Researchers from Catalonia and Germany have shown that Argentinian parrots, a species that proliferates through parks and gardens in Spanish cities, possess a distinct vocal timbre. Each bird carries a unique voice, enabling flock members to identify individuals within noisy groups. This is the first documented case of a nonhuman species using individualized vocal signatures across all calls, not just a single cue.
Conures and parrots are remarkable for their vocal flexibility. They can learn new sounds throughout life, building a vast repertoire. They also vocalize in ways that help flock mates recognize each other on an individual basis. This observation prompted researchers to explore how these birds manage individual identity in their calls.
A study of Argentine parrots conducted by the Max Planck Institute for Animal Behavior and the Museu de Ciència Naturals in Barcelona suggests that each bird bears a unique vocal timbre, akin to a human voice. This discovery in a wild parrot hints that other vocally flexible species, including dolphins and bats, may also carry individualized vocal signatures in their communications. (attribution: Royal Society Open Science)
“It makes sense that Argentinian parrots have an underlying vocal signature,” notes Simeon Smeele of Max Planck, the paper’s lead author. “This is a solution for a bird that changes its song dynamically yet must be recognized within a very noisy flock.”
Humans possess complex vocal repertoires and can often recognize voices. The reason lies in voice signatures: our vocal tracts impart a unique tone to our speech, producing a distinct vocal fingerprint.
To date, evidence for universal animal vocal signatures spanning all calls remains limited.
In many social species, vocal signals help members identify one another. Birds, bats, and dolphins often rely on individual calls that mark identity. However, signature calls sometimes capture identity in a single call type, and researchers have long considered that many animals lack a comprehensive, all-calls signature. In essence, rare cases of a complete individual voice across the call repertoire are now being explored.
Dr. Simeon Smeele, a doctoral researcher at the Max Planck Institute for Animal Behaviour, studies how parrots use their extraordinary vocal abilities to socialize within large groups. Like humans, parrots modulate their vocal tract movements to shape their calls, giving their growls and screams a distinctly human-like quality.
Parrots live in dense groups where dozens of birds speak at once. How can any bird discern who is speaking? The answer appears to lie in distinctive voice cues that convey identity even when sounds blend together.
Studies in Barcelona
The need to navigate complex social networks led Smeele to travel to Barcelona, home to the largest population of individually tagged parrots in the wild. These birds are invasive and roam city parks in flocks of hundreds, presenting a living laboratory for rapid, dynamic communication.
A monitoring program run by the Museu de Ciència Naturals de Barcelona has tagged around 3,000 birds over two decades, a resource that greatly aids research into individual speech recognition.
Using shotgun microphones, researchers captured hundreds of parrots’ calls, gathering more than 5,000 sounds for the largest study to date on individual vocal recognition in wild parrots. They re-recorded some birds over two years to test the stability of calls over time.
The scientists used models to judge how recognizable individual birds are across five main call types.
When they analyzed the five primary calls, they found striking differences in the contact call used to signal identity. The results challenged the idea that the contact call is a fixed fingerprint and suggested that parrots employ a more nuanced mechanism for recognizing individuals across calls.
Using the automatic voice model
To test audio recordings in this framework, Smeele and colleagues turned to a machine-learning model commonly used in human voice recognition. The model identifies speakers by tone of voice and was trained to recognize individual parrot calls categorized as tonal.
After training the model, researchers checked whether it could detect the same individual in different social groups, focusing on calls labeled as growls. The model detected matches three times better than expected, supporting the idea that Argentinian parrots have vocal signatures capable of linking individuals regardless of what they say.
“Argentinian parrots have a vocal signature that could allow individuals to recognize each other no matter what they say.”
The authors caution that the evidence remains preliminary. They emphasize the need to confirm that the model holds up with more data and more individuals, and that birds can recognize this timbre in real vocalizations.
The Barcelona team plans future work with ecological studies, including GPS tagging to map how many individuals share roaming areas. This could illuminate how well a species distinguishes calls from different neighbors, according to Juan Carlos Senar of the Museu de Ciència Naturals de Barcelona.
If Argentine conures indeed harbor a real vocal signature, it would help explain how parrots stay so flexible and social. The findings may extend to other social animals, with implications for studying dolphin and bat vocal ecosystems as well. Researchers hope this work stimulates further inquiry into animal vocal identities across species.
Reference work: rsos.230835 (Royal Society Open Science)
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