Songbirds show signs of recognizing their own bodies in mirrors.
Magpies sing a self-reflective tune to themselves that until now has gone unheard. When placed in front of a mirror, these songbirds realize that they’re looking at themselves, raising the possibility that they have independently evolved the brain power to support a basic form of self-recognition, a new study suggests.
Magpies are the first non-mammal to demonstrate a rudimentary affinity for self-recognition, psychologist Helmut Prior of Goethe University of Frankfurt in Germany and his colleagues report in the Aug. 19 PLoS Biology. Members of the corvid family, which includes crows and ravens, magpies join apes, bottlenose dolphins and elephants as the only animals other than humans that have been observed to understand that a mirror image belongs to their own body.
“When magpies are judged by the same criteria as primates, they show self-recognition and are on our side of the ‘cognitive Rubicon,’” Prior says.
Magpies and other social birds that possess large brains with expanded cortical-like areas should display at least some level of self-recognition, remarks Irene Pepperberg of
Mirror self-recognition tests, which involve marking an animal with a spot that can only be inspected or touched by looking in a mirror, can be tricky to interpret, Pepperberg notes. Using a mirror reflection, one of her parrots scratched a paint mark on his body for nine seconds but ignored the mark for the rest of a 15-minute session, apparently because the mark didn’t come off at first. The same bird made no attempt to scratch a barely visible water mark. “We never published the data because we didn’t think nine seconds meant much,” Pepperberg says.
Evidence of mirror self-recognition among magpies shows striking parallels to what has already been observed in bottlenose dolphins and elephants, comments psychologist Diana Reiss of the City University of New York’s
The question now is whether magpies’ sophisticated social behavior, including intense competition to collect and store food in hidden caches, provides a foundation for mirror self-recognition, Reiss says.
In the experiments, each of five magpies first explored a mirror on its own. The researchers found that three birds — Gerti, Goldie and Schatzi — preferred to spend time in a cage compartment equipped with a mirror rather than in an adjacent cage compartment with a non-reflective plate. The animals closely inspected mirror images, looked behind the mirror and moved back and forth in front of it.
The remaining birds — Lilly and
At that point, the researchers used water-based paint to apply a brightly colored mark — red or yellow — or a black mark to the black feathers of each bird’s throat, just under the beak. The magpies spent two 20-minute periods in a mirror compartment while sporting each type of mark. They spent the same amount of time while marked in the compartment with a non-reflective plate.
Gerti, Goldie and Schatzi used the mirror to inspect brightly colored marks with great care, turning and tilting their heads at close range. On some trials, Gerti and Goldie scratched off red or yellow marks with their feet. Poorly visible black marks attracted the magpies’ attention on only a few occasions.
The same three birds directed virtually no behavior toward brightly colored marks when tested without a mirror.
In contrast, Lilly and
It’s unclear why Lilly and
Reiss, D., and L. Marino. 2001. Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. Proceedings of the National Academy of Sciences 98(May 8):5937-5942. doi:10.1073/pnas.101086398
Plotnik, J., et al. 2006. Self-recognition in an Asian elephant. Proceedings of the National Academy of Sciences 103(Nov. 7):7053-17057. doi:10.1073/pnas.0608062103
Prior, H., A. Schwarz, and O. Güntürkün. 2008. Mirror-induced behavior in the magpie (Pica pica): Evidence of self-recognition. PLOoS Biology 6(Aug. 13):6. doi:10.1371/journal.pbio.0060202
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