Roborovski's desert hamsters ( (Chi and Wang, 2011; Feoktistova and Meshchersky, 2005; Meschersky and Feoktistova, 1999; Meshchersky and Feoktistova, 2011; Nowak, 1999; Ross, 1994; Shar and Lkhagvasuren, 2008; Sokolov and Orlov, 1980)) are endemic to the southern Palearctic biogeographic region. They are most numerous in south, central and northwestern Mongolia. Their northern range extends from the Hunshandake sandy land and the Mongolian Gobi deserts (Gobi Altai Mountain Range, Great Lakes Depression, Valley of the Lakes, Northern Gobi, Eastern Gobi, Djungarian Gobi Desert, Trans Altai Gobi Desert and Alashani Gobi Desert) to adjacent territories of northern China. They are less numerous in the Ordos desert of China, south of the Zaisanskaya Depression in east Kazakhstan and in the southern portions of the Tuva Republic (Russia). Other than transport through the pet trade, Roborovski's desert hamsters are not known as established introduced species elsewhere.
Roborovski's desert hamsters are found in habitats with loose soil that facilitates their habit of digging burrows into the sides of sand dunes. To allow for proper construction, the sand horizon of the soil must be more than one meter in depth. The sandy soils of semi-deserts, steppes and grasslands offer the preferred terrestrial substrate over clay soils. Sparse, shrubby vegetation in these habitats also aids in burrow construction. In Mongolia, vegetation surrounding hamster burrows typically extends to a height of 75cm. Dominant herbaceous or gramineous plants species are caragana (Caragana tibetica), fabales (Ammopiptanthus mongolicus), Cynanchum (Cynanchum komarovii), and Zygophyllum pterocarpum. Agricultural landscapes that are grazed over by stocks of sheeps and goats, grain fields and orchards are also habitat for Roborovski's desert hamsters. Access to water is not a constraint on these hamsters. They are found in areas of low water availability, such as seasonal floodplains or mountain valleys with accompanying low elevation (maximum height of 1450 meters).
The semiarid regions where Roborovski's desert hamsters thrive are subjected to a continental type of climate with high variation in seasonal and daily temperatures. In the Alashan desert of Mongolia, mean annual precipitation is low (ranges from 45 to 215mm per year). Mean annual temperature is moderate (8.3°C), but extremes are reached in January (lows of -35°C) and July (highs of 40°C). There is also variation between the highest daytime and lowest night temperatures; temperature within 24 hours can vary by 15°C or 20°C, due to the low buffering capacity of sparse vegetation. (Carelton and Musser, 1984; Feoktistova and Meshchersky, 2005; Gattermann, et al., 2001; Ross, 1994; Scheibler and Wollnick, 2013; Shar and Lkhagvasuren, 2008; Topal, 1973; Walsberg, 2000)
Roborovski's desert hamsters are the smallest of all hamster species (Subfamily Cricetinae). In accordance with their small body size, the skull is delicate with a long and slender rostrum. The braincase is broad in front, while rounded dorsally. Their auditory bullae are reduced and flattened. These hamsters possess a pair of upper and lower arc-shaped, ever-growing, groove-less incisors. Their dental formula is: I 1/1 , C 0/0 , P 0/0 , M 3/ 3 = 16. The sharpness of the incisors is maintained through resistance to wear on the hard, enamelled, buccal tooth edge. The occlusal surface of the rooted molars is very simple, each with a maximum of two cusps per lamina. No pits are surrounded by enamel. The cusps and folds on the upper and lower molars are directly opposite. The third upper molar is extremely reduced. The incisive foramina is under four millimetres in length and is shorter than the upper toothrow. The vertebral column consists of thirteen thoracic vertebrae and six lumbar vertebrae. Roborovski's desert hamsters are quadrupedal with plantigrade locomotion. There are five digits on each paw. The feet consist of short and broad bones internally, while they are densely furred externally to protect against the heat of the sandy soils. The species has a diploid karyotype of 2n = 34 chromosomes, which is higher than that of striped desert hamsters (Phodopus sungorus).
Their fur is soft and thin. Along the dorsal surface, it reaches a maximum length of approximately 9mm. Roborovski's desert hamsters are cryptic, matching with the environmental sand, with a light-brown coloured pelage and lack of a mid-dorsal stripe. Prominent white patches are above each eye and at the base of each ear pinna. The mouth area, entire ventral surface, limbs and both sides of every foot are also completely covered with thick white fur. Their ear pinnae are grayish-brown anteriorly, with the posterior half and inside being white. There are no seasonal changes in the coloration, volume or density of the fur. Domestication has resulted in altered fur characteristics when compared to the wild state. Wild populations have a slightly greyer tint to their fur, but all fur variants become more grey during moult. In general, Roborovski's desert hamsters found in the pet trade have fur with less vibrant color. The fur of domestic animals is of a disturbed state, with a deformed shaft, cracking of the cuticle and uneven development of the cortex. Coloured domestic variants include pure white hamsters and those with a white head that contrasts a brown torso.
The physiological characteristics of Roborovski's desert hamsters vary seasonally. Within a normal ambient temperature range of 7°C to 31°C, their body temperature is 35.7°C. Acclimation to winter photoperiods and temperatures in September leads to a small drop in body temperature (by 0.21°C, when acclimated to 5°C). Cold acclimated hamsters can decrease their body temperature further (by nearly 1°C) in response to cold nights, but this ability is not apparent during cold sunlight hours. Their metabolic rate fluctuates seasonally, as cold acclimation is met with increases in resting metabolic rate and non-shivering thermogenesis. The thermoneutral zone of these hamsters is between 28°C and 34°C. The highest recorded thermoneutral zone, of approximately 35°C, is found in well-fed individuals during the day. Metabolic rates fluctuate from 1.38ml/oxygen/hour to as high as 8.79ml/oxygen/hour during nonshivering thermogenesis. The basal metabolic rate is 2.61ml/oxygen/hour. Their body mass fluctuates over the year, decreasing in September (to reach lows of approximately 19g in males; 17g in females), then increasing in December to reach a peak mass in the late spring or early summer (of approximately 27g in males; 21g in females). The length of the total digestive tract increases by up to 36.8% during cold acclimation. This species has sexual dimorphism, as the female average body mass throughout all months of the year is lower than that of males.
Roborovski's desert hamsters are immediately distinguished from sympatric gerbils (Subfamily Gerbillinae) or jerboas (Family Dipodidae) due to the presence of cheek pouches and a much smaller, stub-like tail that reaches at most only a fifth of the hamster's total body length. The prominent white patches above the eyes and the light brown color of their pelage is the most easy characteristic to distinguish this species from similar sympatric hamsters. Another important factor is relative body size. Roborovski's desert hamsters are the smallest among all dwarf hamsters with an adult head and body length range of 53 to 81mm. Their tail length ranges from 7 to 11mm, and their ear length ranges from 10 to 14mm. Females typically measure on the lower end of the ranges. Long-tailed dwarf hamsters (Cricetulus longicaudatus) and striped dwarf hamsters (Cricetulus barabensis) are common in the steppes of Northern China. Their pelage colors range from light brown to grey, however, they lack the prominent white patches above the eyes. Both of these species have tails that can reach up to 45% of their head to body length, while the tails of Roborovski's desert hamsters are stub-like. The striped dwarf hamster also has a very bold mid-dorsal stripe, which is completely absent in Roborovski's desert hamsters. When comparing skull morphology, long-tailed dwarf hamsters have a flatter braincase than Roborovski's desert hamsters. All hamsters of the genus Cricetulus have more inflamed auditory bullae. In the Mongolian parts of their range, Roborovski's desert hamsters are sympatric with striped desert hamsters (Phodopus sungorus) and Campbell's desert hamsters (Phodopus campbelli). Both these species have short tails, but they lack the prominent white patches above the eyes. P. campbelli possesses mid-dorsal stripes. Striped desert hamsters are often light grey in color, rather than cryptic brown as seen in Roborovski's desert hamsters, and have a pure white coat during the winter months.
Although Roborovski's desert hamsters are currently sympatric with multiple other species of dwarf hamsters, each of these species maintains their robust identity due to adaptations to particular niches. P. sungorus, following the shift to high aridity conditions that took place at the boundary between the Pleistocene and the Holocene (10 thousand years ago). P. sungorus took advantage of subsequent moistening in the northern and central regions of Mongolia and Kaxakhstan, while Roborovski's desert hamsters persist until today in regions that have remained highly arid. The complex morphological and physiological adaptations of Roborovski's desert hamsters to extremely arid environments are considered primitive. Roborovski's desert hamsters are sympatric with Campbell's desert hamsters in the northern and eastern part of their range, however Campbell's desert hamsters inhabit the stabilized ground of dry mudflats. (Carelton and Musser, 1984; Chi and Wang, 2011; Feoktistova and Meshchersky, 2003; Feoktistova and Meshchersky, 2005; Feoktistova, et al., 2013; Heping, et al., 2007; Jefimow, 2007; Martin, et al., 2001; Meshchersky and Feoktistova, 2011; Natochin, et al., 1994; Neumann, et al., 2006; Nowak, 1999; Qing-Sheng and De-Hua, 2010; Ross, 1994; Scheibler and Wollnick, 2013; Schmid, et al., 1986; Sokolov and Orlov, 1980; Sung and Chang-lin, 1973; Wan, et al., 2007; Xinmei and Dehua, 2004; Zhong, et al., 1981)diverged from its closest relative,
Courtship behaviour begins when females display increased sexual activity during estrus. Mating activities begin as mates approach from a distance, then progresses to olfactory investigation of the anogenital region and contact thereof, circling and lordosis. Mating cumulates with the mounting of mates and then terminates with copulation. Polyestrous female Roborovski's desert hamsters attract attention of males during the winter, spring and summer. They are likely similar to other dwarf hamsters (Phodopus spp.), in that female ovulation and receptivity to mate is spontaneously induced by the presence of males. Once induced, female estrus in Roborovski's desert hamsters lasts four days. In the absence of successful mating, it terminates on day four with the regression of ovulated follicles. As with other dwarf hamsters, obligate monogamy is the likely mating system for Roborovski's desert hamsters. It is possible that females, of this species, like females of the closely-related Campbell's desert hamsters (P. campbelli), have a higher success in delivering litters when post-copulatory contact with the male is sustained. Pregnancy-blocking hormones may be induced by females in the absence of prolonged male contact. (Erb, et al., 1993; Feoktistova and Meshchersky, 1999; Feoktistova and Naidenko, 2006; Scheibler and Wollnick, 2013)
The female uterus is duplex and vagina entry is opened year-round. There are eight mammae. In males, a baculum is present and testes are externally visible. The reproduction period for Roborovski's desert hamsters occurs between February and October. During a single year, up to four consecutive litters are reared. The reproductive cycle is very compressed to accommodate quick reproductive output. Gestation is only 20 to 22 days and an opportunity for post-partum mating exists. The estrous cycle lasts between 4 and 6 days. The length depends on the presence of a fifth cycle stage between pre-estrus and estrus, termed early estrus. Early estrus is unique in its complete lack of leucocytes in the vaginal cytology and a dramatic increase of serum luteinizing hormone levels. Early estrous lasts only 4 to 6 hours and is not present in all females. However, its presence results in the shortening of the pre-estrus stage to 14 to 18 hours and a shortening of the total length of the estrous cycle to 4 days. Estrous females display higher levels of sexual behaviour in effort to entice males, including approaching males for olfactory investigation and lordosis.
The breeding period is not influenced by temperature or photoperiod, as indicated by the ability of Roborovski's desert hamsters to mate and reproduce year-round. The first peak of breeding occurs in April. The second peak occurs between June and July. There is an average 3.6 to 3.9 pups per litter. Litter size may reach as high as 10. A very small peak occurs during autumn and winter. The blood plasma testosterone level in males is maximal during the summer months, though is high enough to sustain breeding in the late autumn and early winter. Due to possible continuation of successful mating in all seasons, this species is not strongly seasonal in its breeding habits. Populations undergo seasonal changes in age structure as the litters come to independence. There is an equal sex ratio of newborn females and males. This sex ratio persists throughout the population independent of age groups. Young of the year may become reproductively active, therefore, summer populations increase due to the breeding activities of both young and old individuals. Reproductive ability increases with the age of both sexes.
Seasonal changes in breeding frequency are met with physiological changes in both sexes. During all months but autumn, male plasma testosterone increases in response to female mid-ventral gland secretions. Males find the midventral gland secretions of females more attractive than those of other males during all seasons except for summer (when breeding activity peaks). When reproducion peaks, female midventral gland secretions are then complimented by urine secretions in order to enable greater success in stimulating a mating response in males. Female progesterone levels increase in spring for preparation of the breeding season, then remains high until autumn and winter. Levels of male plasma cortisol begin to increase in response to female urine in the spring and to the midventral gland secretions of other males in the summer. Cortisol levels in males peak in November, when male breeding rates and testosterone levels strongly decrease. Females are more attracted to midventral glands secretons that have been left by males with high blood testosterone levels. However, females consistently spend less time investigating male odors than males spend on the odors left by females.
Neonates are born altricial. They have incisors and claws, but their eyes, ear pinnae and digits remain closed until a week after birth. The neonates are essentially furless upon birth, and are ectothermic in terms of requiring environmental heat. Prior to effective thermogenesis beginning on day 9, thermoregulation is attempted through huddling, with each other as well as the mother, and by remaining in the underground nest area. By day 14, they are fully furred. The eyes and ear pinnae have opened. By day 15, they can thermoregulate independently through the development of brown adipose tissue, pelage thickening and increase in body mass. Dry food consumption begins 12 days after birth. Lactation ends 18 days after birth. Despite these events being linked closely to the number days post-birth, they are tied more closely to a sigmoidal increase in body mass rather than age. The young reach 70% of their adult body mass by 28 days of age and obtain a steady body mass by 60 days. Although time until independence can vary, a likely low estimate is 20 days. Given the post-partum estrus and potential post-partum mating by the mother, the independence of the first litter at approximately the same time as the birth of the second. (Dong, et al., 2001; Feoktistova and Meshchersky, 1999; Feoktistova and Meshchersky, 2005; Feoktistova and Naidenko, 2006; Feoktistova, et al., 2010; Guanghe, et al., 2001; Hou, et al., 2000; Martin, et al., 2001; McMilan and Wynne-Edwards, 1998; Newkirk, et al., 1995; Nowak, 1999; Ross, 1994; Scheibler and Wollnick, 2013; Shar and Lkhagvasuren, 2008; Wynne-Edwards, 1998; Xixian, et al., 2000)
There is variation in dwarf hamster parental care. This ranges from facultative biparental care in striped desert hamsters to obligate biparental care in Campbell's desert hamster, where fathers activity participate in the birthing process and return displaced offspring to the den. Paternal presence in Campbell's desert hamsters is an adaptive behavioral trait that aids both females and offspring avoid hypothermia during the rearing process in the cold, arid environments of the central Asian steppes where they live. In contrast, biparental care is not necessary for striped desert hamsters because predictable rains and warmer temperatures allow solitary females to more easily rear young. It is likely that juvenile Roborovski's desert hamsters are also only cared for by the mother, as this species is sympatric with the striped desert hamster throughout its range in Mongolian deserts. Therefore, it shares similar environmental constraints which most likely do not require biparental care.
As with striped desert hamsters, male Roborovski's desert hamsters are not always completely absent during the pre-weaning and pre-fledging processes of their offspring. Fathers will often remain in the same burrow network as his family group and therefore coincidentally help with provisioning by adding material to the food storage tunnels. However, males are rarely alone in the nest with the pups and will not contribute more extensively to parental care unless extreme environmental conditions or temperature levels require it. Roborovski's desert hamsters, like striped desert hamsters, likely offer only facultative biparental care in some cases. (Hume and Wynne-Edwards, 2005; Ross, 1994; Wynne-Edwards and Timonin, 2007; Wynne-Edwards, 1995; Wynne-Edwards, 1998; Zhong, et al., 1981)
Roborovski's desert hamsters retain their usual circadian rhythms with vigour up to and during their last weeks of life. Only within 4 to 8 days of death do their activity rhythms become unpredictable. Under laboratory conditions, they experience natural death at a mean age of 26 months. Reproductive aging progresses far more quickly. The fertility and fecundity of related female Campbell's desert hamsters (Phodopus campbelli) is halved by 8 months of age due to impaired ovarian function. Aged striped desert hamsters (Phodopus sungorus) (17 to 27 months) in captivity commonly suffer from histological diseases. Roborovski's desert hamsters may also show signs of these diseases when given a prolonged life in captivity: follicular mite infestation, uterine infection, glomerulonephropathy, cystic rete ovarii, thyroid branchial cysts, focal enteritis, benign and cancerous tumors. Life expectancy is much shorter for wild hamsters and can be as low as 12 months. Reduced lifespan in the wild is caused mainly due to increased parasite load, predation pressure and mortality during extremely cold winters. Other factors reducing longevity in the wild include disease and impact from agricultural machinery. (Edwards, et al., 1998; Feoktistova and Meshchersky, 2005; Johnson, et al., 2014; Kayser, et al., 2003; McKeon, et al., 2011; Weinert, et al., 2009)
Roborovski's desert hamsters are generally solitary, but may be found living in pairs while not rearing young. They are shy and meetings usually result in one hamster running to hide when the other approaches. Sociopositive behaviour towards each other includes investigative sniffing, sitting in contact and allogrooming. They are more passive when compared with closely related hamster species and will freeze when presented with a stressful stimulus. They also present lower levels of exploratory behaviour in a new environment. Towards other small rodent species, Roborovski's desert hamsters, in equal ratio: initiate attacks, are attacked, flee without direct contact, and cause fleeing without direct contact. Aggressive encounters may escalate to one hamster threatening, chasing or biting another until it submits.
Roborovski's desert hamsters are nocturnal both in natural and laboratory settings. When compared to other dwarf hamsters, this species has a more compressed period of nocturnal activity and an earlier nightly ending of such activity. The exact timing of the circadian rhythm is plastic under natural conditions. Spontaneous activity may be observed throughout diurnal hours. In contrast to predation that usually drives small rodents to a crepuscular lifestyle, heat stress during the day is the main factor driving Roborovski's desert hamsters to a nocturnal strategy. Natural photoperiods are the most important stimulus, but the cycle can also be altered by the presence of other species in such a way that offers each species a slightly different temporal niche in light of limited resources. When Roborovski's desert hamsters are the dominant species in the environment, they have been recorded to be active from 1.7 hours after sundown until 7.4 hours after sundown. When present, larger mid-day gerbils (Meriones meridianus) and Mongolian gerbils (Meriones unguiculatus) are the most common of other rodent species to aggressively attack Roborovski's desert hamsters at shared feeding sites. These interactions lead to significant shortening of the Roborovski's active period to between 0.8 and 3.0 hours after sundown due to stress and avoidance behavior.
There is also lunar and temperature plasticity in circadian activities. The onset of aboveground activity during the night and duration of foraging walks increases with increasing moon disc size, being the highest during the full moon phase that provides optimum illumination. There are different affects of temperature on the nocturnal aboveground activity. While activity increases with increasing night temperature and humidity, the effect of daytime temperature on nocturnal activity is not immediate. The positive effect of increasing ambient daytime temperature on nocturnal activity is delayed by up to three days prior to any selected night, and the similar effect of increasing soil temperature is most influential one day prior. The delayed influence of daytime temperature on hamster activity may be due to the influence of temperature on food availability. Both the rates of seed germination and seed coat opening decrease due to water loss during increasing temperatures. Increased temperature in the previous few days results in less abundant foraging material due to slower plant growth rates, leading to a decrease in nocturnal activity.
Hunting and foraging is a species-typical and genetically derived pattern. Hamsters proceed to the edge of their home range then systematically search for seeds or prey. When compared to the closely-related striped desert hamster (Phodopus sungorus), Roborovski's desert hamsters generally have increased locomotor activity in both natural and captive settings. In open field tests, Roborovski's desert hamsters spend significantly more time moving and move at a faster pace than striped desert hamsters. The increased activity of is compared to human attention-deficit hyperactivity disorder, along with the symptoms of inattention and impulsivity. The increased activity has a physiological basis in the lower concentraions of L- and D-serine sedatives in . Another physiological basis for the increased activity stems from having higher concentrations and conversion rates of L-tyrosine (a precursor of dopamine) to D-tyrosine amino acids, which ultimately leads to lower dopamine and serotonin levels in their brain when compared to P. sungorus.
Mesocricetus auratus), such that entrances lead into a 18cm to 45cm long vertical tunnel, or "gravity pipe", that falls into a horizontal nest chamber and usually no more than a single adult occupies a burrow. Nest chambers are up to 20cm wide and contain a spherical nest made opportunistically out of dry material found in the environment. Urination is restrained to a 10cm to 15cm dead-end tunnel, while defecation occurs throughout the entire underground structure. Food storage occurs in multiple tunnels that measure between 100 and 150cm that run at varying angles from the nest chamber.hamsters dig burrows into the sides of sand dunes. They have one or two entrance holes (4cm diameter). They extend deep into the soil (90cm deep), where they contain one nest and two to three food caches. Entrance holes are quickly hidden by loose sand. Nesting material may or may not be present. Burrows are likely similar to those of the closely-related golden hamster (
There is no sign of torpor or hibernation during the winter months, even during extremely low temperatures. Activity does decrease in the winter months: in February and March, (Scheibler and Wollnick, 2009; Scheibler and Wollnick, 2009; Scheibler and Wollnick, 2009; Scheibler and Wollnick, 2009; Scheibler and Wollnick, 2009; Scheibler and Wollnick, 2009; Scheibler, et al., 2014; Bao, et al., 2002a; Bao, et al., 2002b; Carelton and Musser, 1984; Chi and Wang, 2011; Feoktistova and Meshchersky, 2003; Feoktistova and Meshchersky, 2005; Gattermann, et al., 2001; Hamann, 1987; Heping, et al., 2007; Ikeda, et al., 2014; Jefimow, 2007; Kabuki, et al., 2008; Langley, 1985; Meschersky and Feoktistova, 1999; Ross, 1994; Scheibler and Wollnick, 2009; Scheibler and Wollnick, 2013; Scheibler, et al., 2013; Scheibler, et al., 2014; Wan, et al., 2007; Weinert, et al., 2009; Xinrong, et al., 2013; Zhong, et al., 1981)hamsters are active in their burrows for less than ten minutes a day. These hamsters do not store fat in preparation for winter. They do, however, have gradual weight gain over the summer months (from approximately 13 grams in spring to approximately 19 grams in autumn) as weight loss from the previous winter is re-gained. Weight generally decreases during the first six weeks of acclimation to winter temperatures, but only fasted individuals show significant weight loss during the winter months. This can be up to several grams (to reach lows of approximately 21 grams in adults). In all seasons, fasted hamsters regained weight loss within six days of re-feeding. Cold periods are spent in burrows in effort to select ambient temperatures near their thermoneutral zone.
Due to their small size and relatively slow movement, P. sungorus of Northeastern China. Males in that species have larger home ranges than females, and increasingly so during the summer months when breeding activity takes place (June to September). Female home ranges are the smallest during September, during which there is no overlap in female ranges. All other months of the year commonly have overlap in ranges between ages and sexes. If similar to striped desert hamsters, home range sizes are as follows: 1300 to 28250 square meters for adult males, 700 to 9500 square meters for adult females, 400 to 3200 square meters for juvenile males, and 700 to 7950 square meters for juvenile females. Under laboratory conditions, hamsters aged 18 to 30 weeks old ran approximately 3000 wheel revolutions per night. This distance is more or less equivalent to 1.2 kilometers total, which is lower than other dwarf hamsters. The smaller distance covered suggests a smaller home range size. Roborovski's desert hamsters also display higher consistency in the circadian timing of their nocturnal activity than other dwarf hamsters. They are active for a shorter period of time at night (approximately six hours per night, compared to nine hours for Campbell's and striped desert hamsters), which likely decreases their ability to forage over far distances. Studies in natural settings are required for more accurate home range size estimates in Roborovski's desert hamsters. (Dong, et al., 1989; Weinert, et al., 2009)hamsters have small home ranges. Home ranges may be similar to those of the striped desert hamster
golden hamster has shown that vision is used primarily while foraging for seeds and during predatory events towards insects. Auditory and olfactory senses contribute to a lower extent. In the absence of vision, auditory input contributes to a greater extent than olfaction. (Feoktistova and Meshchersky, 1999; Feoktistova and Meshchersky, 2003; Feoktistova and Naidenko, 2006; Langley, 1985; Ross, 1994; Turton, et al., 2010)hamsters have well-developed chemosensory mechanisms to facilitate their nocturnal lifestyle. A range of scents are produced to mark their environments. These scents are derived from urine, feaces, vaginal secretions, and secretions from two specialized glands: the mid-ventral gland and the sacculus. The midventral gland is larger in males. Although the odors from midventral gland secretions and faeces are important as mating attractants, urine marking remains the most common method for Roborovski's desert hamsters of both sexes to find potential mates. Urine marking is done most often by males hamsters when another male's urine is present. The obligate olfactory-binding protein released for urine-mediated chemosignals is termed roborovskin. It belongs to the lipocalin protein superfamily and shows no polymorphism between sexes or individuals. Roborovskin is involatile, thus its chemical signal is resistant to decay. Roborovski's desert hamsters spend more attention sniffing conspecific urine than that of more evolutionarily distant rodent species within their range, indicating how informative this line of communication is. A study with the related
As with all rodents (Order Rodentia), Roborovski's desert hamsters are gnawing animals. Short-term food storage makes use of large diastema between the incisors and molars. As with all hamsters of the family Cricetidae, internal cheek pouches are also used to store and transport food to caches. Cheek pouches are an extension of the oral cavity and, when full, extend past the shoulders and into the diastema. Roborovski's desert hamsters possess both a forestomach and a glandular stomach. The small intestine makes up 60%, the large intestine 27% and the caecum 13% of the total length of the intestine.
Roborovski's desert hamsters consume mainly plant seeds (70 to 90% of their diet), as well as plant leaves and plant stems. Succulent, green plant tissue is typically absent from their diet. In the Russian republic of Tuva, they feed primarily on the seeds of Alyssum desertorum, Caragana spp., Nitraria spp., Dracocephalum peregrinum, g,Astragalus spp., and Carex spp. Coprophagy of their own or another individual's dung may be done for increased nutrient intake. Water intake is partially provided by the insects that make up a small portion of their diet. Beetles (Order Coleoptera), earwigs (Order Dermaptera) and locusts (Order Orthoptera) are most commonly consumed. Although the average daily food consumption of these hamsters is two grams of plant seeds, this mass is positively correlated with body mass. Per unit of body mass, a juvenile consumes more food than an adult. Food intake also increases during the winter months to coincide with the increased need for thermogenesis. Food intake in cold acclimated (5°C) Roborovski's desert hamsters is 5.3 g/day (76.3 kJ/day). The hamsters adapt to temperature and food availability fluctuations by increasing their ability to digest food. They are able to convert food into metabolized energy at around 80% efficiency, but can increase up to 97% during prolonged cold exposure. This is higher than that of other other rodent species. Two to four food caches are stored in underground burrows.
Roborovski's desert hamsters are resistant to dehydration in their arid environments. They are well-adapted to low water availability though the morphological and functional adaptations of their kidney. When compared to their close relatives, striped desert hamsters and Campbell's desert hamsters, Roborovski's desert hamsters have a higher kidney-to-biomass ratio, greater length of nephrons, a reduced number of vasopressin-positive neurons. This is likely due to a greater expenditure of vasopressin during prolonged dehydration. During prolonged dehydration, the urine of Roborovski's desert hamsters becomes exceedingly concentrated at well over the normal average of 3417 mosm/kg (which occurs during periods of unlimited water supply). Water retention is increased in these hamsters, as they excrete only 43% of water consumed within a four hour period. This ratio far less than the 87& and 70% seen in the striped and Campbell's desert hamsters, respectively. The amount of water excretion by the skin and lungs is also greatly reduced during prolonged dehydration. (Carelton and Musser, 1984; Feoktistova and Meshchersky, 2005; Flint and Golovkin, 1961; Guanghe, et al., 2001; Martin, et al., 2001; Meshchersky and Klishin, 1990; Natochin, et al., 1994; Ross, 1994; Shar and Lkhagvasuren, 2008; Sokolov and Meshchersky, 1989; Wan, et al., 2007; Xinmei and Dehua, 2004)
Roborovski's desert hamsters are the most common species preyed-upon by long-eared owls (Asio otus). They make up 18% of the long-eared owl diet in their northwestern Chinese range. Other natural predators include foxes, weasels and other mustelids (Mustelidae), snakes, and owls (Order Strigiformes). Although hawks and falcons (Order Falconiformes) may prey upon Roborovski's desert hamsters, they do not constitute a large threat due to the nocturnal activity of these hamsters.
Anti-predator adaptations include morphological crypsis and behavioural modifications. The dorsal fur of Roborovski hamsters is of a light brown colour that is camouflaged well with the underlying sand from arial vantage points. Although risk of predation is increased through their habit of prolonging foraging activity during highly illuminated nights, anti-predator strategies (including increased sensory vigilance and freezing) are also increased on such nights. The preferred hiding places for these hamsters upon encountering a predator are under shrubby vegetation (for example, Bassia dasyphylla) or in unused foreign burrows. (Gattermann, et al., 2001; Kotler, 1984; Ross, 1994; Scheibler, et al., 2014; Shao and Liu, 2006; Song, et al., 2010)
The burrowing activity of these fossorial hamsters aerates the soil and brings lower mineral nutrients into the topsoil, which in turn benefits vegetation growth. Seed dispersal is another positive impact on plants, as the hoarding activity of Roborovski hamsters directly displaces seeds and places them underground where germination can take route. Other small vertebrate species (for example, Pseudepidalea viridis) benefit from the shelter of deserted burrows that are often left intact, while larger vertebrate species benefit nutritionally from predation upon these hamsters.
Small rodent species in Mongolian deserts that may compete with Roborovski's desert hamsters include Mongolian jirds, mid-day jirds, northern three-toed jerboas (Dipus sagitta), and Mongolian five-toed jerboas (Allactaga sibirica). The largest niche overlap with Roborovski hamsters results from Daurian ground squirrels (Citellus dauricus) in the spring and summer. Mongolian five-toed jerboas (Allactaga sibirica) and northern three-toed jerboa (Dipus sagitta) pose the greatest competition during autumn. The niches of closely-related hamster species, in terms of spatial and food selection, are different enough so that competition within hamsters is not common. Other dwarf hamsters in Mongolian desert steppes include long-tailed dwarf-hamsters (Cricetulus longicaudatus), striped dwarf hamsters (Cricetulus barabensis), and striped desert hamsters (Phodopus sungorus). Community composition and resulting niche overlap of rodents changes frequently in the deserts where they live, over a period of months to a year and depends mainly on environmental factors such as soil moisture content.
While captive Roborovski's desert hamsters are typically free of ectoparasites, wild hamsters act as hosts for many parasitic invertebrates. Common endoparasites and ectoparasites of wild golden hamsters that may also impact the health of Roborovski hamsters include cestodes (Class Cestoda), nematodes (Phylum Nematoda), sucking lice (Order Anoplura), fleas (Order Siphonaptera), ticks (Dermacentor spp.) and mites. Roborovski's desert hamsters are known to be hosts of Amphipsylla fleas (Amphipsylla longispina) and sucking lice (Polyplax qiuae). Ectoparasite load increases with the age of wild dwarf hamsters: almost half of adult Campbell's hamsters display follicle mites (Demodex spp.) in skin scrapings, while only 1% of juveniles do. Although follicle mites are often common when hamsters are housed in communal laboratory environments, the ectoparasite load under domestic conditions rarely results in clinical disease symptoms (itching, hair loss, and inflammation). (Bao, et al., 2002a; Bao, et al., 2002b; Durden and Musser, 1994; Edwards, et al., 1998; Gattermann, et al., 2001; Heping, et al., 2007; McKeon, et al., 2011; Scheibler and Wollnick, 2009; Scheibler, et al., 2013; Shenbrot, et al., 2007; Weinhold, 2008; Zhong, et al., 1981)
Based on mitochondrial DNA haplotypes, domestic Roborovski's desert hamsters are traced back to descendants in the Zaisan basin of Kazakhstan. They were initially domesticated in the Moscow Zoo. Subsequent spreading to other countries soon followed their introduction to the Zoological Society of London in the late 1970's. They have been common in zoos, but their introduction into the domestic pet trade (in Europe, Southeast Asia, North America) has been relatively recent (since the 1990's). Although popular for their unique pelage, they have limited draw as pets due to their increased activity levels that lead to a high stress pre-dispostion and decreased ease of handling when compared to other domestic hamster species due to their increased activity.
Although present in captivity since the 1970's, Roborovski's desert hamsters are not easily maintained or bred in captivity when compared to other hamsters. They are difficult to acclimate and display heightened levels of hyperactivity in laboratory settings. Therefore, their use in laboratory research is limited and they are far less studied in comparison to other dwarf hamsters. Veterinary analysis of individuals kept as household pets remains beneficial, particularly as models of carcinogenesis. Due to there increased activity levels,has been suggested as a model species in the study of attention-deficit-hyperactivity-disorder.
Roborovski's desert hamsters can be economically beneficial to the agriculture industry, as their burrowing activity aerates the soil and brings mineral nutrients into the topsoil. Control of insect pests can also be a small benefit, though less prominent, as insects make up only a small portion of their diet (10 to 30%). (Feoktistova and Meshchersky, 2005; Feoktistova, et al., 2013; Guanghe, et al., 2001; Ikeda, et al., 2014; Johnson, et al., 2014; Kabuki, et al., 2008; Martin, et al., 2001; Vorontsov and Krjukova, 1969)
Roborovski's desert hamsters can be pests in agricultural areas and lead to economic loss. They are able to persist in agricultural fields that have been grazed over by livestock, as well as other cultivated areas that have been built within their range. If similar to golden hamsters (Mesocricetus auratus), Roborovski's desert hamsters may have a preference for establishing in legume fields. Their burrowing activity may disturb the quality of the pasture, while their granivorous diet and food hoarding has possible negative economic implications to grain storage. (Carelton and Musser, 1984; Gattermann, et al., 2001; Vorontsov and Krjukova, 1969)
The IUCN currently lists Roborovski's desert hamsters with a status of Least Concern. However, threats to their survival exist. Their ability to colonize agricultural habitats is limited by rodenticides, harvesting, livestock grazing, burning and ploughing. Construction of railways within the range of the species (for example, the Qinghai-Tibet Railway in the Qaidam desert region, northwest China) is of concern due to the resulting habitat fragmentation, varied chemical or noise pollution, and increased mortality. However, studies have shown that there is no clear zone of effect of railways on Roborovski's desert hamster populations. Despite occasional threats, there are few widespread or major threats to the species. Annual fluctuations in population size occur. Fluctuations alternate between peaks and declines in the Ordos desert of China, but there still has been no detectable trend of decline or increase over multiple years. Populations are generally stable. The large population size of Roborovski's desert hamsters and the wide distribution of this species contributes to its resilience, especially since 18% of it's range occurs within protected areas of Mongolia. (Gattermann, et al., 2001; Hou and Dong, 2000; Qian, et al., 2009; Shar and Lkhagvasuren, 2008; Xixian, et al., 2000)
Phylogenetic evidence based on mitochondrial and nuclear DNA sets the division of three Palaearctic hamster genera (Phodopus, Mesocricetus, and Cricetus) during the late Miocene (7 to 12 million years ago). This divergence coincides with the spread of steppe and open woodlands due to an increasingly drier climate in the European and Asian portions of their Miocene range. Dwarf hamsters form the oldest clade and comprise three species: striped desert hamsters (Phodopus sungorus), Campbell's desert hamsters (Phodopus campbelli) and Roborovski's desert hamsters ( ). The genus is monophyletic with Roborovski's desert hamsters holding the earliest divergence. Dwarf hamsters remain an outgroup group to the other two genera, which themselves split up in the Pleistocene (between 0.8 and 1 million years ago) as a result of habitat oscillations caused by changing humidity levels. Due to the high genetic differences between populations of Roborovski's desert hamsters in the northern parts of their Mongolian and Kazakhstan range, it is suggested that they spread northwards through multiple migration events from more southern territories such as China. (Feoktistova and Meshchersky, 2003; Meshchersky and Feoktistova, 2011; Natochin, et al., 1994; Neumann, et al., 2006; Ross, 1994; Schmid, et al., 1986)
Allison Kolynchuk (author), University of Manitoba, Jane Waterman (editor), University of Manitoba.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
Referring to a burrowing life-style or behavior, specialized for digging or burrowing.
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
ovulation is stimulated by the act of copulation (does not occur spontaneously)
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
the business of buying and selling animals for people to keep in their homes as pets.
chemicals released into air or water that are detected by and responded to by other animals of the same species
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
digs and breaks up soil so air and water can get in
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
Bao, W., D. Wang, Z. Wang. 2002. Metabolism in four rodent species from Ordos arid environment in Inner Mongolia, China. Folia Zool., 51 (Suppl. 1): 3-7.
Bao, W., D. Wang, Z. Wang. 2002. Nonshivering thermogenesis in four rodent species from Kubuqi desert, Inner Mongolia, China. Folia Zool., 51 (Suppl. 1): 9-13.
Carelton, M., G. Musser. 1984. Muroid Rodents. Pp. 289-379 in S Anderson, J Jones, eds. Orders and families of recent mammals of the world. New York: John Wiley & Sons, Inc.
Chi, Q., D. Wang. 2011. Thermal physiology and energetics in male desert hamsters (J. Comp. Physiol. B, 181: 91-103.) during cold acclimation.
Dong, W., X. Hou, Y. Zhou. 2001. Study on the Division of Age Group and the Age Composition of Population of Desert Hamster. Chin. J. Vec. Biol. Contr., 12(3): 168-170.
Dong, W., X. Hou, Y. Yang. 1989. Study on home range of striped hamster. Acta Theriologica Sinica, 4: 109.
Durden, L., G. Musser. 1994. The mammalian hosts of the sucking lice (Anoplura) of the world: a host-parasite list. Bull. Soc. Vector Ecol., 19(2): 130-168.
Edwards, H., C. Tweedie, P. Terranova, R. Lisk, K. Wynne-Edwards. 1998. Reproductive aging in the Djungarian Hamster, Phodopus campbelli. Biol. Reprod., 58: 842-848.
Erb, G., H. Edwards, K. Jenkins, L. Mucklow, K. Wynne-Edwards. 1993. Induced Components in the Spontaneous Ovulatory Cycle of the Djungarian Hamster (Phodopus campbelli). Physiol. Behav., 54: 955-959.
Feoktistova, N., I. Meshchersky. 1999. Behavioural responses of dwarf hamsters (Phodopus roborovskii and Phodopus sungorus) to same-sex and opposite-sex odors in different seasons. Pp. 432-436 in R Johnston, D Muller-Schwarze, P Sorensen, eds. Advances in Chemical Signals in Vertebrates. New York: Plenum Publishers.
Feoktistova, N., I. Meshchersky. 2005. Seasonal changes in desert hamster Acta Zool. Sinica, 51(1): 1-6.breeding activity.
Feoktistova, N., O. Chernova, I. Meshchersky. 2013. Decorative forms of hamsters of the genus Phodopus (Mammalia, Cricetinae): analysis of genetic lines distribution and features of hair changes. Biol. Bull. Reviews, 3(1): 57-72.
Feoktistova, N., M. Kropotkina, S. Naidenko. 2010. Seasonal Changes of Steroid Levels in Blood Plasma of Three Phodopus Species (Mammalia, Cricetinae). Biol. Bull., 37(6): 659-664.
Feoktistova, N., I. Meshchersky. 2003. Interspecies Olfactory Communication in Sympatric and Allopatric Hamster Species of the Genus Phodopus (Rodentia: Cricetinae). Dokl. Biol. Sci., 389: 180-182.
Feoktistova, N., S. Naidenko. 2006. Hormonal response to conspecific chemical signals as an indicator of seasonal reproduction dynamics in the desert hamster, Phodopus roborovskii. Russ. J. Ecol., 37(6): 426-430.
Flint, W., A. Golovkin. 1961. A comparative study in hamster ecology of the Tuva area. Byulleten Moskovskogo Obshchestva Ispytatelei Prirody Otdel Biologicheskii, 66(5): 57-76.
Gattermann, R., P. Fritzsche, K. Neumann, I. Al-Hussein, A. Kayser, M. Abiad, R. Yakti. 2001. Notes on the current distribution and the ecology of wild golden hamsters (Mesocricetus auratus). J. Zool. Lond., 254: 359-365.
Guanghe, W., Z. Wenqin, W. Xinrong. 2001. Biological Habit of Desert Hamster in the Hunshandake Desert in Inner Mongolia. Chin. J. Ecol., 26(6): 65-67.
Hamann, U. 1987. Zu Aktivität und Verhalten von drei Taxa der Zwerghamster der Gattung Phodopus Miller, 1910. Zeitschrift für Säugetierkunde, 52: 65-76.
Heping, F., W. Xiaodong, Y. Zelong. 2007. Niche characteristics of rodents by diverse disturbance in Alashan desert, Inner Mongolia, China. Front. Biol. China, 2(4): 456-462.
Hou, X., W. Dong. 2000. Population Dynamics and Prediction on Phodopus roborovskii in Ordos Sandland. Chin. J. Vec. Biol. Contr., 11(1): 7-10.
Hou, X., W. Dong, Y. Zhou, L. Wang, W. Bao. 2000. Study on the reproductive ecology of Phodopus roborovski population. Chin. J. Ecol., 3: 187-191.
Hume, J., K. Wynne-Edwards. 2005. Castration reduces male testosterone, estradiol, and territorial aggression, but not paternal behavior in biparental dwarf hamsters (Phodopus campbelli). Horm. Behav., 48: 303-310.
Ikeda, H., T. Kawase, M. Nagasawa, V. Chowdhury, S. Yasuo, M. Furuse. 2014. Metabolism of amino acids differs in the brains of Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii). SpringerPlus, 3: 277.
Jefimow, M. 2007. Effects of summer- and winter-like acclimation on the thermoregulatory behavior of fed and fasted desert hamsters, Phodopus roborovskii. J. Therm. Biol., 32: 212-219.
Johnson, J., R. Blair, J. Brandao, T. Tully, S. Gaunt. 2014. Atypical fibrosarcoma in the skin of a Roborovski hamster (Phodopus roborovskii). Vet. Clin. Path., 43(2): 281-284.
Kabuki, Y., H. Yamane, K. Hamasu, M. Furuse. 2008. Different locomotor activities and monoamine levels in the brains of djungarian hamsters (D. sungorus) and roborovskii hamsters (D. roborovskii). Exp. Anim., 57(5): 447-452.
Kayser, A., U. Weinhold, M. Stubbe. 2003. Mortality factors of the common hamster Cricetus cricetus at two sites in Germany. Acta Theriol., 48(1): 47-57.
Kotler, B. 1984. Risk of predation and the structure of desert rodent communities. Ecology, 65(3): 689-701.
Langley, W. 1985. Relative importance of distance senses in hamster predatory behavior. Behav. Process., 10: 229-239.
Martin, R., R. Pine, A. DeBlase. 2001. A manual of mammalogy with keys to families of the world. Long Grove, IL: Waveland Press, Inc..
McKeon, G., C. Nagamine, N. Ruby, R. Luong. 2011. Hematologic, Serologic, and Histologic Profile of Aged Siberian Hamsters (Phodopus sungorus). J. Am. Assoc. Lab Anim. Sci., 50(3): 308-316.
McMilan, H., K. Wynne-Edwards. 1998. Evolutionary Change in the Endocrinology of Behavioral Receptivity: Divergent Roles for Progesterone and Prolactin within the Genus Phodopus. Biol. Reprod., 59: 30-38.
Meschersky, I., N. Feoktistova. 1999. Some aspects of desert hamster Phodopus roborovskii biology. Adv. Curr. Biol., 119(2): 218-222.
Meshchersky, I., N. Feoktistova. 2011. Analysis of genetic diversity of the desert hamster (Phodopus roborovskii) in the northern part of its range. Biol. Bull., 38(1): 82-86.
Meshchersky, I., V. Klishin. 1990. Functional capacities of the kidney in the hamster genus Phodopus. J Evol. Biochem. Phys.+, 26(1): 38-44.
Natochin, Y., I. Meshchersky, O. Goncharevskaya, I. Makarenko, E. Shakhmatova, M. Ugryumov, N. Feoktistova, G. Alonzo. 1994. Comparative studies on the osmoregulatory system in the hamsters Phodopus roborovskii and Phodopus sungorus. J. Evol. Biochem. Phys+., 30(3): 344-357.
Neumann, K., J. Michaux, V. Lebedev, N. Yigit, E. Colak, N. Ivanova, A. Poltoraus, A. Surov, G. Markov, S. Maak, S. Neumann, R. Gattermann. 2006. Molecular phylogeny of the Cricetinae subfamily based on the mitochondrial cytochrome b and 12S rRNA genes and the nuclear vWF gene. Mol. Phylogenet. Evol., 39: 135-148.
Newkirk, K., D. Silverman, K. Wynne-Edwards. 1995. Ontogeny of Thermoregulation in the Djungarian Hamster (Phodopus campbelli). Physiol. Behav., 57(1): 117-124.
Nowak, R. 1999. Walker's Mammals of the World, vol. II. Baltimore and London: The Johns Hopkins University Press.
Qian, Z., X. Lin, M. Jun, W. Pan-Wen, Y. Qi-Sen. 2009. Effects of the Qinghai-Tibet Railway on the community structure of rodents in Qaidam desert region. Acta Ecol. Sin., 29: 267-271.
Qing-Sheng, C., W. De-Hua. 2010. Thermal physiology and energetics in male desert hamsters (Phodopus roborovskii) during cold acclimation. J Comp. Physiol. B, 181(1): 91-103.
Ross, P. 1994. Phodopus roborovskii. Mamm. Species, 459: 1-4.
Scheibler, E., C. Roschlau, D. Brodbeck. 2014. Lunar and temperature effects on activity of free-living desert hamsters (Phodopus roborovskii, Satunin 1903). Int. J. Biometeorol., 58(8): 1769-1778.
Scheibler, E., F. Wollnick. 2013. Oestrus cycle of the desert hamster (Phodopus roborovskii, Satunin, 1903). Lab. Anim., 47(4): 301-311.
Scheibler, E., F. Wollnik, D. Brodbeck, E. Hummel, S. Yuan, F. Zhang, X. Zhang, H. Fu, X. Wu. 2013. Species composition and interspecific behavior affects activity pattern of free-living desert hamsters in the Alashan Desert. J. Mammal., 94(2): 448-458.
Scheibler, E., F. Wollnick. 2009. Interspecific contact affects phase response and activity in Desert hamsters. Physiol. Behav., 98: 288-295.
Schmid, M., T. Haaf, H. Weis, W. Schempp. 1986. Chromosomal homoeologies in hamster species of the genus Phodopus (Rodentia, Cricetinae). Cytogenet. Cell. Genet., 43: 168-173.
Shao, M., N. Liu. 2006. The diet of the Long-eared Owls, Asio otus, in the desert of northwest China. J. Arid. Environ., 65: 673-676.
Shar, S., D. Lkhagvasuren. 2008. "Phodopus roborovskii" (On-line). The IUCN Red List of Threatened Species. Version 2014.3.. Accessed January 07, 2015 at www.iucnredlist.org.
Shenbrot, G., B. Krasnov, L. Liang. 2007. Geographical range size and host specificity in ectoparasites: a case study with Amphipsylla fleas and rodent hosts. J. Biogeogr., 34: 1679-1690.
Sokolov, V., I. Meshchersky. 1989. Water metabolism of Phodopus roborovskii. Zoologichesky Zhurna, 68(5): 115-126.
Sokolov, V., V. Orlov. 1980. Guide to the Mammals of Mongolia. Moscow, Russia: Pensoft.
Song, S., W. Zhao, J. Zhao, M. Shao, N. Liu. 2010. Seasonal variation in the diet of Long-eared Owl, Asio otus, in the desert of Northwest China. Anim. Biol., 60: 115-122.
Sung, W., Z. Chang-lin. 1973. Notes on Chinese hamsters (Cricetinae). Acta Zoo. Sinica 1, 19: 61-68.
Topal, G. 1973. Zur säugetier-fauna der Mongolei. Ergebnisse der zoologischen forschungen von Dr. Z. Kaszab in der Mongolei. Nr. 322. Vertebrata hungarica Musei historico-naturalis hungarici, 14: 47-99.
Turton, M., D. Robertson, J. Smith, J. Hurst, R. Beynon. 2010. Roborovskin, a Lipocalin in the urine of the roborovski hamster, Chem. Senses, 35: 675-684..
Vorontsov, N., E. Krjukova. 1969. Phodopus przhewalskii species nova-A New Species of Desert Hamsters (Cricetinae, Cricetidae, Rodentia) from the Zaissan Basin. Pp. 102-104 in N Vorontsov, ed. The Mammals. Russia: Novosibirdsk.
Walsberg, G. 2000. Small mammals in hot deserts: some generalizations revisited. BioSience, 50: 109-120.
Wan, X., W. Liu, G. Wang, W. Zhong. 2007. Food consumption and feeding characters of Phodopus roborovskii on Hunshandake sandy land of Inner Mongolia. Chin. J. Zool., 26(2): 223-227.
Weinert, D., K. Schottner, A. Surov, P. Fritzsche, N. Feoktistova, M. Ushakova, G. Ryurikov. 2009. Circadian activity rhythms of dwarf hamsters (Phodopus spp.) under laboratory and semi-natural conditions. Russian J. Theriol., 8(1): 47-58.
Weinhold, U. 2008. Draft European Action Plan For the conservation of the Common hamster (Cricetus cricetus, L. 1758). Convention on the conservation of European wildlife and natural habitats, 2: 1-36.
Wynne-Edwards, K. 1995. Biparental care in Djungarian but not Siberian dwarf hamsters (Phodopus). Animal Behav., 50(6): 1571-1585.
Wynne-Edwards, K. 1998. Evolution of parental care in Phodopus: Conflict between adaptations for survival and adaptations for rapid reproduction. Amer. Zool., 38: 238-250.
Wynne-Edwards, K., M. Timonin. 2007. Paternal care in rodents: Weakening support for hormonal regulation of the transition to behavioral fatherhood in rodent animal models of biparental care. Horm. Behav., 52: 114-121.
Xinmei, Z., W. Dehua. 2004. Energy metabolism and thermoregulation of the desert hamster (Phodopus roborovskii) in Hunshandake Desert of inner Mongolia, China. Acta Theriol. Sin., 23(1): 152-159.
Xinrong, W., Z. Xinjie, H. Yingjun, W. Guiming. 2013. Weather entrainment and multispectral diel activity rhythm of desert hamsters. Behav. Process., 99: 62-66.
Xixian, H., D. Weihui, Z. Yanlin. 2000. Population dynamics and prediction on Phodopus roborovskii in Ordos sandland. Chin. J. Vec. Biol. Contr., 11(1): 7-10.
Zhong, W., Q. Zhou, C. Sun. 1981. Study on structure and spatial pattern of rodent communities in Baiyinxile typical steppe, inner Mongolia. Acta Ecologica Sinica, 1(1): 12-21.