Please, take a minute to watch this . Yep, that’s a bird imitating a camera shot. This is a rare showcase of lyrebirds exceptional ability to mimic sounds, but how do they achieve such a striking similarity to foreign sounds? I spent a week reading about avian mimicry, here is what I learned about their specific adaptations, evolutionary benefits of mimicry and perhaps the most impressive example - parrots mastering the mimicry of human speech.
Born to sing
Each species of birds has its own song that youngsters learn by trial and error while listening to adults. To enable fine-tuned sound production, birds have a special vocal organ - syrinx. Syrinx is like a tube located deep in the chest that splits into 2 bronchi and leads to lungs. Birds are able to control the muscles around this tube to regulate how air passes through it. This results produces a sound wave, pressure changes in the air that are detected by the auditory systems of other organisms. Here comes the cool part: syrinx splits into 2 smaller tubes, allowing birds to produce different sounds simultaneously by controlling the muscles on each side of the syrinx independently. Plus, muscles used for vocal control are among the fastest to contract in both mammals and birds: muscles regulating airflow can modulate this flow up to 250 times per second. Interestingly, some species don't have a syrinx - instead of singing, they communicate through throaty hisses. Certainly, there are more adaptations that make birds impressive singers, but the onces above appear to be most common.
Do they mimic sounds for fun?
Apart from species-specific songs, some birds can imitate other species' sounds or even inanimate objects. Is all the effort for fun and giggles or is there another explanation? Well, there is a bunch of explanations, but it seems likely that mimicking other species sounds can be very beneficial in some circumstances. For instance, a prey spicies mimics a sound relevent to the predator to scare him away - it has been reported that some birds produce a snake-like ‘hiss’ when disturbed by predators. Moreover, mimicry can be used to fool other birds in order to benefit from it in one way or another. Vocal mimicry is professionally used by young cuckoo, a brood parasite who imitates their hosts begging calls to get more food. Even more malicious, some birds use mimicry to steal food from others. These smart thiefs mimic sounds of a specific predator that would cause other species to run to shelter and abandon their food. As a result, the thief species gets all the food while the other species is hiding from a non-existent predator. In the case of lyrebirds, the ability to imitate complex sounds might signal mate quality, sort of an advertisement song to attract females. In some species, the accuracy of the resemblance between the mimetic reproduction and the original sound predicted their mating success. Lastly, an example that left me speechless, males might gain reproductive advantage by mimicking a stimulus to which females evolved to respond. Male moths produce ultrasonic acoustic signals during copulation causing females to freeze, thus facilitating reproduction. They basically exploit female’s automatic freezing reaction in response to ultrasonic sounds that evolved as protection mechanish from insectivorious bats. Crazy, right?
Parrots, pets who answer back.
Compared to mammals and non-mammals, parrots are the masters when it comes to imitating human speech. In 1995, a parrot named Puck was credited by Guinness World Records as having the largest vocabulary of any bird, 1,728 words. While I was looking for this Guinness Record, my search engine decided to show me another one. In September 2023 Chico, a 7-year-old parrot in Bulgaria, won the title of “the fastest parrot riding a bicycle”(5m in 14.58 seconds). Okay, back to the main topic. First, I’d like to acknowladge Alex (abbreviation from Avian Language Experiment), the parrot who has been studied for 25 years by an animal psychologist Irene Pepperberg. Alex had a well-deserved nickname ‘Einstein of parrots’ for his learning abilities and a lot of the current understanding of parrots cognition comes the studies in which he participated.
Knowing that most birds are very good at vocalising, what makes parrots different? First, recent studies show that they have an additional brain circuit involved in vocal learning. By looking at the pattern of genes activation during vocalisations in parrots and other birds, scientists showed that the ‘core’ region is present in all songbirds and a ‘shell’ region unique to parrots. Moreover, the ‘shell’ region seems to be larger in the species that are considered to have higher cognitive and vocal abilities, such as African Grey, Yellow lored Amazon. Plus, parrots have a very well-developed tongue musculature which might enable a more precise control of movement and thus the production of complex sounds. Natural mimicking abilities definately help to master human speech. However, there is still a lot of open questions and contreversy in the field of animal cognition and communication, more research is definately needed to understand how our feathered friends communicate. I hope this post makes you turn off your headphones next time you see a bird and appreciate the richness of songs in real life. Have a day!
References:
Chakraborty, M., Walløe, S., Nedergaard, S., Fridel, E. E., Dabelsteen, T., Pakkenberg, B., Bertelsen, M. F., Dorrestein, G. M., Brauth, S. E., Durand, S. E., & Jarvis, E. D. (2015). Core and shell song systems unique to the parrot brain. PloS One, 10(6), e0118496. https://doi.org/10.1371/journal.pone.0118496
Dalziell, A. H., Welbergen, J. A., Igic, B., & Magrath, R. D. (2015). Avian vocal mimicry: a unified conceptual framework: Avian vocal mimicry. Biological Reviews of the Cambridge Philosophical Society, 90(2), 643–668. https://doi.org/10.1111/brv.12129
Pepperberg, I. M. (2010). Vocal learning in Grey parrots: A brief review of perception, production, and cross-species comparisons. Brain and Language, 115(1), 81–91. https://doi.org/10.1016/j.bandl.2009.11.002
Pepperberg, I. M. (2018). Grey Parrots (Psittacus erithacus) – Cognitive and Communicative Abilities. In Field and Laboratory Methods in Animal Cognition (pp. 329–353). Cambridge University Press.
Rössler, T., & Auersperg, A. M. (2023). Recent developments in parrot cognition: a quadrennial update. Animal Cognition, 26(1), 199–228. https://doi.org/10.1007/s10071-022-01733-2
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