Hamburg - Birds recognise their own reflection in the mirror as being themselves and not that of another bird, according to German researchers. The recognition of "self" has been known to exist among primates such as chimpanzees and orang-utans.
There have also been reports that dolphins and elephants share the same ability.
All these animals live in a complex social world, as do humans, which experts believe may be linked to self-recognition.
But the German studies mark the first time that non-mammals have demonstrated this key trait of higher intelligence.
Some birds, especially members of the crow family, are also highly social.
Scientists have now shown that magpies, which are related to crows, pass the mirror recognition test.
Budgerigars and parrots are well known to react to mirrors. But their behaviour suggests they do not understand it is their own reflection in the glass.
In contrast, magpies really do know they are looking at themselves, according to the study led by German psychologist Dr Helmut Prior, from the Goethe University in Frankfurt.
Tests were conducted on five hand-reared birds called Gerti, Goldie, Harvey, Lilly and Schatzi.
The most telling involved placing yellow and red stickers on the birds in positions where they could only be seen in a mirror.
Faced with their reflection, the magpies became focused on the marks as they tried to reach the stickers with their beaks and claws.
On a number of occasions, they succeeded in scratching the stickers off, and only then did the mark-orientated behaviour stop. Black marks that did not show up against the birds' dark feathers did not elicit the same response.
When no mirror was present, the birds took no notice of the coloured marks.
The magpies appeared to be more concerned than chimpanzees about coloured stickers being placed on their bodies.
It may be that from a survival point of view, birds value their feathers more than chimps do their hair, said the scientists.
They pointed out that birds spent about a quarter of their resting time preening.
The scientists wrote in the online journal PLoS Biology: "Altogether, results show that magpies are capable of understanding that a mirror image belongs to their own body.
"We do not claim that the findings demonstrate a level of self-consciousness or self-reflection typical of humans. The findings do, however, show that magpies respond to the mirror and mark test in a manner so far only clearly found in apes, and, at least suggestively, in dolphins and elephants.
"This is a remarkable capability that is at least a pre-requisite of self-recognition and might play a role in perspective taking."
Self-recognition may be essential for the ability to predict the behaviour of others on one's own experience, said the researchers.
The findings showed that self-recognition may have evolved separately in animals with vastly different brain structures, they added.
