The European ground squirrel, also known as the European souslik, is a rodent belonging to the squirrel family. It is known for the shrill whistle it emits. By sitting up on its short hind legs in a "begging" position the souslik is able to keep a careful eye on its surroundings.
The European ground squirrel has a slender build and grows to a length of approximately 20cm with a 6cm-long furry tail. A fully-grown specimen may weigh from 200g to 430g depending on the season. Its fur is short and smooth and generally yellowish-grey in colour, whereby the winter coat is considerably denser than the summer coat. Legs are relatively short yet stout. Its conspicuously large eyes are spaced broadly apart and set back a bit on the sides. The internal cheek pouches meant for storing food are relatively small yet elastic, and around the nose the souslik has long whiskers.
The main distribution range lies in the steppes of south-eastern Europe, with Austria marking the westernmost border of its range. The species prefers steppe and dry grassland habitats, meadows, fallow ground, embankments and grassy strips along pathways and roads. It avoids forests and dense ground vegetation. According to a very dated nature guide, the European ground squirrel was once native to the dry grasslands of today's Donau-Auen National Park and was also common to the broad plains of the Marchfeld region.
Since 2009 there has been a small souslik colony on the grounds of the Schlossinsel at the schlossORTH National Park Centre.
Endangerment and Conservation Status
The species is classified as vulnerable (VU) according to the IUCN Red List. The European ground squirrel is a strictly protected species under Austrian law and like other species in this category its survival must be safeguarded through the establishment of special conservation areas. Nowadays, its distribution range is not only significantly smaller, but also much more fragmented than in the past. This is due in large part to the disappearance of steppe landscapes and the negative effects of today's industrial farming methods. Another problem for the squirrel is the height of vegetation due to less frequent mowing.
The European ground squirrel is diurnal and active above ground. To protect itself, it is constantly on the lookout, scanning not only the ground but the skies above as well. Should a predator be spotted in the vicinity of a burrow, a warning whistle is emitted. Yet the rodent will wait until the very last possible moment before the predator strikes to actually flee.
There are two different types of burrows: the nest, which may be up to one meter deep and have up to five tubes (entrances). It serves as a shelter for raising the young and hibernation, during which time the tubes are sealed from within with soil. In a dead-end tunnel there may be a toilet chamber. The other type of burrow is simpler, with corridors into which the souslik may slip and hide if threatened.
Each souslik has its own burrow which it digs itself. The species in fact loves to dig, but only if it can dig deep down and if the soil is well drained. Using its front legs – and also its teeth – the souslik whisks the soil first underneath its belly and then uses its hind legs to sweep the soil back and away from its body.
Immediately prior to hibernation, which may start as early as August and commences by September at the latest, the European ground squirrel reaches its heaviest state. During the active months in spring and summer it forages for food which it deposits in its burrows, yet this is not stock-piled for the winter. The squirrel's main source of nourishment is vegetarian fare such as seeds, roots, shoots, bulbs, green plants and flowers. Beetles and caterpillars may also occasionally be on the menu.
During the mating season in April, the male attempts to mate with as many females in his territory as possible. Following around 26 days of development in the womb, the female gives birth to anywhere from two to ten young in a soft, padded nest. The young are raised exclusively by the female; life expectancy is between six to eleven years.
There is only minimal social contact among individual squirrels; thus it is not possible to speak of genuine colonies in the case of European ground squirrels.
During hibernation, the Spermophilus citellus seems to be frozen stiff, its body temperature sinking from 37° to 6°C. At the same time, blood volumes also decrease drastically. If body temperature is in danger of falling to under 5°C, these mammals begin to "chatter" with cold (like chattering teeth). During this phase warmth is produced from stored body fat. For this reason, the European ground squirrel emerges from hibernation in the spring only half as heavy as it was the previous fall.