That's​ contrasted with this figure: > The Department of the Interior knows how many wolves and grizzly bears roam its wilds—can’t it keep track of visitors wh

That's​ contrasted with this figure: > The Department of the Interior knows how many wolves and grizzly bears roam its wilds—can’t it keep track of visitors who disappear? The problem is that the grizzly bears are tracked with stoichastic methods. You have 14% reported? Great if you're tracking bear populations - multiply the total tracked by 100/14, and there's​ your total! But for humans, you need to track 100% of them, which is a much harder problem.