Are zoo animals frustrated to be in a zoo?

Most don't really mind but some get frustrated.

Additional Info: Most modern zoos are making great strides, or making an effort to meet the needs of their animals by supplying them with "enrichment foods and toys" to help give them mental and physical stimulation. The goal is to give them interesting, and complex things that they can explore, keeping them from the frustration and boredom that so many animals suffer from. This is not practiced in all zoos, but it is gaining in popularity, especially as visitors become aware of it, and it's benefit for the animals long term well being. For more details, please see the site listed below.