E. V. Ivanter

Long-Term Population Dynamics of Ixodid Ticks and Development of Tick-Borne Encephalitis Foci under Conditions of the Middle Taiga Subzone

Long-term (1995–2003) population dynamics of ixodid ticks and their main hosts (small mammals) and conditions providing for the formation of tick-borne encephalitis (TBE) foci were studies in the middle taiga subzone (Karelia). The results show that the bank vole (Clethrionomys glareolus Schr.) is the main host for the larvae and nymphs of Ixodes persulcatus Schulze, 1930 and for the larvae, nymphs, and adult individuals of I. trianguliceps Birula, 1895. The proportion of ticks feeding on this species (relative to their total number) reaches 63.3% (64.0% of I. persulcatus and 61.1% of I. trianguliceps). Activity of a TBE focus is determined primarily by the abundance of bank voles of older age groups.

Ecological monitoring of urban groups of stray dogs: An example of the city of petrozavodsk

The results of the census of stray dogs and data on their territorial distribution in the city of Petrozavodsk are reported. The population density of these animals has been found to vary within the urban area, depending mainly on the availability of secluded areas to live in and on population control by municipal services.

Ecological and statistical analysis of long-term changes in the abundance of small mammals at the northern limit of the range (Northeastern Ladoga region)

Data on the abundance of 11 species of small mammals, which were collected in the northeastern Ladoga region in 1965–2013, were analyzed using harmonic and component tests. In scarce species, mostly random nonperiodic changes in abundance were observed, whereas abundant species showed consistent periodicity of changes at a frequency of 3.6–5.6 years. The sets of spectral-density curves for all species were processed by the component analysis. For rodents, a 3–5-year periodicity was found, whereas shrews showed a long-term trend in abundance with an increase in the 1970s and subsequent decrease. Sufficiently distinct periodicity in the population dynamics of animals was manifested more clearly in the counts performed with break-back traps rather than with pitfall traps.

Dimensional characteristics of prey and their role in the diet of shrews (Sorex L.)

Harmonious coexistence within the same territory of various shrew species having similar body sizes suggests that they differ in ecological characteristics. Differences in the biotopic distribution of coexisting species of the genus Sorex have been considered in many publications, but their trophic niches and mechanisms for division of food resources are still unclear. Differences in the size of the foraging apparatus itself are too small to cause any visible divergence in food supply between different various species. It has been shown (Zaitsev, 2005) that recent Soricidae are capable of hunting large (relative to their body size) and active prey owing to the specific way of chewing. Therefore, the prey size is rather restricted by the general size of a hunting animal than the size of its foraging apparatus. The suggestion that every shrew species has the upper size limit in prey selection, which is determined by the metabolic costs and physical abilities , is justified (Chernyshev and Demin, 1992). As known, small-sized shrews (Sorex minutus, S. miutissi-mus) are incapable of coping with large invertebrates (hornworms, large ground beetles, etc.) normally consumed by common (S. araneus) and water shrews (Yudin, 1962; Sergeev, 1973). However, the aforemen-tioned large invertebrates constitute an insignificant amount in the diet of insect eaters, and their main staple food objects overlap almost completely (Yudin, 1962; Ivanter and Makarov, 2001). Studying the food supply of wild shrews and its influence on their diet showed, on the one hand, a clear correlation between the amount of consumed invertebrates in the stomachs and their number in soil samples (Churchfield, 1982) and reveled, on the other hand, that there are preferences for particular prey size characteristics (partially overlapping) among the coexisting species S. araneus and S. minutus (Pernetta, 1976). Keeping these shrews in captivity provided data that S. araneus prefers larger food objects in the range of its potential preys. Its feeding selectivity depends on the ratio of abundance of different prey size groups. If other animals occur in the nearby, the frequency with which small objects are consumed increases (Barnard and Brown, 1981). However, when the animals are kept in captivity, it is impossible to consider reliably such factors as food availability and competition, which significantly alter feeding selectivity. In this paper, we made an attempt to reveal, based on analysis of field materials, whether partial prey size selectivity in the diet of shrews can significantly influence the division of …

Ecology of the field vole (Microtus agrestis L.) in indigenous and anthropogenic landscapes of Eastern Fennoscandia

The state of the population, biotopic distribution, and population dynamics of the field vole are analyzed on the basis of long-term studies performed in 1956–2012 in taiga ecosystems of Eastern Fennoscandia affected by anthropogenic transformations. General trends and regional and landscape-related specific features of the effects of forest exploitation on the structure of habitats, abundance, and spatial distribution of the field vole are discussed in comparative ecological aspect.

Daily Activity and Mobility of the Common Shrew (Sorex araneus L.)

Data on the daily activity and mobility of the common shrew (Sorex araneusL.) were obtained by the method of animal marking and recapturing in test plots. Sex- and age-related differences in the locomotor activity of animals were revealed, which depended on population size and the phase of the population cycle. Under natural conditions, animal activity in the daytime proved to decrease to a lesser extent than in captivity. The mobility (locomotor activity) of shrews was shown to depend on population density, reproductive rate, and weather.

Changes in Rodent Populations in Eastern Fennoscandia under the Influence of Anthropogenic Transformations of Boreal Ecosystems

Long-term (1966–2015) stationary and expedition studies in eastern Fennoscandia have revealed specific changes in the structure and abundance of rodent populations under the influence of concentrated forest fells. The general patterns of the influence of intensive forest exploitation on the natural habitats, numbers, territorial distribution, and ecological features of small rodents in the region are analyzed. It has been established that, for most rodent species, industrial harvesting leads to a decrease in the total abundance of populations, as well as to an erratic shift in population dynamics with sudden short recoveries and deep longterm depressions, the formation of a nonresistant mosaic spatial distribution, and a disturbance of the rates and a decrease in the intensity of breeding and population reproduction.

The effect of commercial cuttings on faunal associations in taiga ecosystems: A case study of small mammals in eastern Fennoscandia

The general patterns of the effect of cuttings on the habitat structure, abundance, territorial distribution, and specific ecological features of 11 small mammalian species are analyzed based on long-term studies (1958–2013) covering the overall area of eastern Fennoscandia. The responses to concentrated cuttings common for most of the examined species include a decrease in total population size, transition to an arrhythmic population dynamics with drastic short-term rises and deep long depressions, formation of unstable mosaic spatial distribution, disturbances of the reproduction rates, and a decrease in reproduction intensity.

Effect of anthropogenic transformation of forest landscapes on populations of small insectivores in eastern Fennoscandia

Responses of small insectivores (Sorex L.) to clear felling and formation of an anthropogenic landscape have been studied and found to be ambiguous. Under such conditions, the total population density of the common shrew (S. araneus) increases, but its populations become unstable and sharply fluctuate seasonally and from year to year. The abundance of the Laxmann’s shrew (S. caecutiens) in transformed habitats becomes slightly lower, but its populations acquire certain additional stability. In general, this species negatively responds to felling but nevertheless regularly occurs in young secondary conifer stands. Finally, low-abundance species are either highly tolerant of forest exploitation (the Eurasian least shrew, S. minutissimus) or, on the contrary, show a distinctly negative response to felling in conifer forests (the taiga shrew, (S. isodon).

Study of the trophic relations of small insectivorous mammals

The trophic mechanisms of differentiation and the relationships between various species of small insectivorous mammals, as well as their interaction with the populations of their prey, were studied. The stomach contents of 3225 animals of seven different species (Sorex araneus, S. caecutiens, S. minutus, S. isodon, S. minutissimus, Neomys fodiens, and Sicista betulina) caught in Karelia were analyzed. These species inhabit the same territories, and their main staple food objects overlap almost completely. Thus, the specific nature of their diets is quantitative rather than qualitative. At the same time, the trophic relation of the animals with soil invertebrates becomes weaker from the even-toothed and common shrews to the northern birch mouse. The ecological differentiation and separation of the forage between close species of insectivores were shown to be primarily provided by the different horizons of their habitat (soil and surface layers, grass and shrub tiers, etc.).