Other Names
Russian Dwarf, Djungarian (or Dzungarian), Hairy-footed, or Striped Hamster. None of these alternative names is widely used. In particular, ‘Striped Hamster’ causes some confusion because the (unrelated) Chinese Hamster is sometimes also known by this title. The Winter White Dwarf Hamster is sometimes referred to as the Siberian Hamster.
Introduction
Colloquially speaking, there are three species of ‘dwarf’ hamsters often seen in pet shops – the other two being the Roborovski Hamster and the Chinese Hamster, although, strictly speaking this latter species is not really a Dwarf Hamster at all, despite its diminutive size, but is classed as a ‘rat-like’ hamster. Despite the emergence of these other species, the most popular Dwarf Hamster remains the Russian Dwarf. The alternative appellation of Hairy-footed Hamster refers to the hairiness of the hind feet. An adaptation for scurrying across frozen ground or snow, the hair on this part of their anatomy has a dual purpose: to minimise heat loss through the feet, and to provide a firmer grip on the ground. Russian Dwarf Hamsters are definitely not suitable for young children, being very small, fast and agile, and easily harmed by rough or incautious handling. The two subspecies usually encountered are the Campbell’s Dwarf Hamster (Phodopus sungorus campbelli) and Winter White Dwarf Hamster (Phodopus sungorus sungorus). Some authorities now regard the two animals as separate species (P. campbelli and P. sungorus) because, although quite similar in appearance, in behaviour they are very different. However, I feel they are sufficiently similar to continue to treat them, for the sake of this article, as different races of the same species. Care of both subspecies is identical.
Size
The two subspecies are similar in size. Length: 70–90 mm. Tail: 10 mm. Weight: up to 60g, but 40g. is more usual. Males are slightly larger and heavier than the females. In the wild, where food is less plentiful and the hamsters have to expend more energy collecting it, they can weigh as little as 20–25g.
History in Captivity
The Campbell’s Dwarf Hamster was discovered by Thomas Campbell in 1905. It remained largely unknown before 1961, when the species was first kept by the Leningrad Zoological Society. Stock was sent to the London Zoo in 1963 but, strangely for such a fecund animal, it did not appear to have bred there until 1968. Several laboratories became interested in the species at around the same time. It is thought that it was introduced onto the pet scene in 1970, or soon thereafter, by a Mr Percy Parslow from stock obtained from the Zoological Society of London. It bred well and soon established itself. So common is it in pet shops at the current time that it is rarely exhibited in zoological gardens anymore.
The first record of the Winter White Dwarf Hamster dates from 1770. In the 1960s it was studied and bred in large numbers by the scientist Klaus Hofmann of the Max Planck Institute in Germany, and it was he who was largely responsible for establishing the animal on the pet market. It was introduced into the U.K. by Chris Henwood in 1978 from stock derived from a colony then maintained at Queen Mary’s College, London. The Winter White is not as common in captivity as the Campbell’s, probably due to its later arrival. It is bred in large numbers now and, having a better temperament than the Campbell’s, is more suitable as a pet and I expect it will not be long before it surpasses the Campbell’s in popularity.
Colours, Patterns & Varieties
A word of warning about the albino colour mutation of these animals. An albino animal is one that is completely white all over except for red or pink eyes. The bizarre coloration of the eyes is the result of an absence of the pigment melanin, and what you are really seeing are the blood vessels at the back of the retina. Since the animal, without this essential pigment, is incapable of filtering out or diffusing harmful light rays, bright light can seem very bright indeed and albino animals are usually destined to suffer eye problems in later life and can even, in extreme cases, become completely blind. It is therefore unwise to continue to breed albino animals, or even to purchase such animals thereby encouraging the breeder to produce more. I should add, at this point, that I am in any case opposed to the deliberate breeding of unnatural mutation colours of any animals.
The Winter White subspecies is so-called (sounding, as one zoologist famously remarked, more like a variety of brassica rather than an animal) because, in the wild state, it is said to turn white in winter as a form of camouflage. The extent of this colour change is often exaggerated and rarely does it turn completely white. Indeed, it is generally accepted that the only rodents that do moult to a complete white coat in winter are the various species of Collared Lemming (Dicrostonyx spp.). The catalyst for this metamorphosis in the Winter White Hamster seems to be the reduced length of daylight rather than the falling temperature because the condition is most pronounced when there are less than 8 hours of daylight (which may explain why it is such a rare phenomenon in captivity). During the pale phase, males are temporarily infertile.
Distribution
The Campbell’s Dwarf Hamster is found in Mongolia and adjacent parts of south-central Siberia, Manchuria and north-eastern China. The Winter White Dwarf Hamster occurs in Eastern and Northern Kazakhstan and south-western Siberia.
Natural Habitat
Arid steppe, plain or sand dune, where the vegetation consists of coarse grasses.
Social Structure
Most people are aware that its larger cousin, the Syrian or Golden Hamster, is strictly solitary, but the advice with Dwarf Hamsters has always been that they are a more gregarious species that could safely be maintained in pairs or trios. This is not always the case, however, and fights are not that uncommon. It seems that in the wild they are largely solitary, the male seeking out females only when they (the females) are ‘on heat’. Attempts to keep Dwarf Hamsters in small groups in captivity have proved even less successful, with several people reporting that their animals had lived peaceably together for weeks or even months before, for no reason that could be discerned, they had suddenly started fighting. Interestingly, it is nearly always the Campbell’s subspecies that behaves in this way. Rarely if ever have I heard of the Winter White subspecies behaving like this, and I have little doubt that, in most cases, the Winter White can safely be kept in pairs or even small groups. It seems that the Winter White is a much more sociable animal than the Campbell’s. At one point I had a most successful group consisting of about 15 Winter White Dwarf Hamsters. They bred regularly and not once did I observe any aggression within the colony. I doubt that a group of Campbell’s would have been so amiable.
The two subspecies should not be kept together as it is unlikely they will tolerate each other. Not only that but, should they breed, hybrid animals would be produced, and the breeding of hybrids, whether by design or accident, is inexcusable as it corrupts the gene pool. Some of the resultant offspring would, in any case, be sterile.
Animals kept in pairs pose special problems when one of the pair dies, as it can often be very difficult to introduce a stranger. If the remaining animal is old, it is probably less traumatic to leave it on its own rather than risk an introduction; if it is a young animal, it is worth trying to introduce a companion, but be prepared to separate immediately if the ‘arranged marriage’ does not succeed. Introductions should be carried out on neutral territory. As with many other animals, it is often easier to introduce the female to the male, rather than the other way round.
Temperament
Whereas Winter White Dwarf Hamsters rarely feel disposed to bite their human handler, the Campbell’s Dwarf Hamster is renowned for being rather inclined to ‘nip’. I find this is particularly true with the black colour mutation.
Behaviour
Crepuscular and nocturnal, they appear to be at their most active in the evening and early morning, but have bouts of activity throughout the night. Much more rarely do they venture out during daylight hours. The Winter White subspecies seems less nocturnal than the Campbell’s race. Dwarf Hamsters are fiercely territorial and fights, or skirmishes I should say, are commonplace until a ‘pecking order’ has been established, especially just after the cage is cleaned out or disturbed in some other way. In the wild they are often to be seen in association with Pikas (a little-known animal related to the rabbit), and not infrequently make use of these animals’ pathways and burrows, especially in the winter months. Unlike the lighter, more nimble Roborovski Hamster, they are not particularly skilled at climbing or jumping.
They possess scent glands on the belly (in the case of the Syrian Hamster, the scent glands are located on the hip), with which they mark their territory, but the smell is not strong enough to be detected by our feeble olfactory senses. They are very clean animals and generally choose one or two corners of the cage in which to urinate, which makes life easier for their keeper, but will often defecate anywhere in the cage. Droppings are, however, dry and inoffensive. Like other hamsters, Dwarf Hamsters possess cheek pouches but these are less pronounced than in the case of the larger hamster species and are less frequently used.
Sexing
The anal-genital distance is approximately twice as wide in the male, compared with the female. Females are slightly smaller than males. The female, when viewed from above, has a noticeably rounder rump compared to the more tapered rear end in the male.
Handling
Their agility and small size means they are not suitable for young children. Dwarf Hamsters should be handled regularly to keep them tame. Your movements should be slow, calm and measured. Begin by offering the animal food by hand to win its confidence. Then, when it is unperturbed by your presence, ‘cup’ it gently in both hands or, if you are more experienced, you can use one hand, placing your hand over the top of the animal and folding your fingers underneath it. Make sure it faces your wrist rather than your fingers, as it is less likely to bite in this position as its teeth cannot gain purchase. Do not attempt to wake up a hamster if it is asleep as this is when it is most likely to bite. (Look at it from the hamster’s point of view: how would you like to be suddenly grabbed by a monstrous sweaty hand when you were sound asleep?!!) Until Dwarf Hamsters become tame, they are prone to jumping suddenly out of your hands, so handle it over a table-top as even a short fall can prove fatal. Do not handle it just after the animal has eaten, or you will find it empties its cheek pouches of seeds. Some sources state that Dwarf Hamsters are docile, easy to tame and completely trustworthy. I dispute this generalisation. Among my colleagues, Campbell’s Dwarf Hamsters (but, strangely, not the Winter Whites) do have a reputation for being inclined to bite. Females are the worst culprits, especially untrustworthy when pregnant or with young, and I have known at least two or three specimens which were so aggressive they would run across the cage to bite me whenever I inserted my hand. This is another reason why Dwarf Hamsters should not be procured for young children. The bite is rarely powerful enough to break the skin but it can be quite painful nevertheless. The Winter White, on the other hand, is a lovely animal and hardly ever attempts to bite.
Accommodation
A large glass tank with a close-fitting, wire-mesh lid is best. Cages designed with the larger Syrian Hamster in mind are usually not suitable for Dwarf Hamsters as the bars are set too far apart and escape is only too likely; there should be no more than 8–10 mm between the wires. Cages intended for mice are better, but here you will find your choice severely limited in both size and design. These cages are unimaginative, being too low with usually no second level. Standard laboratory cages can also be used temporarily, but because of the solid sides the hamsters are unable to look out. Some people prefer the interconnecting hamster cages such as Rotastak or Habitrail. I made clear my reservations about these cages in the last issue of ‘Animal News’. But whatever cage is finally chosen, make sure the water bottle is positioned at just the right height: not so high that these small animals cannot reach it but not so low that the spout is in contact with the substrate or you will find the water leaks out through capillary action. Position the cage away from draughts or direct sunlight, in an even temperature, and definitely not on a window-sill.
Litter & Bedding
As with all hamsters, they are adept at burrowing and the substrate should be fairly deep to allow for this natural activity, which is another reason why traditional wire-mesh cages are unsuitable. I have used a deep litter of coarse wood-chips (not sawdust, please, as this is too fine and can irritate the animals’ mucus membranes), although very recently it has been suggested that the phenol oils present in pine (and particularly red cedar) may be detrimental to the health of small rodents. The long-term effects of keeping rodents on pine wood shavings is still unclear, but it is possible that various allergies, nasal discharge, skin inflammation, alopecia, and perhaps even certain cancerous tumours may be caused by the presence of these oils. Shavings from other woods are safer. You will, however, find that most packaging makes no mention of the type of wood used. I once worked in a pet shop where the owners were staunch advocates of the new generation of wood-based cat litters (sold in the form of compressed sawdust pellets) for rodent cages. Personally I don’t trust this material. I find that most rodents will chew it into a very fine and unpleasant dust. In doing so, they ingest a fair quantity of it and, being so desiccated, it expands when it encounters the moister environment of the gut and can, perhaps, cause impaction, although this has yet to be proved.
I mostly use soft meadow hay for bedding, as this will also be eaten. Strips of non-bleached paper or tissue is also fine. Straw, whilst it forms a comfortable bed and the animals enjoy shredding it, is virtually non-absorbent. Avoid bedding that looks and feels like cotton wool. This is sold in pet shops under a variety of guises. According to the manufacturer’s blurb, it is quite safe but there is mounting evidence this is not true. Synthetic substances like this can be ingested and hamsters have been known to choke on it or for it to become impacted in the intestines.
Accessories
Provide plenty of toys in the cage. Some, such as cardboard rolls, plastic tubes, wooden cotton reels, etc., can be collected for free from around the house. A secure ‘bedroom’ area is a must, made either of wood or plastic. Metal, whilst being impervious to a hamster’s gnawing, tends to be too cold to the touch. The ‘bedroom’ need not be elaborate. Even a small cardboard box, open at one end, will suffice. The exercise wheel should be solid plastic, not the traditional spoked breed, which can result in trapped and broken legs. If you have no option but to use the spoked type, render it safer by weaving a strip of card between the rungs. Some hamsters can become addicted to running in their wheel; if this is the case, you should remove the wheel for a short time. Nursing females have even been known to abandon their litter in order to run in the wheel.
Cleaning Out
Should be done about once or twice a week, but a very large cage may require cleaning no more than once a fortnight. I use warm soapy water efficient, but some keepers use a mild detergent. The cage should be thoroughly dry before returning the animals to it. Always remember to replace some of the old bedding, as this will be impregnated with the animals’ familiar smells. Hamsters are olfactory beasts and a cage must smell like home. Rodents can get quite distressed, upon being returned to their cage, to find it smells completely alien. If the animal(s) has/have a cache of food stored in the cage, it is important to replace a small amount after cleaning out the cage, or it/they will think their larder has been raided by a rival animal.
The corner of the cage chosen by the hamster(s) as the toilet area should be cleaned out more frequently, say every 2–3 days.
Feeding
Food consists chiefly of a mixture of seeds, including various millets, grains, cereals, peanuts, and pellets, as well as broken dog biscuit, supplemented with green food, fruit and vegetables in small quantities. Too much green food will cause diarrhoea. Dwarf Hamsters can be allowed proportionately more vegetable matter than can Syrian Hamsters. Apple, carrot, and even pear are better than vegetables (like cucumber) which have a high moisture content. I tend to avoid lettuce altogether. Hay is essential for its fibre content. Dwarf Hamsters consume around 10–15 grams of food a day.
As an occasional treat, small pieces of toasted/stale wholemeal bread can be offered. Animal protein is important. This can be given in the form of meal worms, crickets and other insects, dried cat or dog food, ‘softbill’ insectivorous mixture, or small pieces of hard-boiled egg or cooked lean meat. Sunflower seeds should be offered sparingly as they are rather fattening, and Dwarf Hamsters tend to put on weight easily. Low in calcium, sunflower seeds have been implicated in cases of osteoporosis in some rodents, but they are fine in small quantities.
Treats to avoid include honey bars or chocolate drops, both of which are unfortunately sold in pet shops for hamsters, as soft or sticky foods such as these can cause the cheek pouches to become impacted or even prolapsed. I once had a Dwarf Hamster brought in to me with a prolapsed cheek pouch. This is an example of certain pet-food manufacturers not having a clue about basic rodent biology. They launch a new product with scant regard for the welfare of the animal, simply because it appeals to the majority of pet-owners.
Salt licks and mineral blocks, available from your local pet shop, are also appreciated. Clean drinking water must be available at all times, ideally supplied in a gravity-flow bottle, although Dwarf Hamsters do not drink a huge amount.
It is important to provide wood gnaws. These can be purchased from most pet shops or, alternatively, one can use natural branches or twigs. Like all other rodents, a hamster’s incisor teeth grow continuously throughout its life and it requires something hard to gnaw on to prevent its teeth becoming overgrown or deformed.
Health
All illnesses are potentially serious, so at the first sign of trouble consult your veterinary surgeon without delay. Any sign of diarrhoea must be investigated immediately as dehydration in a mammal as small as this occurs rapidly. A common problem with many rodents is mange, characterised by hair loss and loose flaky or inflamed skin. This is caused by a microscopic mite that lives just underneath the skin. An animal can live with the condition for some time and show no symptoms. Then suddenly the animal is subjected to stress (which can be something simple such as the move to a new home, introduction of a new mate, etc.), and the mites multiply and the condition flares up. This potentially life-threatening condition is treatable if arrested in the early stages. Various cancers are also common, as are ectoparasites such as lice, but in general Dwarf Hamsters are clean, healthy animals that cause few problems.
Hibernation
Dwarf Hamsters are, in general, hardy animals, but, if the room temperature is allowed to drop too low in winter, a hamster may fall into a torpor-like state and may even appear to be dead. On no account should you allow this to happen. A hibernating hamster has barely discernible breathing and is cold to the touch. Check carefully before burying the dear-departed as there are numerous reports of hamsters, albeit mostly Syrian Hamsters, being buried alive! Under laboratory conditions this condition seems most common in January. In a study, up to 30% were in torpor at any one time, but it is unclear whether these results are repeated in the animal’s natural habitat. The percentage is likely to vary according to location and prevailing weather conditions. These results are very misleading because the conditions necessary to induce dormancy were carefully simulated in the laboratory and, under most circumstances, are very unlikely to be replicated in the home. The Winter White Dwarf Hamster has never been known to hibernate.
Reproduction
This species does well in captivity but it is important to make sure that a suitable outlet for surplus stock exists before embarking on a breeding programme. If in any doubt, only single-sex animals should be kept. The optimum age for establishing pairs is 6–12 weeks. The breeding season lasts from February to November. A female signals her readiness to mate by standing still when approached by a male and raising her tail. Both parents assist with looking after the young. Females come into season immediately postpartum, and are capable of having up to 7 litters in quick succession. Such a prolific rate of reproduction should not be permitted, however, as the female would quickly become exhausted. There is still much we don’t know about Dwarf Hamsters. There is a suggestion (unproven) that, in the wild state, pairs mate for life; in which case, this would be the only hamster species to do so. I have read reports that some pairs delay breeding until the previous, older litter is removed, but this is not always the case and is perhaps not even the norm. It has also been suggested that, on occasion, delayed implantation of the egg takes place. This is an adaptation to living in an arid environment where conditions are not always favourable for rearing young. In these circumstances, development of the embryos is suspended until conditions improve.
Sexual Maturity
Campbell’s Dwarf Hamsters are capable of breeding from as early as 5 weeks, but tthey should be bred as young as this. It is wise to wait until at least 12–20 weeks before allowing a female to breed, and a male should be no younger than 12 weeks for a first mating. Winter White Dwarf Hamsters are slower to mature than the Campbell’s; males are not usually ready to breed until 12–18 weeks of age. Females have occasionally been known to breed from 4–5 weeks of age, but this is unusual.
Oestrus Cycle - Every 4 days.
Gestation
On average about 18–21 days, but has been known to be as little as 16 or 17 days or as long as 25 days. Delayed implantation of the egg (see above) may explain the longer-than-average gestations.
Young (Cubs)
Born naked, blind and helpless. Birth weight is as little as 2g. The female may sometimes banish the male to another part of the cage just after the young are born, but it is not long before he is allowed to return. Disturb the new-born babies as little as possible at this early stage and certainly do not be tempted to touch the young or the mother may cannibalise them. It does no harm to delay cleaning out the cage until the offspring are at least 3 weeks old. The skin darkens at 3 days, fur starts to appear at 6–8 days, and the eyes open at 14 days. Young are observed trying solid food and starting to explore the cage from 9 days of age, and they are fully weaned at 18–21 days. I never remove the offspring below 4 weeks, as I consider that leaving them with their parents for at least an extra week after weaning to be very important. By the age of 7 weeks, all the young should be moved into accommodation away from their parents.
Breeding Life
Approx 1 year for females, slightly longer for males.
The (Almost) Unique Male Midwife
To all intents and purposes, the Winter White Hamster is unique among mammals in that, at the birth, the male adopts the role of ‘midwife’ (the only other mammal which has been known to do this is the human animal and then only very recently). The male Siberian Hamster cleans each young as it is born and has even been known to break the umbilical cord. Like the mother, he retrieves the babies if they wriggle from the nest. His motives are not entirely altruistic. The female comes into season again immediately after giving birth and there is a window of only three hours or so in which the male can mate her again. Assisting with the birth means that the male does not miss this crucial moment or risk allowing another male to mate her.
Life Span
On average 18-26 months. The maximum recorded longevity is over 3 years.
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