10.

Striped Dwarf Hamster

Cricetulus barabensis

French: Hamster de Chine / German: Daurischer Zwerghamster / Spanish: Hamster enano rayado

Taxonomy. Mus barabensis Pallas, 1773, Kasmalinskii Bor, banks of Ob River, W Siberia, Russia.

Cricetulus barabensis is in the barabensis species group. In the past, there was confusion about taxonomy of griseus and pseudogriseus, which were eitherlisted as species on their own right or subspecies of barabensis . Both griseus (2n = 22) and pseudogriseus (2n = 24) differ in karyotypes from barabensis (2n = 20), but all chromosomal forms intebreed successfully. Up to six subspecies have been recognized, but actual number is not established with certainty. Subspecific differentiation needs to be clarified pending further studies. Treated here as monotypic.

Distribution. NE Kazakhstan, Russia (W Siberia from Irtysh River E through Transbaikalia to Ussuri region in Russian Far East), Mongolia, N, NE & C China, and extreme NW & NE Korean Peninsula.

Descriptive notes. Head-body 72-124 mm, tail 15-33 mm, ear 14-18 mm, hindfoot 13-19 mm; weight 20-60 g. Dorsal pelage of the Striped Dwarf Hamster is light graybrown to reddish, with mid-dorsalstripe that is prominent or obscured. Ventral pelage is gray, and hairs have gray bases and white tips. Ears are blackish and white framed. Tail is ¢.30% of head-body length;it is dark above and lighter below. Skull has proportionally long rostrum and nasal bones and moderately large braincase. Interoribial region is broad and without supraorbital ridges. Snout is short. Auditory bullae are large. Molars are low-crowned, with cusps arranged in two parallel series. Chromosomal complement has 2n = 20-24 and FN = 38.

Habitat. Arid areas such as steppe, forest steppe, and semi-deserts; frequently found in river valleys, close to other water sources, in croplands, and sometimes in houses.

Food and Feeding. The Striped Dwarf Hamster eats grains, legumes, leaves, and insects. Food is transported in pouches that can carry 3—4 g (exceptionally up to 10 g); green particles were rarely found in pouches. Hoarding of food starts in autumn and caches can contain up to 500 g of grain.

Breeding. Reproduction starts in February-March and ends in November—January. There are two peaks in reproduction: March-April and autumn. Females carry 4-10 embryos (usually 6-7) and have 2-5 litters/season. Latelitters are larger on average; e.g. in Kazakhstan, mean count of embryos is 7-7 in September and 5-7 in June. Newborns weight 1-7 g. Striped Dwarf Hamsters become sexually mature in 22-27 days of age when males weigh 17-18 g. Young females were found pregnant at 14 g. Life expectancy is 1-2 years. In a study in Beijing, China, sex ratio was slightly female biased (1 male:1-1 females) for the entire population, but males outnumbered females in adult and the oldage groups. Density has two seasonal peaks at high densities—one in April and one in August—and a single peak at low densities in March—May. Mating system is polygamous.

Activity patterns. The Striped Dwarf Hamster is nocturnal, active mainly in the first one-half of the night. During the night, individuals can move up to 50-70 m from burrows. The Striped Dwarf Hamster hibernates.

Movements, Home range and Social organization. Striped Dwarf Hamsters dig burrows with 2-3 entrances and 4-5 chambers for food storage and nesting. Tunnels are c.l m long and descend 10-50 cm; they are initially vertical for 10-20 cm and oblique or horizontal afterward. Winter nest is deeper (up to 1 m) than summer nest (40-60 cm). Striped Dwarf Hamsters are solitary for most of the year, but a burrow can be occupied by 4-8 individuals.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Batsaikhan, Samiya et al. (2014), Batsaikhan, Tinnin, Shar et al. (2016), Corbet (1978), Gromov & Erbajeva (1995), Malygin et al. (1992), Musser & Carleton (2005), Poplavskaya et al. (2013), Smith & Hoffmann (2008), Zhang Jie (1986), Zhu Shengkan & Qin Zhiheng (1991).