Actually, to really confuse the issue, any lack of dermal pigment, partial or entire, is called leucism. Piebald is an archaic term (such as the term "buzzard" when we really mean "vulture"). I believe the correct term for piebaldism is partial leucism. And, yes, these pied BPs are actually pied--or partially leucistic--whatever you want to call them. The condition is genetic, as Pete Kahl has proven, and the term used to describe animals that have stark white patches on their skin is "piebald" or "partially leucistic."