Mystery of how homing pigeons navigate solved: Birds use 'gyroscope' in their brain to guide them, study finds
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Humans have used pigeons to carry messages to desired locations for centuries, but how the birds find their way home has remained a mystery.
Now experts believe they navigate using a gyroscope-like area in their brain.
They say that the birds use their memory of the gravity field at their home to guide them home.
Scientists believe that homing pigeons navigate using a type of gyroscope in their brain and use their memory of the gravity field at their home location to guide them back
Dr Hans-Peter Lipp of the University of Zurich in Switzerland and Kwazulu-Natal University in South Africa, said: 'There is widespread agreement that pigeons are able to determine and maintain flight - compass - directions based on solar and magnetic cues.'
But no-one had previously explained how the birds determine their position.
Previous studies have suggested that pigeons navigate using smells or magnetic fields.
After decades of working with pigeons in the Swiss Army, Dr Lipp teamed up with Valeryi Kanevskyi, of the High-Technologies Institute in Ukraine.
He said: 'Valeryi had formulated a simplistic yet astonishing theory.'
The Ukrainian suggested that the birds use their memory of the gravity field at their home loft for guidance.
Dr Lipp said: 'I realised that he had solved the map problem by one simple assumption: birds must have a gyroscope in their brain.'
No-one had previously explained how the birds (stock image) determine their position. Previous studies have suggested that pigeons develop 'map sense' and navigate using smells, or a geomagnetic map
Their team published the discovery that homing pigeons are affected by disturbances in the gravity field, in the Journal of Experimental Biology.
At the beginning of the experiment, the team set out to show that gravity anomalies - without geomagnetic contamination - would mislead pigeons.
To do this, the scientists used a location in the Ukraine - a huge meteorite crater filled with sediment where gravity was weaker than usual.
The researchers wondered whether crossing the edge of the crater could disrupt a pigeon's gyroscope navigation system and send the birds off in the wrong direction.
Pigeon fanciers in the nearby town of Novoukrainka trained birds and over a series of days, 26 birds fitted with lightweight GPS trackers, were released from the middle of the crater.
Of the 18 birds that made it home safely, seven headed in the correct direction and managed to cross the edge of the crater without deviating much from the most direct route home.
However, other birds that set off in random directions seemed to become disorientated at the edge of the crater and when they crossed a second gravity disturbance, lost their bearings again.
The researchers compared the flight paths of the birds that encountered the gravity distortions with birds that had an unhindered return home.
They found that the disturbed birds' routes were much more widely dispersed than the unhindered groups and showed that the birds veered off most severely when they crossed the edge of the meteorite impact.
The scientists believe that the birds initially set a bearing home by comparing their 'home gyroscope setting' with their 'local gyroscope reading'.
But some birds initially set the wrong bearing - taking several days to correct the error and return home – suggesting that they rarely use the alternative navigation strategy of regularly checking the difference between their actual and anticipated return routes.
Dr Lipp hopes to learn more about the cellular mechanisms that allow the birds to detect the weak gravitational forces that keep them on the straight and narrow.
Scientists used a location in the Ukraine - a huge meteorite crater filled with sediment where gravity was weaker than usual - near the town of Novoukrainka.The researchers wondered whether crossing the edge of the crater could disrupt a pigeon's gyroscope navigation system and send the birds off in the wrong direction
A previous study showed that huge flocks of pigeons (pictured) decide when to change direction in mid flight by using a kind of 'democratic hierarchy'
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