If you were captive in a zoo, what would you do? Probably scheme a plan to escape, most likely.
I recently went to a zoo and thought how I would cope with being stuck in such a closed area with minimal interaction throughout the day. Since the likelihood of escape is nearly impossible, the possibilities would be limited. Most of the animals at the zoo tended to be just sleeping or resting in place, which made observations dull. But, can we really expect animals to be interesting at all times? Definitely not, just think of how you would behave in an enclosed area with tons of people of different species viewing you constantly.
With that said, most zoos tend to be on the boring side. Like museums, zoos have become lines of people taking amateur photos of the resting animals.