Wow ... lots of discussion on here!
Littlefootland had been in a state of decay since the (mid?) 1990s. The barn was converted to a bird holding and was closed to the public, and eventually all of the domestic stock were phased out. In 2000, the only animal exhibits in the area were the old aviaries. A new play area was put in (sponsored by Saturn, I believe) in the late 90's, but otherwise is was quite run down.
The bird show (and the bleachers now in Eurasia) used to be in an open area just behind the sand pit in the new kids zoo (prior to that, this area was the summertime outdoor Australian exhibit).
Rockybudgeboa, your thoughts are echoed by many people (visitors and staff). In the past few decades, both the species diversity and number of animals at the zoo has declined. This is, in part, due to more structured breeding programs for many species (with space issues for surplus animals being a limiting factor). Costs are probably a big factor too. This trend has been seen across many zoos in North America ... great herds are rarely seen any more. In some cases, the decrease in diversity has allowed for other enclosures to be expanded, improving the lives of the animals still at the zoo - the current mandrill exhibit springs to mind. In the original pavilion, half of the exhibit had Patas monkeys and the other half (separated my the moat) had DeBrazza's monkeys. The mandrills had their own exhibit by the gorillas. When the pavilion was renovated, the gorilla space was enlarged to (essentially) take over the mandrill area, and the two smaller monkeys were moved so the mandrills could have use of both exhibits ...
Shaboola is the only white rhino at the zoo; she currently has a foot problem and is being held off exhibit while it is treated. Unfortunately, even when she does go out, she often stays up by the gate to the house ... where she is all but invisible to visitors (except for perhaps an ear twitching).
Chimps: a few may have been housed at the zoo in the 1970s, but I don't think they were ever on exhibit. The gorillas have been at the zoo since it opened. As to why the zoo doesn't have both chimps and gorillas ... cost, space, and similarity springs to mind.
I suspect they were carp that you could feed from the bridge. The fish are still in the waterway - they are especially visible at the bridge between Australasia and Tundra, but feeding them can be problematic for the health of the waterways.
I visited the site of the Riverdale Zoo (now Riverdale Farm) many times when I was a kid. A few old zoo buildings still exist on the grounds ...