Spotting

A helpful first step is to see if there's a sign on the cage that tells you the name of the species ad where it came from. After all, if it's on display in a zoo like this it may have come from somewhere completely different than where you spotted it, and knowing where it lives is helpful for identifying it.
Also I think you're supposed to label photos taken of zoo animals as "captive" to avoid confusion.

You should mention that it's captive.