6.

Brandt's Hamster

Mesocricetus brandii

French: Hamster de Brandt / German: Brandt-Hamster / Spanish: Hamster de Brandt

Other common names: Turkish Hamster

Taxonomy. Cricetus brandti Nehring, 1898, near Tbilisi, Georgia.

In the past, M. brandti was considered a subspecies of M. auratus . The two species differ in karyotype (2n = 42 in brandti), color, shape of glans penis, and molecular sequences. Closest relative to M. brandti is M. newtoni . Subspecific differentiation has not been studied. Monotypic.

Distribution. S of Caucasus in Turkey (C & E Anatolia), Georgia, Armenia, Azerbaijan, and NW Iran (as far as Qazvin and Lurestan provinces); small isolated population N of Caucasus between Makhachkala and Derbent in Dagestan (Russia).

Descriptive notes. Head-body 135-195 mm, tail 10-39 mm; weight 108-175 g (captive two-year-olds weight 137-296 g). Brandt's Hamster is similar to the Golden Hamster ( M. auratus) in body proportions, but larger on average and different color. Back of Brandt's Hamster is sand-brown to tawny olive, flanks are yellowish, and belly is gray-white to white, with wide, black transverse band on chest. Yellowish blotch on cheeks and shouldersis intercepted by an oblique black subauricularstripe. Skull and teeth of Brandt's Hamster are similar to those of the Golden Hamster .

Habitat. Dry and rocky grassy sites, areas with stony debris and scattered bushes, and fields of cereals and multiannual crops at elevations of 300-3000 m; damp places are avoided.

Food and Feeding. Brandt's Hamster eats plants and insects. Grain and grasses are stored in burrows. Food is stored, and winter caches contain up to 1-6 kg of grain, leaves, tubers, bulbs, and frequently bones of small and large mammals. In the past,it was considered an agricultural pest. When deprived of grain, Brandt's Hamsters switch diets to green vegetables (e.g. cabbage) but become lighter (weight 89-108 g) than when on diets of grain (108-175 g).

Breeding. Reproductive period of Brandt’s Hamsterlasts from late January to mid-August, but this varies among regions (e.g. late March to mid-summer in Anatolia andJune, possibly April, to October in Transcaucasia). Wild and captive Brandt's Hamsters normally have no litters in November-March. Females can produce firstlitters at ¢.50 days old but reach peak of fecundity at c.1 year old. Gestation is 15 days in captivity and 16-17 days in the wild;litters have 1-13 young, exceptionally 15-16 (even 20). Mean litter sizes vary among regions: 6-6-7-5 young in eastern Transcaucasia, 8-5 young in Anatolia, and 9-8 young in Georgia. A female can have 2-3 litters/year and, under exceptionally favorable conditions, 4 litters/year. Three litters/year are normal in laboratory conditions. Newborns weigh ¢.2:6 g and are blind, deaf, and naked. On day 12-13, they open eyes and start eating solid food and are weaned before they are 20 days old. Individuals born after June do not attain sexual maturity until the following spring. Lifespan correlates positively with amount of time spent in hibernation. Captive hamsters may live up to 4-4 years, but average life expectancy is 1-8 years. Sex ratio is 1:1 in wild populations.

Activity patterns. Brandt's Hamster is nocturnal and occasionally crepuscular. It is a better hibernator than the Golden Hamster . Captive Brandt’s Hamsters undergo autumn fattening and lethargy when exposed to cold. Hibernation lasts ¢.5 months butis interrupted by 1-3 day intervals of euthermia. Wild individuals start hibernating with first frosts in October-December and come out of burrows in late February-April. They may leave their burrows during warm winter days. Bouts of uninterrupted lethargy (body temperatures of 7-9°C) are normally short (4-8 days) but may last up to 28 days. Wild hamsters hibernate in October-March and lose 24% of body mass during winter. On the ground’s surface, they move slowly and are fairly clumsy, but they can move long distances. Brandt's Hamster excavates a burrow on elevated and well-drained sites. Soil is displaced by front feet and moved by synchronous thrusts of hindfeet. Galleries mainly descend 60-75 cm and are up to 6-10 m long. Burrow has 1-3 entrances, and main entrance is frequently an almost vertical shaft that curves abruptly to a horizontal plane at a depth of up to 1 m or more. Galleries and chambers branch from this main shaft and are used for food storage, latrines, and nesting. Nest chamber may be up to 2 m deep and is lined with dry vegetation. Winter burrows are always excavated along edges of arable land, never in fields. Brandt's Hamstersalso excavate simple emergency shelters. Individual burrows may be excavated close to each other with up to 30-40 holes forming a cluster.

Movements, Home range and Social organization. Brandt's Hamster is solitary. Males are less aggressive to familiar neighbors than to unfamiliar males. A female usually assumes a dominant position in a group that allows her to enter burrows of other individuals. Brandt's Hamsters mark territories using olfactory clues. Significant variation in behavior was reported among populations; e.g. individuals in the vicinity of Gori differ from those on the Akhalkalaki Plateau (both in Georgia) by being more aggressive and having young that play togther. When attacked, Brandt's Hamsters fight vigorously, jumping on an attacker and trying to bite it. During defense, they inflate cheek pouches and quickly wave front paws.

Status and Conservation. Classified as Near Threatened on The IUCN Red List. The status is justified by habitat decline and rarity. Densities of Brandt's Hamsters are puzzling. In a study in Anatolia, trapping yielded only three hamsters per 1000 small mammals captured. In contrast, Brandt's Hamsters were 33-5% of small mammals preyed on by Eurasian eagle-owls (Bubo bubo). Population decline was recently reported in Dagestan, presumably following changes in land use, specifically decreases in cereal fields. In Georgia, populations declined by more than 50% over the past few decades, and Brandt's Hamsteris included in the country’s national red book.

Bibliography. Bukhnikashvili (2016), Gromov & Erbajeva (1995), Krystufek & Vohralik (2009), Krystufek, Vohralik & Obuch (2009), Krystufek, Yigit & Amori (2008), Lyman & O'Brien (1977), Neumann et al. (2006), Omarov & Yarovenko (2011), Romanenko et al. (2007), Shidlovsky (1976).