I believe they are the same species. My guess is the offspring will be fertile. Especially if this is not an interspecies pairing but just color morphs of the same genus.
As far as the babies go, if my Mendelian genetics is up to par, the babies will be het for black. So most, if not all will be normal color but carry the black gene. If paired together or with the parents, the babies should produce normals and blacks.