The herd of deer at Seneca Army Depot in the Finger Lakes of New York State has been fenced in since 1941, long enough that the inbreeding between the deer has allowed the white gene to be expressed more often than one seems to see in the wild. Hunting deer by the soldiers at the Depot was encouraged to keep the white deer alive and to take only the brown. This, of course, led to more white deer in the population. Now poor Seneca County is in charge of this land and has to make decisions about how to use it for its best economic gain. Currently, it conducts tours of the deer on certain weekends. See more here.
Funny how unnatural human actions—fencing in land for military installations, culling a herd—create changes in nature itself that are then considered to be natural. Only humans.