Folks are not always blessed with common sense. Less often, you read of them doing remarkably stupid things at the zoo.
We have quite a selection of nasty things here in Arizona, but size is not generally the problem. Snakes, insects, even frogs.
Then there are Javelina - a form of Peccary. We saw some when we were driving around the day before our Arizona house hunt and called our sales agent to find out what they were. He explained, and indicated some folks - for some obscure reason - think they are cute and feed them. Javelina get very mad when they are not fed when they expect to be. None in our neighborhood, just an occasional Coyote.
One other example of human, well, not common sense. Some folks keep Capybara as pets - up to allowing them to sleep in their bed. That also does not necessarily go well. If you don't know what a Capybara is, I won't ruin it for you.