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Caucasian mouse (Sicista caucasica)


Subspecies: Subspecies not described

The first find of one-color mice in the Caucasus (a specimen obtained in the mountain Svaneti by G.I. Radde in 1869) was defined as S. concolor (Satunin, 1896) and subsequently, until the description of Vinogradov (Vinogradov, 1925), the Caucasian mouse was considered as part of the concolor group, which occupies the southern part of the range Sicista.

Vinogradov’s point of view, according to which all the one-color mice living in the Caucasus belong to the species S. caucasica (Vinogradov, 1925), for many years occupied a dominant position in the taxonomy of the genus (Vinogradov, 1925, Vinogradov, 1937, Ognev, 1935, 1948, Ellerman, Morrison-Scott, 1951, Gromov et al., 1963, Gromov, Baranova, 1981 ), although some researchers returned to the old ideas about the status of the Caucasian mouse, considering it as part of a polytypical species S. concolor as one of the subspecies (Kuzyakin, 1963, Bobrinsky et al., 1965, Corbet, 1978, Walker, 1983). The use of the karyological approach in combination with traditional morphological studies not only confirmed the isolation and species rank of the Caucasian mouse S. caucasica (2n = 32, NF = 48), but it also led to the description of a number of twin species of the same-colored mice of the Caucasus, differing in chromosome sets and some other morphological characters: Klukhor S. kluchorica (2n = 24, NF = 44), Kazbeg S. kazbegica (2n = 42, NF = 52, 2n = 40, NF = 50) and Armenian S. armenica (2n = 36, NF = 52) mice (Sokolov et al., 1981, 1986, Sokolov, Baskevich, 1988, 1992). In accordance with modern concepts, these morphologically similar Caucasian endemic species, characterized by a single type of coloration and a similar structure of male glans penis, form a group of closely related species of one-color mice of the Caucasus (see Schoenbrot et al., 1995, Baskevich, 1996). S.caucasica in this group of closely related morphologically similar species, characterized by allopatric distribution, inhabits the western part of the Greater Caucasus.

Conservation Status and Conclusion

Tembotov (1972), studying the altitudinal distribution limits of mammals of the North Caucasus, noted that the largest population of Caucasian mice is in the subalpine zone of the western part of the North Caucasus. These data were confirmed by Topilina (1987) during six-year (1980-1985) stationary studies in the central part of the Caucasus Nature Reserve on the slopes of Mount Dzhuga (valley of the Urushten River) at altitudes of 1400-2000 m above sea level. M.V.G. Topilina (1987) worked out 1,335 cylinder-days and during this period 89 specimens of the Caucasian mouse were mined. Belonging of these animals to S. caucasica was proved by us on the basis of karyological dating (Sokolov et al., 1987). The collections of the zoomusees of Moscow State University, ZIN, and BIN contain numerous collections of mice, presumably of this species, from the territory of the Caucasian Biosphere Reserve. Another relatively large population S. caucasica also registered in a protected area: in the Arkhyz reserve in the valley of the Bolshaya Zelenchuk river (Reznik, 1951, Sokolov et al., 1981, 1987, Baskevich, 1996, 1997). Assessment of populations (populations) S. caucasicaliving on the northern slopes of the Greater Caucasus allows considering environmental status S. caucasica in this part of its range as LR_1., i.e., it belongs to the category of low-risk taxon (LR) and the sub-category of conservation-dependent Conservation Dependent (CD).

On the other hand, the analysis of single finds of one-color mice of the Caucasus from the southern slopes of the western part of the Greater Caucasus in Abkhazia: from Mount Ancho and from the vicinity of Pskhu (collection of the Zoological Museum Zoological Institute in St. Petersburg) and from the vicinity of the village. Avadhara in the Gudauta district (collections of the Institute of Zoology of the Academy of Sciences of Georgia), presumably related to S. caucasica, allows to evaluate this species in Georgia in accordance with IUCN categories ("Red List Categories" v2.2) as a rare, endangered species (EN_B.1.2.c) (highly fragmented, known from less than 5 habitats, and habitat stations are constantly deteriorating due to negative human impacts). According to Bukhnikashvili (1997), it is planned to consider the introduction of this species in the Red Book of Georgia. It should be recalled that the final solution to the question of the taxonomic affiliation of one-color Caucasian mice from Abkhazia with the clarity of their conservation status requires the use of karyological research methods.

It should be emphasized that the modern habitats of the forms of the plain mice of the Caucasus studied today are reduced due to the active anthropogenic impact (excessive grazing, logging, tourism, the construction of villages, roads, industrial pollution). The main anthropogenic factor in the Caucasus is disordered animal husbandry (Tembotov, 1988). Its consequence is a sharp increase in the aridity of mountain landscapes and a significant decrease in the proportion of mesophilic, including endemic, species. All this is directly related to the one-color mice of the Caucasus, the original habitats, which are destroyed, first of all, under the influence of immoderate grazing. The mesophilic subalpine tall grass and alpine forbs are replaced by xerophytic weeds, and in the worst case, slope exposure and erosion are observed. A positive effect of the reserve regime on highland meadows was noted. This circumstance is probably associated with the confinement of most of the known places of finds of one-color mice of the Caucasus to protected areas (Sokolov et al., 1987, Baskevich, Lukyanova, 1988, Baskevich, 1997). Caucasian habitat S. caucasica mice on the territory of the Caucasian reserve allows us to hope for the preservation of populations of this species in the future. Moreover, in the territory of the Caucasian reserve (biosphere reserve), the most stable and numerous population of the same-colored mice of the Caucasus was noted.

Mice are medium sized. The body length does not exceed 68.9 mm, the tail is half longer than the body, its maximum length does not exceed 115, 4 mm. The hind foot is relatively long and in rare cases can reach 22.0 mm, the height of the ear does not exceed 12.8 mm, and body weight - 8.8 g. Coloring of the dorsal side in individuals S. caucasica plain without a black longitudinal strip along the ridge. The color of the upper back is dominated by bright rusty-ocher tones, somewhat muffled by a small admixture of awns, having a black coloring of the upper part. On the sides of the body and cheeks there are no awns with black tips, so these parts of the body are especially bright in color. The ventral side of the torso is usually painted gray-white with a light fawn color. Among the mice from Arkhiz we saw animals in which the lower side of the body was bright white. Tails are two-tone. The structure of glans penis does not differ from that of other species of the same-colored mice of the Caucasus. Slightly widened at the end of the cylindrical shape, glans penis is uniformly covered with small spines; on its dorsal surface there is a longitudinal groove, occupying more than 1/3 of the organ's length. Meanwhile, the structural features of the baculum in S. caucasica species-specific. Os penis carries an extension at the distal end that resembles the shape of an arrowhead. This bone, which has diagnostic value, has the following dimensions (given in five measurements from individuals from the vicinity of Verkhniy Arkhyz settlement): the length of the baculum is 3.5 (lim 3.4-3.9), the maximum width of the rod in the proximal part is 0 , 6 (lim 0.6-0.7), the maximum width of the distal part is 0.4 (lim 0.3-0.5), the minimum core width is 0.2 mm. The shape of the sperm head is elongated-oval, similar in relative size to those of S. kluchorica and differs in these indicators in S. kazbegica and S.armenica. On average, the length of the sperm head in S.caucasica is 4.9 (lim 4.4-5.3) and a width of 3.7 (lim 3.4-4.0) microns. The number of chromosomes in the karyotype of the Caucasian mouse is 32, the number of chromosome arms is NF = 48. Among the autosomes, 4 pairs of metacentrics, 4 pairs of submetacentrics and 7 pairs of acrocentric chromosomes were noted. X-chromosome - acrocentric medium size, YThe chromosome is a very small acrocentric element.

The range of the Caucasian mousy supposedly covers the highlands and midlands of the western part of the Greater Caucasus from the Pshish river in the west to the Bolshaya Zelenchuk river in the east on the northern slopes, and possibly in Abkhazia and adjacent regions of Russia on the southern slopes. The karyologically dated finds of S. caucasica (2n = 32. NF = 48) are so far known only from two points of the western part of the northern slopes of the Greater Caucasus: from the valley of the Urushten river, the spur of Mount Dzhuga from the territory of the Caucasian Reserve in the Krasnodar Territory and from the vicinity of the village. Upper Arkhyz in Karachay-Cherkessia, Stavropol Territory (Sokolov et al., 1987, Baskevich, 1996). Unfortunately, it is not possible to accurately indicate on the geographical map the terra typica of the species: Maykop environs in the Kuban region, height about 2100-2700 m above sea level. (Vinogradov, 1925). The identity of 32 chromosome findings and those of terra typica was established by the shape of the baculum (Sokolov et al., 1981). It should be assumed that the finds of one-color mice, widely represented in the collections, from the territory of the Caucasian Reserve, in the western part of the river basin. The Kuban in the upper reaches of the Belaya, Bolshaya and Malaya Laba rivers and their tributaries belong to this species. So, the collections of S.S. Turova, E. Antonova, Bessonova, A.A. Nasimovich, V.Loginov, Y. Averin. M. Rozanova, V.F. Orlova and N.V. Stein, which presents specimens from the Lagonaki mountain range: Mount Fisht, Bukvenskaya, Oshten, as well as from the mountains of Gefo, Aishkho, Alous, Pshekish, Chugush (= Shugus), Big Bambak, from the valleys of the Kisha, Urushten, Bezymyannaya rivers. In the collections of the Zoological Institute of St. Petersburg there are specimens of mice obtained on Mount Bambak, in the tract Umpyr in the headwaters of Malaya Laba, and in addition in the headwaters of the river. Mzymta of the Krasnodar Territory and in two points of Abkhazia: in the Anchkho Mountains and in the vicinity of Pskhu (collectors NL Orlov, Shaposhnikov and GP Adlerberg). Another specimen of mice from Abkhazia, caught in the Gudauta region near the village. Avadhara, kept in the collection of the Institute of Zoology of the Academy of Sciences of Georgia (Morgilevskaya, 1989). Apparently, some of these points, as rightly noted in the last taxonomic summary (Schönbrot et al., 1995), can supplement the range of the Caucasian mouse after determining the species of animals from these geographical points using karyological analysis.

S. caucasica occurs in the middle part of the forest, subalpine and probably alpine zones, preferring biotopes with well-developed grassy vegetation (see Reznik, 1951, Topilina, 1987, Sokolov et al., 1981, 1987, Baskevich, Lukyanova, 1988, Shenbrot and others ., 1995, Baskevich, 1996, 1997). There is a known find from a place close to points with established species affiliation - Mount Oshten (Zoological Museum of Moscow State University) from the lower boundary of the subnival belt. The optimum of the range is the subalpine tall grass (Topilina, 1987). Altitudinal limits of distribution are from 1500 (valley of the Urushten river) to 2100-2700 m above sea level. m. (Maikop district of Krasnodar Territory, belonging to this species is established by the shape of the baculum).

The Caucasian mouse is the most studied species in terms of ecology in the group of one-color mice of the Caucasus. It was shown that the number of Caucasian mice is rather high in biocenoses that are not subject to human economic activity. Thus, according to our observations in tall grassy meadows along the river bank and in grassy meadows in a park-type forest on the territory of the Arkhyz reserve in late June - early July 1979, we obtained 13 specimens for 12 hunting nights. Caucasian mice, in 1987 from June 16 to 18, 6 animals of this species were caught here, and in 1990 for 2 hunting nights there we caught 4 specimens in the first days of July. S. caucasica. V. G. Topilina (1982), which carried out counts of small mammals in the valley of the river. Urushten on the slope of Mount Dzhuga in the Caucasus Nature Reserve in June-July 1980, it was found that the number of Caucasian mice in the community of small mammals of subalpine tall grass and forest tall grass in this period of time occupied the second place after shrub voles and amounted to 25.5% and 12.5% ​​of the total share of animals caught by crush and cylinder. As a result of 6-year-old (1980-1985) stationary observations there (a total of 1335 cylinder-days were worked out, 89 animals were captured), it was shown that the optimal biotope is subalpine tall grass, individuals S. caucasica were caught during the entire warm period of the year: from May to August, and the abundance of the Caucasian mouse in this optimal biotope reached 24 animals, ranging from May to August from 0.8 to 24 animals per 100 trap-days. In other biotopes S. caucasica - a rarer species. In particular, in the clearings of forest tall grass and in the fir forest V.G. Topilina (1987) caught mice only in mid-June. Their abundance during this period was 6.7 animals per 100 cylinder-days. In the subalpine meadow and in the meadow among the "park" coniferous-deciduous forests, according to the records in the second half of August, the abundance of mice in the valley of the river. Urushten in the territory of the Caucasian reserve was 3.6 and 1.0 animals, respectively (Topilina, 1987). Fluctuations in the abundance of Caucasian mice are associated with a change in the activity of this wintering rodent during the summer period: the Caucasian mouse disappears from catches when nighttime temperatures drop below 1.0-1.5 ° C (Topilina, 1987). An analysis of the age structure of the population in the Caucasian reserve revealed that the majority (more than 76%) of Caucasian mice are one-two-year-old animals, and the proportion of year-olds and animals of three-year-olds is very small (Topilina, 1987). According to Topilina (1987), the ecology of the species precludes the existence of sharp fluctuations in the number of Caucasian mice in different years.

The seasonal activity of this hibernating rodent is determined by night temperatures. At night air temperatures approaching zero, Caucasian mice become inactive and hibernate. The active life of Caucasian mice usually lasts for 3-3.5 months and depends on the conditions of a particular year (Topilina, 1987).

As a rule, Caucasian activity is characterized by nocturnal activity. All individuals of the Caucasian mouse that we caught in the Arkhyz reserve were mined during the morning groove inspections. However, it is possible that the mice can be active in the daytime. Such an observation is known from the report of Reznik (1951), who caught a copy of the Caucasian mouse in the vicinity of Arkhyz during daylight hours. Caucasian mouse feeds, judging by observations in captivity, mixed food (Schönbrot et al., 1995, our data).

Apparently, as in other species of mice, only overwintered individuals participate in reproduction. The breeding season is extended. Its beginning falls on the second half of May - the beginning of June.

According to our data, the mice of the Caucasian mouse, captured in the vicinity of Arkhiz (h = 1550 m) in June 1979 were in a state of sexual activity. A large number of sperm cells were found in smears from the testes and their appendages. The sizes of the testes (length and width) varied from 5.3 x 3.2 to 4.4 x 2.8 mm (Sokolov et al., 1981).

Three females from animals captured in June 1979 were pregnant. One of them gave birth on June 30, the other two on July 3. Each litter had 4 cubs (Sokolov et al., 1981). The race for Caucasian mice from this population in 1979 probably began in the second half of May - early June. In subsequent years, we were able to obtain additional information on the reproduction of Caucasian mice from the Arkhyz population. On June 29, 1989, we caught a pregnant female on demolitions with 4 large embryos measuring 13.8 x 9.8 mm, which corresponds to the breeding dates of 1979. The second pregnant female with 5 very small (2.4 x 2.4 mm) was obtained by embryos on July 2, 1990, which may indicate later breeding dates this year compared to the previous one. Apparently, depending on the climatic conditions of a particular year, the breeding dates of the Caucasian mouse may shift by about 2 weeks. Obviously, breeding times may vary depending on the height of the area above sea level. So, V.G. Topilina (1987), who conducted stationary research in the highlands of the river valley. Urushten on the territory of the Caucasian reserve, reports that in May - early June, sexual activity in the Caucasian mouse was absent. In females captured at this time, filiform uteri were noted, and in males, when the length of the testes was varied from 4.3 to 5.5, the sizes of seminal vesicles were insignificant - 3-3.5 mm. Females caught in July already had a thickened uterus filled with fluid. The breeding season is extended: both females with traces of reproduction and females with filiform uterus can be found in the population at the same time. The size of the litter in the Caucasian mouse varies from 4 to 6 cubs and averages 4.6 young in the brood (11 females studied). In addition to the three captive and two pregnant females already mentioned by us in the first decade of 1980 and in the third decade of July 1987.in the vicinity of Arkhiz, we obtained 3 females with placental spots in the uterus, of which two each had 5, and the third 6. Another female with 5 placental spots in the uterus, obtained there on June 18, 1987, apparently participated in breeding in previous year. In the collections of V.G. Topilina (1987) from the territory of the Caucasian reserve also had two females, with 4 and 5 placental spots. They were obtained in the second decade of July and in the first decade of August 1985. Cubs of the Caucasian mouse are born naked with closed auditory canals and with a shortened tail (Sokolov et al., 1981).

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The study was supported by the Russian Foundation for Basic Research (grant 01-04-49438).