The Blue Whales' Falling Song
All over the world, blue whales have been singing lower and lower, decade after decade. Nobody is sure why.
What was reported
Blue whales, the largest animals ever to live, make deep, slow calls that can travel hundreds of kilometres through the ocean. Each population has its own song.
In 2009, scientists comparing recordings found that every population of blue whales they studied, from California to the Indian Ocean and the Antarctic, had been singing at lower and lower pitch since the 1960s, by about a third in some cases.
Explanations offered
One idea is that, as whale numbers recover from whaling, they don't need to call as loudly to find each other, and lower, quieter calls are easier for them. Another is that changes in ocean noise or chemistry play a part. There's no settled answer.
- When
- Noticed since the 1960s
- Where
- Monterey Bay, California, USA
- Witnesses
- Ocean scientists worldwide
- Status
- Partly explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.
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