Taxonomic Notes
The Vipera ursinii species complex has a large distribution area from eastern France to western China, which was shaped by the last three glacial periods (Ferchaud et al. 2012). In the last two decades some V. ursinii subspecies have been elevated to distinct species level based on molecular and morphological analyses (V. renardi, V. anatolica, and V. eriwanensis). The Greek Meadow Viper (Vipera ursinii graeca) was described as a subspecies of Vipera ursinii by Nilson and Andrén (1988) based on morphological analyses. Ferchaud et al. (2012) proposed that V. u. graeca should be elevated to species level, according to the results of mitochondrial DNA phylogenetic analyses. Based on a mitochondrial and nuclear DNA analyses Mizsei et al. (2017) provided further support for this arrangement in an analysis of combined mitochondrial and nuclear DNA, recognising it as a full species Vipera graeca in order to resolve polyphyly in the Vipera ursinii–renardi complex.
Justification
Global and European regional assessment: Endangered (EN)
EU 27 regional assessment: Endangered (EN)
This European endemic viper has an area of occupancy (AOO) of around 252 km2, and has a severely fragmented population. The species lives only on mountain tops and its 17 subpopulations are completely isolated from each other by unsuitable habitat of deep valleys, forests and rivers. Habitat is continuing to decline in quality and area due to a complex suite of pressures, presently driven primarily by grazing but with the impacts of climate change projected to become increasingly important over the next few decades. Therefore, this species is assessed as Endangered (EN B2ab(iii)). The majority of this species' range lies within the EU27, and the species is consequently also listed as Endangered (B2ab(iii)) within the European Union.
Geographic Range Information
This species is endemic to the European region, where it occurs in the subalpine meadows of the Hellenides mountain system of southern Albania to central Greece (Dimitropoulos 1985, Nilson and Andrén 1988, Nilson and Andrén 2001, Korsós et al. 2008, Mizsei et al. 2016). The known localities include Avgo, Karava, Lakmos–Tzoumerka chain, Tymfi, Tymfristos, Vardoussia, and Voutsikaki mountains in Greece; Dhëmbel, Kulmak, Llofiz, Lunxhërisë, Griba, Ostrovicës, Shëndelli, Tomorr and Trebeshinë mountains in Albania; and the Albanian side of the cross-border mountain Nemerçkë (=Nemertzika in Greek). It occurs at high elevations in subalpine meadows above the tree line, usually between 1,600-2,000 m above sea level, but with an elevational range between 1,300 and 2,100 m asl (Speybroeck et al. 2016).
The entire distribution is severely fragmented and each mountain subpopulation is completely isolated by a large matrix of unsuitable habitat for the taxon consisting of deep, forested valleys and plains. The species is estimated to have an area of occupancy of around 252 km2 (Mizsei et al. 2021).
Population Information
Only 17 subpopulations are known, which are fully isolated from each other. The habitat area of the known subpopulations varies between 2–350 km2. The smallest subpopulation lives on Shëndelli Mountain in southern Albania, where only a small elevational range is suitable for the species. The sum of the available potential habitats is 620 km2 based on distribution modelling (Mizsei et al. 2016, Mizsei et al. 2021). The population is considered severely fragmented, as most of even the largest subpopulations are believed not to be viable in the long term in the face of current and projected pressures and there is no possibility that dispersal from surviving subpopulations will naturally rescue subpopulations or permit recolonisation following site losses. Additionally, the species' specialist microhabitat requirements suggest that even in large areas of contiguous habitat the population size is likely to be small, and potentially prone to genetic drift or inbreeding depression.
The observed mean density is 4.3 specimen /km2, however, this estimate is highly affected by the secretive behaviour and activity pattern of the species, and by levels of search effort, thus the available data are of limited use for accurately estimating the global population size. Currently, there are not enough monitoring data to assess the population trend for this species.
Habitat and Ecology Information
The Greek Meadow Viper lives at high elevations in subalpine meadows above the tree line, with scattered rocks and stone piles and often without shrubby vegetation (Mizsei et al. 2016). A mosaic of open and closed grass and shrub communities on karst characterise the main habitats of this snake species. It is associated with sites where grasshoppers and crickets are abundant (Mizsei et al. 2016). Annual mean temperatures are about 6 °C, and the meadows are partially covered by snow from winter (December) until early summer (May-June). South-facing slopes are generally inhabited as they are usually more open and rocky than north-facing slopes, and presumably allow better thermoregulation because of sun exposure and hibernacula. Different species of Festuca, Poa and Sesleria dominate the open grasslands, and characteristic shrubs are Savin Juniper (Juniperus sabina), Daphne oleoides and Astragalus creticus. Most observed vipers have been found close to shrubs or stone piles in south-facing habitat patches.
Its diet consists mainly of Orthoptera (97%) species, of which the Wing-buzzing Grasshopper (Stenobothrus rubicundulus), Platycleis spp., and the Wart-biter Cricket (Decticus verrucivorus) are the most frequent prey (Mizsei et al. 2019). The abundance of orthopterans is high from June to September. Known predators of the species are the Red Fox (Vulpes vulpes), Common Kestrel (Falco tinnunculus), and the Short-toed Eagle (Circaetus gallicus) (Mizsei et al. unp data). It has up to four offspring (Mizsei et al. unpub. data).
Threats Information
There is a continuing decline in habitat quality because these meadow habitats are exploited as sheep and goat pastures with variable levels of overgrazing (being especially pronounced at lower elevations but present throughout the snake's elevational range - Mizsei et al. 2021). In Greece, much of the pasture within the species' range is used for grazing cattle, which uproot vegetation and damage both topsoil and well as remaining vegetation (Mizsei et al. 2021). Grazing has a homogenising effect on the habitat and has been observed to remove fescue tussocks, reducing the availability of shade and shelter sites as well as the abundance of orthopteran prey (Mizsei et al. 2021). Conversely, abandonment of secondary grassland habitats at lower elevations can also result in habitat loss by reforestation. The species may already have been lost from lower elevations than its current known elevational limit, which are more suitable for grazing due to accessibility and the longer grazing season (Mizsei et al. 2021). These authors consider however that this is unlikely as most low-elevation grazing land was converted from forests and so would not have provided suitable natural habitat for the snake.
In two areas of suitable habitat in Greece there is skiing activity, where the habitat has been altered locally by the construction of ski resorts and roads to access these resorts. Two other mountains where the species is present have active quarrying operations, impacting the snake's habitat through both direct destruction and ongoing road development and traffic supporting the mines. New wind turbine development is impacting some subpopulations.
This is a cold-adapted high montane viper associated with the highest, coldest area in the region, and as such there are very few opportunities for upslope migration in response to a warming climate (Mizsei et al. 2021). Additionally, increasing aridification projected for the Mediterranean is a threat as high precipitation during the coldest quarter has been identified as an important component of habitat suitability for this species (Mizsei et al. 2021). Temperature rise may directly impact this species' thermal ecology, limiting its daily activity and so foraging time (Mizsei et al. 2021). Modelling based on both an "optimistic" (Special Reports on Emissions Scenarios scenario B1, projecting a temperature rise of 1.4-6.4 °C; Carter 2007) and "pessimistic" (scenario A1B, projecting a rise of 1.1-2.9 °C) between 2020-2089 projects that the species will lose 81-90% in the area of suitable habitat within its range, including both known sites and those that are currently suitable where no subpopulations have been found (Mizsei et al. 2021). No suitable habitat (with a mean annual temperature below 10 °C) is expected to remain in the southern Balkans by 2100 (Lelieveld et al. 2012).
The vipers are involved in human-wildlife conflict with local communities, as shepherds intentionally kill snakes to protect livestock. While it is among the least venomous vipers in Europe and likely to be of "no particular danger to humans" (Geniez 2018, Mizsei et al. 2016), an average of 1-4% of sheep suffer lethal bites every year.
Use and Trade Information
Trade in small vipers is common in Europe, but there is scarce information on illegal collecting. The Greek Meadow Viper Working Group is monitoring the most important reptile trade forums and social media, but there is no evidence of any current trade in this species.
Conservation Actions Information
Protected areas presently cover only 13.3% of the species known range in Albania, but more than 90% of its larger Greek range (Mizsei et al. 2021).
There are two in situ conservation projects conducted by the Greek Meadow Viper Working Group (GMVWG). The group has established good working relationships with the shepherds using suitable habitats for this species in Albania and has studied traditional grazing to find a way to reduce overgrazing. A large part of the first project involves distributing the educational poster “Snakes of Albania” in schools to raise biodiversity awareness, create a more snake-friendly environment among locals and provide information on conservation actions. Grazing pressure should be reduced in Albania, and Greek grazing practices should transition from cattle to less destructive sheep (Mizsei et al. 2021).
The second GMVWG project helps shepherds and local stakeholders to prevent snakebites, by informing them about areas where and when vipers are expected to be active, based on habitat preference and yearly/daily activity, to help them avoid encounters in space and time. We disseminate knowledge on how to recognise snakebites on sheep and goats early and the best steps to treat such bites with veterinary medicines and tools to reduce livestock mortality. The GMVWG has recommended that shepherds avoid grazing south-facing slopes where the species is most abundant, or where this is not possible to restrict grazing to hours when the snakes are inactive to avoid the risk of snakebite (Mizsei et al. 2021). Some of this work has been supported by the Mohamed bin Zayed Species Conservation Fund (project number 150510498 "Ethnoconservation of the Greek Meadow Viper and sustainable human use of alpine habitats in the Albanian Highlands").
Mizsei et al. (2021) used a spatial prioritisation method (based on developing an index of sites' conservation value from modelling of habitat suitability, information on known threats to each and their overlap with existing protected areas) to identify areas that would remain suitable for this species' persistence past 2080. The most important, each containing more than 10 km2 of contiguous habitat, were found to be Nemercke, Tymfi and Lakmos-Tzoumerka, in addition to several potential sites where the species has not yet been recorded despite surveys. Research is needed in the identified high-priority areas to clarify the ecology and population genetics of these subpopulations (Mizsei et al. 2021).
Conservation actions targeted at protecting this species will be most effective if they target the similar impacts of habitat alteration, degradation and loss, and the mapping of these threats by Mizsei et al. (2021) should be used to assist in managing these impacts. These should be supported by continuing efforts to educate local stakeholders and monitor the population (Mizsei et al. 2021). An ex situ breeding programme is recommended in order to provide a source of animals that can be used to rescue subpopulations as required (Mizsei et al. 2021).