As I understand it, industrially bred meat chickens become so large, so fast, that they basically can just barely move at all and it's about the time they get that size that they hit the fryer. It's about 2 months, cradle-to-grave, for those guys. A sad life, but a delicious end. I appreciate their sacrifice.
Yard birds will get up pretty much exactly as you describe. 30 feet would be a transcontinental flight for them and that's only if they had a good running start and a strong will to do it.
