Indian Ocean humpbacks singing differently

NEW YORK, Feb. 2 (UPI) -- Humpback whales on both sides of the southern Indian Ocean are singing different tunes, a totally unexpected finding, U.S. researchers say.

Researchers from the Wildlife Conservation Society, Columbia University and colleagues in Australia say they were surprised to find differences in songs sung by whales in Madagascar and Western Australia since humpbacks in the same ocean basin usually all sing very similar songs.

The differences in song between the Indian Ocean humpback populations most likely indicate limited contact between the two regions' populations and may shed new light on how whale culture spreads, a WCS release said Thursday.

"Songs from Madagascar and Western Australia only shared one similar theme, the rest of the themes were completely different," lead author Anita Murray, who conducted the research while a graduate student at Columbia, said.

The songs of humpback whales are generally sung by male individuals on a population's winter breeding grounds, migratory routes, and summer feeding grounds, and are complex arrangements of parts or "themes."

"The reason for this anomaly remains a mystery," Murray said. "It could be the influence of singing whales from other ocean basins, such as the South Pacific or Atlantic, indicating an exchange of individuals between oceans which is unique to the Southern Hemisphere."