Osteological material and the population state of the speckled ground squirrel (Spermophilus suslicus) on the periphery of the species’ distribution (Belarus)

Abstract

The studies were carried out in 2021 near the village of Yushevichi, Nesvizh Raion, Minsk Oblast (Belarus). The content of pellets of three bird species were analysed: Buteo buteo, Buteo lagopus, and Corvus corax. In total, 129 intact and about 30 destructed pellets were processed. Skeletal elements of five small mammal species belonging to five genera of two orders (Rodentia and Eulipotyphla) were found, including remains of nine speckled ground squirrels. The remains of seven of the nine ground squirrel individuals found in the pellets were found in raven pellets, however, the authors believe that this fact does not yet prove a greater influence of the raven on the local ground squirrel population. The pellets analysis and observations of feeding behaviour of the three bird species prove that the speckled ground squirrel is constantly included in the diet of both diurnal birds of prey (genus Buteo) and of atypical predators with a mixed nutrition (raven). Finding of intact skulls of Spermophilus suslicus in pellets of the mentioned bird species is unlikely, which is determined by its considerable size. This circumstance does not allow obtaining most of the craniometric characters, but does not prevent the detection of pathomorphological changes. To compare the craniological characters, we used the skulls of dead ground squirrels (n = 5) found in the field near the village of Yushevichi. These individuals had visible injuries (lacerated wounds, etc.) presumably left both by predators and fights between ground squirrels. The most striking pathomorphological changes were revealed: osteoporosis and osteolysis of dental alveoli of the upper and lower jaws and initial osteomyelitis of the cranial vault (in the parietal and frontal bones). We believe that the speckled ground squirrel’s conservation status should be raised to at least Category II (according to the system of categories adopted in Belarus) for the following reasons: over the past six years, out of 12 known colonies, only four colonies have survived, two of which are practically unviable; stable for 10 years reduction in the number; and range fragmentation (single localities). According to the IUCN classification, it corresponds to category CR (critically endangered).