8 Surprising Facts About Hamsters

A young European hamster with a black tummy and brown and white fur standing upright in a grassy field.

Stefan Huwiler / Getty Images

Hamsters are fur-covered mammals with oversized cheek pouches and short tails. These small rodents live in the wild and some species are popular as house pets. There are 18 hamster species and they are found in a variety of habits, from deserts and plains to sand dunes and agricultural fields across Europe, Asia, and Northern Africa. One species, the European hamster, is critically endangered.

From their elaborate burrows to their continuously growing incisors, there’s much to learn about these little balls of fluff. Here are a few things you may not know about hamsters.

1. There Are 18 Species of Hamsters

Roborovski hamster burrowing in a cave.
Roborovski (or desert) hamster.   Bullet / Wikimedia Commons / CC BY-SA 3.0

Hamsters belong to the family Cricetidae, which includes voles and lemmings as well as rats and mice. The 18 species of hamsters are quite varied. Some are more ratlike, like the seven members of the Cricetulus genus, while the lone member of the Cricetus genus, the European or common hamster, has a unique black fur belly. 

The most popular species for pets are the golden or Syrian hamster (Mesocricetus auratus), and three different members of dwarf hamsters: the winter white dwarf hamster (Phodopus sungorus), Campbell's dwarf hamster (Phodopus campbelli), and the Roborovski hamster (Phodopus roborovskii), the smallest of all hamster species.

2. They Are Nocturnal Creatures

Since they are prey for so many animals, it’s no wonder that most hamsters are nocturnal. They spend their days hiding from snakes, eagles, foxes, badgers, and other carnivores. In the wild, hamsters dig burrows with deep tunnels and multiple entrances for protection and to sleep during bouts of torpor. Being solitary animals, they mostly spend time in their burrows alone.

3. They Are Promiscuous

Male and female hamsters are polygynandrous — they each have multiple mates. During breeding season, males travel from burrow to burrow and mate with whatever female they find, provided said female hasn't already mated. Once she has mated, a copulatory plug forms on the female to prevent any further insemination. Hamsters are territorial, and females frequently kick the male out after mating.

Females will normally birth two to four litters a year — their gestation period is only 15 to 22 days — and litter sizes can range from one to 13 young, though the average is around five to seven.

4. They Are Banned in Hawaii

Given their high reproductive rate and the fact that Hawaii’s climate is similar to the hamsters' native habitat, the critters are illegal in Hawaii. Hamsters could quickly establish large colonies in the state if they ever escaped into the wild, which would pose a problem for agriculture and other species.

Hawaii’s list of banned animals also includes ferrets, gerbils, hermit crabs, and geckos.

5. Their Teeth Never Stop Growing

Like all rodents, hamsters’ incisor teeth have no roots and they never stop growing. By gnawing, hamsters keep their teeth nice and sharp, and prevent them from becoming too overgrown.

Researchers studying rodents’ teeth have discovered that their incisor teeth contain active stem cells. This factor, coupled with rodents’ trait of constantly regrowing their teeth, gives scientists hope of one day replicating the tooth regeneration process in humans.

6. They Hoard Food

A hamster filling its cheeks with rosehips to bring to its hoard
Michaela Walch / Getty Images

Hamsters are built for food storage. Their cheeks are like tiny totes that they can fill with fruit, grains, roots, and leaves. When they find an abundant source of food, they fill their cheek pouches and return to their burrows, where they have prepared food chambers for storage.

Those cheeks have another use too — they allow some hamsters to swim by filling them with air so they can float.

7. They Are Prone to Bacteria and Viruses

Hamsters carry salmonella and, while rare, they are also prone to Lymphocytic choriomeningitis, a virus that can result in flu-like symptoms. Children under the age of 5 and pregnant adults are particularly at risk.

The primary methods of zoonotic disease transfer from hamsters and other rodents to humans is through bites, direct contact with the animal, and indirect contact with contaminated objects.

8. European Hamsters Are Critically Endangered

European hamster stands upright in some soil
The European (or common) hamster is critically endangered. katanski / Wikimedia Commons / CC BY 3.0

Once widespread throughout Europe, the black-bellied, European, or common hamster is critically endangered. The only member of the Cricetus genus, both the range and population of this hamster have declined significantly throughout Western, Central, and Eastern Europe. Changes in agricultural practices, commercial and residential development, pollution, and climate change are the biggest threats to these small animals.

Conservation, monitoring, and reintroduction measures in parts of the hamsters’ range have been successful in slowing the decrease in population. The European hamsters’ decline has occurred rapidly, and plans for conservation throughout all countries in the hamsters’ range are needed to prevent its extinction.

Save the European Hamster

  • Support initiatives that require EU Member States to take measures toward favorable conservation of the species in Europe.
  • Support diversified farming practices that offer food and vegetative cover for the hamsters.
  • Support modifications to infrastructure and private development projects where the hamsters are present.