Hamburg - In a discovery that is likely to rekindle the debate about language in the animal kingdom, researchers in Germany have discovered that some parrots appear to give their offspring individual names.
Animal behavioural scientists at the University of Hamburg say that spectacled parrotlets use a distinctive call for each of their chicks, with no two chicks being given the same 'name' call.
The small South American parrots also apparently have name calls for their mates.
'The birds very definitely use a particular call exclusively with a particular bird and never for any other bird,' says Dr. Rolf Wanker, head of the Hamburg University Zoological Institute's behavioural research laboratory.
Wanker and his team have spent years assessing video and audio recordings of parrot chatter and squawking.
'What is not yet clear, however, is whether these calls can be equated with what we would call names such as Hans or Fritz or whether they could be more generic labels such as 'my baby' or 'my mate',' he adds.
'For that reason we prefer to refer to these calls as labels or name equivalents,'
The studies were inspired by observations in the spectacled parrotlet's natural habitat in Colombia. There, researchers from Hamburg noted that individual parrots seemed to respond to specific calls that other parrots in the same flock ignored.
'A mother bird had the uncanny ability to utter a cry that would result in her chick returning to the nest immediately amidst the cacophany of the other parrots all around,' Wanker recalls.
'It was obvious that the baby knew it was being called,' he says.
At the Hamburg lab, studies showed that these name equivalents are fractional cries lasting between 90 and 120 milliseconds.
The cry is distinctive enough to provide acoustic clues as to the identity of the individual uttering the call and also to the identity of the intended recipient bird.
'A mother bird uses a different call for her baby from the one she uses for her mate, and they respond with calls that correspondent to her identity,' he says.
Similar findings have been achieved with certain primates and with dolphins. Many years ago, British TV science producer David Attenborough showed that macaque monkeys use distinctive alarm calls to alert other monkeys to danger.
Macaques will use one call to identify a panther, thus telling other monkeys to climb up a tree. But they will use a different call to identify a python, thus ensuring that all the monkeys climb down a tree that has a snake lurking in its branches.
The Attenborough findings are of interest because they involve primates in the wild that have had little or no contact with humans.
That contrasts with studies involving chimpanzees and gorillas in captivity in America over the past four decades which have produced startling but highly controversial evidence that primates can learn and use deaf human sign language.
Other studies have determined that birds develop regional 'accents' and 'dialects' depending on their location. Sparrows in the eastern United States, for example, are known to have subtly different chirps from their cousins on the west coast.
The German findings are the first involving parrots. The spectacled parrotlet is among the smallest parrots, only slightly larger than budgerigars. The bright green birds with a distinctive yellow ring around their eyes live in eastern Panama and northern Colombia.
In the Hamburg study, parent birds and their chicks were placed in separate cages within earshot of each other but out of view of each other.
The birds' calls to each other were recorded and later played back to the individual birds to ascertain their response. The findings demonstrated that name-specific calls were used by each bird.
Wanker shies away from calling this labelling behaviour any form of language, noting that it has yet to be proved conclusively whether humans are the only animals capable of abstract linguistic structures.
He also notes that a fierce debate has been raging for decades among ornithologists and linguists over whether songbirds might be using a form of language. But he points out that, in the avian world, parrots are a special case.
'Parrots are unique among avians,' he says. 'They are the primates of the avian world and are very highly developed creatures with complex social systems and prodigious cognitive skills.'
The Hamburg research group plans to expand its study to include macaws at the Hagenbeck Zoo in Hamburg.