The key is training for every situation- predators, rain, thunder, cars, wind- pretty much what ever can spook your bird or distract him. No one trains in all aspects as I know. It takes time and the perfect occasion- waiting for thunder, waiting for rain, waiting for a windy day to take them flying in. Most people don't train birds in scary or unfavorable situation s because they are scary or unfavorable, but they happen. You hear about the birds who got spooked cuz of a sudden storm, or car, or predator, or blew off in the window, or got stuck up in a high treeand were gone for ever. Had they been trained it wouldn't have happened. Had I trained Erin she would had never gotten lost, but we don't expect bad things like a storm, or hawk, or wind to happen. We check the weather and look for predators and when we assume it's safe we take them out, but surprises do occur. And also many people dont jump right to the outdoors free flight, lots let them fly freely indoors first, some only let them fly indoors and never take them out.