Re: A floor or the ground?
You could add a large dig box with grass to whatever room they're in. you could also make a cage for outside that you can put them in with supervision, instead of letting them run loose in a giant aviary, but it would be SOOOO awesome for them to be in an outdoor aviary, so if it's doable, you've got my vote! .
A good idea is to have a tarp that you can spread over the cage for when it rains or something, so that even if they're not in it there's less of a chance of dangerous fungus growing in there. Tarps usually have eyeholes in the corners and sides, so you could have hooks on the outside of the cage for attachment
"Until one has loved an animal, part of one's soul remains unawakened."
- Anatole France
"We have doomed the wolf not for what it is, but for what we deliberately and mistakenly
perceive it to be - the mythologized epitome of a savage ruthless killer - which is, in reality,
no more than a reflected image of ourselves."
- Farley Mowat