Soundbites is a weekly (biweekly, occasionally) feature of the coolest, newest bioacoustics, soundscape, and acoustic research, in bite-size form. Plus other cool stuff having to do with sound. Lots of birds this week, it turns out!
Humans and hermit thrushes show convergent “song cultures”: this is a cool one, and a little complicated. Apparently people have long debated the human preference for simple integer harmonics in our music–these are what generate our scales, both Western and non-Western. It turns out that hermit thrushes also prefer simple integer harmonics, and it’s actively selected for. While this isn’t prevalent among all birdsong, it’s interesting to see that there’s a sort of convergent evolution of this “song culture”!
Fun link of the weekis courtesy of Holger again, who is finding the best stuff on the interwebs. Did you know that the European Space Agency just landed a spacecraft on a comet?!? SO COOL! Here’s another thing I didn’t know: comets sing!! Follow the link and you can hear a comet singing!
Soundbites is a weekly (biweekly, occasionally) feature of the coolest, newest bioacoustics, soundscape, and acoustic research, in bite-size form. Plus other cool stuff having to do with sound. I’ve been doing really well on this weekly thing, but I might break my streak next week as I’ll be in Indianapolis for ASA(!). That just means you’ll get a real blog post from me next week!
Aposematism led to increased vocal diversity in poison frogs: tip o’ the finder hat to my Garcia labmate Lindsey for this one, and it’s brilliant. You know those little brightly colored poisonous frogs? These authors wanted to know if aposematism (displaying bright colors like that as a warning to predators) might lead to increased vocal diversity, since they’d have to worry less about predation. And it did! In conjunction with sexual selection, aposematism allowed the evolution of a broader vocal repertoire!
Silvereyes shift their frequency down in urban noise–and it works: These are silvereyes. They’re really cute. You can find them in Australia and New Zealand (which is where I took this photo). Most animals shift their frequencies up above urban noise, but it turns out silvereyes shift theirs down. This increased the predicted effective space of their alarm call 20%!
“Whistling while you work is only acceptable if you are one of the 7 dwarves. You are too tall to be a dwarf; or the Snow White”, I can imagine Holger, my advisor, saying.
In reality Holger is too wonderful to mind if I whistle while I work or not. But I actually don’t. Which a few unfortunate people that have witnessed it will unanimously agree that it is for the common good. Nevertheless, I get to work on whistles!
The animals that I work with are notorious whistlers! You might consider yourself skillful in whistling, an expert in whistle-flirting and dexterous in folding you tongue and sending loud whistles miles away to your friends on the other side of a soccer field, but that is just like whistling against the wind to dolphins. If you compare your selves to their whistling capabilities you will be embarrassingly defeated. (In every case, several analysts and Experts of Life support that comparing yourself to others can only make you unhappy.)
Dolphins and killer whales, which belong to the Delphinidae family, produce 3 types οf sounds:
1. Clicks used for echolocation that help them navigate, find food and capture it,
2. Burst pulses that are rapid rate clicks and serve similar purpose but with higher definition, and 3. Whistles
Dolphin whistles are generally of narrow bandwidth and frequency modulated sounds that commonly last for half to a few seconds, much longer than the individual clicks and they are of lower frequency. Their characteristic lower frequency allows them to propagate in longer distances and their function is believed to be primarily social.
Whistles are considered to be a product of the same mechanism that generates the clicks: air that goes through the nasal passages of the dolphin’s head. The odontocetes (toothed whales) don’t literally vocalize, since they don’t use vocal cords like we do. They use the air that enters their blowhole to make sound by canalizing it through passages and their melon (the fatty tissue that makes their forehead look rounded). This video: Echolocation and sound production mechanism can give you a good representation of it.The production of whistles seems to require larger volumes of air which makes them unsuitable for echolocation since air volume is reduced by hydrostatic pressure during diving and foraging. Instead, the dolphins are thought to use them for communicative purposes, to stay in touch with their gang in the vast oceans.
I am particularly interested in the whistles. Especially the dolphin whistles. As I described at my previous post, this past summer I collected a bunch of different dolphin species’ acoustic recordings from the Aegean Sea. These recordings will help me create a sound library for the dolphin populations that dwell the eastern Greek Seas, essentially a whistle-bank for the populations in that area.
In addition to the different dialects or accents that the dolphins populations have and I have previously mentioned, they also have names that the scientists call signature whistles. Specifically, the bottlenose dolphins are known to learn and recognize whistles that are unique for every individual in a group and these whistles are used to broadcast the identity and location of the animal that produced them. This characteristic is crucial for the contact between mother and offspring, for feeding and protection from predators. Most of the characteristic whistles are usually unchanged for all the lifetime of the dolphin. But occasionally, when the male dolphins leave their mom to experience the adult life in a group of other males their distinctive whistles actually converge and become very similar!
Besides the dolphins, more animal species seem to find names meaningful. A striking example is the one of the green-rumped parrotlet that lives in Venezuela.
This cute little green parrot is attributed a whistle name by its parents and it gradually learns it by them. In this delightful video you can see how the researcher discovers the learning ability of the parakeets in contrast to the genetic encoding of communication mechanisms in this species.
Birds have actually been the very first research target of bioacousticians. Even though they can fly away and escape the
claws of their scientific fate, it is still easier to study them than the marine mammals that slip away in the open ocean. A remarkable example of unusual bird vocalizations and intriguing to research specie is that one of the superb lyre bird of
South Australia! In this specie the male, in order to attract the girls, besides the elaborated dance and feather display, can also imitate the calls of more than 20 other bird species. This bird is so good at mimicking others that it can confuse even the birds that it is copying.
But the lyrebird is not only imitating other birds; it has evolved his skills beyond living organisms. A real master of mimicry! It is able to incorporate in its repertoire any sound that hears in the forest. Like that of a camera shutter, or a car siren, or chainsaws! Or the sound of the fridge door opening and closing (would be the case if my house was its habitat)…
But seriously, I am not making this up! Check this jaw dropping video to see for yourselves. This bird is either desperate to reproduce or the females don’t really know what they want.
At this point I will paraphrase Snow White; whistling is a lot of work!
Some people seem to have a talent in whistling. They can whistle entire songs, or the more eccentrics can whistle the whole alphabet. They use their lips, teeth and tongue to do it, their fingers in all sorts of strange formations, their palms, and a wide range of imaginative accessories. Personally, it took me several weeks at the age of 23 to learn how to whistle. Soon I was glad for my achievement as it turned out to be a remarkably useful skill when I got a dog. Loud, piercing and sharp… a whistle is hard to ignore. Even if you are a dog.
You might be surprised to discover that whistles are not used uniquely by animals for their communication. Since the Antiquity people used whistles to communicate in very long distances. Whistles can travel much longer than speech and can overcome ambient noise much more effectively. You might have noticed that often people that work in bars use them to signal among them.
In the natural environment, in locations where the landscape consists of deep valleys and steep ravines, whistled languages were common within some human communities. Before the 1940s, when the phone was not widely used yet, people replaced words with whistles to send messages that would overcome distance issues. Whistles have the ability to travel up about to two miles (3.2km), which is much further and with less effort than shouting. Initially these languages were invented and largely used by shepherds, and for long time they were a common way in agricultural communities at isolated villages to transmit news, events or emergencies.
Examples of these communities and their whistled languages still exist! The cases of the Village Antia in the Greek island of Evia, the Kuskoy Village “Bird Village” in Turkey, and the “Silbo” language at La Gomera at the Canary Islands in Spain, are the exceptional cases of alive whistled languages.
In this uncommon language, consonants are distinguished by changes in pitch over different intervals of time and the whistle is a substitute of the original language which gets compressed. The whistled language is not a code, has rather defined characteristics.
Evidently marine scientists are charismatic people with variable interests and acute curiosity . It appears that Cousteau was also interested in analyzing the characteristics of La Gomera’s whistled language!
Nowadays these languages are slowly becoming extinct. However, it is encouraging that in La Gomera at least, the Canary Islands’ government links the whistled language to the identity of the people and recognizes its value as part of the traditional culture in this area and try to preserve it. As a result, La Gomera is one of the few places in the world where children learn to whistle in schools!
Aristotle in the History of Animals wanted to describe what separates animals from people. What is that makes us different: is it the reason, the language or the laughter? Several recent researchers and philosophers suggest that it is the culture. But what do we define as culture. Is it the ability to learn, to mimic, the language? It turns out that both people and dolphins use certain sounds, in this case whistles, in form of language in order to communicate. The human community considers the human whistled language as a cultural heritage worth protecting and maintaining. Similarly, without me trying to attribute human qualities to the animals, cetaceans have social learning skills and cultural capacities that are advanced and worth maintaining as well. It is our doubtless responsibility to protect them.
During my childhood, my mom would wake me up every morning with whistling melodies. I surely despised it. Mainly the wake-up- in-the-morning part. The whistling part was also very disturbing, especially because it was such an effective mean to get me off the bed! Now I am particularly attracted by whistled melodies and I am a fool for songs that include them. So I prepared my favorite Top 10 of songs with whistling, with extra 2 Greek tracks. #1 on the list is my current wake-up-song. I love it! Not the wake-up part, I still cannot get over that…
11. Το ποδηλατο (the bicycle)- Ελένη Βιτάλη
12. Συννεφούλα (the little cloud)- Διονύσης Σαββόπουλος
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