Big Love- page 2 | Science | Smithsonian
(Cheryl Carlin)

Big Love

In a mating ritual, male humpback whales leap, splash and fight. But researchers ask: just what does a female whale want?

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(Continued from page 1)

"The female always sets the pace in these shows," Herman says. Yet around her peaceful bulk, all is mayhem. Whitehook heaves himself half out of the water to charge headfirst at another male. He again launches himself skyward, then falls backward, a maneuver Pack calls a "reversal," which makes a male look larger to his rivals. Whitehook then slaps his long jaw on the water, breaches again and makes yet another reversal.

"Wow! He must be the P.E., the principal escort," says Pack. "There's usually one guy in these pods who does most of the showing off."

"It's his way of showing her—and his competitors—his energy and strength," adds Herman. "He's likely to be the one swimming the closest to her, too, and guarding her, keeping the other males away."

"We think the females choose a particular male," says Herman, "but we don't know that for certain, and we don't know what male attributes the females prefer."

Herman and Pack hope to witness a mating, something never before seen in humpback whales. Their grand pursuit would settle some of the most basic questions about the natural history of the species. If females choose their mates, as Herman suspects, observing the whales' mating behavior could reveal which males are most attractive to females. Scientists suspect that the largest, most powerful—and therefore among the oldest—males in a competitive pod are most likely to succeed in mating. In the past, such large whales may have been prime targets for hunters, which may help explain why the humpback whale population dropped so precipitously in the past century.

I stood with a cluster of tourists on a cliff above the Auau Channel and watched humpbacks breach in the waters below. Improbably, given their mass and bulk, they seemed to hover above the sea before crashing backward. At each daring breach, we whale watchers gasped, laughed and applauded. The humpbacks appeared to be having fun, too, seemingly confirming Herman Melville's description of them in Moby-Dick as the "most gamesome and light-hearted of all the whales."

Humpbacks are among the world's largest creatures. Adults weigh as much as 50 tons and grow as long as 50 feet (impressive, but only half the length of blue whales). Like most "great whales," or those longer than 30 feet, they are members of the baleen family, which means they fuel their massive bodies by filtering shrimplike krill and small fish through plates called baleen, which hang from their upper jaws. They spend most of the year feeding in cold, prey-rich waters in the northern and southern oceans. (This year humpbacks were found north of Alaska in the Beaufort Sea for the first time, possibly because of climate change, says Phil Clapham, a whale expert at the National Oceanic and Atmospheric Administration, or NOAA.)

When it's time to breed, humpbacks make the longest migrations of any mammal—5,000 miles or more one way—traveling from the poles to the tropics in as little as six weeks. Some 5,000 humpbacks gather off Hawaii each breeding season, which lasts from December to May. Other breeding sites are in the warm coastal waters of Australia; Fiji, Tonga and other South Pacific islands; the east and west coasts of Africa; the West Indies; and the tropical parts of the Americas.

Photo records of humpback flukes—which are collected by other teams of humpback researchers around the world as well as Herman and Pack—have revealed a greater degree of flexibility in the whales' wanderings than previously imagined. Instead of heading north to Alaska from Hawaii, some whales cross the Pacific Ocean and end up in Japan. And researchers have been following some whales for so long they've seen young calves grow up and have calves of their own. Starting at about age 5, females give birth every two to three years. Pregnancy lasts nearly a year, and the calves nurse for about ten months. Mother and calf travel to their feeding grounds together, a journey that teaches the calf the annual migration route.

Even male humpbacks are more gregarious and social than their nomadic lifestyle might suggest. Males sometimes form temporary alliances while breeding and feeding, and at times both sexes work together to corral fish for feeding. "They're intelligent creatures," says Herman.

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