Mongolian Gerbil

Mongolian gerbil（圖片來源：Alastair Rae from London, United Kingdom，CC0 1.0 公共領域）

The Mongolian gerbil (Meriones unguiculatus) is a small rodent belonging to the genus Meriones. Adults are of moderate size, with a body length of approximately 11–13 cm. The tail is nearly equal in length to the body, and individuals typically weigh between 60 and 130 grams, with males generally slightly larger than females. Their fur is usually sandy yellow to grayish brown, while the abdomen is white. This coloration helps them blend into the dry grasslands and desert environments where they naturally occur.

Mongolian gerbils are distributed across Mongolia, northern China, and parts of Russia, inhabiting arid environments such as steppe, desert, and semi-desert regions. These areas experience extreme seasonal contrasts, with very cold and dry winters and intensely hot summers. Gerbils possess strong environmental adaptability. They dig extensive burrows in loose soil, and a family's burrow system often contains more than a dozen entrances. In some cases, tunnels may connect with those of neighboring groups. These burrow systems help regulate temperature, allowing gerbils to maintain stable living conditions even during extreme heat or cold.

Mongolian gerbils typically live in family-based social groups. A group usually includes a breeding pair, their offspring, and occasionally some older juveniles. Social hierarchy is well defined, and reproduction is generally dominated by a single dominant male and dominant female. Their territory may span several hundred square meters. Gerbils are highly social animals; individuals recognize each other through scent and communicate through foot drumming and vocal sounds.

This species was first recorded by European scholars in the nineteenth century. Initially, they were mainly used for scientific research. It was not until the mid-twentieth century that they began to be introduced as household pets. Because of their gentle temperament, ease of care, and relatively clean habits, Mongolian gerbils are now among the most common small companion animals. In the wild, their lifespan is typically only three to four months, whereas individuals kept in captivity commonly live between two and five years.

Mongolian gerbil（圖片來源：Peko，採用 CC BY-SA 3.0 授權）

Housing Requirements in Captivity

In captive care, gerbils require a suitable enclosure that supports their natural behaviors and overall health. A rectangular glass or metal enclosure is recommended. Plastic enclosures should be avoided because gerbils' teeth grow continuously and they readily gnaw through plastic, which may create holes or lead to accidental ingestion.

The enclosure should measure at least about 60 cm in length and 40 cm in width to allow sufficient space for running and burrowing. If two or more gerbils are kept together, a larger enclosure is strongly recommended.

Gerbils have a strong instinct to dig. The enclosure should therefore contain a thick layer of bedding made from paper-based material or safe plant fibers, ideally exceeding 10 cm in depth so that they can dig freely. Pine or cedar wood shavings should be avoided because the aromatic oils they contain may irritate the respiratory system. Paper bedding provides good absorbency and produces less dust, making it a safer option. In addition to digging substrate, soft nesting material can be provided so that gerbils can construct resting nests.

The enclosure should include shelters such as small houses or tunnels that provide hiding places. Ideally, each gerbil should have access to its own shelter to reduce potential conflicts. Because gerbils are highly active animals, exercise equipment should also be provided, including a safe running wheel with a solid surface rather than gaps or wire bars that might injure their feet. Items for gnawing, such as wooden blocks, cardboard tubes, or climbing branches, are also beneficial.

The environmental temperature should ideally be maintained between 18 and 24°C. Temperatures above 27°C or below 15°C should be avoided. Gerbils should not be kept in locations with direct sunlight, near air-conditioning vents, or on the floor where temperature fluctuations can be strong.

As social animals, gerbils generally do not thrive when housed alone. Solitary individuals may develop anxiety or depressive behavior. It is therefore recommended to keep two or more gerbils of the same sex together. However, they should either be littermates or introduced to each other at a young age. Forcing unfamiliar adults to share the same enclosure often results in severe fighting.

Feeding Conditions

Mongolian gerbils are omnivorous rodents. In the wild, they feed primarily on herbaceous plants, seeds, and small insects. In captivity, their main diet should consist of a high-quality commercial gerbil feed to ensure balanced nutrition. Pelleted diets are often preferable because they reduce selective feeding and help maintain natural tooth wear.

In addition to the staple diet, small amounts of grains such as oats or sunflower seeds may be offered as occasional treats or training rewards. However, the quantity must be carefully controlled to prevent obesity. Vegetables and fruits can also provide supplementary nutrients. Examples include carrot slices, green peas, apples, or blueberries. Because fruits contain relatively high levels of sugar, they should be given only in small amounts once or twice per week to avoid digestive issues or excessive weight gain. All food items should be cut into small pieces, and any uneaten portions should be removed within a few hours to prevent spoilage.

Water should be provided using a bottle equipped with a ball-bearing drinking nozzle. Shallow bowls should be avoided because gerbils may easily overturn them or contaminate them with bedding. Fresh water must be supplied daily, and the bottle should be checked regularly to ensure that it is not blocked or leaking. Drinking water may consist of bottled mineral water or previously boiled dechlorinated water.

Foods containing caffeine, alcohol, or chocolate are harmful to gerbils and must be strictly avoided. Excessive feeding of high-fat or high-sugar treats should also be avoided because these can negatively affect health.

Breeding Conditions

In the wild, Mongolian gerbils typically breed from spring to autumn. A stable pair bond often forms between a male and female, and the pair may reproduce together over an extended period. Females reach sexual maturity at around two months of age, while males mature slightly later. The estrous cycle of females lasts approximately four to six days. Gestation lasts about 19–30 days, and each litter typically contains four to seven pups. Newborn pups are hairless and blind, and they rely entirely on maternal care and nursing. Weaning usually occurs at around three weeks of age.

In captive care, if breeding is not intended, males and females should not be housed together. Gerbils have strong reproductive potential, and without control their population can increase severalfold in a short time. If breeding does occur, additional enclosures should be prepared so that growing juveniles can be separated later. This helps prevent inbreeding and reduces the risk of aggression caused by overcrowding.

After giving birth, a female gerbil can enter estrus again very quickly and may become pregnant again soon afterward. Repeated pregnancies can place considerable strain on the female's body. For this reason, males and females should be separated when necessary to prevent frequent breeding. If caretakers lack experience in raising young gerbils, disturbance should be minimized after the pups are born. Providing sufficient food and a quiet environment allows the mother to nurse and care for the litter without stress.

Preventing Invasive Spread

The Mongolian gerbil is native to Mongolia and northern China and has become a popular species in the pet trade. However, it is not legally permitted to be kept in all regions. For example, in places such as California in the United States, Australia, and New Zealand, gerbils are prohibited from importation and private ownership. The reason is that escaped, abandoned, or deliberately released individuals could potentially threaten local ecosystems or agriculture.

As a rodent with strong adaptability, gerbils introduced into non-native environments could reproduce rapidly and compete with native small mammals for food and habitat. Responsible ownership therefore requires strict adherence to the principle of not abandoning or releasing pets into the wild. If a keeper is no longer able to care for a gerbil, the animal should be transferred to a legitimate animal shelter or another suitable caretaker rather than being released into the natural environment. Preventing the establishment of invasive populations is an important responsibility for anyone who keeps non-native pets.

Author: Shui-Ye You