A sense of direction

Every year birds migrate to our shores from as far away as Africa and Russia. Amazingly, very few birds seem to take a wrong turn on their journey, with some even returning to the exact same spot year-on-year.

Our understanding of migration is ever-growing - if Ian Newton's recent 500+ page book on the subject is anything to go by!

So with neither road signs nor a computer GPS to guide them, how on earth do birds navigate from one place to another?

I've touched briefly on this subject before on this blog, but wanted to delve a bit deeper.

Magnetic attraction

It turns out that some birds have tiny grains of a magnetic mineral called magnetite in their heads. This mineral can detect the Earth's magnetic field.

To test if birds do use magnetic fields, an experiment in the 1960s took some robins and placed then in cages with artifically created magnetic fields. They found that the birds orientated themselves according to the new magnetic fields, and that the new direction corresponded with the route they would have taken had they been migrating naturally.

Where am I?

We know that birds follow the same migration routes each year, but whether birds learn a 'map' of their immediate surroundings via remembering specific landmarks on their journey is hard to prove.

However, the humble starling has offered some insight into this issue. Just as they were about to start their migration, thousands of starlings were captured in the Netherlands and then released in Switzerland.

The juvenile starlings set off in the direction that would normally have taken them to their wintering grounds had they still been in the Netherlands. The adults, however, corrected for their new location and nearly all reached their normal wintering grounds.

So, it seems that birds with experince of a location can re-find it, and that they must to some extent have 'map sense' - the ability to know where they are in relation to their home, based soley on their current location.

Stars in their eyes

For birds that migrate at night, star positions are important in helpnig them get to where they are going. Birds put in planetariums where the star patterns had been changed became confused, while on overcast nights there tends to be less recorded migration.

That birds use the sun to navigate has been known for over 50 years. And it's thanks, again, to starlings. In experiments that changed the sun's direction, it was shown that starlings corrected their flight paths to take account of the sun moving.

Back to school

Lastly, we come to good old-fashioned learning. For those species who migrate as families (eg geese and cranes) it seems that the young learn the routes from their more experienced parents.

Once learned, younger birds are then able to travel the route successfully themselves.

If that's left you with a sense of wonder, I've got just the thing for you: the trailer for our award-winning film Born to Fly - a film all about the epic migration of European cranes.

Sit back, relax and enjoy this truly incredible story.