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2. Distribution of the common hamster in the Czech Republic after 2000: retreating to optimum lowland habitats
- Creator:
- Tkadlec, Emil, Heroldová, Marta, Víšková, Veronika, Bednář, Marek, and Zejda, Jan
- Type:
- article, model:article, and TEXT
- Subject:
- Cricetus cricetus, questionnaire, and Rodentia
- Language:
- English
- Description:
- Abundances of the common hamster in western Europe declined dramatically over the last 30 years. Recently, severe restrictions in distribution range have also been reported from central European countries. Here we update knowledge of the hamster distribution range in the Czech Republic based on information from six independent sources: (1) monitoring programme for the common vole carried out by State Phytosanitary Administration, (2) monitoring carried out directly by us, (3) questionnaire data from farming companies, (4) questionnaire data from district museums, (5) data from a public server BioLib for mapping species distribution, and (6) observations from nonrelated research activities and persons taking interest in hamsters. The comparison of locations detected after 2000 with those from the last survey > 30 years ago suggests that the range is severely reduced with hamsters retreating to the optimum lowland habitats along large rivers. These results suggest that the demographic mechanisms causing population decline in western populations operate in central Europe as well.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Food selection of Microtus agrestic in air-pollution affected clearings in the Beskydy Mts, Czech Republic
- Creator:
- Heroldová, Marta, Zima, Jan, Griffiths, Huw I., Burda, Hynek, and Sedláček, František
- Type:
- article and TEXT
- Subject:
- field vole, diet, air pollution clearings, and impact on forest regeneration
- Language:
- English
- Description:
- The small mammal community of an air pollution affected area of the Beskydy Mts was studied over a seven-year period. Highest dominance and population density values were found in the field vole (Microtus agrestis) and its feeding ecology and negative impact on reforestation have been evaluated. The vegetative parts of plants, particularly those of monocotyledons, were dominant in vole diets, mainly as the area is largely occupied by the invasive plant genus Calamagrostis. In early spring (i.e. before the growing season started) grasses predominated in the field vole's food (74 % of volume, v). Bark was also consumed to some extent - its importance index value (I) was 4 %. In spring (i.e. after the growing season started) grasslike species were again preferred (v = 57 %) but flowers of Vaccinium myrtillus were also consumed (v = 20 %). Even in autumn grasslike species prevailed (v = 36 %), however, the diet was more diverse and seeds and fruits (v = 30 %) were also eaten. of these the basic food items were those of V. myrtillus (v = 16 %) and of herbs and ferns (v = 16 %) including Oxalis acetosella (v = 14 %). An increase in fungi in the diet was found in autumn. Diet availability and early spring and spring diets ere highly correlated, but this was not the case in autumn. The extent of vole damage to tree regeneration in 3,027 saplings was studied. The frequency of damage was significantly greater in deciduous tree species (15 %). Coniferous tree transplants were attacked only rarely (1.4 %), and usually when the tree was already in poor condition. The greater degree of damage caused to natural and artificial forest regenetarion can only be associated with high vole population densities.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/
4. Measurement error in a burrow index to monitor relative population size in the common vole
- Creator:
- Lisická, Lenka, Losík, Jan, Zejda, Jan, Heroldová, Marta, Nesvadbová, Jiřina, and Tkadlec, Emil
- Type:
- article and TEXT
- Subject:
- bias, colonisation, dispersion, Microtus arvalis, precision, and sampling error
- Language:
- English
- Description:
- Various population indices are widely used to monitor relative population size of many pest and game species to aid their management. However, information on the level of uncertainty associated with their estimates is rarely available. Here we explore sampling and systematic error associated with the index of re-opened burrow entrances which is used extensively in central Europe for surveying common vole populations. We found that relative sampling errors were enormous for low-density populations, attaining almost 400%. However, in high-density populations and for large sample sizes, the relative error dropped below 10% and the estimate is quite reliable. The dispersion of burrow entrances became more clumped at low population densities enhancing further the sampling variation. We demonstrated that the index is related to population size in a non-linear fashion, overestimating the population change at high densities. Consequently, population dynamics of the common vole described by the untransformed burrow index appear more variable than they are in reality.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/
5. Set-aside plots - source of small mammal pests?
- Creator:
- Heroldová, Marta, Jánová, Eva, Bryja, Josef, and Tkadlec, Emil
- Type:
- article and TEXT
- Subject:
- abandoned fields, succession, and rodents
- Language:
- English
- Description:
- Succession of weeds and small mammal species was studied and compared on alfalfa field in two periods (cultivated 1996–1998 and set-aside 2001–2003). Composition of the plant community changed between the two periods of study. In the first period high biomass of green alfalfa biomass was available to the common vole which dominated small mammal community (88.7 %) and pronounced variation in maximal autumnal densities, typical of cyclic vole populations. Massive invasion of seed bearing weeds was stated after the field was set-aside and alfalfa biomass lowered. With the succession of weeds other rodent species such as Apodemus sp. increase their relative abundance (RA) and that of the pygmy field mouse was higher in the abandoned field compared with the common vole. The trend toward increasing RA was quite distinct (Z = 1.883; P = 0.060). Diversity of herb species and the small mammal species increased with abandonment. The monthly RA of the common vole was, on average, lower in the abandoned field than in the former period (Z = 2.353, P = 0.019). Also the cyclicity disappeared and RA of the population exhibited only seasonal oscillations. Biomass of the small mammal community decreased after the field was set-aside (Z = 3.021, P = 0.002).
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/
6. White-tailed deer winter feeding strategy in area shared with other deer species
- Creator:
- Homolka, Miloslav, Heroldová, Marta, and Bartoš, Luděk
- Type:
- article and TEXT
- Subject:
- Capreolus capreolus, Cervus elaphus, Czech Republic, Dama dama, diet analysis, fallow deer, Odocoileus virginianus, red deer, and roe deer
- Language:
- English
- Description:
- White-tailed deer were introduced into the Czech Republic about one hundred years ago. Population numbers have remained stable at low density despite almost no harvesting. This differs from other introductions of this species in Europe. We presumed that one of the possible factors preventing expansion of the white-tailed deer population is lack of high-quality food components in an area overpopulated by sympatric roe, fallow and red deer. We analyzed the WTD winter diet and diets of the other deer species to get information on their feeding strategy during a critical period of a year. We focused primarily on conifer needle consumption, a generally accepted indicator of starvation and on bramble leaves as an indicator of high-quality items. We tested the following hypotheses: (1) If the environment has a limited food supply, the poorest competitors of the four deer species will have the highest proportion of conifer needles in the diet ; (2) the deer will overlap in trophic niches and will share limited nutritious resource (bramble). White-tailed, roe, fallow, and red deer diets were investigated by microscopic analysis of plant remains in their faeces. The volume of bramble decreased in the diet of all four deer species from November to March. The content of conifer needles in the diet of white-tailed and roe deer was negatively correlated with bramble and in spring made up 90 % of their diet volume. On the other hand conifer needles in the diet of red and fallow deer occurred only in January with snow cover. Fallow and red deer started the compensation of winter starvation at least one monthearlier than both roe and white-tailed deer. a high content of conifers in white-tailed deer diet in the second half of the winter fully support the presumption about low nutritional food supply and its diet. It can lead to a markedly impaired condition for white-tailed and roe deer and negatively affect their condition. The dietary overlap of four sympatric deer species was extensive in winter. All species share a limited good quality food supply (bramble) when food is scarce, suggesting that interspecific competition may occur.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/