Rashevska H. Rodents of zonal landscapes of the Right-bank Steppe of Ukraine: species composition, distribution and numbers

The field studies carried in the Right-bank Steppe of Ukraine have resulted in a revision of species composition and assessment of population statuses of a zonal group of rodents. It has been established that in the course of the 20th century the studied area was inhabited by 15 species. The great jerboa (Allactaga major) is currently extinct, while the presence of the bobak marmot (Marmota bobak) is proved. Appearance of the latter became a result of successful acclimatization. It is shown that the odessian souslik (Spermophillus odessanus), northern mole vole (Ellobius talpinus), European hamster (Cricetus cricetus), and the southern birch mouse (Sicista subtilis) are shrinking their ranges and obtained statuses of endangered or rare species. The population statuses of the lesser mole rat (Nannospalax leucodon) and Balkan mole rat (Spalax zemni) are quite stable, though the range of the latter species shows a reduction trend. Mouse-like rodents (the common (Microtus arvalis) and southern (M. levis) voles, wood (Sylvaemus sylvaticus), Ural field (S. uralensis), yellow-necked (S. tauricus) and steppe (Mus spicilegus) mice), except for the grey hamster (Cricetulus mіgratorius), have rather high numbers and stable ranges. It is recommended to change the species statuses in the Red Book of Ukraine: for the odessian souslik from “not evaluated” to “endangered”, European hamster – from “not evaluated” to “endangered”, great jerboa - from “rare” to “endangered”, lesser mole rat – from “data deficient” to “vulnerable”, Balkan mole rat - from “data deficient” to “vulnerable”. The use of a set of craniometric traits with the application of methods of standard and geometric morphometry do not allow 100 % discrimination of individuals in a species group of common voles Miсrotus (superspecies arvalis) in contrast to closely related wood mice, where even exterior traits are sufficient for identification. The GIS-modeling proves that the limitation of ranges of the common vole to the east and the southern vole to the west are caused by interspecific competitive interactions in the shared zone of their dwelling. Zoogeographical zoning of the Right-bank Steppe, basing on fauna of zonal rodents, divides the right-bank steppe area into the Dnipro-Buh and Buh-Danube subareas. It is proved that the anthropogenic changes in the rodent fauna of the Right-bank Steppe are quite comparable in its scope with deformations of the Left-bank Steppe.