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African
Dormouse (Graphiurus murinus) Article by Russell Tofts Other Names: African Dormouse; African Pygmy Dormouse; Black and White Dormouse; Woodland Dormouse; Micro "Squirrel" (erroneously). Introduction Although initially quite expensive to buy, the African Dwarf Dormouse is the most widely sold pet dormouse. As far as I know, my own pet shop in Cambridgeshire was the first pet shop in Britain to regularly stock the species (this was as recently as the 1990s). Reasons why the species is not seen in pet shops more often are not hard to find: the rather high price tag; the fact that, being nocturnal, they are rarely seen by the casual shopper; and the young in particular make good escapologists, all combine to ensure that Dwarf Dormice will probably never be a regular feature of most high street pet shops. They do not make good pets for children, being virtually unhandleable, quick and capable of delivering a swift and painful bite. Appearance The simplest way of describing the African Dwarf Dormouse is to say it superficially resembles an impossibly small squirrel. It has a similar long and furry brush-like tail. The fur is dense and soft in texture. Upperparts are a charcoal grey. The belly is white. The skull is broad and flattened - the perfect shape for squeezing into very tight crevices and holes. The male has a slightly bigger skull than the female. Measurements Combined head and body length 9 cm; tail 7 cm; weight 18-30g. Colours, Patterns & Varieties A rare tan variety exists but, as far as I am aware, this artificial mutation is so far available only in America. The development of other colours is almost inevitable as the species becomes steadily more popular. This will be a pity. The present trend for producing different colour mutations is threatening to dilute and eventually wreck the gene pool of so many captive species. I would therefore urge owners to keep and breed only the original or 'natural' colour. Distribution The African Dwarf Dormouse has a widespread distribution throughout Africa south of the Sahara. Natural Habitat Its habitat, as one of its alternate names suggest, is mainly woodland or forest, but in southern and eastern Africa it will also venture onto the savannah or rocky outcrops, generally near to water. It has even been found in or near human habitation, although it cannot compete with the introduced Black Rat (Rattus rattus). Towards the southern end of its range, near the Cape, it puts on weight during the autumn months, becomes sluggish as the temperature falls, and may even become torpid for short periods. But this is not hibernation in the literal sense of the word, for true hibernation affects only temperate species of dormouse. Social Structure African Dwarf Dormouse need company and are obviously unhappy when housed alone. Several will even use the same sleeping box. It is important to have an equal sex ratio or, better still, rather more females than males. It has been claimed that males in captivity can be very territorial and fights may occur as a result, even to the death. It is not unknown for luckless specimens to be mutilated and partially eaten. I personally have never known them to fight but, of course, most fights, if they occur at all, happen after dark, but you would still see the evidence of fighting, such as blood smears on the cage or wounded animals. Although I have lost two individuals of unknown causes since I began keeping the species, in neither case were the bodies mutilated to suggest they had been killed by their cage mates, and I assume they had died of natural causes. In the wild as many as 11 adults of both sexes have been found in a single nest. The maximum number I have kept in one cage to date has been 13 individuals, with no aggression observed, but other breeders have kept up to 20 individuals together. New pairings should be made from young, immature animals. Adult introductions are difficult, the new animal being viewed as an intruder into the other's territory and invariably is attacked and injured. If breeding is not desired, single-sex groups can be kept without difficulty. Behaviour Adults are strictly nocturnal, but very occasionally young animals, adventurous or in search of food, venture abroad during daylight hours, a habit that wanes following maturity. Disturbing them whilst they are asleep can cause these animals to become stressed, which manifests itself as rapid breathing and a taught body posture. They do not hibernate. Although mostly arboreal, they do venture onto the ground occasionally in search of food. They make their nests in holes in trees, crotches in shrubs, or in the crannies between rocks. Wherever they choose, they line the cavity with finely shredded grasses. In the wild, African Dwarf Dormice have a territory radius of up to 50 metres from the central nest. In both their natural habitat and in captivity, individuals mark their territories. You will find that fresh branches are liberally sprayed within a short space of time of being inserted into the cage. For this reason, it is not recommended that you clean the branches with soapy water, as you would normally for other rodents, because the dormice will be quite distressed at losing their familiar territory 'flags' and will only feel compelled to re-spray the branches immediately. Vocalisation My colony is remarkably silent, but other people have heard this species make various twittering noises and, when alarmed or hurt, a high-pitched shriek. Accommodation A breeding pair requires more space than a non-breeding pair as the former is more likely to have disputes and to argue, and room is needed for them to get away from each other when necessary. Hamster cages are not suitable for these small rodents, as they can escape easily through the bars. The best form of housing is a glass tank with a close-fitting, well-ventilated lid, or else a melamine-covered 'vivarium-type' wooden box with a sliding glass or welded mesh front. Wire mesh should be no larger than 5 mm square. Enclosure size should be no smaller than 50 cm x 30 cm x 30 cm high, preferably larger. Decoration can consist of cardboard tubes, rocks and branches, thick sisal rope draped across the cage from corner to corner, and a solid (i.e. not spoked) rodent wheel for exercise. To make the enclosure look more natural, some keepers have experimented with plastic plants - quite successfully by all accounts, which comes as a surprise to me as I would have thought that plastic plants wouldn't last for long in a rodent cage. In the absence of a proper nest box, they conceal themselves during the day beneath stones and other ornaments. This can be inconvenient, because of the difficulty checking on them and the risk that the animals might be harmed when one replaces the stone beneath which they are crouching. A proper nest box (such as a budgerigar or blue tit nesting box) or finch wicker nesting basket are better solutions. The smaller the entrance hole, the more attractive the box seems to be, although it is not uncommon for Dwarf Dormice to make another ('bolt') hole at the opposite end of the box. It is best to give them a choice of sleeping accommodation. By providing more than one retreat, you allow subordinate members of the colony to rest separately from the others. You may find that sometimes the breeding male temporarily moves out of the 'marital' bed once the babies are born, but this is not always the case. Originally the wooden box I provided as a nest box had only one entrance hole, but they soon gnawed a small hole at the back for themselves. This makes perfect sense. For a species that traditionally lives in holes in trees, it is wise to excavate a bolt hole to prevent finding itself trapped by a snake or similar predator. Some people dismiss wooden boxes as being too unhygienic, preferring instead plastic or metal boxes which can be easily cleaned and disinfected. Wood, they claim, harbours smells. I prefer wood for precisely this reason. Most small mammals are olfactory beasts, relying to a very large degree on their sense of smell, and I believe that their home should always smell of their previous occupation within it. They don’t want everything to have a sweet , fresh fragrance. This is not to advocate that the cage should be dirty, just that it can be a mistake to be too clean. Be warned: these animals will soon destroy any cage constructed from plastic or wood, as I found to my cost when I attempted to keep a not dissimilar species, the Pencil-tailed Tree Mouse, overnight in a large ‘Pen Pal’™ plastic tank. By the next morning, there was a neatly gnawed hole in a corner of the lid and my precious animals were gone. If the cage is made of melamine-covered wood, you should ensure that there are no exposed edges that they can get to work on with their incisors, as they cannot usually make a hole in a completely flush surface. The animals are very clean and do not usually foul their own nest, preferring to use a site elsewhere as a latrine. My original colony habitually used a toy barrel for their toilet. As a consequence of the high fruit content of their diet, faeces are quite wet. I provide them with hay, chopped straw and shredded paper as bedding/nesting material, with coarse wood chips covering the floor of the cage. Dwarf Dormice do not burrow to any great extent, so a litter of about 5 cm is fine. Avoid any bedding material that looks and feels like cotton wool. Whilst certain manufacturers claim to be safe, there are numerous cases of small rodents choking to death on it or suffering impacted intestines. The ambient temperature should be around 70-80º F; if the temperature falls to 60º F or lower, the animals may go into torpor. It is inadvisable to permit this, even though, in certain parts of their range, such as in the South, some wild individuals do enter a state of torpor once a year. Feeding In the wild they enjoy a catholic diet, consuming seeds, nuts, fruits, insects and their larvae, flowers, nectar, pollen-bearing plant anthers, eggs, and even small vertebrates such as geckoes. The key word is variety. Mine receive a wide selection of fruit, a proprietary 'softbill' bird mixture such as Bogena™ (provides necessary animal protein in an easily accessible form), or, failing that, one of the new brands of complete hedgehog foods such as Nutriluxe™, tropical fish flake, various seeds, and a standard rodent mixture (the latter, though available at all times, is the least favoured food item). Two or three locusts or locust hoppers are provided each day when available. A high-quality dry cat food is also a good source of protein. As treat items, scrambled egg or even a little cooked chicken are relished. Artificial nectar can be purchased, but is rather expensive, but maple syrup is a good and cheaper alternative. Sunflower seeds are a favourite, especially when scattered around the cage so that the animals have to search for them, but sunflower seeds are very fattening when fed in excess. Low in calcium, an excess has been implicated in cases of osteoporosis in some rodents. A premium parrot food, which also contains a variety of dried fruits and nuts in addition to sunflower and other seeds, is preferable. Fruit usually consists of small pieces of apple, banana, grapes, pear, or tomato. It is generally stated that citrus fruits are enjoyed least, although my dormice readily consume slices of orange or grapefruit. At first I chopped the fruit very finely, but there was probably no need for this, and later I started to feed it less finely chopped. Usually they take the slices back to their nest box to consume in safety. In the wild, of course, it would be too dangerous to eat in the open with so many potential predators about; much better to remove the food to a hollow in a tree. Suitable live food includes crickets, meal worms, waxmoth larvae, woodlice (also called sow-bugs or pill-bugs), hoppers (immature locusts) and adult locusts. Crickets, in particular, provide environmental enrichment for the dormice because of the effort involved in catching them. It is not always easy to gauge exactly how many insects are consumed because they soon crawl out of the dish and bury themselves in the substrate, only to be discovered again much later when I clean out the cage. But I believe that a lot are taken. Mealworms are an excellent source of protein and essential fatty acids, clean and easy to store in a bed of bran or rolled oats. They should be given about twice a week and should be lightly dusted with a general vitamin/mineral supplement. Not only do mealworms have a hard, relatively indigestible, exoskeleton of cutin (a waxy, waterproof substance similar to your fingernails), but (here's the technical bit) the calcium/phosphorus ratio is reversed. In the case of most food items, there is usually approximately two parts calcium to one part phosphorus, but in mealworms this is the other way round. In extreme cases, to compensate for the calcium deficiency in the diet, the animal’s body may start sequestering calcium from other sources, i.e. the teeth and bones. This does not mean that mealworms must not be used - they are a very valuable resource that is greatly appreciated by many small mammals - but one should be aware of their shortcomings and, as with any single food item, should not feed them to excess. Extra calcium is easily provided by giving the dormice a mineral block or a piece of cuttlefish 'bone'. The exoskeleton of woodlice is a surprising source of natural calcium, but, if woodlice are to be collected, it is important to ensure that no pesticides or other noxious substances have been used in the collection area.. Any commercial hamster treats, such as honey seed bars, are suitable for Dwarf Dormice from time to time. A home-made Sugar Glider diet (details in the Appendix) is also worth considering. My preference is for high-sided ceramic feeding dishes that do not tip easily, placed on the floor of the cage. Water is best provided by a ‘drip’ bottle. Some people have expressed concern about these bottles, fearing that some small rodents may not be able to move the ball bearing in the spout of the bottle sufficiently to get a drink. If you are concerned about this, I suggest including a shallow water bowl in addition to the bottle. Most bottles are of plastic; the older-style glass bottles being virtually unobtainable. This is a pity because the glass bottles had a major advantage over those made of plastic: they were impervious to a rodent's propensity for gnawing. Sooner or later (usually sooner) a plastic bottle hung inside the cage will have a hole gnawed in the top of it, destroying the vacuum, and flooding the cage. For this reason, it is better to fix the bottle on the outside of the cage, with only the double-sleeved metal spout protruding inside. Handling Dwarf Dormice should be thought of as an animal that one can watch (and very entertaining they are) but not handle. Occasionally, however, it does become necessary, when cage cleaning or sexing, for example. Care should be taken as they are very lithe and quick. Being expert climbers, they are able to shin up near vertical surfaces as long as the surface is sufficiently rough to afford a foothold, and, if one is not careful, are particularly adept at running up one’s arm almost unnoticed. For this reason, it is probably best to avoid handling them altogether whenever possible. They tend to bite only if forcibly restrained. But, when they do bite, they bite hard. The tail, used for balance, is similar in appearance to a squirrel’s tail. Typically as long as its body, it is easily damaged and can be shed if the animal is handled too roughly. For this reason, NEVER PULL, LIFT OR RESTRAIN THE ANIMAL BY ITS TAIL. The sudden loss of this appendage does not seem to affect the animal (it barely seems to notice) but it is disfiguring. This seems to be a defence mechanism, enabling the dormouse to make good its escape. Unlike a lizard’s shed tail, it does not regrow, although David Alderton, in his book ‘Rodents of the World’, does seem to think that if only the tip is lost, it does have limited regenerative properties. Sexing Of all rodents, these are among the most difficult to sex. It requires a trained eye to spot gender differences and even the experts get it wrong occasionally. In very young animals it is almost impossible to be sure of the sex. The problem arises because the male has no external scrotal sac. He does possess testicular bulges at the base of the tail, but these are not prominent in all animals. The most reliable method is to gently 'scruff' the animal in one hand (careful, they bite!) and gently but firmly pull the base of the tail at the point where it joins the body. This action forces the testicles of the male to protrude slightly. It is obviously easier if you have at least one of each sex to compare. Reproduction In the wild, substantial, globular nests are constructed from grass, leaves and lichen in cavities in trees and also amongst branches, although nests have also been found in rock crevices and in thatched roofs. Most couplings take place around 10 O'clock at night. People lucky enough to observe their captive dormice copulating, report that, after vigorously chasing and catching her, the male mates with the female several times in quick succession. This pattern is repeated for about an hour. During mating, the male clasps the female around the waist. As he dismounts each time, both animals clean themselves before the chase resumes, followed by another bout of prolonged and energetic copulation, during which the pair appear to remain 'tied' for several moments. So firm is this 'tie' that, if the female attempts to walk away during this time, she will drag the passive male with her. The amount of time the pair remain 'tied' together is open to debate; certainly I have seen no figures. It would be a mistake to see it as a true 'tie' as practised most notably by mating dogs; probably it lasts for only about thirty seconds and certainly less than a minute, but this is still longer than most rodents remain bonded together. Usually just one litter is born per year. Reproduction peaks in the spring and summer months, when an average litter size of 4-6 young is produced, each weighing about 3.5g at birth, but it is not unknown for twins or even singletons to be produced. Gestation, thought to be about 6 weeks in duration, is extremely lengthy for such a small rodent. The first sign that young are present is that the female does not come out at her normal time, or spends much time outside the box. If the new-born young are disturbed by an over-enthusiastic owner, there is a risk she will destroy them. This is particularly true if she is part of a small colony, as other members of the colony seem to increase her stress levels. Although the temptation can prove almost irresistible, my advice is to wait up to 14 days before inspecting the nest. Young Dwarf Dormice are not ready to leave the nest until about six weeks of age. At this age their body length (excluding tail) is a mere 3-4 cm. but they are as agile as their parents and, by flattening their body, can escape through the tiniest crack. The young dormice can safely be left with their parents or can be moved to another cage to start off a new colony. Sexual maturity is reached at 4-5 months. I have found that Dwarf Dormice normally regulate their breeding. Once the cage, or rather the sleeping box, starts to become overcrowded, breeding often stops until numbers decrease. Life Span A captive specimen has been recorded living for 5 years and 9 months, although this must surely be the maximum longevity that can be expected for this diminutive animal. |
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