I think that Topeka Zoo in Kansas and Cougar Mountain Zoo in Washington are pretty nice. Cougar Mountain has a nice collection of macaws and cranes and Topeka has the first indoor tropical rainforest exhibit and a nice selection of African animals.
I loved Healesville as well but I think it's a push to describe it as small. It's on the large side of medium I reckon.Healesville Sanctuary is a little gem in Victoria Australia. Probably the best zoo Ive ever been to
I like a decent small zoo and two I consider to be well done are Shaldon and Living Coasts. Both are about an acre or so and both have very nice collections including rarities galore. An added bonus is they are extremely close together and can easily be done on the same day.
Other noteworthy small collections are Bristol, Newquay and Birmingham nature centre but they are a lot larger than the previous two.
Other small collections that I've not visited but heard good things about would be Exmoor and Hamerton. Both aren't readily accessible by public transport but have very impressive collections and are quite different from mainstream collections.
That's a pretty good summation of most of the best of small(er) UK zoos to which I'd also add Five Sisters (which is growing at a rapid pace and, I believe, may have more species than Edinburgh now) and Wingham (which generally lacks in aesthetics but has quite a nice collection). Monkey Haven on the Isle of Wight is also very well done.
I didn't think Monkey Haven had much going on, maybe I need to look into it more!![]()
Gangelt Wildpark on the Dutch-German border near Brunssum.