The atypical variations include a lead backed phase with a dark grey stripe, a silver back phase with a light grey dorsal stripe, hypomelanistic (leucistic) variations of the red backed form, and the rare white backed, or ghost phase.
The atypical variations include a lead-backed phase with a dark grey stripe, a silver-backed phase with a light grey dorsal stripe, leucistic (pale) variations of the red-backed form, and the rare white-backed, or ghost phase.