Updated distribution and species composition of the amphibians and reptiles along the Lower Danube, Bulgaria

Abstract

In a recently published paper (Popgeorgiev et al. 2019), we compiled for the first time published and unpublished data on localities of the herpetofaunal species observed up to ca. 10 km south of the Bulgarian Danube River. Overall, we identified 687 published records belonging to 62 cells of the 10×10 km MGRS grid. Another 1918 records with real coordinates of our unpublished data from the past ca. 13 years belong to 1269 cells of the 1×1 MGRS grid. As a result, 34 native species – 15 amphibians (4 salamanders and 11 frogs) and 19 reptiles (1 turtle, 2 tortoises, 8 lizards and 8 snakes), and one invasive turtle, have been recorded; further species findings are unlikely. This study further identifies areas that are under-sampled and species such as Pelophylax lessonae that are cryptic. Our data are especially relevant concerning the high economic incentives to change the hydrology of the Danube, which will likely negatively impact the biodiversity along the river and its surrounding.

Distribution of the grass snake (Natrix natrix) and dice snake (N. tessellata) in Bulgaria

“…This is further reinforced when considering that the herpetofaunal data in SmartBirds.org for the area is lacking for a number of common species expected to be found there. Additionally, here we update the known distribution for both species from the vicinity of the Danube River, updating the recent mapping effort along the river (Popgeorgiev et al, 2019). The geographic scope of the previous publication was limited to 10 km from the Danube, and most of the data were from projects targeted at a few protected areas and focusing on the river itself.…”

“…The two study species are among the most common, abundant and widespread ophidian species in Bulgaria (eastern Balkans) (Stojanov et al, 2011). Some notable publications on their distribution include one of the first national mapping efforts by Buresch & Zonkow (1934), and biodiversity assessments of more limited territories, e.g., Eastern and Western Rhodopes (Petrov et al, 2001(Petrov et al, , 2006, Natura 2000 protected areas "Ponor" and "Besaparski Ridove" (Popgeorgiev et al, 2010(Popgeorgiev et al, , 2014a(Popgeorgiev et al, , 2014b and "Oranovski Prolom-Leshko" (Malakova et al, 2018), Vitosha Mountains (Tzankov et al, 2014), Vratchanska Planina Mountains (Naumov et al, 2016), and the Bulgarian part of the Lower Danube River (Popgeorgiev et al, 2019). Multiple other publications provide limited reports.…”