Field material for assessing the diet of grazed domestic animals was collected in the summer season of 2020 on the territory of the Black Lands (the southern part of the Caspian lowland within the borders of the Republic of Kalmykia). The research area belongs to the northern subzone of the desert zone (Zones and Zones…, 1999). Data on the composition of forage plants in the diet of jointly grazed sheep, cows and horses were obtained using the method of microhistological cuticular analysis of excrement. This method is used for the first time to assess the diet of sheep, cows and horses in the study area. 25 plant species were identified in the summer diet of grazed animals, of which 21 species were noted when describing vegetation in the key area. It was revealed that the diet of grazed domestic animal species differs in the ratio of the main forage groups of plants in it: cereals, sedges and various grasses. The share of cereals is the highest in the diet of horses (92%), and the share of various grasses prevails in the diet of sheep (35%).

Materials on the composition of forage plants in the bison diet were obtained within the enclosure of nonconsumptive use at the Rostov Nature Reserve in the summer and autumn seasons of 2018. The described area is located in the sod-forming cereal-grass steppes in the Western Manych River valley. Data on the seasonal dynamics of the composition of forage plants in the bison diet were produced via cuticular microscopic analysis of fecal samples. An electronic database was created for the plant cuticle structures typical of the species providing the floristic richness of grassland for bisons in order to identify the species of the botanical fragments in the fecal samples. Thus, the proportion of cereals in the summer and autumn diets comprised 64% and 84%, respectively. The selectivity indices of cereal species were measured as 2.1 in the summer and 4.3 in the autumn seasons. For motley grasses, it was 0.5 in the summer season and decreased to 0.2 in the autumn. The index value depends on the animals' taste preferences, the species richness in the aboveground phytomass of grassland, and the plant growth stage.

The article presents the research results the food selection and preferences of the social vole Microtus socialis in the dry steppes (northern subzone of the deserts) in the Chernye Zemli State Biosphere Reserve (north-western part of the Caspian Lowland). It is the first time when the data on seasonal variability of food composition of social voles in their permanent settlements has been obtained by means of cuticular microhistological feces analysis. The diet of the voles consists of 31 plant species. The basis of the diet is grasses (55–95%), mainly Poa bulbosa. Forbs are consumed in smaller amounts, but they play an important role in the summer life of the rodent. In spring, the tulip bulbs (Tulipa biebersteiniana) and the terrestrial parts of Chorispora tenella are of greatest importance in the nutrition of the vole. These herbivores do not eat Bassia hyssopifolia, Phlomis pungens, Carduus acanthoides at all. Voles maximize the use of forage diversity in the area of their settlements. The trophic interactions of rodents to certain plant species were evaluated through the preferences of baits containing plant extracts. The social voles consume baits with extracts from different plant species in varying degrees. In general, the consumption of baits containing grass extracts is higher than that of baits containing extracts from most species of forbs. In the group of forbs, the social vole unequivocally prefer baits containing tulip extracts. The baits with other forbs are consumed by two or more times less than those with grass extracts. The social vole gives the least preference to baits with extracts from Senecio vernalis and Tanacetum achilleifolium. Most likely, a high concentration of toxic secondary metabolites is the main reason for voles avoiding certain baits with plant extracts. How to cite this article: Scopin A.E., Dzhapova V.V., Bembeeva O.G., Ayusheva E.Ch., Dzhapova R.R., Abaturov B.D. 2020. Diet selection by the social vole Microtus socialis (Pallas, 1773) in the Northwest Caspian Lowland // Russian J. Theriol. Vol.19. No.2. P.136–148. doi: 10.15298/rusjtheriol.19.2.04.

The fodder resources, nutrition, and food supply of free-ranging Bactrian camels, Przewalski horses, and saigas on a fenced forb-grass steppe pasture are studied. The species composition of consumed plants, food selectivity, digestibility, and amount of consumed forage are estimated seasonally. All three species differ in all diet parameters.

In 2015-2016, we studied the species composition, above-ground phytomass and feeding habits of semi-free Przewalski's horses (Equus ferus przewalskii) in a natural pasture of the steppe valley of the Western Manych. The above-ground mass of plants on the pasture varied within 146.0-168.9 g/m(2). We determined the composition of plants consumed by Przewalski's horses and their proportion in diets using a method of microscopically analysis of faeces. Cereals (Poaceae) and sedges (Cyperaceae) (80 to 100%) were the basis of the diet of the Przewalski's horse in the snow-free period. The value of the herb use varied between 0.8% and 20.5%. The main fodder plants for Przewalski horses on this pasture were the following: Festuca valesiaca, Stipa spp., Bromopsis inermis, Agropyron spp., Carex stenophylla, Kochia prostrata, while Elytrigia repens, Poa bulbosa, Chenopodium spp. were eaten in a small amount. We estimated the nutritive value of forage vegetation and nutrition indicators (daily consumption, the feed digestibility). The feed digestibility was determined by the ratio of inert (indigestible) component (silicon) in the diet and faeces. We calculated the amount of consumed feed from the mass of selected faeces and feed digestibility. A semi-free Przewalski's horse consumed 4.7 kg to 10.7-11.8 kg (dry weight) per day. The maximum intake (11.8 kg/animal per day) was observed in autumn. Feed digestibility of forages by Przewalski's horses in the snow-free period varied between 53% and 62% (average was 56%).

Abstract—This paper reports the results of investigation on the food of free-grazing Bactrian camels in a forb–grass steppe pasture, including anthropogenically disturbed areas with dominance of ruderal annuals. We identified the composition of consumed plants using a microhistological analysis of the feces; the digestibility coefficient based on inert (indigestible) silicon contained both in the diet and feces; the quantity of the forage consumed based on the mass of the feces and the digestibility coefficient; and the energy balance based on interrelations between the actual consumption and the existing requirement norms of camels and wild ungulates in energy. In spring, camels mainly consume graminoids (Stipa sp. and Festuca valesiaca), switching to forbs, largely ruderal annuals, in summer and autumn. The forage digestibility is low in spring (56%), increasing to 69–70% in summer and autumn. Low daily consumption rates of dry forage mass in winter and spring (8–9 kg) are changed to high in summer and autumn (20–26 kg), this reflecting the animals’ winter hypophagy. The amount of energy received during the warm season (1.2–1.8 MJ/kg W 0.75) considerably exceeds the requirements, thus explaining the ability of camels to accumulate a safety store of fat in the humps.

Проведен сопряженный анализ изменения кормовой растительности, питания и состояния сайгаков Saiga tatarica в степных регионах России. Отмечено, что в растительности современных пастбищ существенно возросла доля злаков, уменьшилось участие разнотравья, что отрицательно отразилось на питании и состоянии сайгаков. Показано, что более низкая питательная ценность злаков вызвала снижение переваримости потребляемого корма и не обеспечивает физиологические потребности животных. Установлено, что современные степные пастбища с господством злаков мало или совсем непригодны для устойчивого существования популяций сайгаков и лишь в отдельных местообитаниях с обилием разнотравья сохраняются полноценное питание сайгаков и благополучие их локальных группировок.

Впервые для территории пустынной зоны Калмыкии выявлены различия в признаках ценопопуляций Artemisia lerchiana в растительных сообществах на разных типах почв. Наблюдения проводились в трех растительных сообществах с доминантом A. lerchiana: на зональных бурых полупустынных супесчаных почвах, на песках закрепленных, на солонцах полупустынных мелких. Для ценопопуляций A. lerchiana рассматривали основные признаки: жизненность, продуктивность надземной массы, возрастной спектр особей. Дана оценка семенной продуктивности ценопопуляций. Наиболее высокое видовое богатство выявлено в фитоценозах на песках закрепленных (43 вида). Продуктивность надземной массы ценопопуляции A. lerchiana в растительном сообществе на песках закрепленных в 1,5–1,7 раза выше, чем в растительных сообществах на бурых полупустынных почвах и солонцах мелких. Наибольшее число корзинок, а следовательно, и семян формируется в ценопопуляции A. lerchiana на песках закрепленных.

The article considers the anatomic structure of annual shoot of a Kochia prostrate, a cenosis former of plant communities on brown semidesert sandy loam and sandy soils in a desert zone on the territory of the Republic of Kalmykia It is noted, that the considered species is used as a phytomeliorant of the degraded pastures.

The composition of plants consumed by saiga (Saiga tatarica) on Kalmykian Chernye Zemli during a year was studied. The diet composition of 96 animals was determined oil the basis of microscopic analysis of their feces. At the present time, in the plant cover of Chernye Zemli - the main habitat of saiga - monocotyledons (Gramineae and sedges) with the dominant Stipa capillata prevail. They are less preferable plants for feeding of saiga. Dicotyledons (xerophilous dwarf shrubs) occupy a subordinate position. The yield of the aboveground phytomass does not exceed 10 centners per hectare; the share of dicotyledons is 10%, feather grasses (mainly Stipa capillata) 80%. Monocotyledons predominate in the saiga diet and amount, oil average, to 56% in all the seasons. The low reserves of dicotyledons - the main forage plants of saiga - are a reason for their low participation or absence ill the animal's diet. In winter, saiga pasture oil areas exposed to summer fires. In autumn and mild winters, these areas are intensely overgrown with plants.

At present, the diet of saiga on Kalmykian (Chernye Zemli) pastures mainly consists of monocotyledonous plants (Gramineae, sedges) with the high contents of silica and lignin. Therefore, in all the seasons, the silica and lignin contents in the food of saiga were not lower than 1.33 and 17.18%, respectively; in some seasons, they reached 1.42 and 18.48%. The high content of these elements is accompanied by the low values of food digestibility. The coefficient of digestibility was not higher than 56-60% in all the seasons. The food of such quality does not provide the valuable nutrition of saiga. It only can maintain the definite level of the energy balance. The food of higher quality (high digestibility) can compensate reproductive expenses (lactation, young growth). The present state of pasture vegetation is unfavorable for saiga and does not support the sustainable dynamics of the Kalmykian saiga population.