Hamster

Hamsters are small rodents that belong to the subfamily Cricetinae. This group has 19 species, which are sorted into seven genera. Many hamsters are popular pets.

The best-known hamster is the golden or Syrian hamster (Mesocricetus auratus). It is the type most often kept as a pet. Other hamsters kept as pets include three kinds of dwarf hamster: Campbell's dwarf hamster (Phodopus campbelli), the winter white dwarf hamster (Phodopus sungorus), and the Roborovski hamster (Phodopus roborovskii). The Chinese hamster (Cricetulus griseus) is also kept as a pet, but it is less common.

Hamsters mostly eat seeds, fruits, and plants. Sometimes they also eat insects that live underground. In the wild, they are crepuscular, which means they look for food at dawn and dusk. In captivity, however, they usually follow a nocturnal pattern. This means they wake up around sundown to eat and exercise.

Hamsters have stout bodies with several features that are easy to spot. Their cheek pouches are long and stretch all the way to their shoulders. They use these pouches to carry food back to their burrows. Hamsters also have a short tail and feet covered in fur.

Classification

Further information: List of cricetines

Hamsters belong to the subfamily Cricetinae. This subfamily is part of the larger family Cricetidae. Other animals in this family include voles, lemmings, and muskrats. These are all part of Arvicolinae. The family also includes New World rats and mice, which are in Neotominae, Sigmodontinae, and Tylomyinae. Among these animals, hamsters are most closely related to Arvicolinae. Cricetidae belongs to the larger group Muroidea. It is most closely related to Muridae. Muridae includes Murinae, which are the Old World rats and mice, and gerbils in Gerbillinae.

The first hamsters appeared during the Middle Miocene, about 15 million years ago. This group most likely began in central or eastern Europe. By about 10 million years ago, it had reached eastern Asia. A 2026 study suggests that the ancestor of all living hamsters lived about 5 to 6 million years ago, at the end of the Miocene. It probably lived somewhere in southeast Europe or West Asia.

Etymology

The name "hamster" is a loanword from German. It comes from an older Middle High German word, hamastra. It may be related to the Old Church Slavonic word khomestoru. That word may combine the root of the Russian word хомяк (khomyak), meaning "hamster," with a Baltic word such as Lithuanian staras, which also means "hamster." It may instead come from Persian, like the Avestan word hamaēstar, meaning "oppressor."

A group of hamsters is called a "horde." In German, the verb hamstern comes from Hamster and means "to hoard."

Hamsters have round, stout bodies, short tails, small furry ears, short legs, and wide feet. Their soft fur can be long or short. It can be black, grey, honey, white, brown, yellow, red, or a mix of colors, depending on the species. Four species have a dark stripe running from their heads to their tails. Two are in the genus Phodopus: Campbell's dwarf hamster (P. campbelli) and the Djungarian hamster (P. sungorus). The other two are in the genus Cricetulus: the Chinese striped hamster (C. barabensis) and the Chinese hamster (C. griseus). The Phodopus species are the smallest, measuring 5.5 to 10.5 cm (2.2 to 4.1 in) long. The largest is the European hamster (Cricetus cricetus), which can grow up to 34 cm (13 in) long, not counting a short tail of up to 6 cm (2.4 in). Most hamster tails are hard to see because they are short. However, the Chinese hamster has a tail as long as its body. Hamsters have sharp front teeth called incisors that never stop growing, so they need to be worn down regularly. Hamsters are very bendy, but their bones are somewhat delicate. They also do not like sudden changes in temperature, drafts, or extreme heat or cold.

Hamsters have poor eyesight. They are nearsighted and colorblind, so they do not judge distance well. This does not stop them from climbing in and out of their cages or from being adventurous. They can sense movement all around them, which helps them stay safe in the wild. Hamsters have scent glands on their sides, and on their bellies in Chinese and dwarf hamsters. They use these glands to leave a scent trail and mark their territory, their babies, or their mate. They also use smell to tell males from females, to find food, and to find their own babies. Their ears stand up to catch sounds. Hamsters can hear high-pitched sounds and communicate using the ultrasonic range. Hamsters are omnivores, which means they can eat both meat and plants. Wild hamsters eat seeds, grass, and insects. Pet hamsters can stay healthy on commercial hamster food alone, though vegetables, fruits, seeds, and nuts can also be given. Hamsters are hindgut fermenters, and they often eat their own droppings (coprophagy). This helps them get back nutrients that were digested in the hindgut but not absorbed the first time.

Behavior

Hamsters are known for food hoarding. They carry food in their cheek pouches to underground storage chambers. Their cheeks can make their heads look two or three times bigger when full. Hamsters lose weight in autumn to get ready for winter, even when kept as pets. Most hamsters live alone. If they are kept together, they may become stressed and may fight, sometimes causing serious harm. Dwarf hamsters might get along with siblings or unrelated hamsters of the same sex if they are introduced at a young age, but this cannot be guaranteed. Hamsters communicate with each other and with their owners through body language and by giving off a special scent from their scent glands.

Hamsters can be described as nocturnal or crepuscular, meaning they are active mostly at dawn and dusk. Some writers call them nocturnal. Others note that they spend most of the day underground and leave their burrows about an hour before sundown, so they are mainly crepuscular. In the wild, Syrian hamsters can hibernate. During hibernation, their body temperature falls close to the temperature around them. This thermoregulation lowers their metabolic rate to about 5% and helps them need much less food in winter. Hibernation usually lasts 2–3 days, though it can last up to a week. Syrian hamsters kept as house pets do not hibernate. All hamsters are excellent diggers. They build burrows with entrances, tunnels, and chambers for nesting and storing food. In the wild, burrows protect them from extreme temperatures and predators. Wild hamsters may also use tunnels made by other mammals. The Djungarian hamster, for example, uses paths and burrows of the pika.

Reproduction

Hamsters become fertile at different ages, depending on their species. Syrian and Russian hamsters can start having babies at only 4 to 5 weeks old. Chinese hamsters usually start at two to three months, and Roborovski hamsters at three to four months. A female's ability to have babies lasts about 18 months, but males stay fertile much longer. Females go into estrus about every four days. During this time, they may have a strong smell, and they hiss and squeak if they sense a male nearby. A female ready to breed has a slim body shape when seen from above, while a male's body looks wider on both sides. Male hamsters have very large testes for their body size.

Syrian hamsters are seasonal breeders. They can have several litters a year, usually from April to October in the Northern Hemisphere. A litter usually has about seven babies, but it can have as many as 24. Dwarf hamsters can breed all year. Campbell's dwarf hamsters usually have four to eight babies, and up to 13. Hamster babies are born without fur and cannot see. Their mother prepares a nest before they arrive. They begin exploring after about a week. Hamsters can be bred once they are three weeks old. Females can become aggressive toward males if the pair stays together too long after mating, so they should be separated. A mother may sometimes cannibalize her young if she feels threatened or if she stays with them for three weeks or more. For this reason, the babies should be moved away once they can eat and drink on their own. Syrian hamsters usually live two to three years in captivity, and Russian hamsters about two to four years.

Society and culture

The Syrian hamster, also called the golden hamster (Mesocricetus auratus), was first described scientifically by George Robert Waterhouse in 1839. Scientists could not breed and keep hamsters as pets until 1939. Almost all lab and pet Syrian hamsters seem to come from one brother and sister pair. Israel Aharoni, a zoologist at the University of Jerusalem, brought them from Aleppo in Syria in 1930. Their young were later sent to the United States, where Syrian hamsters became popular pets and lab animals. The golden hamster is the best-known kind and the one most often kept as pets. It has many Syrian hamster variations, such as long-haired types and different colors.

Other hamsters often kept as pets belong to the genus Phodopus. Campbell's dwarf hamster (Phodopus campbelli) is the most common. The winter white dwarf hamster (Phodopus sungorus) turns almost white in winter. The Roborovski hamster (Phodopus roborovskii) is so small and fast that it is hard to keep as a pet.

A hamster show is an event where people bring hamsters to be judged against each other. It is also a place where hamster fans can share their love of these animals. Judging usually aims to promote hamsters that match natural or established types, which encourages careful breeding.

In Hong Kong, the first reported case of an animal passing SARS-CoV-2 to a human involved imported pet hamsters. Researchers had difficulty identifying some virus changes in a global genomic data bank. The city then announced that many hamsters bought after 22 December 2021 would be culled, affecting about 2,000 animals. About 3,000 people secretly worked to adopt abandoned hamsters and keep them as pets. The government later warned that some of these activities would face police action.

Hamsters are also used in research. Cells from babies' kidneys and adults' ovaries help scientists study cholesterol synthesis.

Similar animals

Some rodents are sometimes called "hamsters," even though they are not in the hamster group. One example is the maned hamster, also called the crested hamster. It is really the maned rat (Lophiomys imhausi). Other examples are the mouse-like hamsters (Calomyscus spp.) and the white-tailed rat (Mystromys albicaudatus).