So, the time has come to bin your ‘Tom Tom’ and your ‘Garmin’ in favour of an onboard pigeon. Well, maybe not – but it turns out that pigeons have something in the way of a GPS of their own.
It has long been debated as to how pigeons are able to find their way around but scientists now have further insight into how these wonderful flying bundles of joy (that’s the pigeons – not what they like to drop when flying through the streets of Cardiff) are able to navigate.
When winter (or spring/summer if you live in Wales) is upon us, pigeons are able to use the Earth’s magnetic field to reach the warmer parts of the world. It is still a mystery as to where they hide their magnets to allow them to do this, almost as illusive as a neutrino’s mass (tenuous link I know, but it wouldn’t be the Science section without them), but at least we are now able to tell how the pigeons’ brains are able to use these magnetic field to get around.
David Dickman and Le-Qing Wu of the Baylor College of Medicine collected seven homing pigeons and inserted electrodes into their brains to record the activity of individual neurons. The birds were then placed inside an artificial magnetic field (masking the Earth’s natural magnetism). The test conditions were also completely dark to prevent the birds from using visual signals to navigate.
The researchers then measured how the pigeons’ brain activity changed as the intensity and the angle of the magnets was adjusted. They found that in one area of the brainstem 53 neurons were particularly active.
It is suggested that these cells probably link to an internal map of sorts, a kind of biological GPS. The findings also suggest that rather than the eye or beak the magnets are most likely to be situated in the ear.
Most surprisingly, Prof. Dickman says, is that the birds could do more than simply detect changes in the angle of the field, which would tell them their position relative to the equator. The pigeons were also able to tell when the researchers inverted the magnetic field meaning that the birds can rely on their magnetic sense alone to ensure they are not inadvertently flying in the wrong direction.
Learning about this magnetic GPS may have implications for human health. Dickman says it may one day be possible to restore navigational ability to those who have lost it due to brain injury or neurodegenerative disease such as Alzheimer’s. The paper is a wonderful step forward and points towards more promising results than previous hypotheses. But the questions as to how they actually detect the magnetic field still looms.
It only follows then that this is Dickman’s ultimate goal. Another outstanding question, he says, is how the pigeons don’t become confused when they tilt their head (because it would alter their relative orientation to the Earth’s magnetic fields). One possibility is that they use a combination of the magnetic GPS and the pull of gravity to triangulate their position. The mechanics of magnetic navigation has been up for rigorous debate, so all joking aside this is a step forward, just don’t ask me in which direction – I’m not a bloody pigeon.