>When the grey squirrel arrives in a red squirrel area, the red squirrel population usually disappears within 15 years. The grey squirrel outcompetes the red for food, space and carries a disease, called the squirrel pox virus. This disease kills the red squirrel but has no known lasting effect on the greys. In circumstances where the presence of squirrel pox is confirmed, the extinction rate of red squirrels can be 20 to 25 times faster than that in pox free areas.
grey squirrels are physically and biologically superior and their replacement of red squirrels is completely natural