Skin structure, coloration, and habitat utilization in typical and melanistic morphs of the grass snake (Natrix natrix)

Melanism in the grass snake Natrix natrix (Linnaeus, 1758) from the Danube Delta Biosphere Reserve, Romania

“…We have encountered all three melanistic morph categories, as defined after Zuffi (2008), and as much as we could identify them, they have been previously reported in N. natrix across its range (Fuhn and Vancea 1961;Naumov and Tomović 2005;Zamfirescu et al 2010;Zadravec and Lauš 2011;Mollov 2012;Gvozdenović and Schweiger 2014;Habiboğlu et al 2016;Kolenda et al 2017;Bjelica and Anđelković 2021;Yenmiș et al 2022). Both the present study and recorded cases in literature of melanistic grass snakes rely on visual encounter surveys.…”

“…We still have a limited understanding of the distribution and frequency of the melanistic morph in N. natrix populations throughout its range. Reports of melanistic individuals of grass snakes have been made from Turkey (Baran 1976;Habiboğlu et al 2016;Yenmiș et al 2022), Bulgaria (Naumov and Tomović 2005;Stojanov et al 2011;Mollov 2012), Serbia (Bjelica and Anđelković 2021), Croatia (Zadravec and Lauš 2011), Montenegro (Gvozdenović and Schweiger 2014), Bosnia and Herzegovina (Bašić and Zimić 2016), Slovakia (Jandzik 2004), Poland (Błażuk 2007;Kolenda et al 2017;Bury et al 2020). In Romania, there are only three general literature mentions of melanistic N. natrix, all of them from the Danube Delta Biosphere Reserve (DDBR) (Fuhn and Vancea 1961;Halpern et al 2002;Zamfirescu et al 2010).…”

Will climate change affect the proportion of melanistic northern vipers Vipera berus in a western European population with an exceptionally high rate of melanism?

“…The large numbers of melanistic vipers we observed were most often found not far from water (70%) and in dense, cool forest areas (30%). According to Yenmis et al (2022), melanistic populations of Natrix natrix in Anatolia were living three times closer to water than those with typical colouration and they frequently used areas with numerous insulating rock shelters at the water's edge, which allowed them to cool down more quickly during the hottest periods of the year. The hypothesis that melanistic reptile populations need moister conditions apparently also applies to those living in the tropics (Ineich et al, 2009).…”