Song of the Humpback - Listening Script

I've been studying humpback whales for 25 years now. People always ask me: why do they sing? And I have to be honest - I still don't know. That's what makes it the single most intriguing thing in my career.

The first time I heard the song through a hydrophone, I couldn't believe it. The sound was long and complex - it went on for over 30 minutes. These are perhaps the longest songs sung by any animal. And they change over time, like hit tunes on the radio - all the whales in one area seem to learn the same new version.

We thought they might sing to attract females, so we played recordings to them. But they didn't respond. That was the most surprising result. If the songs were for attracting mates, you'd expect some reaction.

One thing I can tell you is that only male humpbacks sing. Another theory is that they sing to let other males know they are there - a kind of social signal. The desire to socialise is clearly a powerful drive for these animals.

I remember one extraordinary moment. A 13-metre whale approached our photographer, Flip Nicklin. The giant looked him over with one eye, then gently lifted him with a flipper, as if it wanted to swim with him. After 25 years, I'd call myself something of a whale whisperer, but honestly, we're still not much closer to the answer.