Hamsters are small rodents with dense fur, a short tail, and large cheek pouches. They belong to the mammalian family Muridae, which also includes rats, mice, gerbils, voles, and lemmings.
During foraging trips, hamsters use their cheek pouches to carry seeds and grains back to underground food stores that are sometimes quite large. Hamsters mostly eat plantmatter, especially seeds, nuts, soft fruits, tubers, and roots. However, they will also opportunistically predate on insects, small reptiles, bird eggs and nestlings, and even other small mammals.
Hamsters are aggressive animals. They are not very social, and generally live a solitary life. Soon after mating occurs, the male hamster is driven away by the female. Once the offspring are weaned, they are likewise driven away by their mother.
There are about 18 species of hamsters, all of which are found in the Old World. The common or black-bellied hamster (Cricetus cricetus ) is an aggressive, solitary, burrowing animal. This species lives in grassy steppes and cultivated areas of temperate Europe and western Asia south to Iraq. The common hamster is the largest hamster. It has a body length of about 12 in (30 cm), and can weigh as much as a pound. The common hamster has a reddish coat with bold, white markings, and its fur is sometimes used by furriers. The underground burrows of this species include a relatively large, central chamber, with radiating galleries used to store food, or as a toilet.
Remarkably, the winter burrows of the common hamster contain separate storage chambers for each type of food.
The common hamster is an inveterate hoarder, and if the opportunity presents itself, it will store food far in excess of its actual needs. Stores weighing as much as 200 lb (90 kg) have been found. People sometimes dig up the large winter hoardings of the common hamster to retrieve the grain they contain, usually for use as chicken feed. Like other hamsters, this species carries small items of food in its large cheek pouches, although some items, such as large tubers, are carried in the teeth. The pouches are stuffed, and emptied, using the fore paws. The common hamster hibernates in winter, when it blocks up the entrances to its burrow, and sleeps lightly in a bed of straw.
The common hamster is sometimes considered an important pest of agriculture, partly because of its enthusiastic storing of food in amounts far beyond its requirements. As a result, farmers often try to kill these animals using poison, by digging or flooding them out of their burrows, or using dogs.
The golden hamster (Mesocricetus auratus) is a very rare animal that is found in only a few places in the Middle East. For about a century, the golden hamster was only known from a single specimen, collected in 1839. It was not seen again until 1930, when a single family of golden hamsters was discovered in their den in Syria. Three individuals from that group were taken into captivity, and were used as breeding stock for zoos. They were later used as laboratory animals and for the pet trade. It is likely that all of the golden hamsters presently in captivity are descended from that small, original, founder group.
The head and body length of the golden hamster is about 6 in (17–18 cm) and it weighs about 4 oz (97–113 g). The golden hamster breeds quickly. It has a gestation period of only 15 days, and becomes sexually mature after only 8–11 weeks of age. This is the shortest gestation period of any non-marsupial mammal.
Golden hamsters are also not very social or friendly animals, and in the wild they are thought to live in a solitary fashion. However, these animals can be tamed by frequent handling from an early age, and the golden hamster has become quite popular as a pet. Although this species is quite abundant in captivity and is not in danger of extinction, its little-known wild populations are endangered.
The dwarf hamsters (Phodopus roborovskii and P. sungorus ) inhabit the deserts and semi-deserts of southern Siberia, Manchuria, and northern China. They have a head and body length of 2–4 in (5–10 cm) and are virtually tailless. When in captivity, they tame easily and are sometimes kept as pets.
The rat-like or gray long-tailed hamsters in the genus Cricetulus inhabit dry agricultural fields and deserts in Eurasia. The head and body length of these hamsters is 3–10 in (8–25 cm) and the tail is 1–4 in (2.5–11 cm) long. Like other hamsters, the seven Cricetulus species sometimes have large, underground stores, and these stores are excavated by people to retrieve the grain in some areas.
The mouse-like hamster (Calomyscus bailwardi) is another long-tailed hamster, occurring in rocky habitats in the mountains of western Asia south of the Caspian Sea. This species has a head and body length of 3–4 in (6–10 cm), a tail slightly longer than its body, and a weight of 0.5–1 oz (15–30 g). Its upper parts are buff, sandy brown, or grayish brown, its underparts and paws are white, and its tail is thickly haired and tufted. The mouse-like hamster has prominent ears and no cheek pouches.