Dear Readers, I have been very much enjoying the talks organised by the London Natural History Society during the lockdown, and this week’s talk was especially intriguing. It’s true that we listen to birds all the time (though we rarely really understand what they’re saying), but are the birds listening to us, and if so, what do they understand, and why are they doing it? Sabrina Schalz specialises in the study of birds and the attention they pay to human language, and her presentation raised all kinds of interesting questions. You can listen to the whole thing here (and if you live in London and haven’t yet signed up to the LNHS, I can heartily recommend it as a source of information and camaraderie on flora and fauna in the Capital).
First of all, though, what do we mean by ‘eavesdropping’? There are two kinds: when two people are talking, and a third person listens in: or when someone is broadcasting a message to a particular group, but members of other groups can also listen. The example given was a bird sitting in a tree and singing to attract a mate: the bird is only interested in female birds of the same species, but predators might also be attracted to the song, and humans may admire it.
Now, anyone who has had pet birds will know that they listen to us, but why? Birds in captivity may think of humans as their social group, and will listen to work out if food is coming, or if a visit to the vet is in the offing. As is well known, birds of a wide range of species will imitate human speech, and it was shown that some birds are not just imitating, but actually understand what the words mean – the story of African Grey Parrot Alex, who could distinguish between a ‘yellow cube’ and a ‘green ball’ is one case in point.
However, these are very specialised conditions. Why might a wild bird want to listen to humans? One clear example would be when birds are persecuted, and experiments have shown that captive birds are more alert when they hear unfamiliar voices, so this probably translates into the wild. I know personally that woodpigeons in Dorset were much more flighty than the woodpigeons that visit my garden in London, probably because the chance of the rural birds being shot is so much higher.
A third example would be when the bird wants to exploit the human; the example given was the honey guides of Africa, small birds who, when a human whistles, will lead them to a bee’s nest, so that the human can do the hard work of breaking it open, and the bird can then feast on the eggs and grubs. But in an urban environment it’s clear to see that pigeons and seagulls are extremely attuned to human behaviour, to the extent that London pigeons start to gather in parks and squares in the City well before lunchtime in the hope of a few scraps. This isn’t exactly eavesdropping as defined (unless they can recognise the words ‘Marks and Spencer sandwich) but it does show that birds are watching us and trying to work out what we’re going to do all the time. Their survival may well depend on predicting what we’re going to do.
Anyway, I digress as usual. Back to the talk. Schaltz raises the very interesting question of what exactly birds are picking up on when we speak. Birds can distinguish between vowels (Zebra finches were taught to recognise the difference between ‘wit’ and ‘wet’) and also between consonants (Japanese Quail have been taught to distinguish ‘das’, ‘bas’ and ‘gas’).
Budgies and zebra finches can also tell the differences between words that are stressed on their first syllable (‘permit’ as in ‘an authorisation’) and their second syllable (‘permit’ as in ‘allow to do something’).
And finally, and this is probably the most interesting, birds can learn to tell the difference between tone. Some Java sparrows were taught to distinguish between a sentence said in an admiring tone (presumably not ‘who’s a pretty boy?’) and a sentence said with suspicion. Not only this, but they could from the sentence taught to other sentences in the same tone.
Now, onto the subject of Schaltz’s PhD. She studied large-billed crows in Tokyo – these birds are often persecuted in the city, with many being captured and relocated, and she worked with a number of these birds. The aim of the experiment was to see if the birds could distinguish between Japanese (with which they should have been very familiar) and Dutch (a language that they were unlikely to have heard). The birds were played 25 second bursts of each language, and their degree of attentiveness was measured from both their head position (the head is raised when the bird is interested/vigilant) and from the length of time that they spent close to the speaker. All the adult birds spent longer and were more attentive when Dutch was played, though the juveniles seemed pretty much equally interested in both.
How do they tell the difference between the languages? The rhythm of Dutch is very different from that of Japanese, and as it’s already been shown that the ubiquitous Java Sparrows can tell the difference between Chinese (which is syllable-timed) and English (which is stress-timed), this is probably the key factor.
The birds in Schaltz’s experiment were not trained in any way, and so they were self-motivated to listen. The working hypothesis is that because the crows were already persecuted, they would be especially wary of anything unfamiliar, because they couldn’t yet understand the ‘cues’. It’s probably possible that the crows already understand things about tone of voice, volume and even rhythm in Japanese, but don’t yet know these things in Dutch. Learning to anticipate the behaviour of those around you is a key survival skill, and it’s no surprise that these intelligent, adaptable birds are both watchful and curious.
Schaltz’s next study will be on wild carrion crows in London, and she’s trying to find out three things: whether there are differences between species in terms of their understanding of languages, whether there are differences between cities (Tokyo is 97% Japanese speaking, whereas in London 77% of people have English as their main language) and whether the differences in persecution between Tokyo and London will have an impact on behaviour.
I really enjoyed Schaltz’s talk – it’s clear that she’s passionate about the interactions between birds and humans, and she’s really trying to understand things from the perspective of the bird. She wants to increase human understanding and appreciation of the crow family, a group who are much maligned pretty much throughout their range. Finally, as urbanisation grows, she wants to look at the factors that make a successful urban species, and to try to see what would make our cities more welcoming to the many refugee species who are finding the industrialised countryside a less conducive place to live. And, as a family of jackdaws land on the chimney pots opposite my window as I write, I can only wish her luck. Other species have been squeezed to the margins, and anything that increases our wonder and compassion can only be for the good.
Photo One from https://www.youtube.com/watch?v=Pe0sgy6pgGw
Photo Two by gisela gerson lohman-braun, CC BY-SA 2.0 https://creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons
Photo Three by Mike Prince from Bangalore, India, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons