Here's something I forgot to mention about the raccoons. It's natural to try rousing the animals somehow. I don't, because I think I get better pictures by waiting for something surprising, but I understand people who try prompting. Many toss food, mostly popcorn (there's a nearby stand), which can get a half-dozen raccoons to line up, and also to get them digging down under the water, which kids particularly love. Digital cameras have been a bit of a bad thing for poses, since the raccoons here caught on to the meaning of the shutter click and film roll, and will respond. Digital beeps they're more likely to ignore.
For some of the animals making their noises works great -- the meerkats, for example, perk up and face any noise, and the otters will gather around most sounds. (That may be coincidence as they're busy running around all the time.) The binturongs that share the otter enclosure seem to just sigh and wonder why they have to put up with these roommates.
None of the Singaporeans, though, seems to know just what noise a raccoon makes or how to imitate the chirring. There is chirring, but usually for short stretches when one raccoon is too obnoxiously close to another at the wrong time, so it's natural to not know the sound. So instead many have tried to meow at the raccoons.
The raccoons roll their heads at these people and look baffled by it all.
Trivia: The first weekday Peanuts strip not using the four-panel format appeared on 31 March 1952, with an eight-panel strip. Source: The Complete Peanuts, 1950-52, Charles M Schulz.
Currently Reading: The Cyberiad, Stanislaw Lem.