IdentificationEuropean ground squirrel/ or hereafter souslik (Spermophilus citellus) is a medium-sized ground squirrel, with a round body, short tail (20–40% of length of head and body), and reduced outer ears (Fig. 1). Head is convex in profile with large eyes (about 8 mm in diameter) and short vibrissae. The mass is 200-300 g, maximum 500 for the adult males before hibernation.
BiologyReproduction in Spermophilus citellus is constrained by hibernation, limiting the timing of mating and on ground activity. Females deliver only 1 litter annually with litter sizes at emergence from natal burrows ranging from 2 to 11 young/litter. Gestation period for Spermophilus citellus is on average 29 days in the field. Juveniles 1st emerged from their burrows at 25 days of age. Juveniles remain in their natal burrow for about 1 month, and weaning begins in mid-June depending on litter size and maternal condition. The European ground squirrel dig simple temporary shelters and sophisticated underground systems with multiple exists and chambers that could be up to 2 meters deep and 3 meters long. They are obligatory hibernators and spend 5 to 8 (in the mountains) months in the year inactive. During the hierbanation their body temperature could be close to 0 degree. The European ground squirrel is active during the day. It feed manly on seeds and on leaves and small invertebrates in spring.
DistributionEndemic to Central and Southeastern Europe, the range of Spermophilus citellus is disjunct, the Carpathians divide the range into 2 portions. The northwestern portion extends through the lowlands of the Czech Republic, Austria, Hungary, Slovakia, Serbia (to the north of Danube and Sava), and eastern Romania. The southeastern portion extends from eastern Serbia, Macedonia, and northern Greece through Bulgaria to Turkish Thrace, southern and eastern Romania, Moldova, and Ukraine. Extinct in Germany, Poland, and Croatia, the western margin of its distribution is in the Czech Republic. Nonetheless, the species was successfully reintroduced in Poland.
In Bulgaria the species is inhabits well maintained pastures and meadows from sea level to 2600 m above sea level. Here is located the highest known colony of the species - in the vicinity of Belmeken Peak in Rila National Park.