News
Published online: 24 November 2004; | doi:10.1038/news041122-7
Homing pigeons reveal true magnetism
Michael Hopkin

Iron crystals in their beaks give birds a nose for north.

It's official: homing pigeons really can sense Earth's magnetic field. An
investigation of their ability to detect different magnetic fields shows
that their impressive navigation skills almost certainly relies on tiny
magnetic particles in their beaks.

The discovery seems to settle the question of how pigeons (Columba livia)
have such an impressive 'nose for north'. Some experts had previously
suggested that the birds rely on different odour cues in the atmosphere to
work out where they are. But the latest findings suggest that they are using
magnetic cues.

The idea that pigeons' beaks contain tiny particles of an iron oxide called
magnetite is not a new one, says Cordula Mora, who led the latest study at
the University of Auckland, New Zealand. But the particles themselves are
likely to be only a few micrometres across, and no one has ever seen them
under the microscope.

Mora's behavioural experiments therefore give the best indication yet that
pigeons are aware of Earth's magnetic field. She and her colleagues taught
the pigeons to discriminate between magnetic fields by placing them in a
wooden tunnel with a feeder platform at either end and coils of wire around
the outside.

Full Text at Nature
http://www.nature.com/news/2004/041122/full/041122-7.html

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