BBM-Mother nature and scavengers can make whole humans disappear. Squirrels and other rodents will gnaw at bones, coyotes will drag them off to chew on later, same with bears, cougars, wolves, etc. Buzzards and such will pick at whatever they can get to. Mother nature will eventually cover what, if anything, is left. I'd say in an area with a high population of scavengers/predators, it wouldn't take more than a day or two to completely disappear a small child. You could probably still find bones scattered around for a while, but they'd be hard to find and most human bones, especially individually, would be hard to differentiate from animal bones to most people.