They are flighty birds, some species more than others. Scarlets are super flighty, to the point where they will injure themselves easily against bars, trees, wallls, etc, where as something like the glossy ibis is a little more docile. They make a mess in any water you provide! If using a draining pond, it has to be scrubbed and refilled at least once daily just to keep it from being too gross, and it still usually clogs because they produce a lot of waste when kept in groups. Some species can be picky about nesting, especially the flightier ones. They make insectivore pelleted diets which help with feeding, though I know at least scarlets also need fish (they will eat thawed, dead fish). They all have fairly delicate beaks, and one of the most common injuries you will see in captive ibis are broken bills. I'm not sure about permits.