Variation in the coloration of the light elements in the occipital region of grass snakes based on iNaturalist records. Densely documented western part enlarged in bottom map. Small inset map (top) shows subspecies distribution according to Asztalos et al. (2021a): Natrix natrix natrix – yellow, N. n. vulgaris – red, N. n. moreotica – grey, N. n. scutata – green. Hybrid zones hatched. Note that pale orange and orange coloration is largely restricted to two regions: the northeast (range of N. n. scutata) and the southwest (range of N. n. vulgaris, where coloration is mostly less intense). When the crescents or collars fade completely in aged snakes, pale grey or body-like coloration types occur (range of N. n. moreotica and hybrid zones of N. natrix and N. helvetica).

  Part of: Fritz U, Ihlow F (2022) Citizen Science, taxonomy and grass snakes: iNaturalist helps to clarify variation of coloration and pattern in Natrix natrix subspecies. Vertebrate Zoology 72: 533-549.