The Argentine parrot, the first non-human animal with a vocal print per individual

2023-10-04 10:00:03

Las parrots and parrots They are exceptional conversationalists. They can learn an almost unlimited vocal repertoire throughout their lives and at the same time emit calls so that members of their flock recognize them individually. This fact raises the question of how it is possible that your calls can be so variable (changing tone, timbre or volume) and at the same time uniquely identifiable.

A study on parrots carried out by the Max Planck Institute of Animal Behavior (MPI-AB) and the Museum of Natural Sciences of Barcelona could have the answer: individuals have a unique tone of voice, known as vocal printsimilar to that of humans.

This finding in a parrot in freedom raises the possibility that a voiceprint may also be present in other vocally flexible species, such as dolphins and bats.

It is an elegant solution for a bird that dynamically changes its calls but still needs to be recognized individually in a very noisy flock.

imeon Smeele, Max Planck researcher

“It makes sense that parrots have an underlying voice print,” says Simeon Smeele, first author of the paper, from Max Planck. “It’s an elegant solution for a bird that dynamically changes its calls but still needs to be recognized individually in a very noisy flock“.

Humans have complex and flexible vocal repertoires, but we can still recognize ourselves with our voices alone. This is because humans have a voice print: our vocal tract leaves a unique signature on the tonor our voice in everything we emit.

Other social animals also use vocal signals to be recognized. some birds, bats and dolphinsfor example, emit a “contact call” that allows different individuals to be recognized, although this only occurs in this type of call, not in their entire vocal repertoire.

Some birds, bats and dolphins emit a “contact call” that allows different individuals to be recognized.

To date, therefore, there is no evidence that animals have unique signatures that mark all calls made by an individual. In other words, almost no animal has a voice print.

This surprised Smeele, a doctoral researcher at MPI-AB who studies how parrots use their exceptional vocal abilities to socialize in large groupss. Like humans, parrots and conures use their tongue and mouth to modulate calls, meaning “their growls and squeaks sound much more human than the clean whistle of a songbird,” he says.

Parrots marked in Barcelona for monitoring. / Simeon Q. Smeele

Additionally, like humans, parrots live in large, dynamic groups where “there could be dozens of birds vocalizing at the same time,” Smeele continues. “They need a way to keep track of which individual makes which sound.”

Smeele wondered if parrots, possessing the right anatomy and the need for a complex social life, might have also evolved voice prints. To find out, he traveled to Barcelona, ​​where there is the largest population of individually marked parrots in the wild.

Monitoring in Barcelona

Parrots are a Invasive species that swarms through the city parks in flocks of hundreds of birds. A monitoring program run by the Barcelona Museum of Natural Sciences has been tagging the parrots for 20 years, and so far there have been identified 3,000 individualsa great help to Smeele and his study on voiceprint recognition.

Armed with shotgun microphones, Smeele and his colleagues recorded the calls of hundreds of individuals

Armed with shotgun microphones, Smeele and his colleagues recorded the calls of hundreds of individuals, collecting more than 5,000 vocalizations in total, making it the largest vocal study of individually marked parrots in the wild to date. It is important to note that Smeele returned to record the same individuals for two yearswhich revealed how stable the calls were over time.

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The researchers used a set of models to detect how recognizable individuals were within each of the five main types of call characteristics of this species.

Surprisingly, they found high variability in what is known as the “contact call” that birds use to convey their identity. This overturned a long-held assumption that “contact calls” contain a stable individual signal and suggested that the parrots are using something else for individual recognition.

They trained the model to recognize individual calls classified as “tonal” by parrots.

To test voiceprints, Smeele turned to a machine learning model widely used in human voice recognition, which detects the identity of the speaker using the tone of their voice. They trained the model to recognize the individual calls classified as “tonal” by parrots.

Once the model was trained on an individual, they tested to see if the model could detect the same individual from a different set of calls that were classified as “grunts.” The model provided evidence that parrots have a voice print, which Smeele said “could allow individuals to recognize each other thanks to their voice print.”

Confirm the model

The authors note that the evidence is in preliminary phase: “Before we can talk about a true voiceprint, we need to confirm that the model can repeat this result when trained with more data from more individuals, and that birds can also recognize this timbre in vocalizations,” says Smeele.

The Barcelona team will complement future experiments and analyzes with an ecological study, marking the parrots with GPS devices to determine how many individuals overlap in their wandering areas.

This may provide information about the species’ remarkable ability to discriminate between calls from different individuals.

Juan Carlos Senar from the Museum of Natural Sciences of Barcelona.

“This may provide information about the species’ remarkable ability to discriminate between calls from different individuals,” he says. Juan Carlos Senar of the Museum of Natural Sciences of Barcelona.

And if it turns out that conures have a voice print, Smeele says this would provide an answer to the question of how conures and parrots can be so vocally flexible and sociable at the same time.

The implications would also go beyond parrots and conures: “I hope that this finding will spur more work to discover voice prints in other social animals that can flexibly modify your vocalizationlike dolphins and bats,” he concludes.