In most countries, it is possible to visit zoos and see bored animals pacing back and forth in cages... - Peter Singer Quotes from quotely.org

In most countries, it is possible to visit zoos and see bored animals pacing back and forth in cages, with nothing to do but wait for the next meal. Circuses are even worse places for animals. Their living conditions are deplorable, especially in travelling circuses where cages have to be small so that they can go on the road.

Peter Singer