Parrots are exceptional talkers. They can learn new sounds during their entire lives, amassing an almost unlimited vocal repertoire. At the same time, parrots produce calls so they can be individually recognized by members of their flock—raising the question of how their calls can be very variable while also uniquely identifiable.
A study on monk parakeets conducted by the Max Planck Institute of Animal Behavior and Museu de Ciències Naturals de Barcelona might have the answer: individuals have a unique tone of voice, known as a voice print, similar to that in humans. This finding in a wild parrot raises the possibility that a voice print might also be present in other vocally flexible species, such as dolphins and bats.
“It makes sense for monk parakeets to have an underlying voice print,” says the Max Planck’s Simeon Smeele, first author on the paper published in Royal Society Open Science. “It’s an elegant solution for a bird that dynamically changes its calls but still needs to be known in a very noisy flock.”
Humans have complex and flexible vocal repertoires, but we can still recognize each other by voice alone. This is because humans have a voice print: our vocal tract leaves a unique signature in the tone of our voice across everything that we say.
Other social animals also use vocal cues to be recognized. In birds, bats, and dolphins, for example, individuals have a unique “signature call” that makes them identifiable to members of the group. But signature calls encode identity in only one call type. To date, almost no evidence exists for animals having unique signatures that underlie all calls made by an individual. In other words, almost no animals are known to have a voice print.
That surprised Smeele, a doctoral researcher at the Max Planck Institute of Animal Behavior who studies how parrots use their exceptional vocal abilities to socialize in large groups. Like humans, parrots use their tongue and mouth to modulate calls, meaning that “their grunts and shrieks sound much more human than a songbird’s clean whistle,” he says.
Also, like humans, parrots live in large groups with fluid membership. “There could be tens of birds vocalizing at the same time,” he says. “They need a way of keeping track of which individual is making what sound.” [Continue reading…]