Shortly after posting the summary of my second week in Tonga (at the end of which I whined about not seeing any heat runs), I finally got to see a heat run!
We came across five whales in a high-speed chase, with two others on the periphery. They were swimming really(!) fast and diving deep a lot, so all we could do was follow for a while.
When they came up, it was the typical pandemonium...massive snorts, crocodile posturing, a few tail slashes, bubble blowing...the works. Did I mention I love heat runs?
At a few junctures, they slowed down just enough for us to hop in to take a look. Sometimes, whales in a heat run slow the pace a bit so that you can just keep up and watch the action, but these five obviously had somewhere to be. If anything, they sped up, giving us only a few seconds to see them as they buzzed past.
On our final drop, as the five whales passed by, one emitted a shrill, piercing, high-pitched sound, which one of the people with me captured on his video camera. Here's the sound:
I've spent dozens of hours in the water with humpbacks, but this is the first time I've heard this particular sound. Puzzled, I consulted a few friends, and again, Dr Adam Pack came to the rescue, lifting the veil of ignorance from my eyes.
According to Adam, humpbacks often make what's referred to as "social sounds" when they're in competitive groups...screams, trills, barks, etc. After listening to the audio, Adam pegged this as a trill sound.
There apparently are some researchers working on understanding these types of sounds (i.e., non-song sounds that humpback whales make), since there's not much known about what they mean or how they're used.
Thinking back on the past two weeks, it's been a particularly vocal year so far. I've heard singers of course, which seem to be rendering a particularly staccato song this season, but also, I've heard calfs squeeking, gurgling and making baby-like noises (I've heard these often in the past); I've heard one of the two whales in the male-female pair last week making soothing, cooing noises (I'm assuming it was the male vocalising, but I don't know for sure); I've heard one of the whales associated with Speedy (the second ID-ed calf of this season) making gentle, melodic sounds as they trio passed by (I'm assuming it was the escort, but again, I have no way of being certain).
And now, I have this "trill" sound, which was so loud that it stopped me dead mid-finkick as I looked around underwater wondering what was going on. At first, I thought it was a mobile phone ringing, though I quickly realised that would be absurd at 15 to 20 metres down.
It wasn't until later in the evening when we'd downloaded all our footage that we were able to confirm that the sound came from one of the whales.
...so I finally got my heat run, and a trill to boot.
Thanks for the information Adam!