Self-recognition has never been observed in a non-mammal
Magpies can recognise themselves in a mirror, scientists have found - the first time self-recognition has been observed in a non-mammal.
Until relatively recently, humans were thought to be uniquely self-aware.
Scientists now know that most chimpanzees and orangutans can recognise their own reflections.
Some birds react when shown a mirror, but it is unclear if they know they are looking at their reflection, German experts wrote in Plos Biology journal.
Dr Helmut Prior, from the Goethe University in Frankfurt, and his colleagues carried out a series of tests on five hand-reared birds.
In one test, the researchers placed yellow and red stickers on the birds in positions where they could only be seen in a mirror.
On seeing their reflections, the magpies became focused on the stickers as they tried to reach them with their claws and beaks.
On several occasions, they succeeded in scratching the stickers off, which put an end to this behaviour.
Black stickers placed on the birds' bodies did not elicit the same response.
When no mirror was present, the magpies took no notice of the stickers.
"We do not claim that the findings demonstrate a level of self-consciousness or self-reflection typical of humans," the researchers wrote in Plos Biology.
"The findings do, however, show that magpies respond in 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."