It's smallish... You could walk from one end to the other in a few minutes (presuming you didn't stop to look at the animals). However it is a nice collection and has several uncommon species.
I'd have said the Zebra Paddock was at least an acre on it's own.
I'm pretty sure the Zebras came rom Blackbrook after 2009. So if we assume the main area was 1.5 acre, i'd hazard a guess at about 5 acres now.