hamsters

A hamster is a rodent belonging to subfamily Cricetinae. The subfamily contains about 18 species, classified in six or seven genera. A majority of them have expandable cheek pouches, which reach from their cheeks to their shoulders. Because they are easy to keep and breed in captivity, hamsters are often used as lab animals and pets.

Species of hamsters

The best known species of hamster is the Syrian Hamster, also known as the Golden Hamster, Mesocricetus auratus, which is commonly kept as a pet. It is also sometimes mistakenly called a "Fancy," or "Teddy Bear" hamster. Pet stores also have taken to calling them "Honey Bears," "Panda bears," "Black bears," "European Black bears," and "Dalmatian," depending on their coloration, although these are not correct names. There are also several variations, including long haired hamsters that grow hair several centimeters long and often require special care.

All other pet hamsters are four distinct kinds of dwarf hamster. Campbell's Hamsters (Phodopus campbelli) is the most common of the four. They are also sometimes called 'Russian Dwarfs.' However, almost all hamsters originate in Russia, and so this name does not distinguish them. The coats of Winter White Hamsters (Phodopus sungorus) turn white when the hours of daylight decrease. The Chinese Hamster (Cricetulus griseus) is unique among hamsters because it has a prehensile tail about four centimeters long, while most hamsters have very short, non-prehensile tails. The Roborovski Hamster (Phodopus roborovskii), the last of the four dwarf hamsters, is extremely small and fast.

Hamsters as pets

The care of all pet hamsters is fundamentally similar, but there are differences in feeding and housing needs. Dwarf hamsters can be kept with a cagemate of the same gender to prevent loneliness, but Syrians are extremely territorial and will kill other hamsters in their cage. Chinese hamsters can be kept in pairs occasionally, but are more aggressive than other dwarves. Hamsters are nocturnal by nature. Many people prefer them to rats as pets, given rats' generally unsavory popular reputation. Unlike rats, they are not particularly good at learning tricks but can be entertaining to play with and watch. They are also much smaller than guinea pigs, although equally as furry and appealing, so are more appropriate for homes with limited space.

In the United States, the Campbell's hamsters are more popular than the winter white, while the reverse holds in Europe. Roborovski and Chinese hamsters are somewhat more difficult to breed and keep, and are usually only available from breeders. They are the least common type of hamster to be kept as pets.

Housing

Hamsters can be kept both in cages and in terrariums, both of which are available in pet stores. Cages are easier to carry, their bars can be used for climbing, and they usually include a convenient front door. On the other hand, glass boxes keep hamsters from throwing litter out of their cages, provide a better view into the hamster's home, and create a quieter and more sheltered interior. In general, terrariums are more appropriate for dwarf hamsters, which are more sensitive to a disquieting environment and which would otherwise need very narrow-grid bars to keep them from slipping through. Middle-sized hamsters, such as the Syrian Hamster, especially enjoy climbing the cage walls. This, however, is dangerous because the hamster can get its leg caught in the bars and fracture its leg. On the other hand, bars (the cage should have horizontal and vertical bars) are more open to the outside world; cages might be a better choice for these hamsters.

Despite the hamster's small size, appropriate housings should always have a floor space of at least one square foot. Glass boxes must not be higher than their width to allow for a sufficient air circulation. Although smaller in size, dwarf hamsters should have bigger housings than their larger relatives, at least 80 cm by 40 cm (2 feet by 4 feet). The reason for this is that the dwarfs are very active, running and digging a lot, but they often cannot be taken outside their houses for long, because they are not comfortable there and, due to their smaller size, are more endangered when leaving their domicile. Usually hamsters with a bigger and more interesting home will live longer and provide more visual entertainment.

In addition to buying the common housings sold in stores, you can also build customized dwellings. In this case, use only materials that are not dangerous to the animals. Plywood and wood from conifers is not suitable, because hamsters gnaw at their houses and both glue and resin are poisonous for them. Using standard water-soluble white wood glue to join pieces of solid wood, such as birch or beech wood, creates a safe environment for the hamster, although you must frequently check that the hamster is not gnawing through the wood. You can also equip a purchased cage with several intermediate levels, connected using stairs. Using wire grid for these platforms instead of solid wood causes serious injuries and is therefore not recommended.

The perfect place for the hamster's home is a well-lit room of constant, moderate temperature (18 to 26�C, 64 to 80�F), in a place out of strong sunlight that could cause dangerous heating. It is also important to avoid drafts -- especially when wire cages are used. Though they cannot see very far, hamsters become more relaxed and curious when positioned somewhat above the ground (at least 65 cm (2 feet)), from where they can perceive their surroundings.

The floors of the hamster's residence should be covered, including all intermediate levels, with a sufficiently thick layer of litter for rodents. Many types of litter are available in pet stores. Although many materials may work well, some commonly-used materials do not. Cat litter is dangerous, because gnawing and eating the chunks is deadly. Cedar, pine, and any other softwood-based litters or beddings contain aromatic oils (phenols), which can irritate a hamster's respiratory system, liver, and skin. One safe wood litter is aspen shavings. Also, litter made from recycled paper pulp works well to absorb odors and is safe for hamsters. These paper litters have had the inks and other chemicals washed out.

Hamsters are nest builders and a steady supply of fresh strips of tissue or newspaper (with soy-based ink) allows them to build a secure and comfortable spot in a corner of their enclosure or in their hiding house. Hay, from shops or even fresh from the garden, is also a valuable building material for cozy hamster nests, but is discouraged unless guaranteed to be pesticide-free.

Hamster bedding materials made of fluffy cotton cloth are extremely dangerous, as they can tangle around the hamster's neck and limbs as well as pose a choking hazard. If swallowed, they cannot be broken down by the hamster's digestive system.

A sand bath can provide hamsters with entertainment and help them groom. In the desert (their natural habitat) hamsters will roll around in the sand, which cleans their coats and prevents them from getting too oily. Dwarf hamsters in particular enjoy this activity. A sand bath can be made by filling a dish with clean sand. It is important to use a dish that will not tip over. Heavy ceramic and metal dishes are preferred. Chinchilla sand is often available in pet stores and can be used for hamsters, but sand that is powdery or dusty should be avoided as it will pose a hazard to a hamster's respiratory system.

Regular cleaning of a hamster's home is crucial for the hamster's health. The home must be cleaned at least once a week by replacing the soiled bedding where necessary. Hamsters are fairly neat in their bathroom habits if their enclosure is regularly cleaned. They choose one small location in which to urinate and defecate, making cleaning simple. The cages of dwarf hamsters may require slightly less-frequent cleaning (perhaps once every two weeks), and may have many (usually hidden) places used as toilets.

Another important component of a hamster's home is a hiding place where the animal can rest during the day. Not all commercially available houses are adequate. The houses should be of sufficient size and be closed on at least two sides. The same building materials are appropriate for these as for the actual cages. Even a small cardboard box with no ink (or only nontoxic ink) will work although it will have to be regularly replaced. Some houses add features such as a removable roof that helps to take away collected food (especially perishable items).

Syrian hamsters are solitary animals and have to be kept alone once they are mature (around 7 weeks and above). Dwarf hamsters are more likely to accept another house mate. While sometimes two or more animals can live peacefully within one home, there can be fights, so separate them as soon as blood is shed. In their natural habitat, there is substantially more empty space so that each hamster can have its own large territory. If more than one hamster is to live in a cage, then the cage must be larger (at least 40cm x 40cm per hamster) and there must be separate hiding houses for each animal. In any case, even after a long period of peaceful coexistence or even mating, there can be violent biting. In this situation, the hamsters should be separated immediately. Note also that, if a male and female hamster live together without fighting, they will usually reproduce rapidly and cause more space problems.

Gnawing

Despite their cuddly appearance, hamsters have long, thin, sharp teeth that can pierce a finger that is mistaken for a carrot or for a predator. When they are accustomed to being handled and are not startled, however, they are not inclined to bite and can be placed in the custody of responsible school-age children. Like many rodents, their teeth grow continuously and they must have appropriate things to chew on to relieve their instinctive gnawing and to help keep the teeth at a healthy length. They will gnaw on whatever is available, so they must be kept in enclosures that they cannot chew through. When the hamster is kept in or near a bedroom, their nocturnal nature combined with their gnawing habit can become distracting.

Exercise and Entertainment

Like all pets, hamsters need exercise and entertainment to maintain their physical and mental health. An exercise wheel allows hamsters to run full speed to their hearts' content, and is a must, but it should be appropriate for your hamster's small size. Many commercial exercise wheels marketed for hamsters are made with wire rungs that can allow your hamster to slip and fall. Better wheels have a solid plastic ring, and some method to protect your hamster from getting pinched between the wheel and the frame. In addition to a wheel, tubes and toys can provide your hamster opportunities to explore and play. For example, hamsters enjoy wooden tubes that somewhat mimic the burrows that they might have in the wild and allow their owners to enjoy their activities. (Be sure that whatever you place in the hamsters cage is either bite proof or safe for the hamster to chew on.) Plastic "maze" tubes are popular, but if you choose to purchase some you should choose a brand that has air holes at frequent intervals to allow moisture and air to escape.

Clear plastic hamster balls or cars are available, into which the hamster is placed and then, by its own action, explores an entire house or yard. Use these toys only under supervision and use common sense. Unsupervised hamsters in these toys can become trapped against furniture and panic or they can roll down stairs, injuring themselves. Many experts advise against these toys due to the high danger of the hamster getting injured or frightened. If you use them, do not leave them in these toys for extended periods, especially on warm days, and make sure to remove them frequently and allow them access to water or fresh fruits or vegetables. Toys should always invite the hamster to explore and use them at its own will, without forcing or violence. They should only be left in a hamster ball for 10-15 minutes at the most or they can dehydrate.

If they are handled frequently, hamsters enjoy being out of their enclosures and having the opportunity to explore. They can also become very tame if handled frequently. Syrian hamsters will be tame for life once they are tamed. Once tamed, if dwarf hamsters are neglected they will become mean and will bite.

They must be kept away from holes in the wall or in large pieces of furniture, because they will seek out the dark and burrow-like confines of those areas and it can be difficult or impossible to convince them to come out again. Ceramic toys are fun and gnaw resistant, so they are a good choice. If you put your hand against their nose, then they will push up with a (relatively) strong force. Hamsters do seem to enjoy this. It is a form of play when they are outside the cage.

Food

Pet stores can provide basic food for hamsters that provides their nutritional needs, but they also enjoy fresh vegetables and fruits, bird seed, and even living insects like grasshoppers, which make up an important part of their natural diet. However, not all foods are suitable for hamsters and some , such as sweets made for humans or poisonous plants like the leaves of the tomato, may be most dangerous for the hamster's health. Lettuce is also harmful because it can cause wet tail (diarrhoea) - this is extremely bad for the hamster and can kill them. Citrus fruits are also toxic to all hamsters. Campbells dwarf hamsters are susceptible to diabetes, and should not have high sugar foods, such as fruits and corn. Although there is no increased risk for the other dwarf breeds, sugary commercial treats should be avoided due being generally unhealthy. Like with most other animals (and humans), it is not true that hamsters can decide which food is good for them and they will usually eat anything that is offered.

Hamsters should also always have fresh water available. Appropriate drinking devices can be found in stores. Being small animals that are adapted to the life in arid environments, hamsters can also ingest all necessary liquid via sufficient amounts of watery vegetables, such as cucumber, without any negative effects. However, providing water is usually more convenient and can be an easy way to add medication or vitamins to the hamster's diet, although vitamin drops on food or in water tend to be ineffective. Both water and vegetables must be fresh and have to be exchanged frequently, usually once a day. Water must not be given in open jars, since it is likely to be polluted and because wetness is generally very unhealthy for hamsters (they clean themselves very carefully without the need of additional water).

In detail, the solid food components can be divided into three categories: dry, fresh, and animal food. Dry food makes up the bulk of a hamster's diet. Besides the standard rodent food sold in pet stores, most other kinds of seeds, kernels, and nuts can be given. Care should be taken to limit the amount of fat contained within the diet. Especially sunflower seeds, nuts, and sesame are the most nutritious and are to be considered as a treat rather than as basic food. All kinds of grain, rice, noodles (dry), dry peas and lentils on the other hand can be provided more readily: about 120 g for a medium hamster and, depending on size, about half the amount for a dwarf hamster is sufficient. Bread and similar bakery products contain many ingredients (e.g. yeast) that can trouble the hamster's digestion system. They should be given in small amounts for gnawing or be replaced by special wafers as found in pet stores. All dry food should be appropriate in size. Especially small hamsters often cannot cope well with large seeds, even if they are sold under the label "hamster food". Bird food like millet is a noteworthy alternative for small hamsters.

Hay, although a popular choice as it is cheap and easy to find, should not be fed to hamsters as it can cause damage to their sensitive cheek pouches, although sometimes people use a certain type of hay called "Timothy hay" which is still not very good for a hamster.

Fresh food is also an important part of the hamster's diet. As mentioned above, cucumber is a good supplement of water. Fresh carrot, spinach, broccolli, turnip, leaves and even branches of (non-poisonous) plants are also no problem in general. As mentioned previously lettuce can cause wet tail and should be avoided. In addition, no conifer wood must be fed since resin is poisonous for hamsters. Hamsters are known to appreciate Tofu. In smaller amounts, grown hamsters also appreciate apple, pear, sweet paprika, banana, mango, grape, and strawberry. Too many sweet fruits on the other hand are not healthy. All kinds of cabbage should be avoided, since they may cause flatulence, which is quite dangerous for the hamster's sensitive digestion system. It is also dangerous to feed your hamster citrus fruit of any kind.

All hamsters should be given a more conservative diet. If accepted, herbs can also help to strengthen the hamster's health, though they cannot replace a veterinarian in case of a disease. Daisies (the flowers, not the stems or leaves) and dandelions are likewise appreciated. Plants used for hamster foods should never be placed near open windows because hamsters are more sensitive to chemical pollutions, due to their small body weight.

Finally, animal food is a major component of some hamsters' natural food. As pets, a large part of this can be replaced by dry food. Still, hamsters need some animal proteins for their health. While some people like to provide living insects from pet stores to their hamsters (mealworms are very suitable), others will prefer to give them dry dog biscuits. Some hamsters are known to accept yoghurt (natural, without sweet ingredients) or soft cheese (low fat, not too salty), and in any case egg noodles are usually taken gratefully. If (dry or soft) dog or cat food is given, then the fat content has to be checked carefully. Furthermore, it must not contain molasses, which would harm the hamster.

It might be noted that many hamsters tend to carry away food from their food source (by carrying it in their cheek pouches) and hoard it away in a cache hidden somewhere inside their container. These caches, when combined with hamster urine or a leaky water source and poor airflow, can grow mold or start to rot, creating a hazardous environment for the hamster. To keep this from happening, clean hamster cages frequently.

There are also many foods that a hamster should never eat. This includes all kinds of human sweets, such as chocolate or candy, which are unhealthy and even dangerous. Furthermore, poisonous plants (also check indoor plants if the hamster is taken outside its housing) constitute a considerable danger. The various unhealthy and chemically treated products usually consumed by humans can cause problems. Salty foods should not be offered to hamsters. Other foods such as garlic, onions, pickles, raw kidney beans, and raw potatoes should also be avoided.

Campbells dwarf hamsters are especially sensitive to Diabetes mellitus, and other dwarf hamster species may be somewhat sensitive too. Diabetes mellitus in hamsters is often caused by intake of simple sugar. Therefore it is essential to avoid hamster food and snacks containing molasses, honey, sugar, fruit sugar or other sweet stuff. Intake of sweet fruit should be limited to small snacks. Even with golden hamsters it may be useful to follow these guideline in order to avoid overweight and digestion disturbances.

Sex and longevity

Hamsters typically live no more than two to three years in captivity, less than that in the wild. Because of their short life expectancy, hamsters mature quickly and can begin reproducing at a young age (four weeks). However, this is unhealthy for the female in the case of the Syrian hamster. Dwarf hamsters start much earlier than the Syrians. Left to their own devices, hamsters will produce several litters a year with several babies in each litter. Male and female hamsters are therefore usually kept in separate enclosures to prevent the addition of unwanted offspring.

After a female hamster mates, there is a gestation period of 16-18 days before it will give birth. If the mother-to-be is a dwarf hamster, she will drive the male away from the nest when the birth is about to occur. This is normal, and he will be permitted to come back once the pups are a little older. In the case of Syrian hamsters, the male will not take part in raising the young as they are kept separately. However, dwarf males will often assist the mother, bringing her food, sitting on the nest to keep it warm, and tracking down wayward young. The average litter for Syrians is about 7, but can be as great as 24, which is the maximum number of pups that can be contained in the womb. Dwarves tend to have 2 to 8 in a litter. The mother hamster will gather all the pups into a nest which it built. They will be hairless, have closed eyes, nurse from their mother, and move very little. After about a week, they will begin to wander from the nest and eat solid food. After a total of three weeks, the pups will be weaned and can leave the nest for good. They should be separated by sex at this time. One thing to watch out for while hamsters are mating, is that the female doesn't attack the male. Quite often the female hamster will hurt the male hamster, so they must be separated. Hamster owners must make sure that all food has been removed form the cage so the two do not fight over it. There is a possibility that the hamsters will mate even after the female viciously attacks the male. During mating it is the female who is the aggressor. The male does not usually fight back.

When seen from above, a sexually mature female hamster has a trim tail line; a male's tail line bulges on both sides. Male hamsters typically have very large testes in relation to their body size.

Classification of hamsters

Taxonomists currently disagree about the most appropriate placement of the subfamily Cricetinae within the superfamily Muroidea. Some place it in a family Cricetidae that also includes voles, lemmings, and New World rats and mice; others group all these into a large family called Muridae.

• Subfamily Cricetinae
  • Genus Mesocricetus - Golden hamsters
    • Syrian Hamster (Mesocricetus auratus); also called the Teddy Bear hamster.
    • Turkish Hamster (Mesocricetus brandti); also called Brandt's Hamster, Azerbajaini Hamster
    • Georgian Hamster (Mesocricetus raddei); also Ciscaucasian Hamster
    • Romanian Hamster (Mesocricetus newtoni)
  • Genus Phodopus - Dwarf hamsters
    • Dwarf Winter White Russian Hamster (Phodopus sungorus)
    • Campbell's Dwarf Russian Hamster (Phodopus campbelli)
    • Roborovski Hamster (Phodopus roborovskii); sometimes known as the Mongolian Hamster, although this causes confusion with Cricetulus curtatus
  • Genus Cricetus
    • European Hamster (Cricetus cricetus); also called the Common Hamster or Black-bellied Field Hamster
  • Genus Cricetulus
    • Ladak Hamster (Cricetulus alticola)
    • Striped Dwarf Hamster (Cricetulus barabensis including "C. griseus", "C. pseudogriseus", and "C. obscurus"); also Chinese striped hamster, Chinese hamster
    • Tibetan Hamster (Cricetulus kamensis)
    • Long-tailed Hamster (Cricetulus longicaudatus)
    • Armenian Hamster (Cricetulus migratorius); also called the Migratory Grey Hamster, Grey Hamster, Grey Dwarf Hamster, or Migratory Hamster
    • Sokolov's Hamster (Cricetulus sokolovi)
  • Genus Allocricetulus
    • Mongolian Hamster (Allocricetulus curtatus)
    • Kazakh Hamster (Allocricetulus eversmanni); also Eversmann's Hamster
  • Genus Cansumys
    • Gansu Hamster (Cansumys canus)
  • Genus Tscherskia
    • Greater Long-tailed Hamster (Tscherskia triton); also Korean Hamster

Relationships among hamsters

Neumann et al. (2006) conducted a molecular phylogenetic analysis of 12 of the above 17 species of hamster using DNA sequence from three genes: 12S rRNA, cytochrome b, and von Willebrand factor. They uncovered the following relationships:

Phodopus group

The genus Phodopus was found to represent the earliest split among hamsters. Their analysis included both species. The results of another study (Lebedev et al., 2003) may suggest that Cricetulus kamensis (and presumably the related C. alticola) might belong to either this Phodopus group or hold a similar basal position.

Mesocricetus group

The genus Mesocricetus also formed a monophyletic clade. Their analysis included all four species, with M. auratus and M. raddei forming one subclade and M. brandti and M. newtoni another.

Remaining genera

The remaining genera of hamsters formed a third major clade. Two of the three sampled species within Cricetulus represent the earliest split. This clade contains Cricetulus barabensis (and presumably the related C. sokolovi) and Cricetulus longicaudatus.

The remaining clade contains members of Allocricetulus, Tscherskia, Cricetus, and Cricetulus migratorius. Allocricetulus and Cricetus were sister taxa. Cricetulus migratorius was their next closest relative, and Tscherskia was basal.

Similar animals

Note that there are some rodents which are sometimes called "hamsters" that are not currently classified in the hamster subfamily Cricetinae. These include the Maned Hamster or Crested Hamster, which is really the Maned Rat (Lophiomys imhausi), although not nearly as marketable under that name. Others are the mouse-like hamsters (Calomyscus spp.), and the white-tailed rat (Mystromys albicaudatus).

Hamsters in popular culture

As the hamster is generally considered a cute animal, it is often anthropomorphized when found in popular culture. Famous examples of this include the anime Hamtaro and the Hampster Dance (sic).

• Hammy Hamster is a long-running children's show in Canada.

• Hamtaro is an Anime that centers around a group of talking hamsters and their adventures.

• In the Calvin and Hobbes cartoons, the children's book Hamster Huey and the Gooey Kablooie is Calvin's favorite bedtime book.

• Ebichu is an adult-oriented Japanese cartoon (Anime) that depicts a talking hamster as a house-keeper, living with a human female.

• In the Jhonen Vasquez cartoon Invader Zim, the school hamster is called Peepi, who in one episode, is shot by Zim with a raygun increasing his size; turning him into a giant hamster.

• The character Minsc in the RPG Baldurs Gate had a hamster named Boo.

• An homage to the Baldur's Gate character, also named Boo, appears in the online comic Megatokyo.

• There is also a game Hamsterball Gold.

• Inspired by his pet, the comic performer Weird Al Yankovic wrote the marching band song called "Harvey the Wonder Hamster".

• Hamster racing and related wagering has become a small but real pastime in the UK and elsewhere.

• Carniolian hamster

• In March 1986 the British tabloid newspaper The Sun published a famous story in which it claimed that the comedian Freddie Starr had eaten a hamster. The story was untrue.

• In an episode of the BBC comedy series Fawlty Towers first broadcast in 1979, Manuel the Spanish waiter insists that a rat that he has bought as a pet is really a filigree Siberian hamster. Mayhem ensues when a public health inspector arrives at the hotel and the "hamster" escapes.[1]

• Sir Doris is an endlessly hungry pet hamster in the animated program Big Knights.

• Melvin Sneedly from the Captain Underpants book series owned a hamster named Sulu, but after Sulu spanked Melvin, George and Harold adopted Sulu.

• In the SNES videogame Earth Worm Jim, there is a level in which the main character has to cross an underwater facility riding on hamsters.

• Hamster is the nickname of Top Gear presenter Richard Hammond.

• The Golden Hamster Saga is a book series that tells the story of Freddy, a hamster that can read and write.

• A hamster named "S.P.G." is the often abused pet of Vyvyan on The Young Ones.

• Hamsters play an integral role in the TV show Codename: Kids Next Door, and are sometimes the focus of certain episodes.

• One of the insults included in Monty Python and the Holy Grail is: "Your mother was a hamster, and your father smelt of elderberries!"

References

• Lebedev, V. S., N. V. Ivanova, N. K. Pavlova, and A. B. Poltoraus. 2003. Molecular phylogeny of the Palearctic hamsters. In Proceedings of the International Conference Devoted to the 90th Anniversary of Prof. I. M. Gromov on Systematics, Phylogeny and Paleontology of Small Mammals (A. Averianov and N. Abramson eds.). St. Petersburg.
• Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. In Mammal Species of the World a Taxonomic and Geographic Reference (D. E. Wilson and D. M. Reeder eds.). Johns Hopkins University Press, Baltimore.
• Neumann, K., J. Michaux, V. Lebedev, N. Yigit, E. Colak, N. Ivanova, A. Poltoraus, A. Surov, G. Markov, S. Maak, S. Neumann, R. Gattermann. 2006. Molecular phylogeny of the Cricetinae subfamily based on the mitochondrial cytochrome b and 12S rRNA genes and the nuclear vWF gene. Molecular Phylogenetics and Evolution, in press; Available online 17 February 2006.

External links

• The Hamster Society (UK)
• Lindsay Wildlife Museum Hamster Care Page
• Hamster Rescue (UK)
• Starlight Hamstery
• Furry Critters Website (UK)