, primarily interested not in baby-sitting the calf but in mat ing with the female. This system of a dominance ranking among males that com pete for females probably also applies to narwhals, toothed whales with an obvious second ary sexual characteristic, the tusk of the males, as long as ten feet. According to biologist John Ford, the males often travel sep arately from the cows and calves during the summer Arctic mi gration as the ice breaks up. "The males often joust with their tusks (opposite, above), tapping them together in a ritu alized manner," he says. Scar ring frequently seen on the heads of males suggests that the tusk also serves as a weapon. John believes that the calls narwhals produce represent a form of social language, and that the males probably have their own "signature" calls to identify themselves to other males.