Caucasian birch mouse
Sicista caucasica
Mikhail Rusin · Karachay-Cherkess
Key facts in one look
- Diet
- Insects, seeds, berries
- Status in Georgia
- Native, only in Abkhazia
- Size
- Body 4.4–6.9 cm, tail 8.4–10.6 cm, 5.8–7.2 g
- Habitat
- Subalpine meadows, forest glades, 1,400–2,100 m
- Family
- Sminthidae
- Conservation
- NT / NT
The Caucasian birch mouse is a tiny rodent: it weighs just 5.8–7.2 g, and its tail is about one and a half times as long as its body. It is endemic to the western Greater Caucasus and spends most of the year, 8–9.5 months, hibernating. In Georgia it has been found only in Abkhazia: at Lake Ritsa, Pskhu, Avadhara and Mount Anchkho. It looks almost identical to the Kluchor birch mouse and can be told apart reliably only by its chromosomes and genetics. If you see a tiny, long-tailed mouse on a tall-grass mountain meadow, take a photo and do not pick it up.
Identification
Caucasian birch mouse: how to identify it
A tiny, light mouse with a very long tail and long hind feet. The back is reddish ochre-brown with no stripe, and the belly is whitish. In Georgia it is most easily confused with the Kluchor and Kazbeg birch mice, which look almost the same.
The body is 4.4–6.9 cm long and the tail 8.4–10.6 cm, about 150% of the body. The hind foot is 1.7–2.2 cm, about 30% of the body. It weighs 5.8–7.2 g.
The back is reddish ochre-brown with scattered black hairs and no mid-dorsal stripe. The flanks and cheeks are paler and brighter. The belly is greyish white with a yellowish tinge, or bright white, and the tail is two-toned, dark above and pale below.
It can hardly be told from the Kluchor birch mouse by its appearance or skull. It is identified reliably only by its chromosome number (2n = 32) and genetics. So you cannot name the species from a photo, but the place and date are still valuable.
Colour
Swatches are illustrative. Do not identify a species by colour alone.
It is an animal of tall-grass mountain ground: subalpine meadows, glades in fir and mixed forest, and riverbanks with dense, tall grass or a herb layer. It occurs from 1,400 m to at least 2,100 m. It lives in the western Greater Caucasus, on the northern slope in Russia and on the southern slope in Abkhazia. In Georgia it has been found at Lake Ritsa, Pskhu, Avadhara and Mount Anchkho.
It is active at dusk and at night, and at high altitude perhaps by day as well. In cold weather its activity drops sharply. It hibernates for 8–9.5 months of the year, usually from mid- or late August to May. It is most active in June and July. It lives alone. Mating starts in mid-May, right after the mice leave hibernation, and lasts until early June. Depending on the weather, this can shift by up to two weeks. Pregnant females are found from late June to late July, and a litter has 4–6 young. Mice born that year do not breed. In the wild it lives up to about 3 years.
Globally the Caucasian birch mouse is rated Near Threatened (NT, 2020). In Georgia the 2021 national assessment also rates it Near Threatened (NT), while the 2006 Red List of Georgia listed it as Vulnerable (VU) because of its very small range. Its range may be smaller than 20,000 km². Its habitat suffers from overgrazing, the loss of tall grass and building linked to growing tourism. It is far rarer outside protected areas, and its populations are not monitored.
Related guides
Continue with related pages
Only in the mountains of Abkhazia: at Lake Ritsa, Pskhu, Avadhara and Mount Anchkho. It lives on tall-grass subalpine meadows and forest glades, from 1,400 m to at least 2,100 m.
Its stripeless, reddish ochre-brown back and very long tail set it apart from other mice. From the Kluchor birch mouse, however, it hardly differs in appearance: they can be told apart reliably only by chromosomes and genetics. So note the place and date of your photo as well.
For 8–9.5 months of the year, usually from mid- or late August to May. It is active only in a short summer window, most of all in June and July. In that time it mates and raises a litter of 4–6 young.
Yes, it is Near Threatened (NT) both globally (2020) and in Georgia (2021). The 2006 Red List of Georgia listed it as Vulnerable (VU). Overgrazing, the loss of tall grass and tourist building damage its habitat.
References
What this profile is based on
Species profiles are compiled from peer-reviewed literature and established biodiversity databases, and are reviewed as new taxonomic and conservation data become available.
Prepared by the Reptiles.ge editorial team from the sources listed here.
