As I've just realized, knowing what to do with an ill bird (or perhaps more important, what not to do), doesn't help in the slightest when confronted with an apparently healthy bird of prey who's only problem seems to be that it's just a bit to young to fly.
Normally I'd just leave it where I found it (Rule 1 in dealing with more or less wild animals especially young ones) but it insisted in doing it's walking a few steps, hopping and gliding (if caught by a lucky breeze) routine in the middle of a busy place in the city.
Well, when in doubt, let someone else deal with it.
It's now in the department for small animal medicine (everyone from the department for birds and reptiles had already gone home) and if nothing else they have the right phone numbers to call. I'll ask tomorrow what happened.
As a side note:
Ms Bystander No.5, could you please tell me what kinds of "animal testing" you suspect the vets at the clinic to do to the patients? Or you could just shut up and make a better suggestion. (Ok, so you provided the box - still doesn't stop me thinking you an ignorant cow.)