Pigeons' sixth sense eludes scientists

How pigeons are able to detect magnetic fields to navigate their way home remains a mystery, say researchers.
Biologist Dr Jeremy Shaw, from the University of Western Australia, and colleagues, report their findings today in the journal Nature.
"At this stage it's still that needle-in-a-haystack problem," says Shaw.
Behavioural studies show that pigeons are able to detect magnetic fields.
Finding the cells that are responsible for this magnetic sense has eluded scientists.
But in 2003, German-led researchers reported iron-rich magnetoreceptors in six locations of the pigeon's beak.
The team reported finding nerve cells rich in magnetite and haematite, which are highly magnetic.
Shaw and colleagues carried out detailed histological examinations in 270 pigeons but could not confirm these findings.
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