I have birds that will step up from inside a cage with no problem but I've never trained them to do it, it's something that came in its due time when they felt complete trust in me. It's also something that is absolutely unnecessary in terms of safety and that some birds simply do not like so I never ask for it.
Even if clipping did not have negative health consequences (atrophied air sacs and muscles and shrunk tendons), you simply cannot have a clipped bird and cats and it doesn't even matter if the cats show no interest whatsoever in the bird. It's an issue of stress. You can't take away the one and only predator-avoidance strategy a prey animal has and make him cohabit with its species predator without the animal suffering chronic stress (which has been proven over and over to affect their health and shorten their lifespan).





