Besides albinism, there are other factors that can cause animals to be unusually white or to have white fur, feathers or scales on all or a part of the body. Some biologists use the term “partial albinism”, others refer to this as “leucism”, but basically it is a result of a genetic anomaly that affects expression of the dark pigment called melanin. Both leucistic and albinistic individuals show up occasionally in squirrels and other wild animals, but they usually suffer from other health problems and/or are more easily spotted and eaten by predators. Read the article (link below) from the National Wildlife Federation for more interesting information on this phenomenon.