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Sundevall's Jird
(Meriones crassus)

Article by Russell Tofts

Other Names Gentle Jird, Jerusalem Jird, Silky Jird, Swinhoe's Jird, Thomas' Jird. Affectionately called 'Sunnies' by some enthusiasts.

Introduction

Some older books state erroneously that Sundevall's Jirds are untrustworthy, bite without apparent reason, and are really a species for the experienced rodent-keeper only. It is difficult to see how it acquired this reputation. Perhaps the original wild-caught specimens, or F1 generation, were ill-tempered, but, if that was the case, subsequent generations seem to have lost that unpleasant trait, and I have no hesitation recommending this species.

Sundevall's Jirds are widely acknowledged as being the most supremely adapted of all Meriones for arid environmental conditions. They are inquisitive and show little fear of human beings. They are quick to emerge from their sleeping box to investigate any disturbance within the cage and can become very tame. They are easy to maintain, clean animals with no unpleasant odour. Many keepers are adamant that Sundevall's Jirds breed readily, although I have had a conspicuous lack of success breeding them, having successfully bred the species only once, from a female that was almost certainly pregnant on arrival.

Measurements

Head/body length 120-130 mm. Tail length 100 mm. Weight 29-40g. Males are generally heavier. The different subspecies vary in size, with the Pakistani race being arguably the smallest.

Appearance

The Sundevall's Jird, like other Meriones species, is quite rat-like in appearance. Superficially it resembles a much bigger version of the wild Mongolian Gerbil/Clawed Jird (Meriones unguiculatus), although somewhat rounder in shape and more heavily built. It has the same agouti coloration.

The Sundevall's Jird is approximately one-third larger than a Mongolian Gerbil, but still it is one of the smallest of the true jirds, being only about half the size of a full-grown Shaw's Jird. The tail is slightly shorter than the combined length of the head and body.

The pelage is dense, fairly long and silky, with a clear demarcation line between the sandy brown topcoat and the brilliant white of the belly, a phenomenon, widespread in desert animals, known as 'counter-shading'.

The hairs on the tail are short near the base and become progressively longer towards the tip, culminating in a black tuft.

The head is broad and pointed with prominent black eyes. Features are more angular than in other Meriones species. Facially the animal bears a passing resemblance to the much smaller Pallid Gerbil (Gerbillus perpallidus). There is white 'pointing' to the nose, distinctive white 'eyebrows', and small white tufts behind the narrow, well-developed, and unpigmented ears. Whiskers (vibrissae) are either yellow, black, or yellow with a black base. Upper incisor teeth have a narrow groove on the anterior surface.

The slightly elongated hind legs, equipped with strong claws, are superb for leaping and digging. The soles of the feet are covered with fine down-like hairs except for the calcaneal callosity (a naked patch of purplish skin beneath each heel, the purpose of which is to aid grip when climbing). The front paws are ivory in colour, as are the nails.

Females have eight mammae.

Similar Species

The two other jird species it can most easily be confused with are the Libyan (Meriones libycus) and the Shaw's (Meriones shawi). The Libyan Jird is distinguished by having dark to black claws in contrast to the light-coloured nails of the Sundevall's Jird. It differs from the Shaw's Jird by having a short, sharp-ended tip to the tail as opposed to the longer, rounded tail-tip of the Shaw's Jird. These subtle distinctions are easy enough to see in captive animals but, of course, impossible to observe in the field.

Mutation Colours

Only one deviation has so far been reported. In England, specimens have appeared with a small white spot on the top of the head, but this is an infrequent, unpredictable occurrence and the mutation is not yet 'fixed'. In any case, as is well known, I am not in favour of diluting or corrupting the limited gene pool of non-domestic rodents such as this with abnormal colour mutations which permanently ruin the gene pool.

Distribution

Morocco, Mauritania, Niger, Chad, Algeria, Niger, Libya, North Sudan, Egypt, Israel, Lebanon, Jordan, Syria, almost the entire Arabian peninsula, Iraq, Iran, Afghanistan, and Pakistan. The different subspecies vary in size and colour according to where they are found. Most, if not all, those currently kept in Great Britain belong to the subspecies Meriones crassus perpallidus from the salt marshes of Egypt.

Natural History

Found in arid environments including sand dunes, dry river beds (wadis), and flat gravel plains (hammada). There is nearly always some shrub cover. In the case of the wadis, the vegetation is rich and diverse, but in other habitats it is much lighter and scattered. Hammada are generally devoid of living plants. Individuals move from habitat to habitat and back synchronously, a pattern explained by seasonal changes in the vegetation. It avoids rocky habitat, probably because this hampers its burrowing activities, and is absent from mountains. The salt marsh habitat of Meriones crassus perpallidus is an atypical environment for this species, as other geographic races prefer drier habitat. The climate over most of the vast area in which this species is found is characterised by hot, dry summers and relatively cold winters.

Social Structure

A field study in 1977 concluded that this is not a communal species. This is an over-simplified view because, whilst it is true that Sundevall's Jirds are not naturally gregarious animals, leading largely solitary lives and mixing with others of their own kind only during the breeding season, they do occasionally form small colonies. Most of the time, however, burrows are occupied by a single individual or, more rarely and for a short duration, by a true pair. The highest densities are found in sand dunes, but even here it is rare for colonies to number more than four individuals per hectare, although up to eleven animals have been found on occasion. These findings have led some people to keep the male and female in separate accommodation, bringing them together only for mating. Most keepers, however, maintain them in mated pairs, although it is not impossible to keep them in family groups. The maximum I have kept together was a trio of a single adult male and two females, together with their two fully grown offspring. Because the two youngsters were re-homed when they reached sexual maturity, it is impossible to say whether the group would have continued to live together peacefully or whether, as seems likely, the breeding male and his young son would eventually have started to vie for dominance.

Temperament

Opinions differ, but most keepers agree that, whilst most Sundevall's Jirds often object to being forcibly restrained, specimens rarely seem disposed to bite, even when cornered. Bites are not unknown, however, and newly arrived animals should be allowed to settle down before being handled.

Behaviour

Nocturnal. In captivity this species is at its most active between the hours of 8.00 p.m. and 8.00 a.m. but is occasionally active during daylight hours when there are pups in the nest. Only about 5-10% of the night-time activity of wild individuals takes place above ground, under the shrub canopy in the vicinity of its burrow entrance and thus foraging activities are limited by the size and spread of the shrub crown. Sundevall's Jirds forage intensively in one small patch (moving about more than necessary would only attract the attention of predators) and leave for another patch when the food resource is depleted. This is undoubtedly the reason why individuals of this species remain in the close vicinity of each burrow for about three to seven days before moving onto another burrow.

A wild individual's home range is between 1,200-10,000 square metres. In its natural habitat, this terrestrial rodent digs extensive burrows. The older, more experienced animals excavate a complex system of burrows and galleries, often in sand hills, to a depth of one and a half metres. The burrow system is often very labyrinthine, with passages radiating off from other passages, giving a combined shaft length of 30-40 metres. Burrows usually have about three or four entrances, but the more extensive burrow systems may have up to eighteen entrances. There are usually several food storage chambers just below the surface and one or more nest chambers at a greater depth. Younger individuals are less proficient in the art of digging burrows, and theirs are much simpler affairs: usually descending at an angle of 15-30º to a depth of only about half a metre and with generally just a single entrance.

Sundevall's Jirds possess naturally silky fur. To preserve the lustre of the fur and remove excessive grease, they enjoy a regular dust bath. About twice a week, give them a shallow bowl of chinchilla sand, but remove it after about fifteen minutes or you will find they start defecating in it.

Communication

Mostly silent. When alarmed, Sundevall's Jirds communicate by rapidly drumming their hind feet on any suitable hard surface.

Sexing

There is no mistaking the mature adult male. He displays a very prominent scrotal sac, and the distance between the penis and anus is considerable – roughly as long as the first joint of your little finger. The distance between the anal and genital apertures is much less in the case of the female, whose own genitalia is arranged in a Y-shape.

Diet

In the wild state, Sundevall's Jirds enjoy a catholic diet consisting of bulbs, cereals, fruits, green vegetation, insects, roots, and seeds. The plant, Hammada salicornica, is an important part of the diet of wild Sundevall's Jirds. Their seasonal group migration from one habitat type to another often coincides with the growth and flowering of this plant. Almost anything is grist to the mill, even bitter green fruit and dry pulp. And they are not too choosy how they obtain it – even camel faeces can provide a few undigested seeds and other vegetable matter.

In captivity they should be given a good quality rodent mixture. A mix that provides a wide variety of seeds as well as broken coloured biscuits is preferred. They readily consume all kinds of fruit and vegetable – apple, broccoli, carrot, pear, sweet corn, sweet potato, etc. – and seem to benefit from a greater quantity of vegetable matter in their diet than do other kinds of jird. Green vegetation has been shown to be essential for successful reproduction. A few insects such as meal worms should be given two or three times a week, and they cannot resist stale wholemeal bread or Rivetas®.

A general vitamin and mineral supplement, such as Vionate or Nutrobal, can be lightly dusted over the food.

Cuttlefish is useful for keeping teeth in trim and for strengthening bones. As with all rodents, wood gnaws are essential. Some people prefer to buy the expensive packaged ones from pet shops, but non-toxic natural wood is just as good. Fruit tree branches are arguably the best. The bark can be left on as jirds enjoy stripping this and it provides essential trace elements. Branches should be washed in a mild soap solution to remove mildew, wild bird excrement, etc. and allowed to dry before placing into the cage.

Clean drinking water should be available at all times, either in a gravity-flow drinking bottle or heavy earthenware dish.

Accommodation

Glass aquariums, with a secure wire mesh lid, are ideal, although some keepers continue to use conventional cages, usually with some form of 'splash guard' fitted around the base to reduce mess. I find that most such cages are too small, however, and, unlike a glass tank, it is impossible to provide a deep litter, something which most jirds enjoy. Jirds have a habit of pushing their noses through the bars of conventional cages and eventually this can denude the area around the top of the nose. A frustrated or bored jird will gnaw on the bars, an action which will make the sides of the mouth quite sore.

Jirds are notoriously destructive and will attempt to chew through almost anything, particularly plastic. Even robust laboratory cages do not withstand a very determined Sundevall's Jird bent on escape.

Provide a very deep litter of large flaked wood shavings (not sawdust as this is too fine and can irritate the eyes and nasal membranes) or a mixture of chinchilla sand and bird sand (builders' sand is unsuitable, being too hard and gritty).

A nest box is always a good idea, particularly for raising young. I prefer to use wooden nest boxes. Such boxes, loathed by the ultra-hygienists, retain the animals' familiar scents, unlike nest boxes made of metal or plastic, thereby making the animal feel more secure and less stressed. Being made of wood and therefore not impervious to the jirds' teeth, it will need to be replaced at intervals. Hay or tissue paper make good nesting material.

Handling

Before attempting to pick up a jird, first make sure it is aware of you. Even the most benign animal can become defensive if suddenly startled whilst sleeping. The best method is to put your hand over the back of the jird, its head facing your wrist, and gently wrap your fingers around its belly to lift it up. Once in the palm of your hand, you can gently hold the base of the tail to restrain the animal if necessary, particularly important if the animal is not used to being handled. Remember that the skin on the tail is very delicate and easily damaged, so you should never attempt to pick up the animal by its tail as you can some smaller rodents; jirds are just too heavy to be suspended in this way and there is a danger of damaging the tail irrevocably. In extreme cases, the tail can even be lost completely.

Pairing

Pairs should be introduced to each other in a 'half-way tank' or on neutral territory, but getting them to accept each other is still far from easy. The male should be placed in the cage first, followed by the female, and not the other way around or fighting will almost certainly ensue. Generally, if the female is 'on heat', she will accept the male immediately and mate with him straightaway. If not, she might well attack him, in which case the pair should be separated and reintroduced a few days later in the hope of catching the female in season. (It has been shown that the level of energy intake affects the oestrus cycle, but there are no visible signs to human observers when the jird is in season.) If the pair do start fighting, it is inadvisable to attempt to separate them with bare hands because, in the frenzy, the handler is likely to be mistaken for another jird and bitten.

Once mating has occurred, some breeders prefer to place the female back into her own cage to await the birth of the pups. Others allow the male to remain with the female even after the young are born – sometimes this arrangement works very well – but it is not unusual for the male to sleep in a separate shelter, well away from the maternal nest, as the birth of the pups grows imminent.

Reproduction

The breeding season varies from area to area. In Israel and Saudi Arabia, for example, it runs from January to September with peaks in February to May and again in August, whereas conspecifics from Egypt breed from November to June. Pups born in late summer or early autumn are much less likely to survive unless the winter is exceptionally mild. The gestation period is 18-22 days, but can be as long as 24 days. There has been one recorded case of a pregnancy lasting even longer at 31 days. A few days before the pups are born, the female constructs a nest composed of dried vegetation. Her first litter is often quite small (about 1-3 young), but in subsequent litters can produce up to seven offspring. A female produces two to three litters each year.

If the animals are maintained in the colony system, the number in each litter can be expected to remain low at only one or two pups, but in some cases it is unclear whether more are born and simply fail to survive because of the larger number of adult animals in the cage.

As with many other rodents, the female experiences a post-partum oestrus, but implantation of the fertilised egg can be delayed for up to 30 days while the female continues to suckle the previous litter or until environmental conditions improve.

The male takes no part in rearing the young and is often forcibly excluded from the maternal nest. The young, born naked, pink, blind and helpless, develop quickly. Dorsal hair appears at 10-12 days, and ventral hair shortly thereafter at 12-15 days. Although they are not yet fully furred, autogrooming is seen between days 12-17. Eyes open at 16-20 days; also at around that time, they take their first faltering steps, and at 17-23 days they begin taking solid food. The young are weaned at 21-28 days.

In a group situation, you might find that, following the birth of the pups, stress causes the nursing female to carry the babies about all over the cage, sometimes on a daily basis, as she searches for a place where she can feel secure. However, all the young do usually survive.

Parasites

Nothing for the pet-owner to worry unduly about as long as the cage is kept clean and the bedding material renewed at least once a month, but it should be stated that all wild individuals are infested with fleas and many are infested with ticks. The ectoparasite burden ranges from one to over sixty fleas per individual. Of the four flea species recorded in a survey carried out in the Central Negev Highlands, Israel, from 1992 to 1995, the most common flea in most habitats was Xenopsylla conformis mycerini, whereas in wadis covered with loess (a light-coloured fine-grained accumulation of clay and silt particles deposited by the wind) it was replaced by Xenopsylla ramesis. Another flea species, Xenopsylla dipodilli, was found on the captured jirds more sporadically, leading researchers to suggest that animals became infested only when burrows and nests were visited by Wagner's Gerbil (Gerbillus dasyurus) or in cases of behavioural interactions between the two species, as this type of flea is found much more frequently on the latter gerbil species.

Conservation Status

Refreshingly common throughout its wide range, although it is possible that where the range overlaps with similar species, particularly Shaw's Jirds and Libyan Jirds, some local populations have been misidentified.

Life Span

Up to two years in the wild; in captivity more than three years, with one captive individual notching up 5 years 7 months.

Who was Sundevall?

Swedish ornithologist and author (Svenska foglarna, 1856), Professor Carl Jakob Sundevall (or Sundewall) (1801-1875) was curator of the Museum of Natural History in Stockholm from 1841 until his retirement with a pension in 1870. He so loved the museum that, even after his retirement, he continued to donate specimens – mainly birds but also other animals – purchased at his own expense. Although his chief interest was birds, his knowledge encompassed other animal classes as well. Respected for his taxonomic and morphological works, he lent his name to the Sundevall's Leaf-nosed or Roundleaf Bat (Hipposideros caffer), Sundevall's Waxbill (Estrilda rhodopyga) and Sundevall's Writhing Skink (Lygosoma sundevalli), as well as being the first person to scientifically describe the species of jird that now bears his name.

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