Have you considered what would happen to zoos, wildlife "safaris"/et. al., and "sanctuaries"/rescue centers/etc., if we get hit by something like the Cascadian Subduction Zone earthquake? Elephants Rhinos Tigers Leopards Lions (both African and cougars) Bears - polar and brown Cheetah Hippos (the most dangerous animal in Africa - more people are killed by hippos than lions) etc. Then there are all the feral dogs. Of course, humans are still the most dangerous, with only feral/abandoned dogs rivaling them in numbers. But there are a number of places that have wildlife in them that we are not used to, that are not afraid of humans due to being cared for by humans, who might escape in one way or another, should we get hit by "the big one".