Modern climate warming impact on the population dynamics of the small ground squirrel (Spermophilus pygmaeus Pallas, 1778) (Rodentia, Mammalia) in the Ilmenno-Prideltovy region of the Caspian lowland

The influence of the global climate warming on the population dynamics of the small ground squirrel at the border of its range in the northern desert zone on the territory of the Ilmenno-Prideltovy landscape area of the Caspian lowland in 1945–2019 is considered. Data on the numbers of small ground squirrels and the average monthly air temperature in January–February at the Astrakhan weather stations for the last 75 years have been analyzed and statistically processed. It is emphasized that the abundance dynamics of the species is determined by a whole complex of natural and anthropogenic factors. At the same time, in desert conditions, the distribution of air temperature and precipitation by seasons and years is limiting for the small ground squirrel. The January–February temperature effect provoking the awakening of the small ground squirrel from hibernation is analyzed. The high January temperature, followed by the February cooling, led to the mass death of animals, which would subsequently negatively affect the phenology of the main phenomena in the life of this monoestral species, disrupt the population structure and lead to a decrease in the numbers of animals. Against the background of the low January air temperatures, the awakening of the small gopher took place in February–March, and the higher February temperatures provided optimal conditions for a simultaneous exit from hibernation and participation in the reproduction of all sex and age groups of small gophers. Such a combination of January and February air temperatures took place during 1960–1979, which contributed to the growth and preservation of a relatively high level of the species' abundance. The high temperatures of the 1980–2009 winter months provoked the early release of the animals from hibernation: the numbers of ground squirrels decreased and kept at a low level. Against the background of decreases temperatures of the 2010–2019 winter periods, the effect of stabilization of the small ground squirrel population and some increase in the density of the species was observed.