I'm guessing they are stuck on that stick, because their wings have been pinioned (or similar).
There are similar exhibits in many zoos of the world (Jersey used to have some too) but this is the first time I've seen one surrounded by water. My concern would be that if one of the birds fell off, or got a fright and tried to fly away, they'd end up in the water and drown.
And has already been mentioned, they can't pass each other without gymnastics. Nor do they appear to have any form of enrichment other than themselves.
I would suspect, but this is purely conjecture, that the birds probably don't spend more than a few hours at a time out on these perches. At least I hope that is the case.
