New research out of Prince William Sound shows humpback whales might not be the loners, or the ladies men, originally thought. After analyzing more than 30 years of data, Olga von Ziegesar and her group, Eye of the Whale Research, concluded that humpback whales maintain long-term associations, contrary to current scientific literature.
Von Ziegesar has traveled to Prince William Sound each summer for 33 years, documenting hundreds of humpback whales that pass through the sound. After analyzing her data, von Ziegesar, a biologist who studied at the University of California at Santa Cruz, found several humpback pairs returning to Prince William Sound year after year.
Within these groups, she noticed, female whales tend to stick together and males tend to have female partners longer than once thought.
While male humpbacks are thought to be promiscuous, the data indicated the whales seem to have "preferred females" with whom they associate for years. It's hard to say whether they mate or not, von Ziegesar said. Very little humpback whale mating has been documented.
However, fitting the cliché, male humpback whales tend to lose interested in their preferred ladies once the female is older and no longer reproducing.
The opposite has been seen in females. "Their bonds seem to strengthen as they age," von Ziegesar said.
While grouping together might sound obvious for animals traveling as far as humpbacks (they summer in cool northern waters and winter in warm tropical waters), the long-term associations are rarely observed.
"They have to migrate thousands of miles, so of course they aren't going to go alone," von Ziegesar said. "I think it's obvious, but it seemed weird to me it hadn't been proved by other people."
For decades, von Ziegesar and her crew have documented Prince William Sound whales from their camp near Knight Island Passage, a six-hour boat trip from Whittier. The Prince William Sound humpback population is small and isolated, making it easier to track pairs. Only 50 to 100 whales are spotted each year in the region, located east of Anchorage, Alaska's largest city.
Humpback whales, once hunted nearly to the point of extinction, are rebounding. In 2005, 20,000 whales were counted in the North Pacific, and they're increasing at a rate of 7 to 8 percent a year. Von Ziegesar said the population is approaching pre-whaling numbers.
The Eye of the Whale data documented two "clans" of whales. One, called the "Old Ladies," includes two females often seen swimming side by side. Because of their drooping tails, von Ziegesar estimates they're at least 70 years old. Humpbacks typically live 45 to 100 years.
Another group, dubbed "Magellan's Clan," was named after a male been seen off Baja California. Spotted within the group was a whale named Magellan, who often returned to Prince William Sound year after year with certain females.
Loners grouping together
Christine Gabriele, a whale biologist for Glacier Bay National Park in Southeast Alaska, also deals with a small population of humpback whales. She said she's seen whales group together in the past. She suspects they simply have "preferred feeding partners."
"I think that depends on personality," Gabriele said. "Whales have their own preferences and ways of doing things, and that includes whether they like to hang out alone or with their own friends."
Humpback whales aren't like toothed whales, which generally group together in pods. While humpbacks periodically group up to hunt -- often employing the effective "bubble net" technique -- they generally stick to themselves.
Gabriele said that she's seen groups of humpbacks in Glacier Bay Park since she started working there in 1991. This year she saw three groups of about 20 whales, by far the most ever. Within the groups were some loner whales. Exactly why those whales grouped together is something Gabriele is trying to figure out.
Food and other reasons
Laura Howes with the Whale Center of New England said that humpback whales' isolation probably has to do with the huge mammals needing 800 to 2,000 pounds of food a day.
"If you're an animal feeding that much, it makes sense to spread out," she said.
But it might be more complicated than that. Some research shows females humpbacks often help other pregnant whales feed, Howes said, while males tend to vanish.
Last season, Howes watched a pair of humpbacks, Echo and Tectonic, associate with each other off the coast of Maine. Echo did most of the work collecting food, with Tectonic following close behind, scooping up leftovers and "being a mooch," Howes said. When Echo gave birth to a calf, genetic testing proved he wasn't the father. Neither whale showed aggression toward the other, but the reasons for pairing up were unclear.
"There's so much you want to understand," Howes said. "Who knows what they're thinking."
That was a sentiment von Ziegesar seconded. She said humpback whales aren't like creatures you can observe on land. They spend most of their lives underwater and even if scientists wanted to scuba dive to observe them, the whales dive far faster than humans. That's why it's been a slow process in learning more about their social behaviors.
"We only see a small part of their lives," she said. "There's so much we don't see."
Contact Suzanna Caldwell at suzanna(at)alaskadispatch.com