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The reliability of the estimation of residency time of the bank vole Clethrionomys glareolus (Schreber, 1780) and the yellow-necked mouse Apodemus flavicollis (Melchior, 1834) in open populations was assessed by halving the 6-week intervals between trapping sessions. The status of "single-capture" individuals was identified to estimate the probability that they are native young rather than adult invaders. We found that the majority of "single-session" individuals constituted true transients that were present in the study plot for a short time only. They were young, immature rodents with a small body mass and a small number of captures. The probability that the "single-session" individuals stay on the plot for a longer time was 0.35 and 0.37 for voles and mice, respectively. These ostensible transients were trap-prone, fully-grown, mature adults, that revealed their presence on the plot already at the beginning of each trapping session. We found that "single-capture" individuals were mainly young, immature rodents that were not retrapped. The probability that the single-capture rodents are mature individuals, with a longer residency time, was 0.10 and 0.18 for voles and mice, respectively.
A change of B-chromosome frequencies in the population of Apodemus flavicollis (Melchior, 1834) from Cer mountain in Yugoslavia was studied. Five samples were collected during 1989. Specimens with Bs were present in all samples with frequencies ranging from 0.22 to 0.39. Differences between frequencies of animals with Bs in successive samples were not statistically significant. The change in the population size (n) was positively correlated with variation in frequency of animals with Bs (rp = 0.81), but negatively with frequency of Bs per B carrying animals (rp = -0.65). A analysis of variance of external body measures and some cranial characters showed no significant differences between animals with and without Bs.
Populations of two species of woodland rodents were studied: Apodemus flavicollis (A. f.) and Clethrionomys glareolus (C. g.)t inhabiting a set of small wood patches, isolated from large, continuous forest. The species composition, density and population dynamics differed from those in the forest. The rodents used the entire area as a patchy habitat, moving between the woodlots. In the breeding season high mobility caused higher mortality among males, especially in C. g. Sex ratio in C. g. was female biased. In A. f. females prevailed in spring whereas there was a prevalence of males in autumn. Seasonal changes in age structure followed different patterns in females and males. Males prevailed in first spring litters in both species. Males also prevailed among numerous immigrants of A. f. but females prevailed among immigrants of C. g. The demographic processes in these species resulted from habitat fragmentation and different life strategies.
Multiple paternity has been described in a wide range of taxonomic groups (eg invertebrates, fish, reptiles, birds, mammals). In rodents, multiple paternity seems to be common and can lead to both genetic (eg increase in offspring diversity, avoiding inbreeding) and direct (eg higher survival rate of the litter) benefits. The primary aim of this study was to confirm multiple paternity and evaluate its frequency in a wild population of yellow-necked mouseApodemus flavicollis (Melchior, 1834). Animals were trapped in north-eastern Poland in 2004–2006. Five microsatellite loci previously described for members of the genusApodemus were used to examine the occurrence of multiple paternity among the offspring of 10 pregnant females. The analyses were performed using multiplex PCR, estimating the length of amplified fragments with an automated sequencer. The presence of additional alleles indicating multiple paternity was found in 30% (3 out of 10) of the investigated litters. Offspring fathered by a single male were predominant in each litter, with the proportion of individuals originating from other males varying from 16.7 to 20% in the three multiple paternity cases. Our findings indicate that the promiscuous mating system may be considered as an alternative breeding strategy in the yellow-necked mouse.
An unique observation was made when an adult yellow-necked mouse Apodemus flavicollis (Melchior, 1834) attacked a dead bank vole Clethrionomys glareolus (Schreber, 1780).
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.
Reduced connectivity among local populations inhabiting a spatially heterogeneous landscape may restrict gene flow and thus contribute to diminished genetic variation within a population. The aim of this study was to determine the role of geographic distance and habitat barriers in developing genetic structure of a yellow-necked mouse Apodemus flavicollis (Melchior, 1834) population, taking into consideration the spatial organization of the landscape. A field study was carried out in two plots located in NE Poland that differed considerably in terms of the scale of habitat fragmentation: (1) a continuous forest complex, and (2) a mosaic of smaller forest habitats. The plots were separated by a water barrier comprised of a chain of lakes. DNA samples from a total of 654 individuals were examined by microsatellite analysis (5 loci). The results showed that the yellow-necked mouse population was characterized by a poorly pronounced genetic structure throughout the study area, although the statistical significance of F ST for most location pairs indicated that gene flow in the area was not free. The division of the mouse population into three genetically distinct groups clearly demonstrated the significant role of water bodies as a natural barrier effectively hindering free movement of animals and thus gene flow. Analysis of the genetic structure of the mouse population throughout the study area and also within the distinguished groups indicated that the entire study population may be considered as a single metapopulation. Our results suggest that geographic distance alone is not the predominant factor affecting the genetic structure of population, but in the mosaic landscape the relative isolation of individual forest fragments, and barriers hindering movements of individuals and limiting gene flow among local populations played a much more important role.
We used museum collections to study temporal trends of possible changes in skull size, body mass and body length in three species of rodents in Denmark. Skulls of adult Microtus agrestis, Apodemus flavicollis and Apodemus sylvaticus, collected between 1895 and 2004, 1847 and 2002, and 1895 and 2002, respectively, were measured and data on body mass and length were taken from the museum registers. Principal component (PC) analysis was used to combine data of the four skull measurements taken. We tested the relationship of sex, latitude, longitude, month and year of collection to PC1 by a General Linear Model (GLM). PC1, body length and body mass of M. agrestis significantly increased from west to east. In addition, PC1, body mass and body length of M. agrestis declined from summer (August) through autumn and winter to spring (March), probably due to the decline in food availability towards winter. None of the other factors examined (sex, latitude and year) were significantly related to body size. PC1 of A. flavicollis and A. sylvaticus was not significantly related to any of the environmental factors examined.
The importance of Robinia pseudo-acacia stands as a food supply for four species of small mammals, Apodemus sylvaticus (Linnaeus, 1758), A. flavicollis (Melchior, 1834), Clethrionomys glareolus (Schreber, 1780), Microtus arvalis (Pallas, 1778) was studied. The trophic diversity and equitability in all rodent species suggested a rich food supply. Greater trophic overlap as well as greater qualitative and quantitative similarity of food was found in both species of Apodemus only. Robinia stands not only represented a refuge but also offered enough food for all four species of rodents.
The presence of B chromosomes in the yellow-necked mouse Apodemus flavicollis (Melchior, 1834) was analyzed in 320 adult animals from four localities in Yugoslavia. Our aim was to assess the effects of B chromosomes on certain morphometric charac­teristics. The characters that were chosen are included in the taxonomic discrimination of this particular species as well as the sibling species Apodemus sylvaticus (Linnaeus, 1758). B chromosomes were found in all the localities with frequencies ranging from 21.6% to 42.9%. It was ascertained that different frequencies of animals with B chromo­somes change the slope of the regression curve of the length of foramina incisiva (FI) relative to the distance from the 3rd upper molar to the incisor (IM3). This finding questions the validity of use of this relative value in taxonomy without taking into consideration karyological data. It was also established that the relative length of the tail (the body/tail ratio) significantly increase in the presence of B chromosomes. As this index demonstrates significant geographic variability the result could be taken as a trend only.
Feeding habits of field mice Apodemus flavicollis Melchior, 1834 and A. sylvaticus Linnaeus, 1758, and bank voles Clethrionomys glareolus Schreber, 1780 in a mixed farmland area in Northern Germany were investigated from March to December 1992. For semi-quantitative analysis of diet composition, faeces were sampled in the margins of an arable field surrounded by hedgerows. Diets of both A/jocfemus-species were similar, with A. flavicollis tending to eat more animal food and less green plant matter. Except in the early summer, C. glareolus consumed less animal matter than both Apodemus-species, but not consistently more green plant matter than A. sylvaticus. Beech flowers were important food for all species in May, whereafter rye grain became the dominant food item until August. In the autumn and winter, field mice took beechmast and acorns, while bank voles ate berries and fungi, and in December, large amounts of grass leaves. Dietary overlap was, altogether, highest from May to August (about 0.8). Overlap between A. flavicollis and A. sylvaticus dropped moderately after the summer, while that between C. glareolus and either Apodemus-species decreased sharply to levels of 0.2 and lower. Increased probability of competitive interaction between the species in the autumn and winter, corresponding to a more patchy distribution of food resources than in the summer, is discussed as a possible reason for the observed divergence of food habits,
The occupancy of Muscardinus auellanarius (Linnaeus, 1758) nest boxes by Apo­demus flauicollis (Melchior, 1834) and A. sylvaticus (Linnaeus, 1758) was studied over a six-year period from five sites in southern Britain. A. flauicollis was a regular visitor to nest boxes, occupying them more frequently than A, sylvalicus or any other small mammal. Litters of A. flauicollis were uncommon in nest boxes suggesting these boxes were rarely used for breeding. It seems likely that nest boxes form temporary nesting places for individuals, pairs or small communal groups. A. flauicollis sometimes take over nest hoxes occupied by M. avellanarius, usually constructing their own nests and sometimes removing old nest material. M. avellanarius may avoid nest boxes occupied by A. flauicollis earlier in the same year. Boxes favoured by M. auellanarius in one year tended to be reselected by them in the following year, but no such trend was apparent in box selection by A. flauicollis. Overall, there was little evidence to suggest that the presence of A. flauicollis had a significant impact on M. avellanarius occupancy of nest boxes.
We examined a total of 73 Microtus arvalis, 168 Clethrionomys glareolus and 17 Apodemus flavicollis trapped in the Mazury Lakes district of North-Eastern Poland, in the spring, summer and autumn of 1998. Three M. arvalis, (2 in summer and 1 in autumn) carried Ehrlichia sp. (overall prevalence = 4.1%), whereas infection was not detected in the other rodent species. We hypothesize that Ixodes ricinus (the most common tick in the region) with which the animals were heavily infested, constitutes the likely natural vector for this pathogen and that M. arvalis are its natural reservoir.
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