Golden hamster

Golden hamster
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Rodentia
Suborder: Myomorpha
Superfamily: Muroidea
Family: Cricetidae
Subfamily: Cricetinae
Genus: Mesocricetus
Species: M. auratus
Binomial name
Mesocricetus auratus
Waterhouse, 1839

The golden hamster or Syrian hamster (Mesocricetus auratus) is a member of the subfamily Cricetinae, the hamsters.[2] In the wild, they are now considered vulnerable. Their natural geographical range is limited to the north of Syria and the south of Turkey, in arid habitats. Their numbers have been declining due to loss of habitat caused by agriculture and deliberate destruction by humans.[1] However, captive-breeding programs are well established, and captive-bred golden hamsters are popularly kept as pets and used as scientific research animals throughout the world.

Biology

The size of adult animals ranges from 5 to 7 in (13 to 18 cm) long, with a lifespan of two to three years.[3] Body mass is in the range of 120-125 g.[4]

Hamster filling its cheek pouches

Like most members of the subfamily, the golden hamster has expandable cheek pouches, which extend from its cheeks to its shoulders. In the wild, hamsters are larder hoarders; they use their cheek pouches to transport food to their burrows. Their name in the local Arabic dialect where they were found roughly translates to "mister saddlebags" (Arabic: أبو جراب) due to the amount of storage space in their cheek pouches.[5] If food is plentiful, the hamster stores it in large amounts.

A mother with her two young, which are less than a week old

Sexually mature female hamsters come into season (estrus) every four days. Golden hamsters have the shortest gestation period in any known placental mammal at only 16 days. Gestation has been known to last up to 21 days, but this is rare and almost always includes complications. They can produce large litters of 20 or more young, although the average litter size is between eight and 10 pups. If a mother hamster is inexperienced or feels threatened, she may abandon or eat her pups. A female hamster enters estrus almost immediately after giving birth, and can become pregnant despite already having a litter. This act puts stress on the mother's body and often results in very weak and undernourished young.

Hamsters are very territorial and intolerant of each other, with attacks against each other being ubiquitous. Exceptions do occur, usually when a female and male come together when the female is in heat, but even so, the female may attack the male after mating. Even brothers and sisters, once mature, may attack one another. In captivity, babies are separated from their mother and by gender after four weeks, as they sexually mature at four to five weeks old. Same-sex groups of siblings can stay with each other until they are about eight weeks old, at which point they will begin to become territorial and will fight with one another, sometimes to the death. Infanticide is not uncommon among female golden hamsters. In captivity, they may kill and eat healthy young as a result of the pups interacting with humans, for any foreign scent is treated as a threat. Females also eat their dead young in the wild to prevent predators detecting them.

Golden hamsters mark their burrows with secretions from special scent glands on their hips. Male hamsters in particular lick their bodies near the glands, creating damp spots on the fur, then drag their sides along objects to mark their territory. Females also use bodily secretions and feces.

Discovery

Golden hamster

Golden hamsters originate from Syria and were first described and officially named in 1839 by British zoologist George Robert Waterhouse. Waterhouse's original specimen was a female hamster; he named it Cricetus auratus or the "golden hamster". The skin of the specimen is kept at the Natural History Museum in London.[6]

In 1930, Israel Aharoni, a zoologist and professor at the Hebrew University of Jerusalem, captured a mother hamster and her litter of pups in Aleppo, Syria. The hamsters were bred in Jerusalem as laboratory animals. Some escaped from the cage through a hole in the floor, and most of the wild golden hamsters in Israel today are believed to be descended from this litter.[6]

Descendants of the captive hamsters were shipped to Britain in 1931, where they came under the care of the Wellcome Bureau of Scientific Research. They bred well and two more pairs were given to the Zoological Society of London in 1932. The descendants of these were passed on to private breeders in 1937. A separate stock of hamsters was exported from Syria to the USA in 1971, but apparently none of today's North American pets is descended from these (at least in the female line), because recent mitochondrial DNA studies have established that all domestic golden hamsters are descended from one female – probably the one captured in 1930 in Syria.[6]

Since the species was named, the genus Cricetus has been subdivided and this species (together with several others) was separated into the genus Mesocricetus, leading to the currently accepted scientific name for the golden hamster of Mesocricetus auratus.[6]

Survival in the wild

Following Professor Aharoni's collection in 1930, only infrequent sightings and captures were reported in the wild. Finally, to confirm the current existence of the wild golden hamster in northern Syria and southern Turkey, two expeditions were carried out during September 1997 and March 1999. The researchers found and mapped 30 burrows. None of the inhabited burrows contained more than one adult. The team caught six females and seven males. One female was pregnant and gave birth to six pups. All these 19 caught golden hamsters, together with three wild individuals from the University of Aleppo, were shipped to Germany to form a new breeding stock.[7]

Observations of females in this wild population have revealed, contrary to laboratory populations, activity patterns are crepuscular rather than nocturnal, possibly to avoid nocturnal predators such as owls.[8] Owls, however, have also evolved to hunt at dusk and dawn, and even during the day on rare occasions, so the predator avoidance advantage may not apply to owls in particular. Another theory is that hamsters, which are extremely sensitive to temperature fluctuations, may be crepuscular to avoid the extreme temperatures of full daylight and night time temperatures.[9]

Syrian hamsters in captivity run two to five miles per 24-hour period and can store up to a ton of food in a lifetime. They keep their food carefully separated from their urination and nesting areas. Very old hamsters with weak teeth break this "rule" by soaking hard seeds and nuts with urine to soften it for eating. Hamsters are extraordinary housekeepers and often sort through their hoards to clean and get rid of molding or rotting food. They gather food in the wild by foraging and carrying it home in their cheek pouches, which they empty by pushing it out through their open mouths, from back to front, with their paws, until it is empty. If a lot of food is available to carry, they may stuff the pouches so full that they cannot even close their mouths. Although these observations refer to studies using captive hamsters, they shine some light on the hamsters' natural behaviors in the wild.[9]

Golden hamsters in scientific research

Gait of an individual lab-bred hamster

Hamsters are widely used in research. For example, according to the Canadian Council for Animal Care, a total of 6,402 hamsters were used for research in 2006 in Canada, making them the fourth-most popular rodent after mice (910,540), rats (331,560), and gerbils (37,246).[10]

In captivity, golden hamsters follow well-defined daily routines of running in their hamster wheel, which has made them popular subjects in circadian rhythms research. For example, Martin Ralph, Michael Menaker, and colleagues used this behavior to provide definitive evidence that the suprachiasmatic nucleus in the brain is the source of mammalian circadian rhythms.[11]

Hamsters have a number of fixed action patterns that are readily observed, including scent-marking and body grooming, which is of interest in the study of animal behavior.

By far, though, the greatest use of hamsters is in biomedical research. Among other things, because captive golden hamsters are highly inbred (being descended from only a few captured individuals), they have a high incidence of a genetic heart condition causing dilated cardiomyopathy. Several inbred strains of hamsters have been developed as animal models for human forms of dilated cardiomyopathy. The gene responsible for hamster cardiomyopathy in a widely studied inbred hamster strain, BIO14.6, has been identified as being delta-sarcoglycan.[12] Pet hamsters are also potentially prone to cardiomyopathy, which is a not infrequent cause of unexpected sudden death in adolescent or young adult hamsters.

Syrian hamsters are also widely used in research into alcoholism, by virtue of their large livers, and ability to metabolise high doses.[13]

Scientific studies of animal welfare concerning captive golden hamsters have shown they prefer to use running wheels of large diameters (35 cm diameter was preferred over 23 cm,[14] and 23  cm over 17.5  cm,[15]), and that they prefer bedding material which allows them to build nests, if nesting material is not already available.[16] They prefer lived-in bedding (up to two weeks old - longer durations were not tested) over new bedding, suggesting they may prefer bedding changes at two-week intervals rather than weekly or daily.[17] They also prefer opaque tubes closed at one end, 15 cm in diameter, to use as shelter in which to nest and sleep.[18]

The golden hamster can contract contagious reticulum cell sarcoma[19] which can be transmitted from one golden hamster to another by means of the bite of the mosquito Aedes aegypti.[20]

Hamsters as pets

A Syrian hamster listening

Golden hamsters are popular as house pets due to their docile, inquisitive nature, cuteness, and small size. However, these animals have some special requirements that must be met for them to be healthy. Although some people think of them as a pet for young children, the American Society for the Prevention of Cruelty to Animals recommends hamsters as pets only for people 10 years or older and the child should be supervised by an adult. Cages should be a suitable size, safe, comfortable, and interesting. If a hamster is consistently chewing, then it needs more stimulation or a larger cage. A variety of toys, either shop-bought or home-made can help to keep them entertained. Cardboard tubes and boxes are stimulating. Golden hamsters are energetic and need space to exercise.[21] A running wheel is a common type of environmental enrichment.

Most hamsters in American and British pet stores are golden hamsters. Originally, golden hamsters occurred in just one color — the mixture of brown, black, and gold which gave them their "golden" name, but they have since developed a variety of color and pattern mutations, including cream, white, blonde, cinnamon, tortoiseshell, black, three different shades of gray, dominant spot, banded, and dilute.

Long-haired or "Angora" hamsters

A male "teddy bear" hamster

"Angora" hamsters are commonly known as "teddy bear" hamsters. Females have short, velvety fur in many different colors. Male teddy bear hamsters usually have much longer fur than the female variety, culminating in a "skirt" of longer fur around their backsides.

See also

References

  1. 1 2 Yigit, N.; Kryštufek, B. (2008). "Mesocricetus auratus". IUCN Red List of Threatened Species. Version 2014.2. International Union for Conservation of Nature. Retrieved 28 August 2014.
  2. ↑ Musser, G.G.; Carleton, M.D. (2005). "Superfamily Muroidea". In Wilson, D.E.; Reeder, D.M. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 1044. ISBN 978-0-8018-8221-0. OCLC 62265494.
  3. ↑ Hamsters For Dummies. Hoboken: Wiley Publishing. 2007. p. 8.
  4. ↑ Champagne, A. (2006-05-19). "Mesocricetus auratus: golden hamster". Animal Diversity Web. University of Michigan. Retrieved 2015-04-20.
  5. ↑ Dunn, Rob (24 March 2011). "The Untold Story of the Hamster, a.k.a Mr. Saddlebags". Smithsonianmag.com.
  6. 1 2 3 Henwood, Chris (2001). "The Discovery of the Syrian (Golden) Hamster, Mesocricetus auratus". The Journal of the British Hamster Association (39).
  7. ↑ Gattermann, R.; Fritzsche, P.; Neumann, K.; Al-Hussein, I.; Kayser, A.; Abiad, M.; Yakti, R. (2001). "Notes on the current distribution and the ecology of wild golden hamsters (Mesocricetus auratus)". Journal of Zoology (Cambridge University Press) 254 (3): 359–365. doi:10.1017/S0952836901000851.
  8. ↑ Gattermann, R.; Johnston, R. E.; Yigit, N; Fritzsche, P; Larimer, S; Ozkurt, S; Neumann, K; Song, Z; et al. (2008). "Golden hamsters are nocturnal in captivity but diurnal in nature". Biology Letters 4 (3): 253–255. doi:10.1098/rsbl.2008.0066. PMC 2610053. PMID 18397863.
  9. 1 2 Stacey OBrien; field notes
  10. ↑ CCAC – Facts and Figures
  11. ↑ Ralph, M.R., et al., Transplanted Suprachiasmatic Nucleus Determines Circadian Period. Science, 1990. 247(4945): p. 975-978.
  12. ↑ Nigro, V.; Okazaki, Y; Belsito, A; Piluso, G; Matsuda, Y; Politano, L; Nigro, G; Ventura, C; et al. (1997). "Identification of the Syrian hamster cardiomyopathy gene". Human Molecular Genetics 6 (4): 601–607. doi:10.1093/hmg/6.4.601. PMID 9097966.
  13. ↑ Alcohol: an ancient medicine New York Times Nathalie Angier 11 September 2007
  14. ↑ Reebs, S. G.; St-Onge, P (2005). "Running wheel choice by Syrian hamsters". Laboratory Animals 39 (4): 442–451. doi:10.1258/002367705774286493. PMID 16197712.
  15. ↑ Mrosovsky, N.; Salmon, P.A.; Vrang, N. (1998). "Revolutionary science: an improved running wheel for hamsters". Chronobiology International 15 (2): 147–158. doi:10.3109/07420529808998679. PMID 9562919.
  16. ↑ Lanteigne, M.; Reebs, SG (2006). "Preference for bedding material in Syrian hamsters". Laboratory Animals 40 (4): 410–418. doi:10.1258/002367706778476424. PMID 17018212.
  17. ↑ Veillette, M.; Reebs, S.G. (2010). "Preference of Syrian hamsters to nest in old versus new bedding". Applied Animal Behaviour Science 125 (3–4): 189–194. doi:10.1016/j.applanim.2010.04.001.
  18. ↑ Veillette, M.; Reebs, S.G. (2011). "Shelter choice by Syrian hamsters (Mesocricetus auratus) in the laboratory". Animal Welfare 20: 603–611.
  19. ↑ Copper, H. L.; MacKay, C. M.; Banfield, W. G. (1 October 1964). "Chromosome Studies of a Contagious Reticulum Cell Sarcoma of the Syrian Hamster". Journal of the National Cancer Institute 33: 691–706. PMID 14220251.
  20. ↑ Banfield, William G.; Woke, P. A.; MacKay, C. M.; Cooper, H. L. (28 May 1965). "Mosquito Transmission of a Reticulum Cell Sarcoma of Hamsters". Science 148 (3674): 1239–1240. doi:10.1126/science.148.3674.1239. PMID 14280009.
  21. ↑ Alderton, D. (2002). Hamster: A practical guide to caring for your hamster. London: Harper Collins Publishers.

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