This is actually a Red-billed Blue Magpie (Urocissa erythrorhyncha). The Taiwan species has a staring white/yellow eye which is extremely obvious. Interestingly, I found a photo on Google showing the signage in this aviary, and the picture does show the Taiwan species. Whether or not they used to have the genuine article at the bird park I do not know, but this one isn't it.
Quite correct! Never having seen a Blue Magpie I never even noticed the difference in eye colour (and if I had, I would have assumed it was a sexual difference). As you say, the label describes it as Formosan and I had no reason to question it.
