I usually find that going to the zoo early in the morning is the best time. The animals are much more active and the light is better for photography. Unfortunately from time to time this can backfire, especially if there is some you particularly want to see. For me it was the bears – I love photographing the bears and their antics but on this last trip this is all we saw.
There was a cleaner tidying up the enclosure who was more than happy to talk to us about the bears and why there was an electric fence up the top of the enclosure. Aparently the bears would be back out soon but I wasn’t interested in waiting and we didn’t go back. The bears will have to be another day.