Seasonal and multiannual dynamics of rodent species number under the influence of climate factors and anthropic modifications

The research was carried out in agricultural experiment stations in the central area of the Republic of Moldova during a period of 35 years. It was determined that cyclic oscillations with an interval of 3-4 years are not typical of Microtus arvalis, as can be seen in other parts of the area. Intense anthropogenic influence determines the type of numerical dynamics. A certain periodicity is observed in the species Mus spicilegus, but during the last 30 years the dynamics has become acyclic. In the populations of the species Apodemus sylvaticus there was a more pronounced periodicity of the oscillation of the herd, once every two years.

Mice of the genus Mus in the Crimea: species diagnostics, distribution, and ecology

The paper presents the first detailed summary of the current state of mice of the genus Mus in the Crimea, namely of the house mouse (Mus musculus Linnaeus, 1758) and steppe mouse (Mus spicilegus Petenyi, 1882). Morphological structures of the house mouse and steppe mouse are characterized and external and craniometrical features important for species diagnostics are presented. Most of the morphological characters tend to vary within the entire geographic range of both species. Body length of house mice is significantly greater compared to that of steppe mice. Tail length in house mice is greater than in steppe mice, but the tail index is greater in the latter. Therefore, house mice look more ‘short-tailed’, and this feature can be used as an additional diagnostic character. In steppe mice, the tail becomes thinner gradually from base to tip and thus it is awl-shaped. The tail of fit house mice, especially of autumn-winter generations, often has a thickened base, which increases the visual effect of a short tail. Among internal characters, the most significant are the differences between testicles size of mature males. For species diagnostics of mice of the genus Mus, the size and shape of the following cranial structures can be used: location of the root and frontal wall of the crown of the first upper molar (M1) in relation to the diastema; zygomatic process of the maxilla and zygomatic arch; palatine foramens foramina palatinum, and others. These are reliable characters for morphological identification of M. musculus and M. spicilegus in the territory of the Crimea, in the zone of their sympatry. Reliable diagnostic characters are the dimensions of palatine foramens. In general, the entire complex of characters analysed in this study should be used for correct morphological diagnostics of these species. Features of distribution and population dynamics of the house mouse and steppe mouse in the Crimea are studied. It has been revealed that both the house mouse and the steppe mouse are distributed mainly in the lowland part of the Crimea and the forest-steppe belt of the foothills. Data on the ecology of species are presented, including specifics of reproduction and habitat preferences. The place and role of house mice in small-mammal assemblages of various landscape and ecological zones are estimated.

The mound-building mouse (Mus spicilegus) in Western Podillia: expansion on the left bank of the Dnister

New findings of the mound-building mouse on the left bank of the Dniester in the interfluve of its tributaries—the Dzhuryn and the Nichlava (Chortkiv Raion, Ternopil Oblast)—are described. The presence of Mus spicilegus was established based on findings of food stocks common for this species in the form of mounds, which are easy to detect in the field and which can be clearly diagnosed. Both single mounds and their clusters were taken into account. The specifics of biotopic distribution, formation of food reserves, and the role in trophic chains of this species under conditions of the studied region are indicated. The mound-building mouse is one of the few rodent species that maintain a high abundance under conditions of intensive agriculture, which involves mechanical tillage several times a year and a significant level of chemical use. The distribution of the studied species is influenced primarily by two factors: the level of agricultural techniques in agricultural production (arable farming and crop care, quality of harvesting) and the distance from uncultivated areas. The mound-building mouse usually inhabits agricultural lands with a low level of agriculture (minimal chemicalization and mechanical tillage). These are lands allocated for private gardening or farming. Such lands have increased weeds and crop losses during harvesting, which creates a rich food base. After harvesting, such lands usually do not undergo long-term tillage. Results show that the settlement of arable lands comes from natural or other uncultivated areas, where the nuclei of populations are concentrated. In autumn, under the above favourable conditions, population growth is observed in adjacent cultivated lands, where winter food reserves are formed in the form of characteristic mounds. On large-area crops of monocultures cultivated by large agricultural firms, mounds are usually absent. The level of agro-technical pressure on the same area varies from year to year. This causes temporary instability in the appearance of mounds. They disappear where anthropogenic impact has re-emerged significantly and re-appear where there has been a weakening. The role of the mound-building mouse in trophic chains and in maintaining regional biodiversity is shown.

Finds of rare and non-abundant species of small mammals in the territory of Kharkiv Oblast, Ukraine

Eight of the eleven expected rare and non-abundant species of small mammals were recorded in the studied territory: Crocidura suaveolens, Sorex minutus, Neomys fodiens, Dryomys nitedula, Cricetulus migratorius, Terricola subterraneus, Micromys minutus, and Mus spicilegus. Crocidura suaveolens was found in both dry meadows and floodplain biotopes, and it was also recorded nearby to field-protective plantations and human settlements. Sorex minutus was also more common in dry meadows and in floodplain biotopes. Neomys fodiens is a typical floodplain endemic. Dryomys nitedula was more common in oak forests and it is prone to synanthropy. Cricetulus migratorius was found in steppe areas and near fields of agricultural crops. Terricola subterraneus was recorded only in a dry maple-linden oak forest. Micromys minutus prefers floodplain biotopes. Mus spicilegus was found on agricultural crops and in steppe areas.

Mouse-like rodents and shrews in Kharkiv Oblast (Ukraine): species composition, distribution, and current state of populations

Since 1957, zoologists of the Kharkiv Sanitary and Epidemiological Station have been conducting annual monitoring of small mammals in Kharkiv Oblast. To assess the current state of populations of mouse-like rodents and shrews, we analysed a dataset for the period from 2000 to 2018. The small mammal fauna was studied at 117 sites in 27 districts (raions) of Kharkiv Oblast. Various types of oak forests, dry and floodplain meadows, riparian vegetation, steppe areas, forest stripes, gardens, fields, and haystacks were examined. Four species of insectivores and 16 species of mouse-like rodents were identified. The dominant and widespread species in the region are Sylvaemus uralensis, Apodemus agrarius, Sorex araneus, Microtus levis, Myodes glareolus, and Sylvaemus tauricus. Some species are less common and in some areas of the region have not yet been identified, including Sorex minutus, Sylvaemus sylvaticus, Crocidura suaveolens, Micromys minutus, Cricetulus migratorius, and Microtus oeconomus. The least common species with single records include Neomys fodiens, Mus spicilegus, Lagurus lagurus, Terricola subterraneus, Dryomys nitedula, and Arvicola amphibius. Indigenous species of the region include seven species, another seven species are those that increased their number and range, three species have recently appeared in the region due to dispersal from adjacent territories, while, on the contrary, the abundance and range of three species have declines. Microtus oeconomus is characterised by a current southward range expansion. Myodes glareolus, which was mentioned in the last century north of our region, is now widely distributed throughout the region and further south. Lagurus lagurus is an invasive species with periodic population outbreaks in the region and currently is rarely recorded.

Modelling the Bioclimatic Niche and Distribution of the Steppe Mouse, Mus Spicilegus (Rodentia, Muridae), in Ukraine

The Steppe mouse, Mus spicilegus, is endemic to Europe and found to be expanding its home range in recent years. In Ukraine there are indications a north- and eastwards expansion and/or reestablishment of M. spicilegus. We suggest that climatic conditions may be the primary factors that foster or limit the range expansion of M. spicilegus in Eastern Europe. Our objective was to complement the knowledge about the distribution of the species with an estimation of the potential distribution of the species in Ukraine using known occurrence sites (in Ukraine and neighbouring areas) and environmental variables in an ecological niche modelling algorithm. After accounting for sampling bias and spatial autocorrelation, we retained 73 occurrence records. The algorithm used in this paper, Maxent (Phillips et al., 2006), is a machine learning algorithm and only needs presence data, besides the environmental layers. Using this approach, we have highlighted the importance and significance of a number of bioclimatic variables, particularly those characterizing wintering conditions, under which higher mean temperatures enhance habitat suitability, whereas increased precipitation leads to an opposite effect. The broadly northwards shift of the home range of the species in Ukraine could generally be due to the increasing (since the 1980s) mean temperature of the winter season. We expect this expansion process will continue together with the changing climate and new records of locations of the species may be used for monitoring such change.