April 20, 2011

Researchers Study Humpback Whale Navigation Strategy

According to researchers, humpback whales can swim thousands of miles in a straight line, which suggests that they may use a unique compass mechanism.

"They maintain remarkably straight movements for weeks across thousands of kilometers of oceans," lead author, environmental scientist Dr Travis Horton, of the University of Canterbury in Christchurch, New Zealand, said in a statement.

Many animals are believed to navigate using a compass cue, like the Sun or the Earth's magnetic field, which can tell them what direction they are going on a metaphorical map. 

"Using the position of the Sun is very similar to what sailors have always done using a sextant," says Horton.

However, science is still documenting animal migration, and it is not yet able to explain humpback's navigational strategies.

The team used satellite-tracking technology to follow 16 humpback whales as they migrated from locations off the east coast of Brazil, the Cook Islands and New Caledonia.

The team found that whales swam over 3,728-miles south towards Antarctic waters, in a series of straight lines that ranged from 62-miles to 1,200-miles long.

"They go in such straight lines that their directions don't go off course by more than a single degree azimuth," Horton wrote in the publication Biology Letters.

"That's hard to do even in a plane or a boat with modern technology."

He said that the Sun and magnetic field shift by several degrees more than the course set by the whales.

"The position of the Sun and the magnetic field is highly variable, but the whales somehow maintain a constant course."

He said that it is possible that whales are using both solar and magnetic information to help them navigate.

"There have been lots of experiments done on magnetic orientations and lots of experiments done on solar orientations," he wrote. "But extremely few if any that have looked at both, in a coupled system of orientation."

According to the researchers, the whales use the Sun's position, relative to the magnetic field, in order to help them orientate themselves.

Horton said that the straight lines quickly ruled out another navigation theory known as "clock and compass."

This involves compass readings taken at the same time each day.

Horton said that a navigation system like this would be characterized by curved tracks as the animals are pushed off course by currents in between daily compass readings.

"These whales are clearly using something more sophisticated to migrate than anything we've surmised," research biologist John Calambokidis of the Cascadia Research Collective, who wasn't involved in the work, told Wired.  "I'm really looking forward to seeing what this team does next."


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