LIVING ON THE EDGE: DISTRIBUTION PATTERNS OF STEPPE MAMMALS IN TRANSCARPATHIA (UKRAINE)

© 2018 Z. Barkaszi et al.; Published by the Ivan Franko National University of Lviv on behalf of Біологічні Cтудії / Studia Biologica. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://www.budapestopenaccessinitiative.org/ and Creative Commons Attribution 4.0 License), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. UDC 599.32:591.9(477.87)

We analysed the composition of the steppe assemblage in the mammal fauna of Transcarpathia (Ukraine), which is represented by three rodent species such as the European ground squirrel Spermophilus citellus, the common hamster Cricetus cricetus, and the steppe mouse Mus spicilegus. These species have not been considered in the composition of the local fauna or they were mentioned only in general checklists, or even with obvious mistakes in descriptions of both key characters and record localities. Here we present detailed descriptions of distribution of each steppe species based on actual record localities as well as ecological and biogeographic features. In total, we have generalized data on 13 record localities of Spermophilus citellus, 7 of Cricetus cricetus, and 8 of Mus spicilegus. We also revealed and described general trends in the distribution of these species: all of them occur in the lowland part of Transcarpathia between the valleys of the Tisza and Latorica rivers and adjacent areas. Generally, steppe species in Transcarpathia are related to anthropogenically transformed biotopes: the European ground squirrel mainly occurs along banks of dammed rivers in zones of floods, while the common hamster and the steppe mouse are both related to agricultural lands. The absence of natural populations in indigenous biotopes and, in fact, the absence of typical key steppe habitats suggest that steppe species appeared in Trans carpathia as the result of expansion from their main geographic range as suitable habitats gradually appeared at the range periphery. The closest centre of distribution of each species is located beyond the studied region, namely in the Great Hungarian Plain, and the records described here are marginal: they are instable and attributed to the zones of range pulsation, which depends on climatic factors and current landscape features of the lowland part of Transcarpathia. The state and dynamics of rangeedge populations of steppe species in Transcarpathia might be largely affected by the hydrological regi me,

INTRODUCTION
Species diversity is largely influenced by landscape heterogeneity, in each type of which historically unique zonal and local communities emerge. The relatively high diversity of landscapes and ecological communities is particularly common for mountainous regions and adjacent territories, which is due to several ecological factors including geographical and altitudinal zonation, high density of watercourses, ecotone effects, artificially transformed biotopes, etc. (e.g., [39,51]).
The Carpathian Mountains and adjacent regions are located at the junction of forest, forest steppe, and steppe belts of Europe. In a biogeographic context, the Carpathian Basin draws a special interest since it is the westernmost fragment of the Great Eurasian Steppe. Steppe communities that exist here are relatively isolated and they are surrounded by mountain systems having a connection with the East European steppe only through the northern Balkans [30]. Through this relatively narrow contact zone elements of the steppe fauna could enter the Carpathian Basin and disperse further north, inclu ding the territory of Transcarpathia (i.e. Zakarpattia Oblast), which is the most remote northern part of the Great Hungarian Plain (Fig. 1). Such remoteness of Transcarpathia from the steppe faunal core and the immediate proximity of mountain assemblages are the main factors drawing interest to the analysis of the species composition of lowland communities, particularly to the presence and distribution patterns of steppe species represented by range-edge populations in the region. The distribution of steppe species in plains is usually determined by the arrangement of not only the steppe biome's borders itself, but also of river valleys [17,25]. Research on steppe faunal assemblages allowed formulating the concept of "steppe faunal core" (SFC), which in Eastern Europe includes more than 30 mammalian species distributed mainly within the steppe belt but some of them also entering the forest steppe [56]. The SFC naturally decreases westward by the number of species, especially at such important biogeographic barriers as large river valleys, which generally cut the steppe belt from north to south into several "fragments". Earlier, it was shown that the East European SFC consists of 28 mammalian species to the west from the Volga, 16 from the Don, 12 from the Dnipro (Dnieper), 10 from the Southern Bug, and only 7 from the Danube [56].
The Transcarpathian fauna in the context of presence and distribution of steppe species has not been analysed before due to several reasons. Firstly, the region is largely isolated from the steppe belt (both from the Northern Black Sea Region and the Balkans), and, secondly, steppe species are usually not considered in its fauna's composition. Besides, the lack of attention to the steppe elements in the region is caused not only by high rarity of these animals but also because more diverse mountain communities have drawn much more research interest. Therefore, steppe species in the fauna of Transcarpathia were either not considered at all or indicated ambiguously [3,46,47,50,52].
The aim of our research was to analyse the complete available dataset on the exact record localities, geographical distribution, and biotope selection of steppe mammal species in the Transcarpathian fauna, to describe species ranges and current state of population, as well as to analyse changes in the composition and distribution of steppe species in the region.

MATERIAL AND METHODS
Data for analysis of the Transcarpathian steppe mammal assemblage were collected from several sources. Firstly, all available museum collections were examined, including the mammal collection of the National Museum of Natural History, NAS of Ukraine, Kyiv (NMNHU), State Natural History Museum, NAS of Ukraine, Lviv (SNHM) and three zoological museums functioning at Ukrainian national universities in Kyiv (ZMKU), Lviv (ZMLVU), and Uzhhorod (UZZM). A significant part of data was collected by critical analysis of literature sources, inter viewing of local zoologists and interested people (i.e. teachers, gamekeepers, hunters), as well as during field expeditions in 2004-2018 to the places of supposed occurrence of steppe species with suitable biotopes. In total, ca. 40 positive interviews of colleagues and residents were conducted.
A database was created that includes all records and record localities of steppe mammal species, which was applied to construct maps of distribution by QGIS software using layers of own creation, Google map data and public domain maps (Natural Earth).
The taxonomy and nomenclature used in this paper follows the scheme proposed earlier for the mammal fauna of Ukraine [60].

RESULTS AND DISCUSSION
In subsequent sections, we present the composition of steppe faunal assemblage in Transcarpathia. Each species is described according to a common scheme: 1) gene ral information, 2) signs of presence and field diagnostics, and 3) former and current records.

Composition of the steppe faunal assemblage in Transcarpathia
According to the latest surveys of the mammalian fauna of the Ukrainian Eastern Carpathians [2,3,63] and other publications [22,45], the presence of 10 typical steppe species of mammals could be expected in Transcarpathia: Data collected during recent years clearly suggest the presence of only three of the 10 possible steppe species, namely of the European ground squirrel (Spermophilus citellus), common hamster (Cricetus cricetus), and steppe mouse (Mus spicilegus), representing three families, Sciuridae, Cricetidae, and Muridae. It is not by chance since at range edges and under unfavourable conditions the fauna is represented exclusively by species of different genera or even families, described as the "principle of monotypization of higher taxa" [62].
The occurrence of the European ground squirrel in fauna of Transcarpathia was first described with record details by Reshetnyk [42]. Later, the species was mentioned without details in different general fauna surveys (the latest by Bashta and Potish [3]), and its range was recently reconstructed with information on then known records [64]. The common hamster was usually listed for the local fauna either based on ambiguous records and without description and mapping of distribution [3,43] or it was not mentioned at all [31,34]. The first report on records of M. spicilegus appeared in 2007 [3], although accompanied by slightly ambiguous descriptions, which allows suggesting that the species might have remained undiscovered in the region until recently. The idea of the absence of the steppe mouse in the fauna of Transcarpathia was supported earlier by the results of analysis of old mice samples [29].
The presence of the steppe polecat (M. eversmanii) suggested earlier in the Trans carpathian fauna (e.g., [52,55]) is questionable. Firstly, current records of the species are unknown and museum specimens from Transcarpathia in zoological collections of Ukraine are absent too [13]. Secondly, analysis of literature sources revealed that localities of the species' records presented in fauna surveys (e.g., [3,52,55,63]) originated from Abelentsev [1], who, however, also had no actual materials and presented records referring to two older sources. In one publication cited by Abelentsev, there is no information on the steppe polecat in Transcarpathia at all [12], while searches for the other source (Konyukhovich, 1953 as cited in [1]), were unsuccessful. However, we suggest that all records of the polecat in Transcarpathia originate only from the latter source. Currently, there is no evidence that the steppe polecat is present in fauna of Transcarpathia.
The European ground squirrel, Spermophilus citellus (Linnaeus, 1766) General information. The European ground squirrel in one of the least studied rodents in the Ukrainian fauna. The species is distributed in Central and Southern Europe, including the countries of the European Union neighbouring with Ukraine [24; 40]. The ground squirrel reaches the territory of Ukraine by three range fragments including the Transcarpathian one [61]. The occurrence of the species in Transcarpathia had been debated for a long time (e.g., [50,46,47]), although it was strongly suggested [41].
According to old sources, the European ground squirrel was a common species in the Tisza river's valley in the late 19th century [35]. However, it was "first" discovered in Transcarpathia only in 1964 near Chop [42], where the species occupied old dams along the Tisza and Latorica rivers and had an abundance of ca. 25-30 specimens per hectare. Later, the European ground squirrel was mentioned only formally referring to Reshetnyk's works (e.g., in [3,21]). The first revision of the species' distribution in the region was carried out in 2010 with our participation [64], which is here complemented by recently obtained data.
Signs of presence and field diagnostics. If present, the species is easily noticeable and well known to locals, especially herders and hunters. Interviewing of locals usually gives positive results: they easily recognise and describe the species by its typical stance (and sometimes its voice too) and characteristic vertical burrows.
Records. We found 24 specimens from 4 localities in museum collections ( Table 1). All specimens were collected in 1964 and 1966 and they are deposited in the mammal collection of NMNHU. In total, we have knowledge about 13 record localities of the European ground squirrel, the majority of which were reported by our zoologist colleagues from the Uzhhorod National University. Practically all record localities were reported from lowlands of southwest Transcarpathia, the area located along the state border. Field research conducted in 2004-2006 and 2014-2018 between Uzhhorod and Chop, Chop and Berehovo, and Berehovo and Khust were unsuccessful further suggesting the high rarity of the species. Published data are extremely scarce: Reshetnyk [42] recorded the species in the vicinities of Chop. Later, in the survey of the mammal fauna of Transcarpathia, another record from "Selmentsi," Uzhhorod Region was reported [3].
The common hamster, Cricetus cricetus (Linnaeus, 1758) General information. The common hamster is a rare steppe mammal species that has been shown to display a clear tendency of population decline and range contraction during recent decades in Ukraine [31,43,57] as well as generally in Europe [26,38,49,54]. In the region of the Ukrainian Carpathians, the species' distribution is restricted to piedmont and adjacent lowland areas of Ciscarpathia (i.e. Prykarpattia) and Bukovina [43].
Regarding Transcarpathia, the status and distribution of the common hamster have been generally debated. For instance, Turyanin [52,53] described the species for "lowland forest steppe areas of all Ciscarpathian regions" (p. 103), but did not mention even a single record of the species for Transcarpathia. The common hamster is not listed either for Transcarpathia in the latest surveys of the Ukrainian mammal fauna [34,57]. Some information, although, again, without any specific description or cartographic data, is given in the latest survey of the mammal fauna of Transcarpathia [3]. The authors of this survey stated that the common hamster occurs in various secondary biotopes along the Tisza and Latorica rivers. However, on the added map, they indicated that the species is distributed in the entire lowland part of Transcarpathia despite their statement that the hamster is extremely rare in the region. On the other hand, according to the Red Data Book of Ukraine (RDBU), the common hamster is absent in Transcarpathia at all [31]. * Знахідки, вказані у нашому попередньому огляді [64] Reliable records of the species in the region have not been published, which also indicates the lack of data and insufficient research into the hamster's distribution in the region. However, during recent years we have received more and more reports on records of the species and even its relatively high abundance in some locations. The increase of abundance is probably due to a population outbreak, which occurs periodically in this species [14,37]. Such population growth was observed in 2012-2016 with a subsequent decline in Uzhhorod Region (V. Chumak, personal communication).
Signs of presence and field diagnostics. Since the common hamster occurs mainly in agricultural lands and behaves quite aggressively, its presence is well known to locals. Sightings of hamsters and cases of trappings were reported from several sources ( Table 2). Curiously, in some Ukrainian speaking villages of Mukachevo Region, the local name of the hamster is "hyrchyk" (Ukr.: «гирчик»), which is practically the ukrainized reproduction of the species' Hungarian common name "hörcsög." This may indicate the longtime presence of the hamster in such villages, at least since the 19th century, when the region was a part of Hungary.
In addition to reports received from colleagues and locals, we also conducted field research in order to find hamsters in locations beyond the reported ones, but without positive results. Museum specimens of the common hamster from Transcarpathia are deposited mainly in the mammal collection of NMNHU, most of which were collected in the 1940s and 1960s.
Records. The list of records includes museum specimens and records reported by zoologist colleagues and local residents ( Table 2). In total, we have information on 7 record localities of the species.
The steppe mouse, Mus spicilegus Petényi, 1882 General information. The steppe mouse is a common species in the fauna of the Carpathian Basin, including the countries neighbouring with Transcarpathia such as Slovakia [8,9,23], Hungary [5] and Romania [4]. For Transcarpathia, the steppe mouse was first mentioned in 1934 from the floodplain of the Borzhava river, namely from vicinities of Velyki Komiaty, Vynohradiv Region [48]. However, further revision of specimens revealed that they belong to M. musculus [29]. The steppe mouse was not mentioned at all in publications of the second half of the 20th century until the latest review of the mammal fauna of Transcarpathia [3]. Although, it can be also related to the fact that the species status of the steppe mouse was accepted in Ukraine only in 1989 [33], shortly after it took place in Europe [6].
However, the description of the steppe mouse in the abovementioned fauna review [3: 156] contains several contradictive statements, including 1) the necessity of discrimination of M. spicilegus from Apodemus agrarius, 2) the uncommonly large size of mounds described (4 m in diameter and 0.8 m in height), and 3) the construction of mounds from grass and remains of plants mixed up with soil. In practice, the issue is to discriminate the steppe mouse from M. musculus, the size of mounds is far smaller and their structure also differs from that described in the mentioned source. Therefore, the authors of the review might describe some crop residues left in the fields by farmers instead of mounds built by the steppe mouse.
Signs of presence and field diagnostics. In the field, there are two reliable signs of the species' presence: firstly, the specific mounds built by the animal, and secondly, if the animal was captured, the absence of musky scent which is a very specific feature of its sibling species, the house mouse, M. musculus. According to our data, mounds of the steppe mouse in Transcarpathia (Fig. 2-3) do not differ substantially from those studied in other regions of Ukraine (we have examined hundreds of them). Usually, they are located on fallows, ruderal lands, field edges, and harvested crop fields (sunflower, corn, and wheat). Small ("young") mounds have conical shape, they are 20-70 cm in diameter and 25-35 cm in height, while "older" and wellconstructed mounds (especially secondyear ones) are elongated, 100-160 cm in length and up to 40 cm in height. Mounds represent, basically, plant materials collected by the animals and covered by a ca. 5-7 cm thick layer of ground. Around the mound, several (usually 10-15) pits can be found from which the mice dug out the soil. The inner structure of the examined mounds in Transcarpathia is usually represents three well distinguished layers: closest to the ground and in the centre of the mound we found ears of grasses, mainly of Setaria viridis, covered by a relatively thick layer of haylike plant material, while the outer layer represents a ca. 5-7 cm thick cover of ground. Stocks of grains, achene, beans, siliques, follicles, etc. were not revealed, which allows suggesting that mounds serve rather for isolation (thermo-and hydro-) than food stores for winter.
Records of the steppe mouse in Transcarpathia have yet been reported only based on the species' specific mounds, and attempts of trapping animals have been unsuccessful. Currently, there are data about records of mounds from 8 localities (Table 3).

Distribution and changes in abundance of the studied species
Analysis of all available data, often highly scarce due to the rarity of the studied species, allows reconstructing the distribution range of steppe species in Transcarpathia. In particular, data show that the range of the European ground squirrel has two segments in the region covering biotopes along the state border (Fig. 4), which are practically the continuation of the species' main range located in the Great Hungarian Plain [10,18]. The European ground squirrel is represented in the region by a very scarce population, which is concentrated in the northwest part of the Transcarpathian lowland (Uzhhorod Region). The species' distribution is related almost exclusively to anthropogenically transformed biotopes, mainly used as pastures. The vast majority of records is from the zones of former floodplains that were already dammed by the time of the species' first records (in 1964). Earlier, it was suggested that damming of floodplains could be playing a major role in either preservation of ground squirrel population or, basically, its emergence in the result of dispersal from neighbouring regions of Slovakia and Hungary [64]. The current population decline and range contraction of S. citellus in Transcarpathia, which has been observed during recent decades, in our opinion, might be rela ted to the decrease in livestock abundance leading to the contraction of the area of pastures and to their successional overgrowth.
Unlike the European ground squirrel, the common hamster has demonstrated a gradual increase in abundance and range, which could be related to the growing area of agricultural lands in the region. According to our database, the common hamster, similarly to the ground squirrel, has a mosaic distribution in Transcarpathia existing in a number of local settlements. Most of the records are known from the lowland parts of Uzhhorod and Mukachevo Regions, particularly from the area between the valleys of the Uzh and Latorica rivers. The other, smaller range segment is located between the valleys of the Tisza and Borzhava rivers in the south of the Transcarpathian lowland (Fig. 5). The two range segments are certainly isolated, particularly by the area of the former Szernye Mochar (i.e. Chornyi Mochar), a grand wetland complex, which currently, however, is substantially drained.
Available data show the contraction of the southern (B) range segment, while in the western segment (A) the abundance of hamsters has increased in the past 10-12 years.
In particular, we have data on frequent sightings of hamsters by locals near their estates, as well as on catches of hamsters by domestic predators. For instance, in Korytniany, Uzhhorod Region cats could catch about 25 to 30 hamsters during summer around a single estate (V. Chumak, personal communication). In addition, frequent records of roadkills also evidence the increase in abundance, e.g. in summer 2007 the average number of roadkills on the 10 km long road section of Korytniany-Uzhhorod was 3-5 hamsters every morning (V. Chumak and R. Kish, personal communication). The growth in abundance of hamsters has been probably a temporal outbreak thus the general tendency of population decline still takes place and the species should be considered vulnerable in Transcarpathia. According to the Red Data Book of Ukraine [31], the reason for population decline of the common hamster in Ukraine is its extirpation by people. Indeed, during fieldworks in spring, hamsters may suffer largescale extirpation (V. Chumak, personal communication), although, as we can see, even under the constant pressure of this factor the Transcarpathian population has managed to survive and even increase its abundance. In our opinion, the local hamster populations in both range segments are more threatened by a wide use of pesticides, which became a common practice during recent years.
Another important factor having influence on hamsters in case of population growth is the death of animals on roads, which has become usual in the western (A) range segment (in particular, near Korytniany and Rakoshyno). Obviously, the species has no adaptations to roads as environmental factors, and animals die when crossing roads attempting to migrate to new sites. For comparison, during census of roadkills conducted in 2004 in Transcarpathia we did not find any dead hamsters [58], although we inspected roads that run through currently known localities. This also confirms the significant population outbreak of hamsters during at least the last 10 years.
The steppe mouse is a recently discovered thus a little known species in the Trans carpathian rodent fauna. The species appeared here in the early 2000s and currently known records allow suggesting that the steppe mouse also has a mosaic distribution in the region having two range segments and, respectively, two routes of expansion from the neighbouring Slovakia and Hungary (Fig. 6). However, such hypothesis in the light of little available data is highly preliminary and new findings can be expected from other parts of the region. A significant number of mounds revealed in each locality allows suggesting that the steppe mouse became a common species in areas of its occurrence. In Transcarpathia, the steppe mouse inhabits fallows, vineyards, and agricultural lands (corn, sunflower, and cereal fields) adapting to crop rotation. The examined content of mounds in vicinities of Hut, Berehovo Region revealed the absolute predomination of ears of perennial grasses, particularly of Setaria viridis. This concerns even mounds located directly on crop fields. Possible further range dynamics of the species in the region should be a subject of subsequent research.
Noteworthy, all three steppe species have generally similar outlines of their distribution range, as well as similar range fragmentation into two segments, western and southern (see . The range of each species tends to the lowland parts of valleys of large rivers in the bordering areas of Transcarpathia.

Range dynamics in the context of landscape transformation of the Transcarpathian lowland
Landscape transformation, especially of anthropogenic origin, has a large impact on distribution patterns of steppe species. Being adapted to steppe and steppe-like biotopes, habitat loss leads to range contraction and fragmentation, especially on its edge. Among steppe species of Ukraine, such process takes place in the greater mole rat (Spalax microphthalmus), which population existing on the species range edge in Eastern Ukraine underwent significant fragmentation during the past few deca des [65]. Howe ver, largescale landscape transformation also can create new habitats on range peripheries suitable for emergence of new populations. In case of steppe species in Transcarpathia, we witness an example of the latter process.
All three steppe species occur in Transcarpathia in anthropogenically transformed biotopes and their abundance directly depends on human activity (decrease in cattle breeding and successional overgrowth of pastures, increase/decrease of the area of arable lands, use of plant protection chemicals, etc.). It begs the conclusion that distribution ranges of steppe species in the region are not natural but secondary. Moreover, the absence of natural populations in indigenous biotopes and, in fact, the absence of typical key steppe habitats suggest that steppe species appeared in Trans carpathia as the result of expansion from their main geographic range as suitable habitats gradually appeared at the range periphery.
Natural complexes of the Transcarpathian lowland sufficiently changed during the past two or three centuries, and the current landscape had been formed by the middle of the 20th century. This could also explain the former absence of currently known steppe species in the Transcarpathian mammal fauna. Landscape transformation occurred here in two main ways as the result of which unique animal and plant communities were lost. On the one hand, it was the largescale deforestation [20,36]. On the other, it was the regulation of rivers with damming of streambeds, as well as the drai nage of the Szer nye Mochar (i.e. Chornyi Mochar) along with the Szernye Lake in its eastern part. Szernye Mochar was a grand wetland complex in the central part of the Transcarpathian lowland between the valleys of the Latorica and Tisza rivers (Fig. 7) and it was almost completely drained in the period from the 1870s to 1950s [7,28]. Both processes, i.e. defo restation and river regulation, led to the gradual increase of the area of disturbed and cultivated landscapes. Obviously, it contributed to the dispersal of steppe plant and animal species to Transcarpathia from the Great Hungarian Plain.
The natural reasons for emergence of the steppe mammalian assemblage in Trans carpathia could be related to the ecological plasticity of species in its composition. In particular, all three species occurring in the region show generalist tendencies allowing them to occupy suitable habitats that appear on range periphery.
An important biological feature of steppe species of Transcarpathia is also their way of wintering. All of the studied species, representing the northernmost steppe assemblages, have specific wintering adaptations practically allowing them to avoid the direct influence of factors of winter. The ground squirrel and the hamster hibernate in burrows, while the steppe mouse winters under the protection of mounds.
Analysis of species ranges shows that the common hamster is absent in the area of the former Szernye Mochar, while the European ground squirrel occurs locally only in its northwesternmost part. In our opinion, such distribution pattern is due to the annual amassment of water on significant areas of the former Mochar in winter or in spring (Fig. 8). Respectively, the water can fill up the burrows while the animals are hibernated thus being unable to escape and eventually dying.
Therefore, regular annual flooding is probably an important limiting factor for the ground squirrel and the hamster in the central part of the Transcarpathian lowland, while  [7]), which was gradually drained between the 1870s and 1950s. Consequently, unique wetland complexes were lost in areas that constantly (1) or temporarily (2)  it has less impact on the steppe mouse. The steppe mouse winters close to the surface and, since it does not hibernate, in case of flooding is able to get into safety in time, while the ground squirrel and the hamster are hibernating in burrows which can be suddenly flooded when the animals are sleeping. Settlements of the European ground squirrel and the common hamster in the southern part of the former Szernye Mochar (range segment B) exist in welldammed and canalized areas where the influence of flooding is limited, just as the distribution of these species into neighbouring and periodically flooded areas, which can explain the species' restricted distribution in this part of the region.

Protection and prospects of steppe species conservation
Patchy distribution pattern has an important influence on population dynamics, in particular due to increasing of edge effects, limited gene flow in the result of isolation between separate segments and the main part of the species range, increasing of inbreeding, etc. [11,15,16]. As a result, the effective population size decreases that leads to reduction in natural population growth as well [44]. The influence of such processes probably takes place in the Transcarpathian part of the range of steppe species, which explains their low abundance and rarity, and, in the same time, makes topical the issue of their conservation. Currently, conservation issues especially concern two species, namely the European ground squirrel and the common hamster, which are keystone species in steppe and forest steppe ecosystems [56].
The current situation with S. citellus in Transcarpathia is critical due to contraction of the area of suitable habitats thus the species is close to extinction. In the latest edition of the Red Data Book of Ukraine, the species was already listed as extinct [32]. As proposed earlier [64], the most promising ways of restoration of the ground squirrel population in Transcarpathia could be the implementation of a complex of conservation measu res including the artificial release of animals. However, the decline in the area of suitable habitats, in particular due to significant reduction of cattle breeding and of grazed pastures in the region, might prevent the ground squirrel's restoration. Further existence of the species in the region is practically impossible without creating protected areas with a respective level of grazing pressure.
As mentioned above, in recent years, local increase of the hamster's abundance had occurred on the background of general population decline in both Europe and Ukraine. The hamster is threatened in Transcarpathia due to its direct extirpation by people and domestic carnivores (probably by wild ones too), death on roads, use of plant protection chemicals, etc. The reduction of springsown cereals in favour of winter sown cereals can also affect the survival of population, since in case of reduced food supply females of the common hamster probably do not produce enough offspring for a sustainable population [27]. Yet in case of longterm preservation of current population trends, the expansion of the species' range could be expected in the region.
Currently, the steppe mouse is in the stage of range expansion and its dispersal in the region seems not to be limited by any obvious factor. Since the species is more common for agricultural lands, especially for fieldedge habitats, human economic activity contributes to the species dispersal. The current dispersal of the steppe mouse in Trans carpathia is similar to its expansion northward in the main part of the species range in Ukraine, both in Podolia and in central and eastern Ukraine [19,59].
Steppe species exist in Transcarpathia on the edge of their geographic range surrounded by the Carpathians. Ecotone effects and respective consequences at the junction of steppe, forest steppe, and mountain biotopes determine the biogeographic uniqueness of Transcarpathia as a model region in the study of coexistence of different faunal assemblages, in particular of steppe species alongside forest and mountain ones.