Distribution and status of the European Ground Squirrel (Spermophilus citellus) in Bulgaria [Rozšíření a stav populace sysla obecného (Spermophilus citellus) v Bulharsku]
Yordan Spasov Koshev
The European ground squirrel (Spermophilus citellus) is an endangered species and typically inhabits steppes and open woodland of Central Europe and the Balkans. Knowledge about its distribution and status in the southern part of its range is scanty. Distribution of the species in Bulgaria over two periods (1950–1989 and 1990–2008) and recent status of 90 colonies in three model regions (mountain region, Sofia field and Thracian valley) are evaluated in the paper. Data on 254 UTM squares inhabited by S. citellus during the first period and 212 UTM squares inhabited during the second period were available, but these data could not be compared because of the different survey methods used. S. citellus colonies in southwestern Bulgaria may be already extinct and population decline is supposed to take place at the southwestern periphery of the species’ distribution range. About 30% out of 90 investigated colonies have disappeared, 28% are vulnerable and only 42% are stable. The biggest part of the extinct colonies was found in the Sofia field and Mountain region. Pastures are the most frequently occupied land use type (72%) in Bulgaria and major threats for the S. citellus population include pasture degradation, building up, intensification of agriculture, interruption of biological corridors and flooding. The S. citellus population in Bulgaria has been probably declining and current status of the species is unfavourable. The S. citellus conservation status in Bulgaria should be enhanced and the species should be included in the new Red Book of Animals in Bulgaria in the category “vulnerable” and should be protected according to the national biodiversity legislation.