In the 2023 PD news thread I wrongly identified it as an emperor goose, for which I'm sorry. The species is not listed for PD and was not signed, so presumably this single individual is an escaped or feral individual.
This Snow goose is pinioned , so definitely not a bird that could fly in -or would survive at all alone for long time...
probably again an example how "unimportant" waterfowl are for most zoos... but fairly cheap to by and to put anywhere as a nice addition to make a setting more interesting- not a good idea