Humpback Whales in Tonga 2010

At the beginning of August each year, I find myself struggling with the same dilemma…how to describe the events and experiences of my first week or so in Tonga.

On the one hand, I'm so exhausted and have so much to get done that I want to write as little as possible, but on the other hand, so much has happened that I feel compelled to share everything, even though I know I can never cover it all. There's just too much.

Usually, as is the case right now, a strong(!!!) cup(s) of coffee is what tips the balance and unfreezes my brain.

Morning cup of coffee at the Aquarium

A Bit of Background
The main reason I arrived in Tonga a little bit earlier than usual this season was to kick-off a joint project with my friend Dr. John Potter to study sound, specifically the melodies produced by humpback whale singers.

By way of background, humpback whales make a lot of different sounds, most of which we have probably never heard.

Sound seems to be as vital to humpback society as vision is to ours. (I realise that's not an apples-to-apples comparison. To be more accurate, I should have compared sound to light…but bear with me.)

If you think about it, this makes complete sense. It's difficult to see over any significant distance underwater, since water is much denser than air and also contains more suspended stuff to interfere with vision. Sound, however, can travel farther and faster underwater than it does on land.

In this context, humpback whales depend on sound for much of their communication, including the use of what most people know as whale song. A few general points about humpback whale song:

- The term "song" in relation to humpback whales refers a consistent, repetitive series of sounds produced by a whale over a period of time, with the same sound sequences being reproduced by other whales in the relevant group of whales (in other words, not a random string of sounds that's never made in a similar manner again).
- You can hear a whale singing from several kilometres away.
- No one knows what is being communicated in song.
- We also don't understand if/ how messages are encoded in song.
- Only males appear to sing.
- Whale songs are unique to each group of whales and evolve over time.
- Whales are widely known to sing in their wintering grounds (like Tonga), but they also do so during migration and in their summer feeding grounds.
- There's almost certainly much more we don't even know we don't know.

John trying to look astute

In addition to these general points, there is a commonly accepted understanding that all the males of a particular group of whales sing the same song at any given time.

A few years ago, however, I heard a whale making sounds that made me stop and think: "Whoa, wait a minute, that's not the same song!"

I didn't have a hydrophone with me, so I couldn't make a recording, which, of course, meant it was impossible to share what I had heard. The best I could do was to use an analogy: If listening to normal whale song in Tonga is like listening to Mozart, what I heard that day was more like a Chuck Berry riff. It was that different.

With no explanation for what I had heard, I began to listen more carefully to whale sounds in following years. On several occasions, I heard what I thought were singers vocalising in a way that didn't match the other whales.

I conveyed this information to Dr. John Potter. One thing led to another, and eventually, we conceived a joint project to study humpback whale song in Tonga. (Note: The previous few sentences just glossed over four years or so of discussion, relocation of a yacht, arranging of specialised equipment, and innumberable insults traded over email and Skype.)

That, in short, is how we ended up on John's yacht Jocara on 29 July 2010, armed with a high-tech 4-channel hydrophone array, recording equipment, and lots of cameras…on a mission to find singers around Vava'u.

As with all new projects, there was a bit of futzing around to figure out what exactly we needed to do, how we needed to do it, and what we would do with whatever we managed to get done.

Along the way, we faced a few challenges, including inclement weather, a broken engine, and one instance in which we nearly snapped John's expensive hydrophone array in half.

But if there's one thing I've learned, little annoyances and minor crises that command your immediate attention at any given time are never the things that matter. We dealt with them each in turn and kept our minds focused on our goal…learning a lot in the process.

The Goal
I think it fair to say that a lot of people have studied or are studying whale song. Some have done so in Tonga.

So the natural question to ask is…what makes our project different?

I can think of three things.

First, John and I want to combine audio and visual data in order to get a more complete understanding of what's going on. Simply recording song, for instance, means you don't get the benefit of seeing what the whale is doing.

Is it in the classic head-down pose? If not, what position is it in? How big is it? Is it moving? Is it interacting with another whale(s)?

Conversely, just taking photos makes it impossible to associate sound with an image. This is the problem I've faced to date. I can get great photos of singers, for instance, but it's difficult for me to convey what I heard.

By combining audio recordings with visuals (photos, video where possible), we hope to associate all possible data.

Second, we are looking specifically for possible correlations in audio and visual data. What does this mean?

Recall that earlier, I noted that no one really knows what information is being communicated by song or how it's being encoded.

John has a theory, which he explains this way: Think of a karoake bar. Let's say 10 people all sing the same song. Same notes, same words, same everything.

Even with all the song parameters kept constant, however, none of the renditions will sound the same.

In other words, there is information encoded in how the song is sung and presented.

If you can't see the actual people singing the song, you would probably draw different conclusions, for instance, about two people, one whose voice is weak and crackly, the other whose voice is a deep, soothing baritone.

Drawing the analogy to whales, one possibility might be that the valuable information in the song is not the song itself, but the singing of the song. In other words, it might be possible to learn something about the singer by listening to the quality of the song, as opposed to the notes and phrases in the song. (I don't know if I'm using technically accurate terms, but you get the point.)

So by associating visual and audio data, we're trying to figure out a way to test this possibility.

To put it simply: Is there, for example, a difference in the way a young whale and an old grizzly bull sing? If so, can we figure out what the difference is and determine its significance? Can we then "read" certain information about a singer just by listening?

Third, we're going to be open-book. Much of academic work is done behind closed doors, in a black box so to speak. There are some good reasons for this, but there are also drawbacks.

I'm sure there are people who would disagree with me, but I believe that given the efficient communication technology we have now, sharing of information is the best way forward.

My humpback whale calf ID project, for instance, has been completely open-book, and it's produced wonderful results. I've made lots of friends, received valuable help from other people, and this year, I've already had a few people come up to me in Vava'u to tell me they will do their best to send me information.

One major criticism of an open-book approach is that the quality of data/ input can suffer if contributions come from an "uneducated" public. My view…that's complete garbage.

Weeding out suspect information is easy enough, and the peer review process hasn't even come close to preventing fraud in science publications.

Plus, for this endeavour, I have John, who will be rigorous in examining data and drawing conclusions. And in the event we make a mistake, I'd rather have someone point it out quickly than continue working on something that's wrong.

Ok, enough preamble.

Snap, Crackle, Pop
Somewhat of an aside, but one of the first things we recorded was the sound of snapping shrimp.

If you're a diver, you may have come across these tiny crustaceans, characterised by having one claw much larger than the other, and the top pincer on the large claw disproportionately bigger than the lower pincer.

These shrimp snap their large claws shut from time-to-time, producing a loud snapping sound:

[mp3]http://www.tonywublog.com/wp-content/uploads/2010/08/shrimp.mp3[/mp3]

I already knew that they live all over the world on every coral reef, but what I didn't realise is how many there are, or how much noise they collectively make.

Nor did I realise that it's not the snapping of their claws that makes the sound. Since John loves(!) talking and being in front of the camera, I'll let him elaborate:

No one knows why the shrimp snap their claws to produce this loud sound, though we mused that it "must having something to do with food or sex" (doesn't everything, after all?).

Whale Song
Over the eight days we spent on the water, we were able to record three singers.

The first was a really young, small whale. In fact, we were all fooled, and initially thought it was a calf.

I was able to locate the whale in reasonably shallow water and get a good look, so I'm confident that it was no more than 10 metres in length. I was also able to take several nice photos of the singer:

The smallest singer I've ever seen, perhaps 9 to 10 metres in length.

Piecing together bits and pieces from other boats, here is the narrative of about four hours in the life of this particular singer:

- The young whale hooked up with another whale near the main entrance to the Vava'u island group. It's possible they were completely separate before the first boat sighted them joining, or they may have been travelling together and were only temporarily apart.
- After a brief interval, the whale began to sang, and the other whale was not in sight. The people in the first boat were unable to find the whale underwater, but listened to the song in the water, and also watched this whale surface over several cycles, with the other whale appearing from time-to-time.
- The first boat passed the whales to a second boat, and the second boat observed the whales continuing this behaviour. With the whales disappearing for 20-30 minutes at a time, the boat was also unable to locate the whales underwater and left the area.
- We had been watching the boat and whales from a distance, and moved in after the second boat left. The whales disappeared for about 30 minutes. Just as we were about to give up, the singer surfaced together with the other whale and both swam leisurely down the coast of Hunga (one of the main islands).
- The whales were in no hurry, slowing down on occasion and looping back a couple of times. We followed past the Hunga anchorage. The water south of the anchorage gets a bit rough, so I thought we should try getting in to take a look.
- Just as we got ready, the whales disappeared again for an extended period.
- Eventually, I got into the water and heard a singer. I thought it was quite far away, but as it turned out, I was quite close. It took a few up-and-down cycles for me to find the whale, but when I did, I noticed something.
- Even when I was directly above the young whale, I didn't feel any reverberation in my body. There was no "booming" effect. If you've ever been in the water next to a mature singer, you know there's usually a big booming bass that makes your abdomen jiggle.
- Just before getting into the water, I noticed a whale swimming south along the coast. I thought it was an entirely different whale from the pair we had been following, but later, it sounded as if there might be a second singer nearby (we have yet to listen to the recordings carefully to double check). It may have been the "partner" whale that we had seen travelling together with the singer.

It took a few more days to find another singer we could locate and record. Again, it was a small one, not more than 10 metres long. (For reference, big bulls can be 15 metres or more).

The second young singer we recorded. It was too deep to get a better photo.

This one was even more intriguing than the first.

Again, we were outside Hunga. As soon as I got into the water, I had the feeling that: "It's not the same song!"

Once John put the hydrophone array in, he confirmed my gut instinct. It wasn't the same.

But that's not all…after a few up-and-down cycles, the whale started to sing what sounded like the proper song. In other words, it changed.

Please bear in mind that everything I'm writing is subject to spending quality time listening to and studying the audio recordings, but our initial guess is that the first two whales we recorded were sexually immature, and might just be practicing, or as John puts it "kicking the can around" (John is from the UK so struggles with English).

At the very least, the second whale seems to have vindicated my "They don't all sing the same song!" observation to some degree.

The one qualification, however, is that the initial series of sounds from the second whale probably doesn't qualify as "song" per se, at least not according to the definition I set out above.

If the whale were indeed just practicing, it could've just been a series of random sounds…testing the vocal chords, so to speak, perhaps like an opera singer warming up before a performance.

If our observation turns out to be correct, it may help explain why immature male whales make the long, arduous trek from Antarctica to Tonga (and other wintering grounds). They might be here to learn the ropes and figure out such things and how, where and when to sing.

One other point of interest about this whale…it may also have been travelling with another young whale (like the first one was). We saw another small whale surface nearby a couple of times, though we didn't observe them together at any point.

Question: Has anyone ever come across any other information referring to young humpback whales on wintering grounds making continuous sounds that seem like song at first blush, but aren't actually the song of the season?

Finally, on our last day on the water, we recorded a much larger singer, probably full-grown. I didn't get a photo, because it was a travelling singer (swimming about 300m during each singing cycle), but I did get a good look at the whale as it descended.

Also, when I was positioned above the whale, I felt the booming bass in my abdomen, a stark contrast to the sound from the smaller singers.

What Does This Mean?
Clearly, John and I have a lot of follow-up work to do. We have to listen to the recordings carefully, and John has to conjure up some of his acoustic voodoo to produce nice graphs to examine.

This will take time, but at this juncture, I think it's fair to make these statements:

- Immature whales sing on the wintering grounds.
- Immature whales also make continuous song-like sounds that seem not to be actual song, perhaps practicing.
- There appears to be a qualitative difference in the sound level produced by immature whales and mature ones.
- We've only scraped the tip of the iceberg.

Hydrophone Array

I'm delighted with this outcome.

With limited time, equipment and budget, John and I were able to correlate visual and audio data for three whales. We managed to gather initial support for John's hypothesis that young whales come to Tonga to practice/ learn, and also back up my previous observations that not all the "songs" being sung here are the same.

And best of all, we have lots of ideas about how to carry this project forward.

Over the coming months, I envision working with John to assemble the data into a user-friendly format (i.e., something even I can comprehend) and posting the information online. Given my travel schedule and John's full-time job, it'll take a few months, but we'll definitely get it done. Stay tuned!

I still have more I want to write about the non-singer whale encounters we had, but given how long this post is already, it's probably better for me to put the remaining stuff into a separate post.

Note: If you visit Vava'u and come across a singer, it would be great if you can jot down and send me the date, GPS position, and approximate size of singer. An in-water photo would be great too if possible. Audio recordings could be useful as well, if you happen to have a decent hydrophone.