In Bulgaria:

European ground squirrel references from Bulgaria (last update 20.12.2008) (pdf)

2010 - NEW!!!

Koshev Y. 2010. Interspecific aggressive behaviour of European ground squirrel (Spermophilus citellus L.). – Biotechnology & Biotechnological Equipment, 24 (2) Special Edition: 671-674. (full pdf).


Koshev Y. 2009. Distribution, isolation and recent status of European ground squirrel (Spermophilus citellus L.) in Pazardzhik district, Bulgaria. Annual of Shumen University “Konstantin Preslavsky”, Faculty of Natural Science, XIX B6: 97-109. (full pdf).
Golemansky V., Y. Koshev. 2009. Systematic and ecological survey on coccidians (Apicomplexa: Eucoccidida) in European ground squirrel (Spermophilus citellus L.) (Rodentia: Sciuridae) from Bulgaria. – Acta Zoologica Bulgarica, 61 (2): 141-148. (full pdf).
Stefanov V., E. Markova. 2009. Distribution and current status of the European souslik (Spermophilus citellus L.) in Sofia valley and the adjacent areas. – Biotechnology & Biotechnological Equipment, 23 (2) Special edition: 381- 384. Available in internet (full pdf):
Markov G., A. Atanasova, I. Raykov, H. Dimitrov, M. Gospodinova. 2009. The fragmented landscape of agricultural areas in Bulgaria: Implications for conservation of European ground squirrel (Spermophilus citellus L., 1766) today. – Mammalian Biology, 74, Suppl. 1: 18 (abstract).


Koshev Y. 2008. Distribution and status of European ground squirrel (Spermophilus citellus) in Bulgaria. - Lynx (Praha), n.s., 39 (2): 251-261. (full pdf).
Georgiev D., E. Raichev, K. Koleva. 2008. Ground squirrel (Spermophiluscitellus, Rodentia, Mammalia) in Kazanlak filed conditions. – Journal of Agricultural Science and Forest Science, 7 (2): 63-66. [In Bulgarian with English summary] (full pdf).
Koshev Y., I. Pandourski. 2008. Structure and variability of alarm calls of European ground squirrel Spermophilus citellus L. 1766 (Mammalia: Rodentia) from Western Bulgaria. – Acta Zoologica Bulgarica, 60, 1: 99-105. (full pdf).
Koshev Y., M. Kocheva. 2008. Daily activity pattern in free-living European ground squirrels Spermophilus citellus (Mammalia: Rodentia) from Northwestern Bulgaria. – Acta Zoologica Bulgarica, suppl. 2: 149-154. (full pdf).


Golemansky V., Y. Koshev. 2007. Coccidian parasites (Eucoccidia: Eimeriidae) of European ground squirrel (Spermophilus citellus L., 1766) (Rodentia: Sciuridae) from Bulgaria. – Acta Zoologica Bulgarica,59, 1: 81-85. (full pdf)
Koshev Y., M. Kocheva. 2007. Environmental factors and distribution of European ground squirrel (Spermophilus citellus) in Bulgaria. – Journal "Ecology & Safety. International Scientific Publications",1: 276-287. (full pdf)


Koleva K., D. Geourgiev. 2005. Seasonal changes in the colony of Spermophilus citellus (Linnaeus, 1766) (Rodentia, Mammalia) in the vicinity of Dabovo (Stara Zagora region). – In: Proc. Sc. St. Conference “Conservation of biodiversity and management of protected areas”, BBF and SU “St. Kliment Ohridski”, Sofia, Bulgaria, 114-124. Available on Internet: [In Bulgarian, English summary] (unpublished).
Stafanov V. 2003. Methodology for European ground squirrel monitoring – proposals. In: Boteva D. (ed.). Development and applying system of ecological monitoring in National Parks “Rila” and “Central Balkan”, 187- 216. Available on Internet: [In Bulgarian] (unpublished).
Stefanov V. 2006. Conception for conservation of European ground squirrel’s (Spermophilus citellus) habitats in NATURA 2000. 42pp. Available on Internet: [In Bulgarian] (unpublished).
Zidarova S. 2003. Some special feature in dispersion and biology of European ground squirrel, Spermophilus citellus L. (Mammalia, Rodentia) in Sofia district. Master thesis. Sofia University “St. Kliment Ohridski”, Sofia, 70pp. [In Bulgarian].


Belcheva R. G., D. Ts. Peshev. 1979. Intersubspecific sex chromosome differences in Citellus citellus L. (Rodentia, Sciuridae). – Experimentia, 35: 595 - 596.
Belcheva R. G., D. Ts. Peshev. 1985. Constitutive Heterochromatin in the Ground Squirrel Citellus citellus L. (Sciuridae, Rodentia) from Bulgaria. – Zool. Anz., Jena, 215 (5/6): 385 - 390.
Dimitrova P. 1974. The white blood picture in Citellus citellus L. and its cyclic change. – Bull. de l’Institut de Zoologie et Musee, XL, 153-166 [In Bulgarian with English summary]
Dimitrova P. 1975. Comparŕtive blood morpho-physiological investigation between European souslik Citelluscitellus L. and Red squirrel Sciurus vulgaris L. PhD Thesis (BAS). [In Bulgarian].
Markov G. 1952. The mammals in the forest shelter belts in Dobrudja. – Nature (Sofia), 3: 62-65. [In Bulgarian]
Markov G. 1957. Untersuchungen uber die Systematik von Citellus citellus L. Izvestija  Zool. Institut, Sofia, 6: 453-490. [In Bulgarian, German summary]
Mitev D. 1968. Studien uber die taxonomie von Citellus Citellus L. (Mammalia) in Sudbulgarien. – Trav. Sc. Ec. Nor. Sup. “Paissi Hilendarski”, Plovdiv,  6 (2): 137 - 142. [In Bulgarian with German summary]
Paspalev G., Tz. Peshev. 1957. Beitrag zur Okologie des Citellus citellus L. in Bulgarien. Bull. Padol. Inst. Bulgarischen Acad. Wiss. 4, 175-189 [In Bulgarian with German summary]
Peshev D. 1987. Cytological characterization of the European souslik (Citellus citellus L.) in Bulgaria. – In: Proceeding from conference “Contemporary achievements of the Bulgarian zoology. Sofia, BAS: 371 -375. [In Bulgarian]
Peshev Z. 1955. Investigations on systematics and biology of Citellus citellus L. in Bulgaria. Bulletin de l’Institut zoologique de l’Academie des sciences de Bulgarie, 4-5, 277-325. [In Bulgarian with English summary]
Stefanov S. 1957. On some seasonal morpho-hystological changes in the gonads of the Europan souslik (Citellus citellus balcanicus subsp. nov. Markov, 1956) around Sofia. – Annuaire de l’Universite de Sofia “St. Kliment Ohridski” - Biol. 69(1): 57 - 67. [In Bulgarian]
Straka F. 1959. Some special feature on feeding on souslik in Bulgaria. – Nature (Bulgaria). [In Bulgarian]
Straka F. 1961. Beitrag zur Biookologie und Bekampfung des Europaischen Ziesels (Citellus citellus L.) in Bulgarien. – Bulletin of the Central Scientific-Research Institute of Plant Protection, 1, 24-63. [In Bulgarian with German summary]
Tsvetkov Ts., T Takeva. 1989. Studies on the estrus cycle of the ground squirrel Citellus citellus L. at experimentally induced hibernation. – Cryobiology, 26(5): 508-511.
Tsvetkov Ts., T Takeva. 1991.  Some seasonal changes in the thecal gland in the ovaries of hibernators Citellus citellus L. – Cryobiology, 28(5): 503-508.
Yotov S. 1993. Spatial structure and behaviour of European ground squirrel (Citellus citellus L.). Master thesis. Sofia University “St. Kliment Ohridski”, Sofia, 48pp. [In Bulgarian]
Yotov S. 1998. A literature review of the Citellini tribe and field research on the population structure, behaviour and possibilities for re-introduction of the European souslik (Spermophilius citellus L., 1776). Student thesis. Central European University, Department of Environmental Science and Policy, Budapest, Hungary, 70pp.




Amori G. 1996. Spermophilus citellus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species; Available from:
Armitage K. 1981. Sociality as a life-history tactic of ground squirrels. – Oecologia, 48: 36–49.
Franguedakis-Tsolis S., J. Ondrias. 1985. Geographic variation of the ground squirrel Citellus citellus (Mammalia: Rodentia) in Greece with a description of a new subspecies. – Saugetierkundliche Mitteilungen, 32: 185-198
Gur H., M. Gur. 2005. Annual cycle of activity, reproduction, and body mass of anatolian ground squirrel (Spermophilus xanthoprymnus) in Turkey. – Journal of Mammalogy, 86(1): 7-14
Hoffmann I.E., E. Millesi and J.P. Dittami. 1997. Survival and longevity in European ground squirrels, Spermophilus citellus. – Advances in Ethology, 32: 258.
Hoffmann I.E., E. Millesi, K. Pieta and J.P. Dittami. 2003. Anthropogenic effects on the population ecology of European ground squirrels (Spermophilus citellus) at the periphery of their geographic range. – Mammalian biology, 68(4): 205-213.
Hoffmann I.E., E. Millesi, S. Huber, L.G. Everts and J.P. Dittami. 2003. Population dynamics of European ground squirrels (Spermophilus citellus) in a suburban area. –  Journal of Mammalogy, 84: 615-626.
Huber S., I.E. Hoffmann, E. Millesi, J.P. Dittami and W. Arnold. 2001. Explaining the seasonal decline in litter size in European ground squirrels. – Ecography, 24: 205–211.
Huber S., Ĺ. Millesi, Ě. Walzl, J. Dittami and W. Arnold. 1999. Reproductive effort and costs of reproduction in female European ground squirrels. – Oecologia, 121: 19–24.
Katona K., O. Vaczi and V. Altbacker. 2002. Topografic distribution and daily activity of the European ground squirrel population in Bugacpuszta, Hungary. – Acta theriologica, 47(1): 45-54.
Krystufek B. 1999. Spermophilus citellus (Linnaeus, 1766). – In: Mitchell-Jones A.J.(ed.): The atlas of European mammals. London (Academic Press): 190–191.
Krystufek B. 1990. Nonmetric cranial variation and divergence European sousliks (Citellus citellus) from Yugoslavia (Rodentia, Sciuridae). – Bonn. Zool. Beitr., 57: 351-355.
Krystufek B. 1993. European souslik (Spermophilus citellus; Rodentia, Mammalia) of Macedonia. – Scopolia, 30: 1-39.
Krystufek B. 1996. Phenetic variaton in the European souslik, Spermophilus citellus (Mammalia: Rodentia). – Bonn. Zool. Beitr., 46(1-4): 93-109.
Millesi E., A.M. Strijkstra, I.E. Hoffmann, J.P. Dittami and S. Daan. 1999ŕ. Sex and age differences in mass, morphology, and annual cycle in European ground squirrels, Spermophilus citellus. – Journal of Mammalogy, 80: 218–231.
Millesi E., S. Huber, J.P. Dittami, I.E. Hoffmann and S. Daan. 1998. Parameters of mating effort and success in male European ground squirrels, Spermophilus citellus. – Ethology, 104: 298–313.
Millesi E., S. Huber, K. Pieta, M. Walzl, W. Arnold and J.P. Dittami. 2000a. Estrus and estrogen changes in mated and unmated free-living European ground squirrels. - Horm. Behav., 37: 190–197.
Millesi E., S. Huber, L.G. Everts and J.P. Dittami. 1999b. Reproductive decisions in female European ground squirrels: factors affecting reproductive output and maternal investment. – Ethology, 105: 163–175.
Millesi E., S. Huber, M. Walzl and J.P. Dittami. 2000b. Follicular development and hibernation in European ground squirrels. - In: Heldmaier G., M. Klingenspor  (ed.): Life in the cold. Berlin (Springer): 285–292.
Ozkurt S., N. Yigit, E. Colak, M. Sozen and M. Gharkheloo. 2005. Observation on the ecology, reproduction and behavior of Spermophilus Bennet, 1835 (Mammalia: Rodentia) in Turkey. – Turkish Journal of Zoology, 29: 91-99.
Ruzic A. 1978. Der oder das Europaische Ziesel (Citellus citellus). In: Niethammer J., F. Krapp (ed.): Handbuch der Saugetiere Europas 1. Wiesbaden, (Akademische Verlagsgesellschaft): 122–144.
Vaczi O., B. Koosz and V. Altbacker. 2001. The effect of ambient temperature on daily activity pattern of European susliks. – Ethology, 36: 279.
Vaczi O., B. Koosz and V. Altbacker. 2006. Modified ambient temperature perception affects daily activity patterns in the European ground squirrel (Spermophilus citellus). – Journal of Mammalogy, 87(1): 54–59.


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