Fin Whale Sounds

Whales are well known to sing underwater; but some species, including fin whales, are relatively poorly studied. And this is where Miriam Romagosa, from the University of the Azores, comes in with her paper looking at how these animals can change their tunes, altering the intervals between the notes, and assimilating new songs from outside the group. There’s still a lot to learn, but, as she explains to Chris Smith, it’s a big step forward…

Miriam - Fin whales produce a very low frequency songs; so low frequency that we cannot hear them. And these songs are believed to act as a mating displays to attract females or to compete with other males. What we found is that these songs have a greater plasticity in their songs than we previously thought, and they can change their songs very quickly. We found that one of the parameters of the song, the interval between sounds, it changed very quickly. And during the transition period of this change, there were some songs that were hybrid that included both these intervals. So the change and the presence of hybrid songs during this transition period may mean that things are learning from each other and they're synchronising their song to all using the same rhythm.

Chris - How do you know who was singing what though? Can you recognise individuals from a population and therefore see how they're changing? Or are you just considering a whole population? And the mixture of the cacophony, as it were of sounds that that come along, that are produced by the whole assemblage of whales?

Miriam - Our study used recordings from autonomous recorders at the bottom of the sea. So we didn't track the whales, we just analysed the songs as a whole population.

Chris - So do you know what motivated them to have different songs in the first place? Is this just one group that have sung a certain way for a long time and they happen to have some kind of territorial or breeding overlap with another group that sing a slightly different way and they both adopt each other's sound? Or was something else the reason why you think they ended up with a different song?

Miriam - What happens with humpback whales, for example, is that some migrants arrive to a, a new population with a different song. And then the rest of the humpback whales of these this other population adopt this new song. This is what is called cultural revolutions in humpback whales. We don't know if this happens with fin wheels because we don't know the origin of the new song. So we cannot say the fin whales may also have cultural revolutions. But because this happened in a very large area of the North Atlantic with different ecological characteristics, this was not caused by something that happened in the environment. So we believe that perhaps fin whales coming from another region we don't know, started singing the new song. And slowly all the fin whales in the Mid-Atlantic change their songs.

Chris - Do you know why one song is considered superior to another? Why should they adopt an incoming song? Is it just novelty that the animals like that because it stands out, it's different, and so you are more likely to get noticed so you beat the competition for a while? Or might there be some other reason why you get this cultural revolution of song?

Miriam - We don't know <laugh>, actually, scienctists studying humpback songs don't even know. But one hypothesis is the novelty. Females may prefer novelty, but what it seems that is really important for fin whales is the synchronisation in rhythms. We don't know why, but this is something that happens everywhere in all oceans. And they also synchronise during the season, so they have seasonal variations in their rhythms and they also synchronise seasonally. So desynchronisation might mean something to them. Perhaps it facilitates localisation, but we don't know.

Chris - Apart from understanding more about their biology, are there any immediate implications of this? We learned this week researchers publishing a paper in the journal Nature actually why some groups of whales make the sounds they do. And anatomically how, which was a mystery before amazingly, I'm surprised that we didn't understand that. But this tells us more about the constraints on the sorts of songs those groups of whale can make, and that tells us a bit about how better to conserve them and not to make noises that might disturb them. What does the discovery of these new song patterns in the fin whales that you've come across mean in those terms?

Miriam - Yeah. Well, the studies like, like this one, help understanding the limits of song variation in fin whales, for example. This frequency decrease cannot go on forever and the study in Nature now confirms it because the structures that produce sounds in these species limits the range of frequency. These animals can produce sounds. So if they had to avoid atrogenic noise, like for example, from shipping, so they are able to communicate with each other. They may not be able to avoid these noise by increasing or decreasing their frequencies because they are limited, they're anatomically limited. And these studies help to understand the limits of, of these song variations.

Chris - And what will you go back and do now? Is it possible to go a step further and try to pursue individual animals and see how their song evolves or how static it is over time and see what the effect of one of these incoming rhythm changes is on individuals? So rather than just look at the population level, you've got the chance to see how individuals respond, adapt, and update their song patterns like this.

Miriam - Yeah, I would actually like to do tracking and especially put acoustic recording tags to the animals and study how they change their songs individually and how they interact with each other. But it's challenging because these animals are very pelagic; when they sing is during the winter and normally here in the Northern Atlantic in offshore areas. But it's, it is a project that you know, that I, I have in mind for the future.