It makes total sense, really, but of course for island countries like mine, it's a lot easier, and there's usually more reason, like the fact that so much of what's here isn't found anywhere else. We have so few mammals (other than introduced) that insects and birds filled their niches, so if you introduce any new new mammals, they're a threat to the native animals because they eat the same things or whatever, so it makes total sense. And then there's the agriculture that is a huge part of our economy, so they don't want anything to upset what little balance there is with that, either. Which is why even bringing fruit, vegetables, bark, wood products, animal products in when you fly HAS to be declared (and/or biffed), as so much of it is not allowed. Eat that apple on the plane, peeps, don't bring it in here — an instant $400 fine if you're caught (and you will be; we have sniffer dogs for this at the airport!)