Hamsters are rodents (order Rodentia) belonging to the subfamily Cricetinae, which contains 19 species classified in seven genera. They have become established as popular small pets.Barrie, Anmarie. 1995. Hamsters as a New Pet. T.F.H. Publications Inc., NJ . The best-known species of hamster is the golden or Syrian hamster (Mesocricetus auratus), which is the type most commonly kept as a pet. Other hamster species commonly kept as pets are the three species of dwarf hamster, Campbell's dwarf hamster (Phodopus campbelli), the winter white dwarf hamster (Phodopus sungorus) and the Roborovski hamster (Phodopus roborovskii), and the less common Chinese hamster (Cricetulus griseus).
Hamsters feed primarily on seeds, fruits, vegetation, and occasionally burrowing insects. In the wild, they are crepuscular: they forage during the twilight hours. In captivity, however, they are known to live a conventionally nocturnal lifestyle, waking around sundown to feed and exercise. Physically, they are stout-bodied with distinguishing features that include elongated cheek pouches extending to their shoulders, which they use to carry food back to their burrows, as well as a short tail and fur-covered feet.
Classification
The hamster subfamily Cricetinae forms part of the broader family Cricetidae, that also includes voles, lemmings and muskrats (all of which are in Arvicolinae), and New World rats and mice (Neotominae, Sigmodontinae and Tylomyinae). Within Cricetidae, Hamsters are most closely related to Arvicolinae. Cricetidae is placed as part of the broader clade Muroidea, within which Cricetidae is most closely related to Muridae, which includes Murinae (the Old World rats and mice), and gerbils (Gerbillinae) among others.
The earliest hamsters appeared during the Middle Miocene, around 15 million years ago, with the origin of the group likely being in central or eastern Europe, reaching eastern Asia by around 10 million years ago. A 2026 phylogenetic analysis found that the ancestor of all living hamsters probably only lived around 5-6 million years ago at the end of the Miocene, probably somewhere around southeast Europe or West Asia. Subfamily Cricetinae Genus Allocricetulus Species A. curtatus—Mongolian hamster Species A. eversmanni—Eversmann's or Kazakh hamster Genus Cansumys Species C. canus—Gansu hamster Genus Cricetulus Species C. barabensis, including "C. pseudogriseus" and "C. obscurus"—Chinese striped hamster, also called Chinese hamster; striped dwarf hamster Species C. griseus—Chinese (dwarf) hamster, also called rat hamster, sometimes considered a synonym of C. barabensis Species C. longicaudatus—long-tailed dwarf hamster Species C. sokolovi—Sokolov's dwarf hamster Genus Cricetus Species C. cricetus—European hamster, also called common hamster or black-bellied field hamster Genus Mesocricetus—golden hamsters Species M. auratus—golden or Syrian hamster Species M. brandti—Turkish hamster, also called Brandt's hamster; Azerbaijani hamster Species M. newtoni—Romanian hamster Species M. raddei—Ciscaucasian hamster Genus Nothocricetulus - grey dwarf hamster Species N. migratorius—grey dwarf hamster, Armenian hamster, migratory grey hamster; grey hamster; migratory hamster Genus Phodopus—dwarf hamsters Species P. campbelli—Campbell's dwarf hamster Species P. roborovskii—Roborovski hamster Species P. sungorus—Djungarian hamster or winter-white Russian dwarf hamster Genus Tscherskia Species T. triton—greater long-tailed hamster, also called Korean hamster Genus Urocricetus Species U. alticola - Ladakh dwarf hamster Species U. kamensis - Kam dwarf hamster
Cladogram of the relationships between the living genera, after Pan et al, 2025, with tribes after Dirnberger et al, 2026:
Fossil genera After
†Collimys †Rotundomys †Colloides †Nannocricetus †Cricetulodon (paraphyletic) †Neocricetodon †Stylocricetus †Pseudocricetus †Apocricetus †Tragomys †Hattomys †Hypsocricetus †Moldavimus †Sinocricetus
Etymology The name "hamster" is a loanword from the German, which itself derives from earlier Middle High German . It is possibly related to Old Church Slavonic , which is either a blend of the root of Russian () "hamster" and a Baltic word (cf. "hamster"); or of Persian origin (cf. Avestan: "oppressor"). The collective noun for a group of hamsters is "horde". In German, the verb is derived from . It means "to hoard".
Description
Hamsters are typically stout-bodied, with tails shorter than body length, and have small, furry ears, short, stocky legs, and wide feet. They have thick, silky fur, which can be long or short, colored black, grey, honey, white, brown, yellow, red, or a mix, depending on the species. Two species of hamster belonging to the genus Phodopus, Campbell's dwarf hamster (P. campbelli) and the Djungarian hamster (P. sungorus), and two of the genus Cricetulus, the Chinese striped hamster (C. barabensis) and the Chinese hamster (C. griseus) have a dark stripe down their heads to their tails. The species of genus Phodopus are the smallest, with bodies long; the largest is the European hamster (Cricetus cricetus), measuring up to long, not including a short tail of up to .
The hamster tail can be difficult to see, as it is usually not very long (about the length of the body), with the exception of the Chinese hamster, which has a tail the same length as the body. One rodent characteristic that can be highly visible in hamsters is their sharp incisors; they have an upper pair and lower pair which grow continuously throughout life, so must be regularly worn down. Hamsters are very flexible, but their bones are somewhat fragile. They are extremely susceptible to rapid temperature changes and drafts, as well as extreme heat or cold.
Senses Hamsters have poor eyesight; they are nearsighted and colorblind. Their eyesight leads to them not having a good sense of distance or knowing where they are, but that does not stop them from climbing in (and sometimes out of) their cages or from being adventurous. Hamsters can sense movement around at all times, which helps protect them from harm in the wild. In a household, this sense helps them know when their owner is near. Hamsters have scent glands on their flanks (and abdomens in Chinese and dwarf hamsters) which they rub against the surface beneath them, leaving a scent trail. Hamsters also use their sense of smell to distinguish between the sexes and to locate food. Mother hamsters can also use their sense of smell to find their own babies and identify which ones are not theirs. Their scent glands can also be used to mark their territories, their babies, or their mate. Hamsters catch sounds by having their ears upright. They tend to learn similar noises and begin to know the sound of their food and even their owner's voice. They are also particularly sensitive to high-pitched noises and can hear and communicate in the ultrasonic range.Fritzsche, Peter. 2008. Hamsters: A Complete Pet Owner's Manual. Barron's Educational Series Inc., NY .
Diet Hamsters are omnivores, which means they can eat meat and plant matter. Hamsters that live in the wild eat seeds, grass, and even insects. Although pet hamsters can survive on a diet of exclusively commercial hamster food, other items, such as vegetables, fruits, seeds, and nuts, can be given. Although store-bought food is good for hamsters, it is best if fruits and vegetables are also in their diet because it keeps them healthier. Hamsters in the Middle East have been known to hunt in packs to find insects for food."hamster." Encyclopædia Britannica. Standard Edition. Chicago: Encyclopædia Britannica, 2007. Hamsters are hindgut fermenters and often eat their own feces (coprophagy) to recover nutrients digested in the hind-gut, but not absorbed.
Behavior
Feeding
A behavioral characteristic of hamsters is food hoarding. They carry food in their spacious cheek pouches to their underground storage chambers. When full, the cheeks can make their heads double, or even triple in size. Hamsters lose weight during the autumn months in anticipation of winter. This occurs even when hamsters are kept as pets and is related to an increase in exercise.
Social behavior
Most hamsters are strictly solitary. If housed together, acute and chronic stress might occur,Kuhnen, G. (2002). Comfortable quarters for hamsters in research institutions. In "Comfortable Quarters for Laboratory Animals" Eds V. Reinhardt and A. Reinhardt. Animal Welfare Institute, Washington DC. pp.33-37 and they might fight fiercely, sometimes fatally. Dwarf hamster species might tolerate siblings or same-gender unrelated hamsters if introduced at an early enough age, but this cannot be guaranteed. Hamsters communicate through body language to one another and even to their owner. They communicate by sending a specific scent using their scent glands and also show body language to express how they are feeling.
Chronobiology
Hamsters can be described as nocturnal or crepuscular (active mostly at dawn and dusk). Khunen writes, "Hamsters are nocturnal rodents who are active during the night", but others have written that because hamsters live underground during most of the day, only leaving their burrows for about an hour before sundown and then returning when it gets dark, their behavior is primarily crepuscular. Fritzsche indicated although some species have been observed to show more nocturnal activity than others, they are all primarily crepuscular.
In the wild Syrian hamsters can hibernate and allow their body temperature to fall close to ambient temperature. This kind of thermoregulation diminishes the metabolic rate to about 5% and helps the animal to considerably reduce the need for food during the winter. Hibernation can last up to one week but more commonly lasts 2–3 days. When kept as house pets the Syrian hamster does not hibernate.
Burrowing behavior All hamsters are excellent diggers, constructing burrows with one or more entrances, with galleries connected to chambers for nesting, food storage, and other activities. They use their fore- and hindlegs, as well as their snouts and teeth, for digging. In the wild, the burrow buffers extreme ambient temperatures, offers relatively stable climatic conditions, and protects against predators. Syrian hamsters dig their burrows generally at a depth of . A burrow includes a steep entrance pipe ( in diameter), a nesting and a hoarding chamber and a blind-ending branch for urination. Laboratory hamsters have not lost their ability to dig burrows; in fact, they will do this with great vigor and skill if they are provided with the appropriate substrate.
Wild hamsters will also appropriate tunnels made by other mammals; the Djungarian hamster, for instance, uses paths and burrows of the pika.
Reproduction
Fertility
Hamsters become fertile at different ages depending on their species. Both Syrian and Russian hamsters mature quickly and can begin reproducing at a young age (4–5 weeks), whereas Chinese hamsters will usually begin reproducing at two to three months of age, and Roborovskis at three to four months of age. The female's reproductive life lasts about 18 months, but male hamsters remain fertile much longer. Females are in estrus about every four days, which is indicated by a reddening of genital areas, a musky smell, and a hissing, squeaking vocalisation she will emit if she believes a male is nearby.