Humans invented the names Big Bird and Tweety Bird, but new evidence suggests at least one species of parrot creates its own names for friends and family members.
Since vocal labeling indicates that the namer must first be able to imagine the individual or object in its mind, the discovery likely means bird thoughts and communication are far more complex and closer to human levels than previously realized.
The namers in this case are spectacled parrotlets, Forpus conspicillatus, which are small bright green or blue South American parrots.
"We have shown that they use specific calls that only refer to the individual in question," said Ralf Wanker, lead author of the study. "To my knowledge it is the first time that labeling or naming is described for animals in this way."
He added that other studies suggest bottlenose dolphins and another bird, budgerigars, match their calls to others, similar to how humans often copy the tone or volume of the person they are speaking with, as for baby talk.
Wanker and his team housed two groups of the birds in a simulated natural environment. The researchers noted social ranks within identified bird families.
They then made audio recordings of 17 individuals from five different families. The recordings captured birds vocalizing with other specific birds.
Computer analysis of the sounds revealed that initial contact calls were unique for each parrotlet and indicative of the individual's social standing.
For example, when one bird, Eddi, communicated with his mate, Renee, he used a specific call. Eddi also used specific, yet similar, calls when addressing each of his offspring, Uvo and Ustinov.
The researchers also found that when the sounds were played back to the birds, the parrotlets paid greater attention when their apparent name was called out, similar to how a human might turn around if someone in the room called out his or her name.
The findings are published in this month's Animal Behavior.
Wanker, a Hamburg University ornithologist, told Discovery News that no one can yet fully decipher the birdcalls or determine what the parrotlets are pondering, but the findings provide some clues.
"I think they have a mental representation of at least their family members because they use only one call type for one specific individual," he explained.
"They do not use this call type for other individuals, thus they must be able to make a mental connection between the individual and the certain call."
Claudia Moudry, an expert on parrots and owner of the Berkeley, Calif., pet store Your Basic Bird, told Discovery News that she was not at all surprised by the findings.
"I know of one African gray parrot whose owner also has three cats," she said. "Whenever a cat comes near the parrot, the bird will call the cat by its correct name."
Moudry also said one of her female parrots, an 18 year-old, had never seen another bird of its own species. She obtained a male parrot of the same species and put him downstairs.
"I don't know what they were saying, but they communicated a lot without even seeing each other or being on the same floor," she said.
"Whatever the male said, it must have excited the female. Her hormones kicked in and, for the first time, she laid an egg."