Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 29

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  dormouse
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
The circadian and monthly activity rhythms of dormice Glis glis (Linnaeus, 1766) and their foraging for a preferred food source (hazels) have been studied. Dormice showed a monophasic pattern of activity from June to early November. The daily active period started from or after sunset, and ended usually before sunrise. In June and September, however, the foraging was prolonged ca 1 hr after sunrise. This suggests that the active phase is limited by the endogenous cycle of dormouse rather than by photoperiod. Hazelnut intake began in June before the fruits were ripened, and went on until the supply was exhausted, in August.
Life tables for two populations of the common dormouse Muscardinus avellanarius (Linnaeus, 1758) are presented. The mortality rates qx of the common dormouse appeared to be relatively constant and did not follow a typically mammalian "U" shaped curve with age. Mortality rates increased evenly with age both in females and males, in both populations, whereas a decrease in qx was observed only among males in their third year of life. Specific characteristics of the qx curve for the common dormouse include the relative longevity of this small rodent, and rather constant mortality during hibernation in all years of life.
The factors influencing the presence/absence of the edible dormouse Glis glis (Linnaeus, 1766) in forest fragments in Mediterranean central Italy were investigated by performing repeated nocturnal surveys in 38 woodlots. The various woodlots were different from each other in terms of area, degree of isolation, and floristic and structural characteristics. The effects of different types of forest management and human activities on dormouse distribution were also analysed. Dormice occurred in all the surveyed high forests, while no sign of their presence was detected in coppices with a rotation cycle short (<18 years). There were significant differences between coppices and high forests, but not between grazed and ungrazed woodlots, and rotational and non-rotational forests. Correspondence analysis corroborated the empirical evidence, showing a close association between presence of dormice and high forests, and, to a lesser degree, rotational forests. Concerning environmental parameters, favourable woods were those with high trees and with low stem number, while the specific tree assemblages proved to be scarcely important. Wood area was more important than isolation in predicting presence or absence of this rodent, as the highest probability was associated with woodlots of 40-50 ha area and more. These results did not provide evidences about the importance of the amount of residual habitat in the 10 km2 surrounding the woodlot and the presence of hedgerows as ecological corridors.
The autumn diet of the edible dormouse Glis glis Linnaeus, 1776 in northwest Spain was investigated on the basis of analysis of the stomach contents of 32 indi­viduals captured in September and October of 1985 and 1986. Remains of Quercus robur acorns and Corylus auellana hazelnuts accounted for 86.5% of the total dry weight of the 32 samples, while blackberry remains accounted for 10.2%. Remains of vegetative plant structures (leaves, etc) accounted for only 3.3% of total dry weight. Insect remains were frequently present, but in very small amounts (about 0.01% of total dry weight). Dormouse hairs and ectoparasites were also frequently present, presumably as a result of accidental ingestion during grooming.
A karyotype of 2n = 52 chromosomes was found in twoEliomys quercinus (Linnaeus, 1766) specimens from two different localities of Tirol (Austria). The karyotype is similar to the one described in the Italian Alps, suggesting that these mountains were not a barrier to the northern expansion of this chromosomal race.
Food resources and population density are key factors influencing spatiosocial organisation. We compared the space use of two dormiceGlis glis (Linnaeus, 1766) populations differing in density, one high and the other low, in a breeding year 2002 (when trees masted) and in a non-breeding year 2001 (with reproductive failure and a total lack of mast). In the low-density population males always had larger home ranges and travelled longer distances than females. In the high-density population such differences between sexes became significant only in the breeding year. Home ranges and distances travelled each night were larger in the low-density population, but only for males.
Adult Muscardinus avellanarius (Linnaeus, 1758) were found to be sedentary, showing small home ranges. The mean range area for males (n = 46) throughout their active season was 1.0 ± 0.05 ha, whereas for females (n = 33) it was 0.8 ± 0.05 ha. Male home ranges partially overlapped those of females and each other, whereas female home ranges hardly ever overlapped. In separate years adult dormice were sometimes found to change their home ranges. Dispersal was a necessary stage in the life of the young. The mean distance travelled from the birth place by young born in May-July (it = 65) was 360 ± 30 m, whereas the distance travelled by young born in August-September (n = 109) was 130 ± 10 m. The greatest travelled distance was 1200 m. About 90% of the young that survived the first winter became sedentary in the first autumn of their life, the remainder during the following spring.
Mammals are common predators on bird nests. However, their species identity frequently remains unknown. Here we present long-term data (1975–2005) from a central European woodland on the predatory effect of three dormice species (Rodentia, Gliridae) on cavity-nesting birds. Dormice are mostly frugivorous during the active late-summer season, but shortly after they terminate hibernation, they frequently depredate cavity-nesting-bird nests. The seven bird species studied, lost on average between 2.9 to 18.4% of their broods. MigratoryFicedula flycatchers suffered the highest brood losses, while the residentParus titmice and the nuthatchSitta europaea had much lower brood losses. The three dormice species differed significantly in their predatory effect during different avian breeding stages. The edible dormouseGlis glis (Linnaeus, 1766) depredated both eggs and nestlings equally, while the common dormouseMuscardinus avellanarius (Linnaeus, 1758) and the forest dormouseDryomys nitedula (Pallas, 1778) destroyed more nests during egg laying and the incubation period. Among adult birds, females were taken more frequently by dormice than males. Among avian species, adultFicedula flycatchers were more often depredated than the titmice and nuthatch. Our study provided further evidence, that among the traditional studies on the costs of reproduction, parental mortality at the nests needs to be considered and that incubating or brooding females might be under higher predation risk than the males.
The structural materials of twenty one nests of the Japanese dormouse Glirulus japonicus (Schinz, 1845) collected at Mt Fuji and Mt Akadake in 1988, were analyzed. Fifty seven species of bryophytes were found: 42 species of Musci and 15 of Hepaticae which constituted the major portion of the materials sampled. Most of these species were epiphytes on tree trunks, and this confirms the supposition that the Japanese dormouse uses arboreal space.
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.
The response of common dormouseMuscardinus avellanarius Linnaeus, 1758 population to availability of nest sites was studied by manipulating the nestbox grid and ring-marking dormice. Abundance of adult dormice more than doubled in the 25 × 25 m nestbox grid in comparison to the 50 × 50 m grid, as a result of increased nestbox density from four to 16 boxes/ha. This effect already became apparent in the first year after additional nestboxes were made available and resulted from dormouse immigration, mostly from adjacent areas without nestboxes. In the second and third years, the number of two-year-old and older resident dormice, which had their home ranges in this plot, increased considerably. The average size of dormouse home range decreased by approximately half both in males and females in the 25 × 25 m grid compared to the 50 × 50 m grid. The proportion of breeding adult females did not differ between the two grids in spite of different adult dormouse density. Shortage of secure nest sites was a limiting factor for the common dormouse population abundance in the forest where natural tree hollows were absent, and high nestbox density increased environmental carrying capacity.
The dormouse Eliomys quercinus is a forest rodent undergoing long periods of winter hibernation. The species presents a surprisingly large diversity of chromosomal races, which geographic distribution was shown recently to predate the Pleistocene glaciations. Previously reported data on the karyotypes of the garden dormouse in France come from the northeast of the country, where the 2N = 50 race occurs. New data are presented from specimens trapped near the Atlantic coast (departments of Vendée and Charente-Maritime), in the Pyrenees, the Alps and in the Massif Central. The French Alpine chain, close to the Italian border, is inhabited by the 2N = 54 race. A karyotype with 2N = 48 chromosomes, of Iberian type, is found north of the Pyrenees, near the central Atlantic coast and also in the south of the Massif Central, whereas the 2N = 50 race occurs in the north of the massif. A hybrid between these two races (2N = 49) was found in Vendée. These facts reveal that neither the Pyrenees nor the Alps constitute a biogeographic barrier to the dormouse and strongly suggest that the present population of northern France derives from a postglacial recolonisation movement initiated in the southernmost regions of France or in the Rhône valley.
We studied the seasonal and annual variation in diet composition of the fat dormouse (Glis glis) in Lithuania, a locality situated on the northern periphery of the dormouse range and outside of the range of the European beech (Fagus sylvatica). After emergence from hibernation, dormice fed on oak acorns (from the previous year), inflorescences of various trees, vegetative parts of plants and food of animal origin (birds, their eggs and insects). In June, soft mast and seeds of birches supplemented the dormouse diet, and diet composition was the most diverse during this period. In July, raspberries and fruits of glossy buckthorn constituted the bulk of dormouse diet, but seeds of birches dominated in a specific year. Hard mast (mainly acorns) dominated the diet of G. glis from August until the beginning of hibernation in October. A high prevalence of acorns, comparatively high proportion of birch seeds and low proportion of food of animal origin in the diet, as well as feeding on fruits of glossy buckthorn, are specific features of feeding by G. glis in Lithuania. The diet of G. glis on the northern periphery of its range resembles its diet on the eastern periphery of the range where beech trees are also absent. According to the composition of G. glis diet, feeding conditions in both of these peripheral regions are poorer in comparison to central or southern regions.
The Gliridae from three Late Miocene localities of the Republic of Moldova – Chimishliya (age MN12), Gura Galbene (MN12), and Gradishte (MN11/12) are described and their taxonomic position discussed: two are assigned to Myomimus, one each to Vasseuromys, Muscardinus and Gliridae gen. and sp. indet. The most abundant fossil remains were found in Chimishliya (nine teeth) and the most taxonomic diversity was observed in Gura Galbene (Myomimus dehmi/maritsensis, Myomimus sp., Muscardinus and Gliridae gen. and sp. indet). Discovery of the specimen of Muscardinus from Moldova fills the stratigraphic gap of genus occurrence between MN11 and MN14 in Europe. Scarcity of fossil remains does not allow for reconstruction of the transformations of the dormice fauna, though presence of particular genera is indicative of specific palaeoenvironment conditions in the Late Miocene of Moldova.
Fresh faeces of dormice found in nestboxes along the permanent transect in Białowieża Forest were analysed. The study area was a managed forest of diverse biotopes. In total, 196 samples of faeces of the forest dormouse (Dryomys nitedula) and 62 of edible dormouse (Glis glis) were examined. In the faeces analysed, the following categories of food remains were distinguished: chitin carapaces, calcareous shells, feathers, seeds, plant fibres. In the forest dormouse, chitin carapaces were found in 100% of samples, but in only 8% of the edible dormouse samples. Feathers were noted in 36% of samples of forest dormouse faeces, but only in 12% of samples from the edible dormouse. Calcareous shells were found in 14% of forest dormouse samples and 1.6% of edible dormouse faeces. Remains of animal food were found in 100% of samples of forest dormouse excrements, but only in 29% of samples from the edible dormouse. The highest percent of faecal samples with animal remains was found in the edible dormouse in July, while in the forest dormouse seasonal variation occurred only in some types of animal remains. Most of the chitin carapaces identified in forest dormouse faeces came from Chilopoda (45%), Hemiptera (33%) and Coleoptera (22%). In faeces of the edible dormouse the majority were remains of butterflies (55%). The results presented here suggest an almost total separation of the food niches of the two dormouse species.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.