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Content available remote Landscape approach to bank vole ecology
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The effects of spatial distribution and variability of suitable habitat patches in a landscape on metapopulation dynamics of bank vole, Clethrionomys glareolus are presented and discussed. Numerous examples of field data are presented. Some results of modelling the effects of spatial characteristics of the landscape on bank vole metapopulation survival probability are presented and discussed.
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Multi-annual dynamics and population structure of the bank vole in three localities of southern West Siberia is analyzed. Relative abundance of voles tended to decrease towards the perphery of the range. The summer abundance correlated significantly with certain weather parameters of previous winter or spring season. No correlation between maturation rates in youngs-of-the-year and density was observed. Population dynamics of the bank vole in southern West Siberia is governed primarily by environmental factors. This is due to non-optimal climatic conditions on the periphery of the species range causing high winter morality and ultimately, maintaining low level of density on which self-regulatory mechanisms are not involved.
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Bank voles Clethrionomys glareolus Schreber, 1780 were first discovered in Ireland in 1964. They are confined to the south-west and, judging by their rate of spread, are a recent introduction. Mitochondrial DNA was extracted from 81 bank voles from 5 localities. Only 2 haplotypes were observed, indicating that the founder population was small. There were marked differences in the relative frequencies of haplotypes between sites. These are most readily explained by local founder effects brought about by the habitat preference of this rodent and sustained by the territorial behaviour of females.
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The distribution and three-dimensional structure of the lingual papillae were studied by means of scanning electron microscopy. The elongated tongue in the bank vole is about 12 mm in length and about 3 mm in width. The characteristic features of the tongue are the median sulcus on the apex of the tongue, considerable narrowing in the body of the tongue and a well developed intermolar prominence. On the surface of the apex and body of the tongue three morphological types of the filiform papillae and fungiform papillae were observed. The intermolar prominence of the tongue is covered with conical and saw-like filiform papillae. On the posteriolateral margin of the intermolar prominence two foliate papillae were found. A single oval vallate papilla was situated in the median line of the anterior part of the root of the tongue. The posterior part of the lingual root is flat without papillae. The distribution and types of the lingual papillae found in the bank vole are similar to those in species of the Microtinae family.
EN
The whole rodent community (eight arvicoline species) has been followed at Pallasjarvi, at the northern limit of Clethrionomys glareolus in Finnish Lapland, since 1970. Dynamics were cyclic until the mid 1980's but since then the pattern has been stable. Also the species abundances have changed. The delayed density dependence, characterising the cyclic period, is not found during the stable period. Causes for this change in cyclicity are discussed. The bank vole is the most common rodent species in forests up to its northern limit. The long-term, Year around live trapping studies and feeding experiments suggest e.g. that delayed maturation of young is not optimal but due to social constraints. Food addition resulted in higher densities, but the effect on the density-dependent structure was negligible and the dynamics were not affected by food addition.
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Content available remote Regional differences in dynamics of bank vole populations in Europe
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Fluctuation patterns of bank vole populations were reviewed for central and north-western Europe. Many fairly stable populations occur in central and western Europe while clearly cyclic populations, with an interval of 3-4 year between peaks, are typical for northern Fennoscandia. There is a transition zone around 60 stopni N. In forests in central Europe dominated by oak, and less so by beech and lime, bank vole populations demonstrate outbreak dynamics with peaks at 6-9 year intervals, related to mast seeding. Both cyclic and outbreak populations show pronounced annual variations in reproduction and survival. Community conditions are described for these types of populations and annual variations in food supply are denoted. Isolated (island) populations are characterised by generally high densities and high adult survival. Factors that have been suggested to explain the various dynamics differ: predation and food for cyclic performance, food alone for outbreaks and social factors within circumscribed populations.
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Industrial factors exert considerably influence on the level of bank vole abundance and dynamics in numbers of the bank vole by decreasing habitat quality and disturbing the balance of reproduction, mortality and migration. As a result of industrial degradation and fragmentation of habitats, accompanied by the reduction of their ecological capacity and area, the level of the bank vole abundance is considerably reduced. The dynamics in numbers of the bank vole in impact populations is characterized by a lower leveland an increased amplitude of dynamics. At significant industrial loads, dynamics in numbers lose periodicity and are characterized by a longer phase of depression
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Content available remote Predation and the dynamics of the bank vole, Clethrionomys glareolus
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Theoretical analyses and data suggest that the interaction between bank voles and their predators generates a locally stable equilibrium, regardless to the composition of the predator guild. The suggested primary proximate source for stability is female territoriality. Predation_per se_appears to be destabilizing. Whether or not predation regulates bank voles appears thus to be a semantic issue, depending on the operational definition of the concept of regulation. Confusion has arisen as different operational definitions have been tacitly used by different authors. The predicted intrinsic stability of bank vole-predator systems is most clearly displayed in the southern part of the boreal zone. Currently, even the dynamics of bank voles of taiga landscapes in Finnish ?apland are close to the predicted multiannual stability. In those boreal areas, where grassy and productive Microtus habitats are relatively abundant, sustained, multiannual cycles appear to be generated by the interaction between small mustelids and Microtus spp. When desities of Microtus decline, fidelity to Microtus habitats becomes suboptimal for predators. Consequently, cyclicity seems to be externally imposed on bank voles, due to changing habitat preferences of predators during the course of the mustelid-Microtus cycle. In the temperate zone, masting (seed crops of deciduous trees) increases the reproductive rate of bank voles and ameliorates female territoriality, initiating a transient increase in the numbers of bank voles and their predators. Beforethe system reaches its new equilibrium, the mast is over. Due to the combined effect of high predator numbers and normal reproductive performance, bank vole numbers then decline to the low level typicalfor post-mast years. Depending on the frequency of masting, the post-past low can be followed by a stable phase or immediately by a new mast-triggered outbreak. Although fundamentally different mechanisms appear to account for multiannual density fluctuations in temperate and boreal bank vole populations, both phenomena can be interpreted as consequences of extremal perturbations upon intrinsically stable predator-prey systems.
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The present knowledge of the helminth fauna and ecology of helminths in the bank vole Clethrionomys glareolus is reviewed, with special emphasis on the geographical variability of helminth assemblages. The helminth fauna of bank vole is highly predictable throughout its distribution range, with the possible exception of England and Wales. In the latter region, helminth species diversity was lower and species dominance relationships were different, compared with those on the continental regions. The patterns of seasonal and long-term population dynamics of helminths are reviewed, showing that life-cycles do not determine the patterns of seasonal variability of helminth populations. Although some helminth species show patchy spatial distribution in the field, (high) aggregation of helminth species among host population is shown to pe due to differences between host individuals in exposure and/or susceptibility, rather than spatial heterogeneity on a higher scale. Two unpublished experiments show that the ubiquitous helminth species of bank voles, Heligmosomum mixtum (Nematoda), has the potential to act as a mortality factor if the quality of the host diet is poor, but bank vole populations are unlikely to be regulated by this nematode.
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Roads and highways represent one of the most important anthropogenic impacts on natural areas and contribute to habitat fragmentation, because they are linear features that can inhibit animal movement, thereby causing barrier effects subdividing the populations adjacent to the roads. The paper examines to what extent a narrow (2-lane) and a wide (4-lane) highways represent barriers for two small mammal species: bank volesClethrionomys glareolus Schreber, 1780 and yellow-necked miceApodemus flavicollis Melchior, 1834, and whether displaced rodents are able to return across roads of different widths. The study was performed at four sites in the Czech Republic. The capture-mark-recapture method was used to determine crossing rates. At two sites, the animals captured close to the road were transferred to the other side and released, to compare return movements across the roads with the movements made by the non-transferred animals. We found that the narrow highway did not prevent movement of neither of the species, although voles crossed only after they had been transferred. Wide highways, on the other hand, completely prevened crossing of both species. While the narrow highways acted at individuals level, the wide highways affected the population subvision.
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The aim of the study was to test a hypothesis that small rodents in natural con­ditions are able to distinguish between the scents of neighbour (N) and stranger (S) individuals of conspecific. Experiments were carried out in a 100-year-old alder forest of the association Circaeo-elongatae Alnetum (Koch. 1926), on a population of bank voles Clethrion.om.ys glareolus (Schreber, 1780). Experiment I found higher capture rates in traps with the scent of N individuals (n = 35) and showed that the rodents could distinguish between N and S scents. Analysis of 90 sheets of Bristol board laid down in the forest in experiment II showed that rodents left significantly more traces of faeces and urine on sheets with the N scents. Experiment III showed that at distances of as much as 200 m from the place of origin of a donor there had been no decrease in the interest of other voles in its scent. Experiment IV increased the distance at which a fall-off in interest in the N scent was sought. As a result of 856 observations of the reactions of voles to the scents of donors originating at different distances, it was found that voles treated as N individuals those donors coming from distances of up to about 1000 m. Analysis of 840 sheets of Bristol board with scents of donors originating between 200 and 1400 m away used in experiment V showed that those smelting of donors from 1200 and 1400 m away were visited significantly less often by the rodents than others. A distance of around 1000 m may thus be the threshold for a decline in the interest of rodents in the N scent.
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