Heres how pigeons find their way home

By fitting pigeons with recorders that pick up brain activity during their flights, neuroscientists have confirmed that the birds use features from a landscape to find their way home.

London, November 9 : By fitting pigeons with recorders that pick up brain activity during their flights, neuroscientists have confirmed that the birds use features from a landscape to find their way home.

The scientists also hope that they will soon be able to understand how birds use other types of navigational signals at different points in a journey. They believe that pigeons use the Sun, Earth's magnetic field and possibly smells as guiding cues when navigating.

Hans-Peter Lipp, a behavioural neuroscientist from the University of Zurich in Switzerland, had shown in 2004 that pigeons probably also use visual information. He noted that the birds tended to turn when they hit obvious landmarks like a highway exit.

The tracking experiments conducted with the help of modern global positioning system (GPS) loggers to the pigeons' backs collected good information about the birds' location, but no one has been able to measure directly what information the pigeon use to navigate or what they think in flight.

"If we see a bird continuing along its path after crossing a bump in the magnetic field that would normally cause it to change direction - is this because it failed to sense the information or had a good reason to ignore it? What's going on in their minds?" Nature magazine quoted Lipp as saying.

Working with biological engineer Alexei Vyssotski, Lipp developed tiny electroencephalogram (EEG) recorders that can pick up electrical signals from the brain, and coupled them to GPS loggers.

The researchers fitted devices on the heads of anaesthetized pigeons that lived in a loft inland of the Italian coast, near Rome. The birds were then sailed across the Mediterranean and released them some 50 kilometres from home.

Analysing simultaneous GPS positions and the EEG-recorded brain waves, the team found only low and high frequency waves as the birds flew over the featureless sea, probably a sign of normal brain activity.

However, as soon as the birds began to fly over the land, fluctuating levels of mid-frequency waves emerged. The mid-frequency waves observed by the researchers (12-60 Hertz) were the same as those seen in mammals when they start to pay attention to something.

With a view to ensuring that these frequencies were really relevant to the navigational task, the researcher conducted another series of experiments closer to home. They released the birds 5 kilometres away from their loft, requiring them to fly over a highway exit that the birds used as a major landmark.

The intensity of the mid-frequency band increased when the pigeons approached and crossed this highway exit.

Lipp says that the methodology is proof of principle that the little device can monitor brain activity related to navigation.

"What we really want to use it for is to search for changes in brain activity when the pigeons cross sites that contain navigational information invisible to humans, such as electromagnetic sources, for example," he says.

ANI