Indicator species of steppe mammal communities in the Askania-Nova Biosphere Reserve: population status and biotopes

The state of the populations of representatives of three key steppe rodent families, namely birch mice (Sminthidae), jerboas (Allactagidae), and hamsters (Cricetidae s. str.), is analysed against the background of the history of nature management and conservation. These three groups are represented by one species each—the southern birch mouse (Sicista loriger), the great jerboa (Allactaga major), and the grey dwarf hamster (Cricetulus migratorius). All of them have been present in the territory of the reserve since the first information about its fauna was recorded. In terms of time, their habitat conditions—which have changed as a result of ploughing of steppe areas in both the buffer and anthropogenic zones, reducing the grazing pressure on the remnants of steppe vegetation in the buffer zone, and the complete cessation of virgin lands in the protected area—have had a mixed impact on the status of the populations. The conservation of virgin steppe proved to be unfavourable for the great jerboa population, which is sensitive to height and density of grass, and these animals disappeared from the ‘South’ and ‘North’ sectors, mainly localising in the pastures around sheep farms. The reduction in the number of sheep during the crisis period of the agriculture also led to a decrease in the area of habitats favourable for the great jerboas. It is quite possible that this species is no longer to be found in any of the Reserve’s zones. The most favourable habitat for the southern birch mouse is the natural core of the Reserve. The results of forty years of research on this species indicate a significant amplitude in the dynamics of its population. Since 1991, the birch mouse population has been in deep decline, the reasons for which have not been studied. It is assumed that the species is polycyclic during the day with a shift in the time spent on the surface to daytime hours, so the species is not accessible to owls. The dwarf hamster is distributed outside the natural core, in forest belts and perennial grasses. Its abundance in the protected area is much lower compared to that in transformed ecosystems. In general, this species is in a good condition. An analysis of various survey methods and their application by the author in 1979–2023 is presented. Information on changes in weather factors and their impact on the phenology of the studied species is also provided.