Mr Bishop, are you not familiar with the work of Melissa Mayntz? Mrs Mayntz has written a 2020 article titled, "Bird Migration - How it works, How do birds migrate correctly?"
You seem to have missed this article in your long list of book references? To paraphrase, she asserts scientific research has been completed on a number of migratory birds and several techniques for birds navigation have been discovered. These include, magnetic sensing, geographic mapping, star and sun orientation, and learned routes.
Therefore, scientists as well as teachers are well within their rights to claim they know how birds migrate, along with the who, what, where, and when. Electromagnetism as Mr Scomato says, is a powerful navigational tool used by birds, but not the exclusive tool.
But, why only concentrate on birds? There is considerable documentation that cats and dogs when taken away from their homes, have been known to travel hundreds and sometimes thousands of kilometres to return to their home.