What is the story of the black leopard that escaped from the Zurich Zoo?

In Chapter Eleven, Pi explains that, no matter what, there will always be animals who try to escape from zoos, even though generally animals do not wish for “freedom.” The escape attempts are often because the offending animal’s enclosure is unsuitable, or because something within its enclosure has frightened its Animals are always escaping from something, never to.

As an example, in 1933 a female black leopard who was being abused by her co-habitating leopard escaped from the Zurich Zoo and managed to evade capture and survive for ten weeks before she was shot.