Sicista kazbegica, Sokolov, Baskevich & Kovalskaya, 1986

Don E. Wilson, Russell A. Mittermeier & Thomas E. Lacher, Jr, 2017, Sminthidae, Handbook of the Mammals of the World – Volume 7 Rodents II, Barcelona: Lynx Edicions, pp. 9-48 : 42

6.

Kazbeg Birch Mouse

Sicista kazbegica

French: Siciste du Kazbegi / German: Kazbeg-Birkenmaus / Spanish: Raton listado de Kazbegi

Taxonomy. Sicista kazbegica Sokolov, Baskevich & Kovalskaya, 1986 ,

upper reach- es of the Terek River, subalpine zone, 2200 m, Suatisi Ravine , 14 km north-west of Kobi , Kazbegi District, central Greater Caucasus, Georgia.

Western Montane Species Group. Sicista kazbegica is closely related to three other species endemic to the Caucasus. Two of these are also endemic to the Greater Caucasus: S. caucasica and S. kluchorica . The third species, S. armenica , is endemic to the Lesser Caucasus. V. E. Sokolov and colleagues in 1986 described S. kazbegica based mainly on its karyotype and chromosomal morphology. They stated that it was very similar in pelage color and penile anatomy to S. caucasica and S. kluchorica . Sicista armenica was not compared because it was not yet described. Diploid number does not usually vary within species of Sicista , but Sokolov and M. I. Baskevich in 1992 discovered a population of S. kazbegica with 2n = 40 in North Ossetia, Russia, that differed from 2n = 42 in the type series of S. kazbegica from upper reaches of Terek River, Georgia. According to Sokolov and Baskevich and Baskevich in 1996, difference in diploid number resulted from a single chromosomal rearrangement, a tandem translocation; These two karyotypic forms that inhabit northern versus southern slopes of the central Caucasus are thus considered populations of S. kazbegica and not separate species. Results of random amplified polymorphic DNA (RAPD) polymerase chain reaction (PCR) analysis by Baskevich and colleagues in 2004 showed greatest genetic similarity between S. caucasica and S. kluchorica and that S. kazbegica was more genetically similar to these two species than to other species of Sicista . Molecular phylogenetic analyses by Baskevich and colleagues in 2016 and T. Cserkész and colleagues in 2017 supported a close phylogenetic relationship among the three Caucasian endemics and indicated a close relationship with the Eastern Montane Species Group. Their results also indicated that species status of S. kazbegica is well supported based on analyses of nuclear interphotoreceptor retinoid-binding protein (IRBP) and cytochrome-b gene sequence data. Monotypic.

Distribution. C Greater Caucasus, Kazbegi District of Georgia and North Ossetia, Russia, and possibly adjacent Ingushetia; E limit is unknown.

Descriptive notes. Head-body 62-2—-67-2 mm, tail 94-5-109-5 mm, ear 9-6-11-1 mm, hindfoot 16-7-18-6 mm; weight 6-5-8 g. Dorsum of the Kazbeg Birch Mouse is reddish brown or yellowish/grayish brown, with conspicuous black guard hairs; sides of body and cheeks appear paler and brighter due to absence of black-tipped guard hairs. Venter is grayish white. Hindfoot is long, ¢.28% of head-body length. Tail is relatively long, ¢.160% of head-body length, and not as distinctly bicolored as that of the Caucasian Birch Mice (S. caucasica ), the Armenian Birch Mice (S. armenica ), and the Kluchor Birch Mice (S. kluchorica ). Condylobasal lengths are 17-2-18-5 mm, zygomatic breadths are 9-9-9 mm, interorbital breadths are 3-5-4 mm, and lengths of upper tooth rows are 3-2-3-6 mm. Surface of glans penis ofall four species endemic to the Caucasusis covered with small keratinized spines but lacks larger spines or penile spikes projecting out of terminus that characterize species in the Northern and Steppe species groups. Diploid number is 2n = 40 in the North Ossetia population and 2n = 42 in the Kazbegi population. External and cranial measurements were recorded from adult males captured in North Ossetia, Russia, published by G. I. Shenbrot and colleagues in 1995 and 2008.

Habitat. Subalpine meadows and mixed forest at elevations of 1850-2200 m. Subalpine meadows with tall forbs and grass provide optimum habitat for Kazbeg Birch Mice. Individuals have been captured in mixed birch ( Betula , Betulaceae ) elfin forest, interspersed with sparse willow ( Salix , Salicaceae ) and understory of Caucasian rhododendron (Rhododendron caucasicum), fruiting blueberry ( Vaccinium myrtillus) and lingonberry (V. vitis-idaea), all Ericaceae , and dense tall forb and grass cover.

Food and Feeding. Little is known, but Shenbrot and colleagues and Baskevich in 2000 stated that captive Kazbeg Birch Mice ate insects, seeds, and berries.

Breeding. Peak of the breeding season probably commences toward the end of May and beginning ofJune, according to Baskevich in 2000. Reproductively mature males, as determined by presence of sperm in testes, have been captured in late May through mid-July, as discussed by Baskevich. Females with filiform or threadlike uteri, indicating no previous pregnancies, were captured in late June and earlyJuly. Litters have 4-7 young, according to Shenbrot in 2016. Sokolov and colleagues suggested that breeding season of the Kazbeg Birch Mouse is correlated with elevation because the same breeding season was noted for the Kluchor Birch Mouse captured at similar elevations.

Activity patterns. Kazbeg Birch Mice are nocturnal and likely also crepuscular. Baskevich in 2000 stated that earliest captures occurred in late May; they are likely active for 3-3-5 months/year. There is no information about burrows and nests of Kazbeg Birch Mice, but closely related species burrow under moss, beneath or inside rotting logs and stumps and emerge after snow recedes and warmer temperatures stabilize.

Movements, Home range and Social organization. Kazbeg Birch Mice are probably solitary. Shenbrot and colleagues in 1995 and 2008 suggested that the Kazbeg Birch Mouse is more common in North Ossetia due to preservation of habitat than in neighboring Georgia where cattle grazing and other human activities degrade habitat. Baskevich in 2000 reported that only one Kazbeg Birch Mouse was obtained in a small mammal survey in 1988 during late May in the Tseydon River Valley, North Ossetia. At the samesite, eleven individuals were trapped within four days in late June 1989 and comprised 27-5% of all small mammals (rodents and shrews) captured, second only to field mice (Apodemus sp.). In 1990, four individuals were captured in mid-July and comprised 14-3% of small mammals captured; voles,field mice, and shrews were more frequently captured.

Status and Conservation. Classified as Endangered on The IUCN Red List. This classification is due to limited distribution of the Kazbeg Birch Mouse, fewer than five verified collecting localities, and habitat threats such as overgrazing and agricultural activities. Population trend was classified as unknown. Baskevich in 2000 estimated that its distribution is less than 5000 km? and Shenbrot in 2016 and Baskevich in 2000 emphasized that suitable habitats outside protected areas will continue to decline and thus negatively impact populations of the Kazbeg Birch Mouse. Overgrazing has resulted in replacement of tall mesophilic subalpine and alpine grasses with xerophytic weeds and significantly reduced ground cover that hastens erosion. International collaborative action plans such as the Ecoregion Conservation Plan for the Caucasus published in 2012 have developed goals to conserve and protect habitats, fauna, and flora in the Caucasus due to its designation by Conservation International and other groups as a biodiversity hotspot based on high levels of diversity and endemism.

Bibliography. Baskevich (1996, 2000, 2016), Baskevich, Okulova et al. (2004), Baskevich, Potapov & Mironova (2016), Cserkész, Fulop et al. (2017), Shenbrot (2016), Shenbrot et al. (1995, 2008), Sokolov & Baskevich (1992), Sokolov et al. (19864), Zazanashvili et al. (2012).

Figures

1. Long-tailed Birch Mouse (Sicista caudata), 2. Chinese Birch Mouse (Sicista concolor), 3. Tian Shan Birch Mouse (Suwcsta ttanshanica), 4. Caucasian Birch Mouse (Sucsta caucasica), 5. Kluchor Birch Mouse (Sicista kluchorica), 6. Kazbeg Birch Mouse (Sicista kazbegica), 7. Armenian Birch Mouse (Sicista armenica), 8. Altai Birch Mouse (Sicista napaea), 9. Gray Birch Mouse (Sicista pseudonapaea), 10. Northern Birch Mouse (Sicista betulina), 11. Strand’s Birch Mouse (Suwcista strandi), 12. Southern Birch Mouse (Sicista subtilis), 13. Hungarian Birch Mouse (Sucista trizona), 14. Nordmann’s Birch Mouse (Sicista loriger)

Distribution. C Greater Caucasus, Kazbegi District of Georgia and North Ossetia, Russia, and possibly adjacent Ingushetia; E limit is unknown.