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Steppe
Lemming Article By Russell Tofts Other names Steppe Vole. In addition, the Steppe Lemming is sometimes also incorrectly referred to as the Sagebrush Vole. This is a misleading term more correctly applied to the American Lemmiscus curtatus. Whilst it is true that the two species are very similar in appearance, they should not be confused. In some major reference works, details of one species are carelessly grafted onto the other, thereby creating some fictitious composite animal. Differences between the two species are quite subtle. Among them, Lagurus lagurus has smaller ears and a tail that is shorter than the hind foot. The true Sagebrush Vole was once thought to be a subgenus of Lagurus, but is now believed to be more closely related to the meadow voles of the genus Microtus. Introduction Advantages to pet-keepers of this animal are immediate and multifarious: the animal is small, easy to maintain, does not hibernate, tames readily, has no associated unpleasant odour, and is friendly and easy to handle. It is inquisitive, quick to investigate any disturbance within the cage, and fearless towards humans. The Steppe Lemming a misleading title because it is properly thought of as a vole rather than a lemming was originally included with the mice of the genus Mus when first described in the eighteenth century. Widely available and inexpensive, it is regrettable that the species is now found increasingly often in pet shops, where purchases are often made on impulse. Rarely do the people who work in pet shops hand out information sheets with the animals they sell as a matter of routine but, without this basic service, the customer is not to know that Steppe Lemmings differ in their requirements from other pet rodents and, if these specific needs are not addressed, probably will not survive for long. Not knowing any different, the uninformed customer, after proudly installing his latest acquisition in its new home, proceeds to treat it as a conventional rodent, feeding it on a standard rodent diet, and is bewildered and disappointed when, only a few short weeks later, the animal is dead. One must be careful not to confuse the Steppe Lemming with the better known, more widely studied, true lemmings of the genus Lemmus or the Collared and Arctic Lemmings of the genus Dicrostonyx. As remarked above, the Steppe Lemming shares more similarities with the voles, to which it is closely related. Although much of the biology and behaviour is the same, true lemmings are not closely related to the Steppe Lemming and have usually proved very difficult to maintain in captivity, mainly because most species feed on large amounts of moss, fungi and lichen, particularly the tough, shrubby lichen Cladonia rangiferina (mistakenly called reindeer 'moss'), which are difficult to provide in quantity. The Steppe Lemming should, in theory, be much easier to keep as its requirements are less specialized. This is indeed the case providing certain strictures are adhered to. When I first became involved with the species, it surprised me that, although Steppe Lemmings were starting to crop up in pet shops, nobody to whom I spoke, including zoological writers, eminent biologists and such well-respected bodies as the London Zoo, could claim any long-term success with the species. One author, rather audaciously, even included a short chapter on it in her popular book about the care of rodents in captivity, only to admit that she had not succeeded with the species either. Her lack of success had not, however, prevented her from including it in her book. What were all these people doing wrong? Their experiences showed the same tedious consistency: initially the animals seemed to thrive, but then started dying off rather faster than they bred. There did not appear to be anything particularly remarkable about the species, and it always bred readily enough, but mortality (usually sudden and unexpected without prior symptoms) was often quite high, often equalling or exceeding the birth rate. After the first four individuals I acquired had all died within exactly four weeks of arrival (bought on the 8th June in 1998, the last one died on the 8th July the same year), I resolved to do something about it. I have spent several years investigating the causes of premature death with the result that I now believe that I have identified most, if not all, of the problem areas. Measurements Total length: 87-140 mm. Head/body length: 80-120 mm. Tail length: 7-20 mm. Weight: 25-35g. Appearance Superficially the Steppe Lemming resembles a Russian Dwarf Hamster. It is a stocky animal of about the same size as a Dwarf Hamster, with a pale grey or cinnamon back and a buff to silvery white belly and a black dorsal stripe extending along the spine. The short tail is hairy (as are the soles of the feet) and barely noticeable. The coat is longer and softer in feel than that of the closely related Microtus voles. Disadvantaged by not having either blubber or dense fur for insulation, oils in the coat provide a waterproof cover, helping to protect the animal from the cold climate, but this does mean it is prone to overheating. The neck is short and almost non-existent, so that the face appears to be set into the body. The muzzle is blunt. The Steppe Lemming has very long vibrissae, extremely small ears (to minimise heat loss) and small eyes. Legs are short. The toes are equipped with stout claws for digging. Distribution From Southern Russia, Ukraine, Kazakhstan and Dzungaria to Siberia, Western Mongolia, Chinese Turkistan and Sinkiang. Until around 1900, Steppe Lemmings could be found in the vicinity of Kiev, about 300 km west of their present range, but died out in this area because of habitat loss as more and more of the grasslands were converted to agriculture. In prehistoric times its range appears to have been even more extensive than it is today. Fossil remains show that in the Pleistocene era it occurred over much of Eurasia as far west as Great Britain. Similar Species In Mongolia and North Sinkiang, the range of the Steppe Lemming overlaps with that of the Yellow Steppe Lemming (Lagurus luteus). Natural Habitat Mainly dry steppe, but also found in semi-desert areas and occasionally pastures and cultivated fields. Social Structure In the wild, Steppe Lemmings are known to live in large, loose colonies. In the more restricted confines of a cage, however, the species is prone to spontaneous outbursts of aggression towards subordinate members of the colony, and it is best to house them in pairs, trios or small family groups consisting of no more than about 6-8 individuals. When kept at this level, it is rare for animals to fight, particularly if the colony has a low male to female ratio. I know one person who successfully kept sixteen females in a 76 cm (30 in.) long aquarium. Had there been any males present, the experiment might not have been so successful, as adult males can be quite aggressive towards each other. Being social by nature, Steppe Lemmings should not be kept on their own if at all possible. Attacks by conspecifics, usually caused by overcrowding or the unwise introduction of unrelated individuals into a colony, are a major cause of sudden deaths. Injuries are rarely apparent, however; the animal dying usually from shock or from internal haemorrhaging, and consequently it is not always immediately obvious that fighting is the root cause, unlike some other rodent species where the victim is partially flayed. Most violent deaths seem to occur in the nest box, leading me to suggest that a nest box should have two entrance holes at opposite ends, thereby preventing a subordinate individual from becoming trapped in the box by a more dominant animal. Even better than nest boxes are open-ended tubes or hollowed out tree branches. Introducing new animals into an established colony is usually impossible; the newcomers are invariably chased and bitten. Having worked themselves up into a frenzy of excitement, members of the colony often then turn on each other, as well as on the new arrivals. Once, before I knew much about the importance of territoriality, I made the big mistake of attempting to integrate some newly arrived specimens into the main colony in order to alleviate the high incidence of in-breeding I was experiencing at that time. To my horror, the newcomers were immediately set-upon. Unfortunately all the lemmings looked alike and I could not be sure which were the newcomers and which were my original animals. I rounded up all those that were being victimized and then found that I had removed more animals than I had in fact just put into the tank! There was just no way of knowing which were which. Unthinkingly, I had irreversibly disrupted the entire colony which, prior to this incident, had been very peaceful and productive. It was a salutary lesson Pairs should be put together for the first time on neutral ground. Not all animals get on well together. For several months I was forced to keep one male on his own as he bullied any potential mate I tried with him. Eventually, however, he did find one he liked and settled down amicably with her. It was incomprehensible to me why he had accepted her as a mate (she appeared identical to every other female Steppe Lemming I had tried with him) and yet had rejected all previous ones. Predators Steppe Lemmings are the staple diet for many of the mammalian and avian predators of the steppe, particularly owls, Rough-legged Buzzards (Buteo lagopus), Corsac Foxes (Vulpes corsac), polecats (Mustela putorius), stoats (Mustela erminea), weasels (Mustela spp.), and gulls (Larus spp.). Larger mammalian carnivores such as Badgers (Meles meles), Wolverines (Gulo gulo) and even Brown Bears (Ursus arctos) also prey on them. A weasel or stoat can take more than one a day, and a large owl up to seven a day, whereas a fox can consume as many as 100 each month. With such losses it is no wonder that Steppe Lemmings reach sexual maturity quickly and produce large and frequent litters. Predator numbers rise and fall in synchrony to the fortunes of the lemmings. Temperament Although totally fearless towards its keeper, the Steppe Lemming is trustworthy and quite handleable. Being so small, however, Steppe Lemmings should be handled only when absolutely necessary. Only very rarely does it bite and, even when it does, its bite is weak, no more than a painless nip, and not sufficient to break the skin. Behaviour Steppe Lemmings are sometimes described as nocturnal, but this is not strictly true. Although they are at their most active at night, and also at dawn and dusk, they have bursts of activity throughout the day and night in roughly 2-4 hour cycles. The species is active all year round and does not hibernate. In the wild, Steppe Lemmings rarely move far from their burrows except during times of migration. These burrows are of two distinct types: simple temporary burrows about 30 cm in depth providing shelter from danger, and larger, more complex, burrows used for permanent residence. The latter, comprising several interlinking auxiliary tunnels, extend up to 90 cm below the surface and have 2-3 entrances. About half way down these permanent burrows are spherical, grass-lined nest chambers about 10 cm in diameter. The most famous feature of lemmings is, of course, their mass migrations. Although it is the larger (unrelated) Norway Lemming that indulges in the most dramatic of these journeys, Steppe Lemmings too migrate in similar fashion, but their meanderings are not as noticeable or as famous. As with the Norway Lemming, the wild population of the Steppe Lemming expands and contracts with cyclical regularity. Numbers fluctuate considerably over successive years, increasing dramatically in some years until eventually the food supply is almost exhausted. At this point the population 'crashes' and many starve to death. Every 3-5 years the lemmings congregate in huge numbers to undergo mass migrations in search of more favourable conditions. Vocalisation Mostly silent except for high-pitched squeaks emitted when alarmed. Sexing Males can be distinguished by the prominent bulge of the testes. The anal-genital gap is approximately twice as wide in the male as in the female. Diet As the Steppe Lemming bears a superficial resemblance to the Russian Dwarf Hamster, there is a temptation to treat it as such, particularly in respect to its diet. This is a mistake and the principal reason why so many Steppe Lemmings have failed to survive for more than a few months. In the wild it lives on a fairly bland diet of roots, grasses and sedges, plant tubers, bulbs, green vegetation, and only a limited amount of seeds. Insects are probably also taken occasionally. The species appears to be sugar-intolerant. There is no reason why they would need to metabolize sugar in their natural habitat and, as with several other desert, montane and polar rodents, they have evolved to live without it. Therefore they must not be given any fruit or vegetables. For a long time the Steppe Lemming has had the doubtful honour of displacing the guinea pig as a traditional laboratory animal and, in retrospect, it is easy to see why laboratory technicians enjoyed a success with this species that was largely denied to private breeders and zoos. The secret lay in the frugal diet given, for economic reasons, to laboratory animals. Private breeders, through misplaced kindness, were offering food that was to 'rich' and, even worse, too high in the naturally occurring sugar, fructose, found in fruit. Quite simply, they were killing their animals through kindness. Mine are given a guinea pig food containing alfalfa, a small quantity of non-molassed hamster/gerbil mixture (one that is low in sunflower seeds or peanuts), and various millet seeds, millet sprays, fresh grass and hay. Occasionally a pinch of a proprietary 'softbill' bird food, such as Bogena, can be added as a convenient source of protein. Other items worth considering are the coccidiostat-free grass pellets normally fed to guinea pigs, and natural cattle cubes (without urea additive). Steppe Lemmings, for their size, consume prodigious amounts of food, but too 'rich' a diet can lead to the animals becoming overweight, causing the breeding rate to fall and shortening life span. The molar teeth grow continuously. Because of this adaptation, Steppe Lemmings are capable of eating more abrasive grasses and a greater quantity of grass than rodents with rooted molars, a characteristic shared with all species of meadow voles (Microtus spp.) and the Florida Water Rat or Round-tailed Muskrat (Neofiber alleni). Thin twigs of willow should be given for gnawing. Lemmings in general do not store food. In the case of Steppe Lemmings, however, in high summer, with grass so abundant, some of the grass stems they have sheared off are often left lying uneaten on the ground. About one in ten individuals have learnt to take this grass into their burrows to store as winter hay. Clean, fresh drinking water must be available at all times. Water intake varies considerably between individuals on an almost daily basis. In its natural habitat, the Steppe Lemming seems to require relatively little water, but this is probably due to its herbivorous diet. If the diet is very dry (as is often the case in captivity), Steppe Lemmings consume large quantities of water, reducing pro rata when the proportion of green plants in the diet is increased. In captivity, it cannot survive for more than a few hours without water, and therefore it is important particularly during hot weather to check the water level several times a day to make sure the dish has not become dry. Several keepers (including myself) have noticed that, for some reason, Steppe Lemmings seem reluctant, or incapable, of using a traditional rodent water bottle. More observation is needed to confirm if this is the case. I provide my Steppe Lemmings with a water dish, or a bottle and a dish. I have never observed them drinking from a bottle, nor does the level in the bottle appear to decrease, but they drink frequently from the dish. Accommodation A conventional hamster cage is unsuitable because, in most cases, the bars are too wide. A laboratory cage, glass or plastic tank are really the only options worth considering here. A ten gallon tank is ideal for a breeding pair or a small family group. A lid is not always necessary, other than to exclude potential predators such as dogs, cats or inquisitive children, since Steppe Lemmings cannot jump. They are, however, fast and nimble and, should any individual contrive to escape, it can be exceedingly difficult to recapture. The tank should be filled it to a depth of not less than 5 cm, and preferably as deep as 10-15 cm, with a peat substitute (such as coir fibre), coarse wood shavings, or a mixture of the two, and overlaid with a generous cover of sweet meadow hay. The hay is used both for food and as a nesting material. The litter must not be allowed to become damp as Steppe Lemmings are susceptible to pneumonia and other respiratory ailments. If the water is provided in a shallow open dish, it should be raised off the floor a little way by standing on a half brick. Make sure the lemmings do not carry bedding into the water or you will find the water leaks out through capillary action. As mentioned before, a nest box is usually not necessary. Not only is there a danger of subordinate members becoming trapped in it, but overcrowding can create humid conditions in the box. Tissue paper or hay are suitable for bedding and nesting. Cardboard, plastic or ceramic tubes can be provided for exercise, and twigs and branches given for gnawing. Steppe Lemmings enjoy an exercise wheel if a way can be found to prevent it becoming buried in the litter. More elaborately but probably impractical for most amateur keepers this species, which is susceptible to lung ailments, does well in an environment with cold, filtered air. They also benefit from a summer/winter photo period. Not being specialised desert animals, their urine is not as concentrated as that of the typical desert-dwelling rodents like gerbils and jirds, so the tank needs cleaning out frequently, but always check to see there are no young babies in the nest. Reproduction Most litters are born between March to October, but the species does breed prolifically throughout the year. The oestrus cycle is about 7 days. Between 4-12 offspring (average of 8) are born naked and blind after a gestation period of 20-22 days. Nursing mothers are remarkably tolerant of other females and often share the same nest. Males take no part in the rearing of the young. At birth the babies weigh little more than one gram. They develop quickly. The birth weight doubles in five days and doubles again by 12 days. Eyes open at about 11-12 days. The young also start to take solid food at around this time. They are fully independent at 18-21 days and sexual maturity is reached at only 4-6 weeks of age. Males mature later than females. Many breeders report a relatively high neonatal mortality rate, with most deaths occurring at around weaning. The reason for this is not clear. Adult females produce up to five litters in a year but, in the laboratory, where animals are raised intensively with little concern for welfare, it is not uncommon for females to have as many as 10-12 litters a year, but such over-productivity can shorten their life expectancy. Conservation Status It is considered to be Lower Risk and therefore of no cause for concern at the moment. But its population is highly variable. Locally it is the most abundant animal on the steppe. Population estimates in the Kazakh area, near to the Caspian Sea, give a density of 30-50 animals per hectare. Although generally considered to be a serious pest because of the damage it does to crops and pastures, with such inestimable numbers living in a part of the world inhabited by relatively few humans, coupled with a phenomenal breeding rate, its future seems assured. Life Span The mortality rate of wild Steppe Lemmings is very high. During the breeding season, of the animals alive one month only 70 percent are alive the next, many falling prey to predators. They burn up energy fast and, even for those lucky individuals which successfully elude the attention of predators, their natural life span cannot be very long. In captivity 20 months is the maximum longevity that can usually be expected, although occasionally particularly tenacious specimens notch up 2-2.5 years. History in Captivity Steppe Lemmings were first bred (in the laboratory) about 1940 in the former U.S.S.R. From there, colonies were established in the early 1960s in Germany and Great Britain and subsequently elsewhere. This does not mean that I personally condone its use as a laboratory animal; I am merely relating the reasons behind it. To Summarise After many months of trial-and-error, I was at last able to claim success. The species was breeding well and the death rate was low. The main points I had established for the successful husbandry of Steppe Lemmings are as follows. Some of these claims were bold, controversial, and hitherto unrecorded. i) Steppe Lemmings, like Degus and certain other rodents, seem to be sugar-intolerant and prone to diabetes. When I first kept them, I fed them on a standard diet of hamster food, plenty of grass, hay, and a few slices of apple daily, but I was losing them at the rate of about one a month. When I withdrew the apple and other fruit from their diet, losses were immediately reduced. Several that were inadvertently fed on a molassed-based rodent food also died. At that time I went away for a few days, leaving the lemmings in the charge of someone whom I thought I could trust. This person disregarded my written instructions and once again gave them apple to eat. In less than a week, thirteen specimens had died. These experiences, circumstantial though they were, provided me with the suspicion that this species must be fed a diet very low in sugars. ii) Although in their natural habitat Steppe Lemmings live in extremely large colonies, in captivity they seem to do better in pairs or small family groups. Even when kept in relatively small colonies ten individuals, they do seem to fight a lot. Below this level, fights are uncommon. iii) They cannot tolerate warm conditions. The loss of two of my animals during a sudden heat wave one summer may be attributed to this. They prefer cool, clean air. Filtered air is desirable, but not essential. iv) Prone to respiratory ailments and, for this reason, their environment must not be allowed to become damp or excessively humid. v) Cleanliness of the tank or cage is very important and must not be neglected. vi) They enjoy fresh grass, but this must be collected from areas untainted by exhaust fumes, chemical sprays, dog urine or other noxious substances. vii) They succumb very quickly to lack of water, and it may be necessary to check the water level several times a day to make sure the water dish has not become dry. viii) They seem reluctant to use a water bottle. It is a good idea to provide a water dish in addition to a bottle. ix) The species is short-lived anyway. The reason
for the high mortality rate that many keepers, including some professionals,
have experienced is likely to be a combination of these factors, rather
than any single cause. But, if the recommendations listed above are followed,
there is no reason why this delightful animal one of my favourites cannot
be maintained successfully. Description Steppe lemmings
are relatively small, about the size of a Dwarf hamster. They are long
and slender not dissimilar to the appearance of a Chinese hamsters body.
They are usually between 8-12cm long with a very short tail that will
measure no more than 2cm’s. Distribution From Southern
Russia, Ukraine, Kazakhstan and Dzungaria to Siberia, Western Mongolia,
Chinese Turkistan and Sinkiang. Steppe lemmings
are relatively easy to handle if started from a young age, can make a
wonderfully tame pet. Steppe lemmings rarely bite and when they do it
is usually a nip which isn’t strong enough to break the skin. Social
Behaviour Sexing
Accommodation
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