Gerbils

There are more than 80 different species of gerbil found through an area stretching from the Middle East into Africa and eastwards into Asia, but only one has become well-known as a pet.This is the Mongolian gerbil (Meriones unguiculatus), which, as its name suggests, lives in this part of eastern Asia. 

Gerbils occur in arid areas, and this is reflected not just in their sandy coloration, but also their pale underparts which reflect heat from the sand. They have powerful hind legs and long tails which enable them to move easily by jumping. The dark tip to the tail is fragile, so that if it is grabbed by a would-be predator, it will be lost, enabling the gerbil to escape otherwise uninjured.

Living in open countryside where there is little available cover, gerbils have highly developed senses, with keen eyesight and hearing. This can even alert them to the approach of avian predators such as owls, with these rodents being able to detect the sound of their wing beats. 

Gerbils can become quite tame if handled gently from an early age, but they can also move very quickly, which means they are less suited to being kept by young children, compared with rabbits and guinea pigs, which are more content to be handled and stroked. They are more suited as pets for teenagers. Even so, it is important to bear in mind that like other rodents, gerbils can inflict a painful bite if they are frightened, and they should always be handled with care. Holding the base of the gerbil’s tail provides a good way to restrain it, so it can be scooped up in your other hand.   

Housing

In the wild, Mongolian gerbils live communally in underground burrows and so require similar accommodation in the home. Ordinary wire-topped cages are not particularly suitable for them, because they will tend to scatter much of their bedding out through the sides in such cases. A converted aquarium is likely to make a suitable environment, especially because this will also provide more space for two or three of these social animals. This is made possible by acquiring a special ventilated hood, which extends snugly around the sides of the aquarium, complete with a sliding cover to give access to the interior.

Glass tanks are most widely-used, but bear in mind that larger sizes are heavy and rather cumbersome to handle, so an acrylic design may be a better choice if available. It is particularly important that the gerbils’ quarters are not place in front of a window, where in direct sunlight, the temperature of the interior may otherwise rapidly rise to a fatal level.

The base of the tank can be lined with coarse shavings, as sold for pet bedding, but never sawdust, as this can easily enter the gerbils’ eyes and cause irritation. Suitable retreats should also be provided, allowing them to hide away. These can include clay flowerpots and clean cardboard tubes, as well as items available in pet stores. A special fitment which holds the water bottle firmly in place off the roof or on a side, allowing it to hang down so the gerbils can reach the spout easily, will also be needed. An open water pot will not be suitable, as it is soon likely to become full of shavings.{break}

Wooden blocks for gnawing are important to enable the gerbils to keep their teeth in trim. As far as toys are concerned, beware of anything that could serve to trap a gerbil’s tail, as the tip especially is vulnerable to injury. It may also be a good idea to have smaller temporary housing where the gerbils can be kept while you are cleaning their quarters.  Otherwise, if they escape into the room, they can be difficult to catch, because they are so agile and move quickly, being able to jump as well as run. 

Feeding

Dry seeds form a significant part of a gerbil’s diet, just as occurs in the wild, although they will also eat some fresh greenstuff. Certain species may even eat small invertebrates such as mealworms, although these are not essential, certainly for the Mongolian gerbil itself.  Gerbil seed mixes should be comprised primarily of cereal-type seeds such as crushed oats, wheat and barley.

Some flaked maize may also be present in seed mixes for them, but beware of offering too much sunflower seed, or indeed peanuts. Both have a relatively high oil content, in contrast to cereals which contain predominantly carbohydrate. Too much reliance on oil-based seeds will predispose gerbils to obesity, and may also be implicated in cases of skin problems. Furthermore, a large amount of sunflower seed in the diet can predispose gerbils to fractures. 

Although seed-based diets remain most common, there are also pelleted foods now available, containing all the nutrients that gerbils require to stay in good health. As with the seeds, they simply need to be tipped into a heavyweight earthenware pot which cannot be tipped over. The gerbils will then help themselves, holding and nibbling their food in their front paws. 

A little fresh food, in the form of sweet apple can also be provided regularly. Other possibilities include small pieces of raw cabbage and carrots, as well as dandelion flowers which are often a particular favourite. It is vital with these fresh foods not to leave them uneaten for long in the gerbils’ quarters however, because otherwise they could start to turn mouldy, representing a danger to their health. Any uneaten food should be removed by the end of the day.

Do not be too worried if your gerbils appear not to drink much water. This is quite usual, because originating from semi-desert areas, so they have evolved the ability to survive with little fluid, partly by producing a very concentrated urine. Even so, they should always have access to a supply of fresh drinking water.  

Varieties  

A number of different colour varieties now exist in the case of the Mongolian gerbil, quite apart from the normal agouti form. This is creating by the presence of blackish banding called ticking, extending around the individual hairs and alternating with lighter coloration here.

The earliest recorded colour variant in the case of the Mongolian gerbil was the variety now known as the white spot. As their name suggests, gerbils of this type display irregular small white areas in their fur - typically two or three such spots in the vicinity of the head.  Where the white areas are significantly enlarged, such gerbils are described as being patched. 
 
The self varieties are distinguished by their more even coloration. The black was amongst the first of this group of colours to emerge. In this case, the upperparts are a glossy shade of black, with their underparts being of a matt shade. The lilac represents the dilute (paler) form of the black, being greyish with a pinkish hue to its coat. Crossings between black Mongolian gerbils and the argente gold created this variety.

The argente gold itself is a bright, deep golden colour with whiter underparts. The eyes are pink, as are the ears, thanks to the absence of dark melanin pigment.  In addition, the lilac’s coloration has been further diluted, creating the paler dove variety.

The white varieties can be distinguished on the basis of their eye coloration. The first to emerge was the pink-eyed, although the coloration of these gerbils is not entirely white. They are always pure white at birth however, and then start to develop traces of black fur on their tails, by the time they are about 9 weeks old. Ruby-eyed whites are similar, resulting from crosses between pink-eyed individuals and darker grey agoutis, but recognisable by their darker eye coloration. 

“Agouti” is the term used to described the natural colouring of the Mongolian gerbil. It refers to the alternating light sandy and blackish bands of colour running down each hair.  When this sandy colour is lost, being replaced by white areas, this gives rise to the grey agouti. In the dark-eyed honey, ticking in the coat develops as the gerbil grows older. It starts off with a sandy appearance therefore, with ticking then becoming apparent in the coat from about two months of age, darkening its appearance.

The dark-eyed honey in turn has played a significant role in developing the Fox varieties, like the polar fox, which displays white rather than yellow colouring. Schimmels are a group which alter in appearance as they grow older, becoming lighter in colour as they mature. The champagne form is a unusual spotted variant, with an orange coat  whose colour fades to merge with its white spots as it grows older.  

There are colourpointed varieties of the Mongolian gerbil as well, named after the corresponding cat varieties. The Siamese shows more contrast between the colour of its extremities, known as points, and its body colour, compared with that of the  Burmese which has a relatively darker body. 

Other species

Several other gerbils and jirds are occasionally available, usually from specialist breeders. They include the pallid gerbil (Gerbillus perpallidus), which is of a more golden shade than its Mongolian relative, with white markings extending up around the eyes. Their requirements are similar.

Not all gerbils are as social however, with the Jerusalem Gerbil (Meriones crassus) also being more inclined to bite when handled.  Aggression can also be a feature of Shaw’s jird (M. shawi) - a close relative of the Mongolian gerbil. Such species need to be housed on their own, with pairs being introduced cautiously in a neutral enclosure for breeding purposes.

The most unusual of gerbil sometimes offered as a a pet is the fat-tailed (Pachyuromys duprasi). Coming from the northern Sahara region in Africa, it has a particularly broad, pink tail. This acts as a fat store, not unlike a camel’s hump, helping the gerbil to survive when food is in short supply.  It too needs to be housed  on its own, with mating encounters being closely supervised.  

Health care

Gerbils can suffer from diarrhoea, which may be triggered by sudden changes in diet or a more sinister cause, in the form of Tyzzer’s disease, which is a bacterial infection. Do not introduce a gerbil from outside an established group to the colony, as it may be carrying this infection, which is difficult to treat successfully. A sick gerbil will appear hunched-up, with its fur looking rather rough too.

Gerbils need to be handled with care, especially because they are prone to epilepsy, and fits can be triggered by prolonged handling. Some strains appear to be more vulnerable to epileptic seizures than others, which cause them to appear to faint and start twitching. If left quietly alone, gerbils generally recover from such episodes without problems.

As they grow older, female gerbils can suffer from tumours within the reproductive tract.  The most obvious sign will be loss of weight and condition, with no treatment being available. In both sexes, a sudden increase in the volume of water being drunk is often indicative of diabetes, which strikes gerbils most commonly from middle age onwards.