Science probably has no more of an idea of the true nature of instinct than does a lay observer.
Popular science would have us believe that instinct requires thousands of generations to become ingrained in the genetic blueprints of a species. It's just instinctive behavior. Well, instincts take tens of thousands, even millions of years to develop. They can't just be switched on and off in a mere few thousand years. More than a curiosity of migratory behavior, it's a longtime tourist attraction for bird-lovers and romantics from around the world.