A Gerbil is a small mammal of the order Rodentia. Once known simply as "desert rats", the gerbil subfamily includes about 110 species of African, Indian, and Asian rodents, including sand rats and jirds, all of which are adapted to arid habitats. Most are primarily diurnal (though some, including the common household pet, do exhibit crepuscular behavior), and almost all are omnivorous. Gerbils are typically between six and twelve inches (150 -300 mm) long, including the tail which makes up approximately one half of their total length. One species however, the Great Gerbil, or Rhombomys opimus, originally native to Turkmenistan, can grow to more than 16 inches (400 mm) in length. The average adult gerbil weighs approximately 2 1/2 ounces. Pet gerbils have an average lifespan of 2-4 years. Some have been known to live to 5-6 years.
There are several reasons for the popularity of gerbils as household pets. The animals are typically non-aggressive, and they rarely bite unprovoked or without stress. They are small and easy to handle, since they are sociable creatures that enjoy the company of humans and other gerbils. Gerbils also have adapted their kidneys to produce a minimum of waste to conserve body fluids, which makes them very clean with little odor. The pets are incredibly industrious and will explore new environments, and they will build, construct, and enjoy elaborate networks of tunnels if given an environment that allows for it. This is easily observable as gerbils are active during all hours of the day, as opposed to the more nocturnal rodent pets. They can "recycle" everyday paper-based items, such as cardboard products like toilet paper tubes and brown paper bags, into toys and nesting material, chewing the material into small bits. If the chewed material is allowed to accumulate to a depth of 4-6 inches deep, they will tunnel through it.
The typical Mongolian gerbil is a desert species, and lives underground in a network of tunnels, which include chambers with families. Adults move away and meet others from other chambers, extend the network, create their own chamber, and breed. Gerbils come up for food and water; there is no evidence of hoarding food, but gerbils will eat a lot of fatty foods in one sitting, suggesting supplies in the form of fat reserves rather than food storage. Gerbils do not hibernate and are diurnal. Their long tails help them to balance when they stand up on their hind legs. Gerbil movement is more like hopping than running, and their large back feet are furry on the bottom to protect them from the heat of the sand. Gerbils are fast but overly inquisitive. In their natural environment, they are mostly insectivores, and additionally gain moisture from desert plants that store water in them. A gerbil has fur all over its body, including the tail, as this prevents it from getting sunburned.
Normal gerbil behavior includes jumping, climbing, chewing, and digging. The digging motions are very common: the gerbil moves its arms rapidly. They are curious and not easily startled. They love to burrow and hide. Gerbils are social animals, and prefer to live in groups. Often very large groups live well together, as long as the living environment is big enough; otherwise, the gerbils may become frustrated and attack one another. Groups of females are much more quarrelsome than groups of males, but if fighting occurs among males it is usually much more vicious. Males will very rarely attack females, however.
Sunflower seeds, pumpkin seeds, and peanuts are favorites of most gerbils, though they have individual preferences and too many sunflower seeds may result in illness. They also enjoy fruit peels such as that from a banana. In fact, gerbils will eat almost anything: dog biscuits and chews; rat food; rabbit food; guinea pig food; oats; and various "special" treats from pet shops, which in fact were not appreciated nearly as much as some parsnip cores. Most weeds dubbed as safe for grazing animals like rabbits or guinea pigs can be eaten by gerbils as well. Pet gerbils will especially enjoy live crickets, grasshoppers, and locusts as food, tearing the insect apart and eating the juicy insides. It is good for you to feed your gerbil vegetables such as carrots or an apple. Take care not to feed them too much of these foods as they contain a lot of moisture and can cause an upset stomach. Avoid lettuces, as the nitrates can prevent oxygenation of the blood, and citrus fruits. Sugary treats are bad for gerbils; they rot the teeth and the sugar is hard for a gerbil to digest. Lastly, do not feed your gerbils food with high water content, such as celery or watermelon, as the water will cause the gerbil to have the runs, or "wet-tail" as it is commonly known. Gerbils can go without water for around two weeks, provided they have plenty of food to produce the water, they will always take water if it is available.
Gerbils do not need water to get clean - what cleans them is a sand bath. When taking gerbils out for exercise, a small basin of cool sand will be much appreciated, and true to instinct, a gerbil will roll over in the sand. The effect is instantaneous - their fur becomes much smoother and shinier.
Gerbils often have what looks like boxing matches; this is most common amongst young gerbils (gerbil "pups"). These are gentle play fights, which usually end in the winner pinning down the loser and grooming it. However, if a pair of gerbils is fighting closely in a ball shape, with both gerbils biting deeply and drawing blood, careful but swift intervention is in order by the pet owner, using a jar or oven mitts to avoid getting bitten. Gerbils like to sleep in a group, often on top of each other. Sometimes they will absentmindedly groom each other when half asleep. Gerbils have a form of purring called "bruxing" which they do when they are being groomed or while they enjoy being stroked in the hand by their owner. Squeaks can occasionally be heard from them, and a squeak is usually an indication of annoyance. When another gerbil steps on another without thinking, it will give a squeak, or when a gerbil tries to steal another's food, it will turn with a squeak, and when a male tries to mate an unsuspecting female, she may well turn around sharply to face him and squeak at him. Gerbil pups will squeak more often when very young, sometimes when feeding, or if they have strayed from the nest. Gerbils will raise their hackles and arch their backs to show aggression, often turned to the side and leaning against the other gerbil's body. Usually this is a warning that a fight is about to occur, and if this behavior is observed it is wise to quickly intervene. Gerbils will also alert each other to danger by thumping on their hind legs, usually triple thumps repeated in a steady sequence. Gerbils will also thump when sexually excited. Younger gerbils are more likely to start thumping than older ones.
Gerbils, when fighting, may chase each other around frantically, amid small screams of protest by the victim. This is usually a case of bullying by one gerbil. If the feeling is mutual, the gerbils will stare each other down, pounce on one another, and clamp their teeth around each other's neck, faces, or such in an attempt to draw blood. Gerbils can injure each other seriously in this way. Gerbil fighting is very loud and may last a long time. Gerbils often fight on their hind legs swiping at their opponent with their forepaws. Gerbils fighting will usually be on top of each other, rolling over and over rapidly. If gerbils are left to resolve the dispute, they will most likely fight to the death. A lead up to a fight can include chasing, persistent sniffing and following, and one gerbil forcing another to stay in a single area. A defeated gerbil will often be quiet for some time and remain in a single area. They will very likely stay away from their attacker for some time unless they attack it again. If the fight turns into a chase, the gerbil chasing will most likely try to bite the legs and tail of the opponent.
Health Problems: Misalignment of incisors due to injury or malnutrition may result in overgrowth, which can cause injury to the roof of the mouth. Symptoms include a dropped or loss of appetite, drooling, weight loss, or foul breath. Common injuries are caused by gerbils being dropped or falling, usually while inside of a "run-about ball", which can cause broken limbs or a fractured spine (for which there is no cure). A common problem for all small rodents is neglect, which can cause the gerbils to not receive adequate food and water, causing serious health concerns, including dehydration, starvation, stomach ulcers, eating of bedding material, and cannibalism. Diarrhea can occur, usually caused by a virulent strain of Ecoli or Salmonella, which is most common among weaning gerbils (3-6 weeks). Symptoms include lethargy, thinness, increased irritability, hunched posture, fluid or bloody diarrhea, and a wet, soiled anal area and tail. It is treatable with antibiotics, yet the gerbil may remain a carrier of the germ and spread it to other uninfected gerbils. For this reason, a gerbil that has had diarrhea should not be chosen to breed with. Between 20 percent and 50 percent of all pet gerbils have the seizure disorder epilepsy. Fright, handling, or a new environment causes the seizures. The attacks can be mild to severe but do not typically appear to have any long-term effects, except for rare cases where death results from very severe seizures. Gerbils can lose their tails due to improper handling, being attacked by another animal, or getting their tail stuck. The first sign is a loss of fur from the tip of the tail, then, the skinless tail dies off and sloughs, with the stump usually healing without complications. The most common infectious disease in gerbils is Tyzzer's disease, which is often caused by either stress or bacteria, and produces symptoms such as ruffled fur, lethargy, hunched posture, poor appetite, diarrhea, and often death. It quickly spreads between gerbils in close contact. A gerbil leaning to one side quite obviously can spot a problem with the inner ear. The fluids in the ears affect balance. However, this does not appear to affect the gerbils too much, which have an aptitude of just getting on with things, and getting used to their conditions. Gerbils with "extreme white spotting" coloring are susceptible to deafness, this is thought to be due to the lack of pigmentation in and around the ear. As desert animals, it is easy to make the mistake that as gerbils are used to bitter cold in the night and boiling heat in the day, they can be left in direct sunlight or in subzero temperatures. This can cause damage to a gerbil. The reason they survive in the desert is because they take frequent shelter in their tunnels. Many gerbils living together and plenty of bedding help gerbils stay warm. In heat, they will trample their bedding flat. Heat can make gerbils noticeably lethargic, so the choice of shade is important. They do sweat when very hot, and become thirsty more often than usual. Forgetting to clean a pet gerbil's cage for weeks can be a problem. Ammonia will build up, and gerbils may have trouble breathing. In the wild, gerbils will dig more burrows when their current one is filthy, but in cages this cannot happen. Symptoms of a respiratory infection may include exhaustion, apathy, and a strange clicking or wheezing noise. One way to help solve this problem is to give the gerbil antibiotics.