Myodes Glareolus Schreber Research Articles

Reproductive capacity of male bank voles (Myodes glareolus Schreber, 1780) – age-dependent changes in functional activity of epididymal sperm

The influence of age on male bank voles’ reproductive tract development, epididymal sperm quantity and functional activity was investigated. Experiments were carried out on male bank voles aged 1.5 to 15 months (n=10 each in 8 age groups). The developmental stage of the reproductive tract was assessed by the weight of testes, seminal vesicles and coagulation glands. In each age group the number of epididymal sperm and their functional activity were examined. Epididymal sperm functional activity was assessed by motility, viability, maturity, head morphology and integrity of the sperm tail membrane. Ageing males were heavier than pre-pubertal and mature ones. Male age also affected the testes, seminal vesicles and coagulation gland development. The heaviest accessory sex glands were noted in 3-month-old males and the lightest in pre-pubertal (1.5-month-old) and older (12- and 15-month-old) males. Sperm counts were significantly higher in 3-, 4- and 5-month-old males than in pre-pubertal and old males. Generally, adult males aged 3- and 4- months, produced sperm of better functional activity. In conclusion, the best male reproductive capacity is found in bank voles of 3 to 4 months of age.

Modeling Spatial Niches of Small Mammals Using the Example of <i>Myodes glareolus</i> in Mosaic Southern Taiga Forests

Based on long-term (2010–2014) studies carried out in the forest ecosystems of the Central Forest Biosphere Reserve, two models of the spatial niche of the bank vole (Myodes glareolus Schreber, 1780) were constructed using factor analysis (ENFA). Models with a sufficient level of quality characterize the characteristics of the species’ niche. The modeling results make it possible to describe the structure of the optimal habitat for the bank vole in mosaic southern taiga forests at different levels (scales) of spatial organization.

Features of craniological signs of <i>Myodes glareolus</i> Schreber in the Kostroma Region

As part of the comprehensive monitoring of the state of the ecosystems of the Reserve Kologrivsky Les, studies of the Myodes glareolus Schreber population organization were conducted for eleven years (20122022). To compare the values of craniological signs of the control population, similar measurements were considered in rodents living on the territory of Minskoe forestry in the Kostroma Region (20212022). The paper provides data on the size and proportions of the skull of this species. Osteological indices characterizing the nutrition ecology of the studied populations and their craniometric appearance were calculated. The variability and correlation of 17 craniometric signs of Myodes glareolus was analyzed in order to diagnose the degree of optimality of conditions for the existence of this species populations, as well as to assess the state of the environment in complex biological monitoring programs. Data were obtained on the patterns of variability of metric and nonmetric features of the skull in a number of years, and the influence of the sex structure of the population, the dynamics of its population, weather and climatic factors on the determinism of craniological measurements was studied. Sexual dimorphism according to these parameters was expressed slightly. There was a positive correlation of signs in rodents living on the territory of the biosphere reserve as the most optimal habitat in comparison with the territory of Minskoe forestry in the Kostroma Region, where a negative correlation was predominantly revealed. A strong correlation was established between some craniometric features characterizing the specifics of nutrition, population density, average precipitation and average air temperature. In addition, weak correlations between the body weight of individuals and the dimensions of the skull were revealed. When studying the fluctuating asymmetry of non-metric features of the left and right sides of the upper and lower jaw, a low level of the FAnm coefficient was found in the studied populations. Dynamic changes in the level of fluctuating asymmetry of rodents were insignificant. A weak negative correlation of the fluctuating asymmetry and the values of the average precipitation during the study periods were established. No significant correlation was established for the other factors. The results of the presented comprehensive study of the craniometric features of Myodes glareolus on the territory of the Kostroma Region indicate a stable state of populations in the considered environmental conditions.

The phenomenon of the shrinking size of bank vole (Myodes glareolus) in an anthropogenic environment (experience of 50 years of observations)

Fifty years of continuous monitoring of the bank vole population (Myodes glareolus Schreber, 1780) revealed the phenomenon of shrinking body size of individuals, manifesting in significant reduction in their regular size and mass parameters. Field observations were carried out in the Kaniv Nature Reserve (Cherkasy region, Ukraine) during the first half of summer every year. In the forest biotopes of the reserve, this species is dominant in the group of rodents. The research period covered various stages of the existence of the protected ecosystem. Its small area, location ina densely populated region of Ukraine and interaction with neighboring territories which are involved in economic activities have always caused anthropogenic pressure on the protected area. Its nature and intensity determined the changes in the protection regime and the loss of reserve status in 1951–1968. Later, the territory of the reserve experienced increasing technogenic pressure accompanied by radioactive contamination. In this work, to compare their characteristics, four complete cycles of the density dynamics of the bank vole population (from depression to depression) were selected, the duration of which was 4–5 years. The first three cycles correspond to qualitatively different periods in the existence of the ecosystem and the population of the studied species, and the last one corresponds to the relatively current situation. Over the recent 30 years, the size and mass parameters of individuals of bank voles have deсreased, - this phenomenon was called shrinking. The process was also observed to tend towards consistent increase in scale. Differentiated analysis shows that in different sex and functional groups of animals, the decrease in exterior parameters can reach 30.3%. Shrinking is especially notable in the group of adult females that are actively involved in reproduction (compared to the second cycle, considered as the control, the decrease in parameters among these is 33.2%). Juveniles of this sex lost 31.8% of their fatness. Besides, in the population of voles, the proportion of large-size individuals was significantly reduced. The group of animals that overwintered significantly reduced its representation, and its existing representatives had much smaller exterior parameters. The studies found that the shrinking process is stable over time, which does not allow it to be considered a random phenomenon or an artifact of research. This phenomenon has no correlation with the amount or availability of food. It occurs against the background of numerous changes in various aspects of population dynamics, which gives grounds to associate it with anthropogenic changes in the environment. Shrinking is believed to be realized through various mechanisms. Firstly, as a result of mortality, the largest individuals and reproducing females with the greatest energy needs disappear from the population, and secondly, the growth and weight gain of young animals is slower. As a result, decrease in the size and mass parameters of individuals reduces their specific energy needs and allows the population to bring their requirements in correspondance with the capability of the environment to support a certain number of resource consumers. An analogy was drawn with the Dehnel’s phenomenon, described for shrews of the Sorex genus, whose body size and weight decrease is an element of preparation for experiencing adverse winter conditions. Based on similar concepts, the shrinking of its elements can be considered as a specific population strategy to maintain the ecological balance.

Мишоподібні гризуни Дністровського каньйону: особливості видового складу та структури угруповань (на прикладі урочища Червоне)

We conducted an analysis of populations of muroid rodents of the Dnister Canyon National Nature Park on the example of the natural landmark “Chervone.” For the investigation of the muroid rodents, we applied the trap-line method using factory-made live traps. According to methodology, the traps were located within a homogeneous habitat and four different sites were studies. Field data collected during 2017 and 2018 (summer and autumn cenuses) in four different habitats were analysed. The species composition of muroid rodents was investigated in four different biotopes (habitats) near the Dzurynskiy waterfall: hornbeam forest, pine forest, floodplain of the Dzuryn river, and pasture. The studied habitats were identified according to the National Habitat Catalogue of Ukraine. During the research, 75 specimens of muroid rodents were caught in 800 trap-nights. We recorded six species of muroid rodents: Sylvaemus tauricus L., Sylvaemus sylvaticus L., Apodemus agrarius Pallas, Micromys minutus L., Myodes glareolus Schreber, and Microtus arvalis Pallas. The most numerous species was Sylvaemus tauricus — 23 individuals (31 %). The quantity of other species was as follows: Apodemus agrarius (28 %), Sylvaemus sylvaticus (17 %), Myodes glareolus (16 %), Microtus arvalis (7 %), and Micromys minutus (1 %). The abundance of rodents was lower during the summer period compared to autumn, which can be related to the anthropogenic pressure on the investigated area. In addition, we investigated the sex and age structure of muroid rodent populations. We discovered that 45 individuals out of 75 were males and 35 were females. Additionally, 63 individuals were adults (Ad.) and 12 were juveniles (juv.). To summarise the received data, we calculated the number of individuals per 100 trap-nights. The abundance of individuals fluctuated from near 3 ind./100 t.-n. (Sylvaemus tauricus) to 0.125 ind./100 t.-n. (Micromys minutus). The relatively low species diversity of muroid rodents in the Dnister Canyon National Nature Park could be the result of small areas of insular habitats (separated territories with relatively similar landscape) and strong fragmentation of the researched area.

Vegetation cover and microtine rodents spatial distribution under conditions of Nizhny Novgorod oakwood

This paper deals with the problem of the connection between small mammals spatial distribution and the vegetation cover. The study was carried out during the summer period of 2018 and 2019 in the landscape protected area Oakwood of the NNSU Botanical Garden in the province of Nizhny Novgorod. Three relevs were set up in various plant associations: Ulmetum pulmonarioso-asaroso-aegopodiosum, Acereto-Tilietum pulmonarioso-impatienosum (noli-tangerae), Querceto-Acereto-Tilietum asareto-aegopodiosum. A standard geobotanical description was carried out according to the generally accepted method using a series of Raunkier sites registration. Microtine rodents were trapped by standart traps and live traps. The caught animals turned out to belong to 2 genera and 3 species: the bank vole Myodes glareolus Schreber, the pygmy wood mouse Apodemus uralensis Pallas, and the field mouse Apodemus agrarius Pallas. The low population size of animals, as well as the fact that Apodemus agrarius is a co-dominant, may indirectly indicate the anthropogenic pressure in the investigated oak groves. Ecological plasticity of the species Myodes glareolus has been confirmed. Bank voles inhabit micro-habitats with the average data of illumination as well as shaded ones. In general, the vegetation projective cover and the presence of Norway maple undergrowth are crucial for the microtine rodents spatial distribution. Small mammals choose sites with a minimum number of Acer platanoides undergrowth, and gravitate to places where the projective cover of grass has moderate rates (from 35 to 50%). The Principal Component Analysis (PCA) using a vegetation cover species spectrum showed the presence of a significant factor for microtine rodents, which is associated with nitrophilous species (common nettle and touch-me-not balsam). The presence of those plants may indicate a significant anthropogenic pressure on the vegetation cover. In addition, it is important that plants belong to a particular eco-coenotic group. The species Myodes glareolus and Apodemus agrarius differ on the nemoral factor, and their ecological niches do not overlap.

Experimental Investigation of Interrelations between Small Rodents and Red Wood Ants

Investigations of the mechanisms of the spatial-behavioral interaction of members of diverse and significant guilds such as red wood ants and small mammals have been started only recently, and many questions remain obscure. We have investigated interrelations between red wood ants Formica aquilonia Yarr and the common vole Microtus arvalis Pallas, the bank vole Myodes glareolus Schreber, and the pygmy wood mouse Sylvaemus uralensis Pallas in laboratory experiments. We first describe the defensive behavior of rodents and reveal a stereotype of the hunting behavior of the common vole towards dangerous insects. In all three rodent species, defensive behavior increases with an increase in the number of ants used in the tests, which corresponds to simulated natural situations with gradations of the dynamic density of insects. We speculate about the relationship between the defensive and hunting behavior of rodents towards red wood ants.

Гетерогенність популяцій гризунів на термінальних фазах динаміки щільності

<p>The population structure of populations of two vole species (Myodes glareolus Schreber, 1780 and Microtus subterraneus de<br />Selys-Longchamps, 1836) were analyzed towards the peaks and depressions of their dynamics of density. Field researches were<br />conducted throughout the first half of summer during 2000-2013. The sample was more than 800 individuals.<br />Reactions of populations of rodents to changes of living conditions during dynamics of the population are provided with speciesspecific<br />reorganizations of sex and age structure. On the basis of allocation of functional and physiological groups, comparison<br />of their contribution to changes of density of populations is carried out. Specifics of this approach consist that at allocation of<br />such groups as criterion the similarity of a functional condition of individuals connected with features of growth, development<br />and unity of a reproductive state is accepted.<br />Changes of living conditions during dynamics of population density, cause realization of species-specific population reactions<br />are being show. In population of a bank vole delay of intensity of reproduction in years of density peaks is reached due to<br />preservation of a considerable share of the wintered individuals. It is followed by simplification of age structure and change of<br />a sex ratio towards prevalence of females. The analysis of coefficients of a reproduction shows that the wintered individuals<br />provide 1/3 population increase. In years of the low density of an intensification of reproduction the maximum realization of<br />biotic potential of young animals promotes. Also as the buffer a large number of individuals who will enter at reproduction the<br />next year remains.<br />In population of pine vole the priority mechanism of regulation of reproduction is the effective date variation in a reproduction<br />of bulk of representatives of spring and summer generation. In the conditions of an overpopulation (density peak) the share of<br />animals who don't breed is maximum and exceeds quantity of breeding almost twice. The wintered individuals aren't enough<br />and they don't provide such essential contribution to a reproduction as at a bank vole. In depression phases the quantity of the<br />breeding voles of the current year of birth more than twice increases, they provide the further growth of population.</p>

Patterns of multiannual changes in the spatial structure of a bank vole (Myodes glareolus) population in hornbeam-oak forest

This article presents the results of research on changes in the spatial structure of a population of bank vole (Myodes glareolus Schreber, 1780) in the context of a study of multiannual dynamics of population density. The field research took place in Kaniv Nature Reserve, Cherkassy region, Ukraine, in May – June 2009–2012. In forest biotopes of the reserve the dominant mammal species is the bank vole The period of research spanned four consecutive phases of long-term dynamics of density of population of this species, and also of the rodent community in general (growth – peak – decline – depression). The trapping of the animals was carried out by means of the traditional method of study plots. Parameters of spatial distribution of individuals – aggregation coefficient (K) and density of individuals within concentrations (m) – make it possible to gain an adequate impression of the structure of populations on the basis of data on distribution of individuals within the study plots. It has been established that the spatial structure of populations of rodents naturally changes in the course of multiannual dynamics of the population. During alternation of separate phases reorganizations of the spatial distribution of bank vole populations consisted of changes in the quantity and size of concentrations, and also the density of their placement. A scheme of changes in spatial structure in conditions of cyclic fluctuations of density is presented. Absence of concentration during the depression phase of dynamics is defined by the insignificant number of consumers of environmental resources, which causes a surplus and availability of these resources and is indicated also by the fact that compact distribution of animals interferes with successful realization of reproductive potential. Intensive reproduction and rapid rate of increase in a population, which are characteristic of a growth phase, cause formation and growth of separate concentrations. Increase in their area prevents rapid growth of density within these populations, and action of negative effects of overpopulation is weakened by redistribution of young animals. The phase of peak population causes merging of borders between separate concentrations and the creation of a uniform concentration with a high internal density. Later (decline phase) such concentration breaks up into a number of small concentrations which are concentrated in the most optimum habitats. We found that multiannual pulsation of the spatial structure of a population occurs over absolutely different time periods and is similar to the seasonal pulsation. It is possible to draw analogies between separate phases (years) of dynamics and certain seasons because at such stages the development of populations has similar patterns.

Long-term population patterns of rodents and associated damage in German forestry.

Several rodent species can damage forest trees, especially at young tree age in afforestation. Population outbreaks of field voles (Microtus agrestis L.) and bank voles (Myodes glareolus Schreber) in particular can cause losses. Analyses of long-term time series indicate good synchrony of population abundance in rodent species associated with damage in forestry. This synchrony could be related to the effect of beech (Fagus spec.) mast in the previous year on population growth rates of both species. In shorter time series from Eastern Germany, damage in forestry was mostly associated with autumn abundances of rodents. Environmental factors such as beech mast and snow cover did not explain additional variation in rodent damage to trees. Beech mast is a good indicator of long-term rodent abundance in Northern German afforestation areas. However, rodent damage to forestry in Central Germany did not seem to depend on environmental parameters other than rodent abundance at large scale. As a result, there is still uncertainty about the link between environmental predictors and rodent damage to forestry, and further experimental work is required to identify suitable environmental drivers and their interplay with other potential factors such as the local predator community. © 2016 Society of Chemical Industry.

Identification of Hepatozoon erhardovae Krampitz, 1964 from bank voles (Myodes glareolus) and fleas in Southern Hungary.

In order to investigate the prevalence and life cycle of apicomplexan parasites, small mammals were live-trapped with modified Sherman traps in Southern Hungary between 2010 and 2012. Altogether, 528 rodents (Apodemus flavicollis Melchior, 1834, Apodemus agrarius Pallas, 1771, Myodes glareolus Schreber, 1780, Microtus agrestis Linnaeus, 1761, Mus musculus Linnaeus, 1758 and Micromys minutus Pallas, 1771) were collected and four shrews (Sorex spp.) were by-catched. Captured animals belonging to non-protected species were euthanized, and spleen samples were preserved for histological and molecular analyses. During the examination of spleen smears, Hepatozoon parasites were observed in eight out of 48 bank voles (M. glareolus). DNA was isolated from altogether 221 spleen samples, and 18S rDNA was amplified using two different PCR protocols. The eight bank vole samples were positive with PCR, but none of the other M. glareolus spleen samples or any of the tissue samples from other species were found to be infected. Sequenced amplicons were very similar to Hepatozoon spp. detected in M. glareolus in Spain and Poland. Ectoparasites were collected from the small mammal carcasses and from the vegetation. Hepatozoon DNA was not found in the 181 ticks removed from the small mammals or in the 162 ticks collected with flagging, but was detected in all three flea species (4/43 Megabothris turbidus Rothschild, 1909, 3/10 Ctenophthalmus assimilis Taschenberg, 1880 and 7/78 Ctenophthalmus agyrtes Heller, 1896). Based on gamont morphology, vertebrate and arthropod host species and DNA sequences, the parasites in our study can be identified as Hepatozoon erhardovae.

Quantifying the past and future impact of climate on outbreak patterns of bank voles (Myodes glareolus).

Central European outbreak populations of the bank vole (Myodes glareolus Schreber) are known to cause damage in forestry and to transmit the most common type of Hantavirus (Puumala virus, PUUV) to humans. A sound estimation of potential effects of future climate scenarios on population dynamics is a prerequisite for long-term management strategies. Historic abundance time series were used to identify the key weather conditions associated with bank vole abundance, and were extrapolated to future climate scenarios to derive potential long-term changes in bank vole abundance dynamics. Classification and regression tree analysis revealed the most relevant weather parameters associated with high and low bank vole abundances. Summer temperatures 2 years prior to trapping had the highest impact on abundance fluctuation. Extrapolation of the identified parameters to future climate conditions revealed an increase in years with high vole abundance. Key weather patterns associated with vole abundance reflect the importance of superabundant food supply through masting to the occurrence of bank vole outbreaks. Owing to changing climate, these outbreaks are predicted potentially to increase in frequency 3-4-fold by the end of this century. This may negatively affect damage patterns in forestry and the risk of human PUUV infection in the long term.

Evaluation of abundance of residents and immigration by irretrievable requisitioning of the bank vole (Myodes glareolus Schreber, 1780)

The activity of average statistical species was approximated by normal distribution. This is provided by calculation of the part of resident animals without repeated hatching, i.e., the edge effect. Residence beyond the space covering 99% of species activity was considered as nonresidence. The appearance of nonresidence in general can be considered as "excursions" and "resettlement." The experiments on requisitioning of small settled animals from a preliminary marked site were carried out. It was shown that the number of settled small animals calculated using results of requisitioning corresponds to the number found during labeling with amendment to the edge effect, and immigration was constant and is not initiated by requisitioning. Only resettlements had an influence on the settlement of free space. The expected velocity of settling of the free space was calculated according to evaluation of the value of settlement and the share of "migrants" among immigrants. Second labeling of the place of hatching has shown that the expected and real paces of settlement are close.

Tula Virus in Populations of Small Terrestrial Mammals in a Rural Landscape

Over 5 years (2000-2004), populations of small mammals from a rural landscape in southern Moravia (Czech Republic) were investigated for the presence of Tula virus (TULV) antigen using the ELISA set Hantagnost. In total, 1566 individuals from 10 species were examined. The prevalence in the common vole (Microtus arvalis Pallas 1778), the main reservoir of TULV, was 10% (n = 871). The prevalence of TULV antigen increases with its population numbers. The highest number of TULV antigen-positive common voles was found in set-aside plots and winter crops, such as rape and winter wheat. All these habitats are important for common vole overwintering. Older and heavier individuals were more often hantavirus antigen positive. From the other small mammal species, 186 pygmy field mice (Apodemus uralensis Pallas, 1811) were examined, of which 3 were positive, which represents the first hantavirus antigen positive record for this species, and of 195 wood mice (Apodemus sylvaticus Linnaeus, 1758) only 1 was positive. The remaining five rodent species (Apodemus flavicollis Melchior, 1834, Mus musculus Linnaeus, 1758, Micromys minutus Pallas, 1771, Myodes glareolus Schreber, 1780, Microtus subterraneus de Sélys-Longchamps, 1836) and two Soricomorpha (Sorex araneus Linnaeus, 1758, Sorex minutus Linnaeus, 1766) were hantavirus antigen negative.