Published online 12 October 2010 | Nature | doi:10.1038/news.2010.532

News

Swim from Brazil to Madagascar is longest known.

A humpback whale has set a distance record by migrating from Brazil to Madagscar. Brandon Cole/naturepl.com

A lone female humpback whale travelled more than 9,800 kilometres from breeding areas in Brazil to those in Madagascar, setting a record for the longest mammal migration ever documented.

Humpback whales (Megaptera novaeangliae) are known to have some of the longest migration distances of all mammals (but see slideshow showing other notable migrations), and this huge trek is about 400 kilometres farther than the previous humpback record. The finding, by Peter Stevick, a biologist at the College of the Atlantic in Bar Harbor, Maine, and his colleagues, is published today in the journal Biology Letters1.

The whale's journey was unusual not only for its length, but also because it spanned an ocean basin, multiple breeding zones and almost 90 degrees of longitude. Typically, humpbacks move between high-latitude feeding areas and low-latitude breeding grounds, without much variation in longitude — and the longest journeys recorded until now have been between breeding and feeding sites. What's more, those that travel the farthest are usually males, whereas females are generally very loyal to their breeding sites. "The main take-home message is that the movement patterns of these animals are messier and less constrained than we tend to think," says Stevick.

Whale tail

The whale in question was first spotted off the coast of Brazil, where researchers photographed its tail fluke, took skin-biopsy samples and used chromosome testing to determine the animal's sex. Two years later, in 2001, a tourist on a whale-watching boat snapped a photo of the humpback near Madagascar.

The whale's tail fluke was spotted off Madagascar. Freddy Johansen

To match the two sightings, Stevick's team relied on an extensive international catalogue of photographs of the undersides of flukes, which have distinctive markings. Researchers routinely compare the markings in each new photograph to those in the archive.

The scientists then estimated the animal's shortest possible route: an arc skirting the southern tip of South Africa and heading northeast towards Madagascar. The minimum distance is 9,800 kilometres, says Stevick, but this is likely to be an underestimate, because the whale probably took a detour to feed on krill in the Southern Ocean near Antarctica before reaching its destination.

No fluke

Most humpback-whale researchers focus their efforts on the Northern Hemisphere because the Antarctic is a hostile environment that is hard to get to, explains Rochelle Constantine, who studies the ecology of humpback whales at the University of Auckland in New Zealand. But, for whales, oceans in the Southern Hemisphere are more expansive and amenable to unobstructed travel, says Constantine. Scientists will probably observe more long-distance migrations in the Southern Hemisphere as satellite tagging becomes increasingly common, she adds.

ADVERTISEMENT

Daniel Palacios, an oceanographer at the University of Hawaii at Manoa, says that the record-breaking journey could indicate that migration patterns are shifting as populations begin to recover from near-extinction. Behaviours often change as population densities grow; for instance, animals may disperse to avoid competition for food, he says.

But the real reasons for the whale's impressive trek remain a mystery. The female could have been following prey, exploring new breeding habitats, responding to distant calls, or simply wandering astray. "We generally think of humpback whales as very well studied, but then they surprise us with things like this," Palacios says. "Undoubtedly there are a lot of things we still don't know about whale migration."