European Souslik
The European souslik Spermophilus citellus is endemic to Europe. Its populations became increasingly fragmented and are facing serious declines across most of its range throughout last decades.
The European souslik is endemic to Europe. It is undoubtedly an important natural element of the steppic grassland ecosystem. In the short grass steppe habitat the species represents one of the main prey for several top predators listed in Annex I of the Birds Directive, such as the Imperial Eagle Aquila heliaca, Lesser Spotted Eagle Aquila pomarina, Saker Falcon Falco cherrug etc. and also other species such as the Steppe Polecat Mustela eversmanii or Marbled Polecat Vormela peregusna. In some habitats it might be also an important consumer of primary production able to limit spreading of some plant species, including invasive plants, such as the Silver-leaved Nightshade Solanum elaeagnifolium. In some countries the European souslik can serve as an umbrella species for extensively used grassland habitats and associated species.
European Souslik, © Dimitar Gradinarov
DESCRIPTION OF THE SPECIES
The European souslik Spermophilus citellus is a ground dwelling (living in burrows) rodent resembling the squirrel but with the tail far shorter and thinner and the body colour of mottled ochre-yellow. The body length of full grown wild animal is about 18 -24 cm (GRULICH 1960, RUŽIĆ1978) and the weight of adults ishighly variable, being lowest after the hibernation and highest in the late summer– 145 to 520g (MAT ĚJŮ 2008), 150 to > 400g (MILLESI et al. 1999). Males are significantly heavier than females (MILLESI et al. 1999, MATĚJŮ 2008).
STATUS
According to the 2008 IUCN Red List vers. 3.1, the species is considered Vulnerable, with a decreasing population trend. In 2007 reporting to the Habitats Directive 92/43/EC the species has been evaluated in unfavourable bad status for Alpine and Continental biogeographical regions and in Unfavourable inadequate status for Mediterranean and Pannonic regions. International group of experts on research and conser vation of S. Citellus declared in 2006 that the species is threatened over most of its range.
THE BIOLOGY
The European souslik forms colonies of various sizes. It is a mammal with diurnal activity and an obligatory (true) hibernant. According to GRULICH (l. c.) and RUŽIĆ (1978), the maximum life span of the S. Citellus is 3 to 5 years. Plants represent at least 80% of the diet of the spacies and it includes leafs, shoots, flowers, fruits and stems of various grasses and herbs.
European souslik, © Svetoslav Spasov
DISTRIBUTION
The European souslik is distributed throughout central and south-eastern Europe, where it occurs approximately south of 50° northern latitude. The current species range is divided in two by the Carpathian Mountains. The north-western part extends through Poland, the Czech Republic, Slovakia, Austria, Hungary, northern Serbia and western Romania, whilst the south-eastern part extends from eastern Serbia, Macedonia and northern Greece through Bulgaria, southern and western Romania to European Turkey, Moldova and Ukraine.
KOSHEV (2008) established that the percentage of extinct colonies was highest in the Sofia field (58%) and in mountain region (32%). There are also extinct S. citellus colonies around south-western corner of Bulgaria. The study of STEFANOV et MARKOVA (2009) established that after 1985 the species has been found only on 15 localities in Sofia valley (38.5% of the total number of territories confirmed for the region). KOSHEV (2009) carried out assessment of distribution of the species in Trakia valley and he found out that 18% of all known colonies perish.
THREATS
The major part of critical threats to European souslik is linked to agriculture – the most important factor shaping the current habitats of S. citellus. The critical threats are connected either to lack of grassland management – such as low (insufficient) intensity of grazing or mowing, or a total absence of those – i.e. land abandonment.
Also inappropriate practices such as monoculture / absence of crop rotation, over - fertilisation (e.g. using of muck), use of chemicals, but also change in agriculture practices including agriculture intensification and conversion of grasslands to arable land or their afforestation are mentioned among critical or very important threats across member states concerned.
Second group of critical threats also has an impact on habitat availability for S.citellus. Urbanisation, residential and commercial development as well as traffic development (with subsequent problems such as the barrier effect, mortality due to collision with vehicles, pollution etc.) are causing fragmentation and degradation of habitat for S. citellus, reduced habitat connectivity, reduced dispersal, reduced genetic exchange and reduced fecundity / genetic depression.
At the very end coincidence of these factors leads to extinction of local European souslik populations. Other critical and very important threats which usually concern only some of the range countries include flooding/inappropriate water regime, fire, increased predation (also by domestic animals), diseases and parasites, trapping, poisoning and poaching, but also missing or wrongly directed conservation measures. Special emphasis should be put on the agri-environment schemes (AES) for grasslands, which in some countries are not flexible enough. For instance if the payments in AES require late mowing of grasslands due to focus on some bird species, this can harm some species which need short grass throughout the vegetation season (end of May and June) – like European souslik.
