I visited today for the first time since the end of April 2011. It was a nice day and the zoo was busy - partly because of a guinea pig show and a herptile conference. Admission prices are still reduced because they are still making good after the hard winter. For example, all the toilet facilities are portaloos (but the one I used was clean and pleasant). The old toilet block was wired off but looked OK from the outside.
I don't know how many of the changes since my last visit are due to the weather, some of them may have happened before the winter.
Anyway all the aviaries around the car park on the left hand side of the drive have been demolished, except one. The aviaries on the right hand side have been combined with the larger aviary behind them, holding American white ibis, night herons, mandarins and Pacific white-fronts. The Tropical House was closed and there were only a few birds in the outdoor aviary with the pool at the end of the house - I saw squacco herons, turnstones and a few small teal (probably Bernier's, but I didn't get a good look). The large aviary with the sloping roof behind the entrance building is also under repair.
The old secretary bird aviary and the one behind it (for sacred ibis?) have both gone - only the roof supports remain. Since my last visit a new aviary for snowy owls has been completed behind the tea room.
The only mammals I saw were meerkats, warty pigs, ring-tailed lemurs, Siberian chipmunks, rabbits and guinea pigs - although I overheard someone saying that they still have a sitatunga.
Many of the less common bird species have also gone (to Hillside I hope). But there are still 8 species of crane, greater flamingo, Darwin's rheas, milky eagle owls, Ypecaha wood rails, plus a few pheasants, Dalmatian, white and brown pelicans, lots of ibis (notably the noisy buff-necked and the strange hadada) and more waterfowl than you can shake a stick at. Not bad for £5 entry.
It's also worth noting that the website is a disaster area at the moment, but it is due for revamping soon.
Alan