One has to ask oneself how in the world birds find their way.
Overall, there are three theories. Namely that the birds use the sense of sight, a magnetic sense or the sense of smell. Or maybe a combination.
– All schools will say they have the answer. But when a study comes out that indicates that birds navigate by magnetic fields, another one immediately comes out that shows that the birds can easily find their way without magnetic fields.
– So the riddle is not solved yet, says Anders Tøttrup, deputy museum director at the Statens Naturhistoriske Museum, to Videnskab.dk.
One of the senses that birds seem to use when they leave the northern hemisphere behind them in the autumn is the sense of sight.
Most migratory birds fly at night, where one would otherwise think that the sight was not very familiar. But studies have shown that the birds seem to orient themselves after the stars.
– Studies have been made where scientists have manipulated the starry sky by putting birds into a small planetarium. They show that the birds fly in a different direction if you move the stars, says Anders Tøttrup.
He adds that the North Star is the one to stand still in the night sky, so it will make sense if the birds calibrate their direction just after it.
Another part of the theory of sight is that birds use the Sun as a beacon to find their way.
Other research suggests that birds navigate Earth’s magnetic field.
– Researchers have found something magnetic in birds that some believe they are navigating. However, there is no evidence that the substance has anything to do with birds’ navigation, says Anders Tøttrup.
If the theory is to be properly investigated, it requires removing the magnetism of one group of birds and comparing their ability to find their way with a control group that has not been manipulated.
But that’s easier said than done, because scientists are still looking for the place in birds’ DNA where the magnetic is. And when they can not find it, as you know, it is difficult to remove it.
Finally, it is unclear how much the sense of smell means during bird migration.
– There are definitely seabirds that use the sense of smell to find food or to find their way back to their young. But we do not know how big a role smells play for migratory birds.
– Experiments have been made where the olfactory nerve in herring gulls has been cut, and this gives them great problems finding their way, says associate professor Knud Andreas Jønsson from the Statens Naturhistoriske Museum.
In other words, there is no conclusive evidence.
Thus, there are many indications that birds use several clues in their orientation. One of the clues is probably the primary, and others can come with the birds’ experience.
Source: The Nordic Page