This species is in need of a full taxonomic revision (W. Wüster pers. comm. 2022, Taxonomy Committee of the IUCN SSC Viper Specialist Group). The name Vipera transcaucasiana has been treated as either a full species or a subspecies. The latter is the arrangement currently best-supported by genetic data (Ursenbacher et al. 2008, Roussos 2015, Geniez 2018, Freitas et al. 2020) and the IUCN SSC Viper Specialist Group presently treats V. transcaucasiana as a subspecies of V. ammodytes.

There is "huge" genetic variability within Balkan populations of V. ammodytes (Ursenbacher et al. 2008, Čubrić et al. 2019) which does not correspond to recognized subspecies (Tomović, 2006). Populations in the Cyclades, Peloponnese, western Greece, and western parts of the Balkans may represent a distinct species (Roussos 2015, Speybroeck et al. 2016). Cattaneo (2021) described a new subspecies from the Vipera ammodytes ssp. buchholzi from the Greek central Cyclades islands of Paros, Antiparos and, perhaps, Strongylo.

European regional assessment: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

This species is assessed as Least Concern for Europe and for the EU27 Member States in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a threatened category.

In the European region, this species ranges from Romania (except the north), northeast Italy, Slovenia and southern Austria throughout the Balkans (Balkan parts of Croatia and Serbia, Bosnia and Herzegovina, Montenegro North Macedonia and Greece), to Turkish Thrace (Speybroeck et al. 2016). It has been recorded from Ammouliani Island, Chalkidiki (Strachinis 2022). It occurs on most islands in the Ionian Islands (except Zakynthos) and the Cyclades (other than the Milos Archiplago, western Cyclades, Thira archipelago, and peripheral islands), the Sporades (Skiathos, Skopelos, Alonissos and Adelfia), Evia, Salamina and Thasos (all in Greece) (Speybroeck et al. 2016). It does not occur on the islands of the Eastern Aegean or Crete. The species ranges from sea level up to 2,450 m asl. (on Mt. Stavroita adjacent to Mt. Olympus) (Tuleschkov 1959 in Heckes et al. 2005).

The species distribution ranges out of Europe to northern Asian Türkiye and the upper valley of the Kura River in southern Georgia (Geniez 2018, Baran et al. 2021).

It is very common in much of its range. Densities appear to vary widely across its range: from 5-24 individuals/ha in Romania (Ghira 2016) and 15-22 in northeast Italy (Luiselli 1996) to 23-34 /ha in Romania (M. Tudor in prep.) and approximately 30 individuals /ha on Golem Grand Island in North Macedonia (Tomović et al. 2022). More recent surveys in the South Tyrol area of Italy recorded densities as low as one to two per site (Plasinger et al. 2014). The mean estimated densities for five different sites in Western Bulgaria varied between 1-6 individuals /ha (95% C.I., max values 9-40 ind. /ha) (Dyugmedzhiev et al. 2020a).

Based on the index devised by Jelić et al. (2013) - which incorporated available data on exploitation, life history traits, habitat breadth and adaptability to modified habitats - this species was deemed at "no risk of decline" at present in a large part of the Balkans. In Slovenia, Krofel et al. (2009) found a 41% decline in the number of UTM cells with recorded occurrences since 1995. In the Dobrudja area of Romania and Bulgaria the species appears to occur in small, fragmented subpopulations limited to remnant habitat patches with "more or less strictly delimited" borders that prevent dispersal, which are generally bordered or intersected by roads (Tudor 2010).

This species is associated with stony areas from the sea cost up to alpine elevations, but generally favours areas with some vegetation (Speybroeck et al. 2016) and shrubland and forest habitats are of particular importance (A. Strugariu pers. comm. 2022). It can occur opportunistically in other habitats. It typically occurs in areas that are relatively drier than surrounding vegetation, including open woodland, scrub, sandy areas, hillsides, screes, stone walls, but also traditionally cultivated land, gardens and vineyards with some complex microstructure (Heckes et al. 2005). There are records from swampy areas, including umbrella pine forest near a lagoon in the Peloponnese (Bringsøe 2019), the reed belt along Lake Skadar and swamp forest on Ada Bojana Peninsula in Montenegro (Heckes et al. 2005). In the north of its range, it favours open, sunny areas, but can be found in a broader range of habitats further south, in some cases including cool, humid situations. Most subpopulations from Dobrudja (southeastern Romania) inhabit open Mediterranean shrublands both with and without rocky microhabitats, and are typically absent from the rockiest areas (A. Strugariu pers. comm. 2022). There are subpopulations in the Katerini area of the Greek coast that occur in completely non-rocky shrubland (J. Crnobrnja-Isailović pers. comm. 2022). Where it occurs in sympatry with other vipers in northwestern Slovenia the nose-horned viper tends to occur in greater proportion in rock piles, exhibiting niche partitioning with the asp viper (found in shrub and grassland areas between rock piles) and the adder (at higher elevations and on cooler, north-exposed slopes) (Mebert et al. 2015, 2017).

At least in Bulgaria it is active at temperatures above 15 °C, predominantly diurnally, but exhibits some crepusular or nocturnal activity (Dyugmedzhiev et al. 2020b, 2021). The species is viviparous; females give birth to 1-20 young (Beshkov 1977, Dushkov 1978, Luiselli and Zuffi 2002, Zadravec 2014, Šoltić 2017, Geniez 2018, Anđelković et al. 2021, Tomović et al. 2022). It may hibernate for as long as six months at high elevations (Speybroeck et al. 2016). It has a maximum age greater than 15 years (Jelić et al. 2013). The diet consists mainly of small rodents, lizards, birds (Anđelković et al. 2021), and a feeding attempt on a centipede has been recorded (Arsovski et al. 2014).

The species is or was locally impacted by overcollection in parts of its range (e.g., in Croatia, Serbia, Montenegro, Bulgaria - Tzankov et al. 2017 - Romania and isolated subpopulations in the Alps) by collection of animals for venom extraction. Collection for the illegal pet trade (and the legal trade in Balkan countries where the species lacks legal protection - A. Strugariu pers. comm. 2022) may also be a pressure on exploited subpopulations, and illegal collection for venom "milking" has been reported in North Macedonia (Sterijovski and Arsovski 2020). As with many snakes, this species is generally persecuted by people (e.g. Sterinovski and Arsovski 2020, Čubrić and Crnobrnja-Isailović 2022).

In the Dobrudja area of Romania and Bulgaria the species appears to occur as a small, fragmented subpopulation limited to remnant habitat patches with "more or less strictly delimited" borders that prevent dispersal, and are generally bordered or intersected by roads (Tudor 2010); in surveys between 1995 and 2008 this researcher recorded the species in only 65.8% of 38 historically known localities in Dobrudja, although the species remained common in areas with little human presence. Should relatively intact areas of Bulgaria become subject to development, road expansion or mass tourism the species could be locally impacted (Tudor 2010). An increase in the number of monasteries and hermitages in this area has increased local encounter rates between humans and snakes, and consequently the direct killing of the latter (Tudor 2010). Habitat loss has also been identified as a threat to the South Tyrol (Italy) subpopulation, including forest expansion and rock extraction for commercial and industrial use (Plasinger et al. 2014). The snake's distribution in Turkish Thrace includes the regions where human population density and industrial development are dense (A. Avci pers. comm. 2022).

Jelić et al. (2012) recorded that in some Adriatic islands the viper had become exceptionally rare or extinct, due to the predatory activity of the introduced Small Indian Mongoose. This species was first introduced to the island of Mljet in 1910, and has since spread to other islands and recently to the mainland (Southern Croatia, Bosnia and Herzegovina and Montenegro). The viper is considered extinct in Mljet island, and very rare in Korčula (Jelić et al. 2013). The isolated but dense population on island Golem Grad (North Macedonia) is not subject to any current threat, but the tiny surface area of the island (20 ha) make this population very prone to stochastic events that could easily render it critically endangered or even extinct in a short time period (Sterijovski and Arsovski 2020).

This species is of great medical importance in Europe (Crnobrnja-Isailović et al. 2020), so there is some wild collection of this species for venom extraction. Farms have been established for this purpose (Tudor et al. 2015), but collection from the wild is ongoing (Sterijovski and Arsovski 2020). The species is legally traded commercially as a pet in parts of the Balkans, including trade in captive-bred individuals (A. Strugariu pers. comm. 2022).

This species is listed on Annex II of the Bern Convention, on Annex IV of the European Union Habitat and Species Directive and is protected by national legislation in parts of its range. It is present in many protected areas. It is listed as nationally Critically Endangered in Austria (Gollmann 2007). The subspecies Vipera ammodytes montandoni is regarded as Critically Endangered in the Vertebrates Red List of Romania, and V. a. ammodytes as Endangered (Botnariuc and Tatole 2005). In Slovenia it is listed as Vulnerable (Anonymous 2010) and in Albania as Near Threatened (Anonymous 2013). It is present in many protected areas. Overcollection in this species is largely a consequence of a lack of coordination between serum producers in different states, and a lack of adequate export controls in Montenegro (where the species is not legally protected - Gvozdenović and Iković 2022) and Bosnia and Herzegovina, and further regulation is needed to limit exploitation (Ajtić 2009). It is not protected in Türkiye (A. Avci pers. comm. 2022).

There is a need for further taxonomic studies (Freitas et al. 2021). Protection of distinct genetic lineages - such as one found in Montenegro which is not presently protected (Gvozdenović and Iković 2022) - may be warranted to preserve overall genetic diversity (Jelić et al. 2013). Subpopulations in Turkish Thrace should have their risk of extinction evaluated (A. Avci pers. comm. October 2022).