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 are distinct from the typical pattern, including a lead-backed phase with a dark grey stripe, a silver-backed phase with a light grey dorsal stripe, pale versions of the red-backed form (leucistic), and the rare white-backed, or ghost phase.