Not sure about in North America, but at least in Europe, they are rather common, held in over 40 zoos across the continent. The problem is that their nocturnal nature (and the fact that, being a native species, displaying them in a natural, outdoor setting makes more sense than putting them in a nocturnal house) I have never seen one. I've looked for them both in captivity and in the wild several times in several countries, but never seen them once, sadly.
