An index method of estimating relative population densities of the Common Vole (Microtus arvalis) at landscape scale
ABSTRACT Many issues in fundamental and applied ecology require the use of sampling protocols at the sectoral or even regional scales at which many important ecological mechanisms occur. The lack of workable sampling methods at these scales is a major obstacle to the analysis and understanding of these mechanisms. We test the validity of an index method of estimating relative population densities, applicable along transects of several kilometers in length, for a population of Common Voles (Microtus arvalis). The results show that the index method of estimating relative density is well adapted for monitoring variations in the abundance and spatial distribution of Common Vole populations and authorizes studies for a wide range of objectives and spatial scales.
Full-textDOI: · Available from: Patrick Giraudoux, Sep 27, 2015
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- "The score of relative density of E. tancrei was the number of intervals where fresh E. tancrei indices could be observed (see e.g. Giraudoux et al. 1995; Quéré et al. 2000). The NDVI (Normalized Difference Vegetation Index), an index commonly used to estimate the relative density of plant cover, was computed from a Landsat ETM image acquired the 16th of June 2004. "
ABSTRACT: SUMMARY From continental to regional scales, the zoonosis alveolar echinococcosis (AE) (caused by Echinococcus multilocularis) forms discrete patches of endemicity within which transmission hotspots of much larger prevalence may occur. Since the late 80s, a number of hotspots have been identified in continental Asia, mostly in China, wherein the ecology of intermediate host communities has been described. This is the case in south Gansu, at the eastern border of the Tibetan plateau, in south Ningxia, in the western Tian Shan of Xinjiang, and in the Alay valley of south Kyrgyzstan. Here we present a comparative natural history and characteristics of transmission ecosystems or ecoscapes. On this basis, regional types of transmission and their ecological characteristics have been proposed in a general framework. Combining climatic, land cover and intermediate host species distribution data, we identified and mapped 4 spatially distinct types of transmission ecosystems typified by the presence of one of the following small mammal 'flagship' species: Ellobius tancrei, Ochotona curzoniae, Lasiopodomys brandtii or Eospalax fontanierii. Each transmission ecosystem had its own characteristics which can serve as a reference for further in-depth research in the transmission ecology of E. multilocularis. This approach may be used at fine spatial scales to characterize other poorly known transmission systems of the large Eurasian endemic zone, and help in consideration of surveillance systems and interventions.Parasitology 06/2013; 140(13):1-12. DOI:10.1017/S0031182013000644 · 2.56 Impact Factor
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- "M. arvalis populations were sampled using an index technique developed previously and validated by comparison with classical trapping techniques (Delattre et al. 1990, Quéré et al. 2000). The technique was based on recording surface signs (presence/absence of vole droppings within 10 m intervals) along transects ranging from a few hundred metres (patch scale) to several kilometres (local scale) in total length. "
ABSTRACT: Vole demographics are often modified close to wooded environments. Population monitoring in such settings reveals substantial edge effects, although these have seldom been quantified. This study compares the abundance of common voleMicrotus arvalis (Pallas, 1778) populations at various distances from three types of wooded environment (hedgerow, copse and forest) and in two types of habitat (temporary and permanent grassland). In temporary grassland, substantial edge effects were detected along the boundaries of forests and hedgerows. At 100 m from the forest edge, voles were twice more abundant than at 50 m, four times more than at 25 m and eight times more than at 5 m. In permanent grassland, the edge effect was such that voles were practically absent up to 100 m from the forest edge. For both types of grassland, the edge effect was more pronounced for forest habitat than for hedgerows, that is, for elements with a large surface area of wooded environment. Our results suggest that landscape context may greatly affect the local abundance of voles. Given the considerable damage done byM. arvalis, the presence of wooded patches in grassland areas leads to lower vole densities in adjacent areas and this might be an alternative method to controlM. arvalis as a pest species. Key wordsedge type-habitat quality-landscape ecology-landscape composition-predation riskActa theriologica 03/2009; 54(1):51-60. DOI:10.1007/BF03193137 · 1.20 Impact Factor
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- "Methods grounded on surface indices allow monitoring at a smaller scale (over large areas). This would not be possible with standard trapping (Giraudoux et al. 1995, Qué ré et al. 2000). Furthermore, some species are difficult to catch with surface traps (e.g., the subterraneous Ellobius tancrei); moreover, SBBT and INRA traps do not capture species over 70 g and BBBT traps over 200 g. "
ABSTRACT: Small mammal assemblages were surveyed in five areas of the northern Junggar basin, Xinjiang, China, using standard trapping methods and index transects. In total, 23 species were recorded. The relationships between habitats and the distribution of the main species were described at local scale in Baihaba, Altai mountains. Three types of assemblages linked to (i) forest (Myodes rufocanus, Microtus agrestis, Myodes rutilus, Apodemus peninsulae, Sorex isodon), (ii) transitional areas and farm-land (mixed pool of species including Apodemus uralen-sis), and (iii) grassland (Ellobius tancrei, Microtus obscurus, Cricetulus migratorius) were identified. Addi-tional species, such as Microtus oeconomus, could be found along small streams. At a broader scale, species composition was estimated in Kokehada, Narenhebuke and Fuhai areas and compared. Although ecological gra-dients from mountain grasslands to cold semi-desert partly explain differences in assemblage composition on a regional scale, similar habitats at the same altitude may, however, harbour different assemblages. For example, Spermophilus erythrogenys was the dominant species of the Kokehada grassland and Microtus obscurus and Ello-bius tancrei were dominant in Baihaba grassland. In con-clusion, the need for multi-scale standard descriptions of small mammal assemblage distribution in the northern Junggar basin of China is indicated.Mammalia 12/2008; 72(4). DOI:10.1515/MAMM.2008.048 · 0.68 Impact Factor