We notice different kinds of birds flying around our homes at different during different seasons of the year but some of us know when birds left our area and fly towards another area and how do they know it is the best time to migrate.
Image Source https://www.allaboutbirds.org/how-do-tired-birds-choose-where-to-stop-during-migration/
Birds travel for 1000 of miles during migration and after few months they travel back to home. They migrate at exactly the same time each year and they almost follow the same route during migration.
According to one of the research migratory birds have vision based magnetoreception they can see the magnetic fields and our Earth behaves as a giant bar magnet and our planet is wrapped in slopes and curves of magnetic field.
Image Source : http://slideplayer.com/slide/8667123/
