Comparison of natural and re-introduced populations of the steppe marmot (Marmota bobak) in Donetsk Oblast, Ukraine

The paper presents data on distribution and abundance of the steppe marmot in the territory of two northern raions (districts) of Donetsk Oblast — Sloviansk and Lyman. Research was carried out in 2011 to 2020. In total, 284 burrows were recorded belonging to 25 home ranges. The largest marmot settlements in the studied territory comprise up to 29 burrows. The number of burrows on a home range varies from 1 to 29, in average 11.4. The total abundance of the steppe marmot is over 100 animals in Lyman Raion and over 20 individuals in Sloviansk Raion. The marmot population in Sloviansk Raion is re-introduced—370 individuals were released in 1991—, while the population in Lyman Raion is of rather natural origin. The optimal habitats for the steppe marmot are chalk slopes of southern exposure, where its home ranges consist of the highest number of burrows. Permanent inhabited burrows are located in the middle part of the slopes, whereas the vast majority of protective burrows are below the slope and at the bottom of the beams. All settlements are located on the right bank of rivers. The largest marmot settlements are confined to poor Cretaceous and, less frequently, sandy soils with sparse vegetation. The natural marmot population in Lymansky Raion shows a tendency to slow dispersal and population growth, while the abundance of the re-introduced population is much smaller than the number of released animals. The density of the natural population remains low despite the many uninhabited areas suitable for the marmots. Settlements are formed as separate disconnected groups. New marmot settlements are often formed in places of old settlements. Natural populations are more stable compared to re-introduced ones and the density of natural steppe marmot population is also higher. Poaching, especially in Sloviansk Raion, is a major threat to the marmot, as well as the overgrowth of the steppe by shrubs due to decrease in grazing. Marmot settlements on the Cretaceous steppes are almost insensitive to reduced grazing. In Lyman Raion, fires and ploughing of balka slopes, too, negatively affect the species. Development of epizootics is unlikely given the low density of the marmot. The marmot populations can be preserved and can even expand their range in the region if sufficient protection measures are provided.

Landscape as a factor of natural selection on reactivity for steppe marmot (Marmota bobak)

Marmots use a sound signal to inform their neighbours about the danger. Vocalization is the response of marmots to the visual perception of a potentially dangerous stimulus. For the first time at the intraspecific level the relationship between the rhythmic structure of the signal and the habitat elevation of populations is shown using the example of the steppe marmot (Marmota bobak). An increase in elevation is accompanied by an increase in the relative excess of positive forms over the nearest negative forms of relief. The dismembered relief reduces the visual detection range of danger. With an increase in the habitat elevation of populations, the repetition periods of sounds in the signal decrease. In the range of habitat elevations of the steppe marmot from 120 to 730 m, the median of the repetition periods decreases from 5.35 to 2.17 s. The increased rhythm is a consequence of the increased reactivity of marmots. It has been suggested that a complex of reactions to visual detection of danger controls the amygdale. The alarm call of marmots was recorded in the field.

Why the steppe marmot (Marmota bobak) should not be included into the Red Book of Ukraine

Suitable lands for the steppe marmot are dry meadows and clear beams (without woody vegetation), which make up to 20 % of the territory of the steppe forest-hunting zone. Suitable lands for this species are large enough in area. It was found that with the excess of the optimal number, the intensity of reproduction of the species decreases, some animals move to less-suitable or even unsuitable lands causing increased animal mortality. Re-acclimatization of the species is carried out mainly by game husbandries, which have released more than 2330 individuals since 1991. The inclusion of the steppe marmot into the Red Book of Ukraine will destroy the possibilities of re-acclimatization.

Current state of the steppe marmot (Marmota bobak) population in Striltsivskyi Steppe (East of Ukraine)

The Striltsivskyi Steppe Nature Reserve (with a total area of 522 hectares) was created in 1948 to preserve the steppe marmot population; however, according to the population state studies carried out in the course of the reserve operation, a decrease in the marmot population has been established. This article is aimed to provide current data related to the marmot population monitoring results. The author established the number of colonies as well as adult and this year’s individuals inhabiting the nature reserve territory in 2020. The author explored the structure of each colony’s site and studied their area, shape and number of permanent and temporary burrows to analyze the state of the population. Only a quarter of all colony sites located in the territory of the reserve can be characterized as permanent ones. According to the author, despite a slight increase in the number of colony sites in the northern part of the Kreydyanyi Ravine and slopes towards the Cherepakha River, the entire population tends to decline. A high level of age structure misbalance and pronounced population fragmentation are observed, which are more evident in the left-hand slope in the northern part of the Kreydyanyi Ravine and in the vicinity of the Zapovidna Balka, which characterizes the population state as unstable. Changes in the vegetation cover are the principal reasons for these processes: increased area occupied by bushes, high grass stand, dry grass residues and predators (foxes and domesticated dogs). It is possible to forecast that the number of steppe marmot will continue to fall due to the current state of the vegetation cover state and absence of large grazers. The state of colony sites improves in the territories of with cattle grazing and haymaking. The state of colony sites and number of individuals in the colonies improved to a certain degree in the slopes towards the Cherepakha River where cattle grazing was carried out. As many as four colonies were found there in 2018 while their number reached ten in 2020. Exclusively reserve status under the current steppe conditions without large grazers will fail to improve the marmot population. The author suggests carrying out such actions aimed to prevent the decrease in the number of marmot population in the nature reserve territory as introducing cattle grazing, haymaking in the territories of colony sites, removing high grass near permanent burrows and conducting ecology awareness-building campaigns among the local population to prevent illegal hunting.