Mammal and bird bone remains from Upper Holocene sediments at the Nizhneirginsky Grotto were studied. Nizhneirginsky Grotto is located in the northern part of the Ufa Plateau in the Middle ...Fore-Urals. The sequence of deposits contains three layers which have been accumulating during the last 4150 years. Identified mammal elements include 9839 bone remains of 29 species belonging to five orders, i.e., Eulipotyphla (435), Chiroptera (1608), Lagomorpha (52), Rodentia (7688), and Carnivora (56). Recovered bird remains include 1946 bones of 38 species. Most identified species currently inhabit the Nizhneirginsky Grotto area. The analysis of alterations in the first lower molars of arvicoline rodent species caused by the digestion showed that eagle owl (Bubo bubo, Linnaeus, 1758) is the most possible agent responsible for the accumulation of small mammal assemblages in the grotto sediments. An unusually high number of birch mouse fossils was noted over the entire sediment section of the grotto (MNI on average by layers is 8.1–15.4%). This phenomenon, probably, has a taphonomic origin and is associated with the predation activity of mustelids. Palaeoenvironmental analysis of small mammal assemblages based on the habitat weighting method showed the predominance of open landscapes and woodlands around the grotto during the Late Holocene. This landscape did not change in the last 4150 years. The connection of the history of the yellow-necked mouse in the northeast of its modern range with the palaeogeographic events of the second half of the Holocene was established. The material from the sediments of the Nizhneirginsky Grotto shows that the species was common in the northern part of the Ufa Plateau, in the Irgina River valley, in the period of 4150-3100 cal BP, which coincides with the maximum distribution of broad-leaved trees in the Fore-Urals during the mid-Subboreal thermal maximum (SB-2; 4200-3200 BP). Pika's (Ochotona, perhaps O. pusilla, Pallas, 1769) sinister mandible was found among osteological material from the upper part of layer 2 which dates to 710 ± 20 cal BP (1240 ± 20 cal AD). This is the first find of the pika's remains of such late age in the Middle Urals and in adjacent territories. The species was common in the northern part of the Ufa Plateau during Late Pleistocene and Early Holocene. Steppe pika is now disjunct from the Nizhneirginsky Grotto by approximately 200–300 km to the south and to the south-west. O. pusilla probably inhabited the valley of the Irgina River as a relic of the Late Pleistocene and Early Holocene faunas as early as 12th and 13th centuries AD.
Based on studies conducted in 2017, the features of formation and changes in the isotopic (δ
18
O and δ
2
H) and chemical composition of natural waters on the western border of the Ufa plateau were ...revealed. Within the Ufa plateau, waters were tested in three hydrodynamic zones of the Orda cave and the adjacent territory. Changes in the isotope-hydrochemical parameters in the horizontal and vertical directions are noted. Data from isotope-hydrochemical monitoring allowed us to establish that the replenishment of groundwater reserves on the western border of the Ufa plateau occurs mainly due to isotopically light winter precipitation, which is explained by the speed of water exchange in the karst system and the time of atmospheric precipitation in the aquifer. According to isotope data, the time of water inflow from the basin of aquifer into the aquifer was determined, which is approximately equal to six months. The latter indicates that there is some delay in the transfer of isotopic signal from the precipitation to the groundwater. The use of Spearman’s rank correlation coefficient made it possible to clarify the relationship of surface waters with waters in different hydrodynamic zones. No connection was found between the isotopic compositions of atmospheric precipitation and the waters of the vertical downward circulation zone, the connection with the composition of the waters of the horizontal circulation zone was also not established, and with the waters of the siphon circulation zone was partially established for one source. This correlation suggests that the groundwater on the western border of the Ufa plateau has a predominantly mixed aquifer recharge.
