Well, my grasp of their situation is that on islands, their habitat is limited in extent, and this renders populations less robust. As development has proceeded, that habitat has been destroyed, and fractured, leaving those relic populations far more vulnerable. At the same time, farmer's resistance to the depredations of pigs on their crops has further put pressure on the species.

On a continent, such as N. America, there is little limit on the available habitat to an omnivore like pigs, and the feral domestic hogs that have become problematic are not facing the same pressures island pigs face. Neither is that species already limited in number, as island pigs are. Domestic pigs are on every continent but Antarctica today. It is practically inconceivable that feral hogs could be endangered as island species' are.