A magnetic compass needle, you must have learnt at school, always points to the North. This is because the earth itself is a magnet and its magnetic lines of force stretch from the magnetic North Pole to the magnetic South Pole. Similarly, some scientists say birds too are sensitive to this magnetic field. This enables them to fly in the right direction. However, no organ has been found in the birds, which does the work of a magnetic compass needle. Experiments have shown that the birds know the exact direction in which they have to fly because of objects in the sky like the sun. This means they use the sun like a compass. But we cannot say with certainty how birds find their way home after migrating thousands of kilometres.