They are in crowded conditions. Humans do the same things will kept locked up in crowded conditions.
What are you arguing is akin to saying that humans need to be locked up in solitary confinement because if you keep them "free" in close quarters they will start committing acts of violence against each other. You would have a hard time arguing that the Japanese in US/Canadian "relocation centres" should have been kept in solitary confinement because there were instances of "inmate-on-inmate" violence/rape.