Natalie Wolchover wrote a fascinating piece for LiveScience.com on how zoos attempt to satisfy the predatory instincts of animals they keep.
Wolchover talks to Smithsonian National Zoo public affairs assistant Jennifer Zoon who says that while predatory animals the zoo keeps are fed a diet comparable to what they would get in the wild, actual hunting by animals has to be simulated. Oddly enough, the primary concern about allowing any sort of live predation (such a releasing a live rabbit in a tiger enclosure) is potential harm to the predator,
As Andrew Circo of the San Diego Zoo told the British newspaper the Guardian in 2008, “We do not feed live animals for a very important reason. Sometimes those animals fight back and, in exercising their instincts, may injure one of our endangered … animals. And when dealing with many endangered species, you do not want to take a chance that an injury could lead to other health complications. Not even our snakes get live mice.
Zoos apparently try to satisfy the predatory urges of such animals mostly by simulating live animals with cardboard dummies, large balls and similar object to simulate prey, and in some cases causing the dead carcass of an animal intended for feeding to move to give the predator animal the illusion that it still needs to kill its food.