Southern Birch Mouse
Sicista subtilis (Pallas, 1773)
Sicista loriger Nathusius: Miller, 1912: 537-538.
Order Rodentia
Family Zapodidae
Conservation status: in Bulgaria: Critically endangered CR [B1 b(i, ii, iv)], BDA-III; International: IUCN [LR/nt], BeC-II, HD-II, IV.
General distribution. The steppe zone of the Palearctic – from Eastern Austria, Hungary and Romania to Altai, Balkhash lake and Baikal lake, probably also Northwestern China.
Distribution and abundance in Bulgaria. Until 1985 two findings were known. At the beginning of the 20th century a report was published of an individual from Bulgaria without an exact habitat [1]. The second report is from the middle of the 20th century, from the surroundings of General Toshevo (Dobrich region) [2].
Habitats. Steppes with different grasses, forest steppes, arable areas [3]. According to data from the region of Constanta (Romania), the species is represented by low numbers in fallow lands and areas occupied by forage cultures, and in April and August it also enters areas with corn cultures; it is absent in the arable fields and the field-protecting belts [4].
Biology. It is active mainly in the night, but goes out in search of food also during the day. Hibernates in the winter. For shelter it uses holes and tunnels of other rodents and different other shelters. The feeding of the species has not been studied in Bulgaria. According to data from the literature, it feeds on seeds of herbaceous plants and insects [5]. There are no data about breeding in Bulgaria. According to literature data, the mating period is from the end of May to the beginning of June. A second generation is not proved. The number of the young is up to 7, most often 5 [6]. A major lethal factor is predation. It is attacked by predatory mammals and nocturnal birds of prey. In Bulgaria it has been found in pellets of owls (the village of Kamen bryag, Dobrich region), [7]. It probably competes for food resources with the much more numerous steppe mound-building mouse (Mus spicilegus).
Similar species. None.
Negative factors. Extensive agriculture, pollution of the soils with pesticides and fertilizers, restricted opportunities for re-settling, a restricted range of the species in Bulgaria.
Conservation measures taken. The species is protected according to the Biological Diversity Act.
Necessary conservation needed. Studies on its numbers and distribution; collection of information on its biology and ecology; establishing the state and the distribution of the optimal habitats; estimation of the threats. Working out a plan for management, including conservation measures. Organization of targeted monitoring.
References. 1. Miller, 1912; 2. Petrov, 1954; 3. Burton, 1987; 4. Hamar & Sutova, 1963; 5. Ognjev, 1948; 6. Gromov et al., 1963; 7. Peshev et al., 2004.
Author: Vasil Popov
