Golden hamster

The golden hamster or Syrian hamster (Mesocricetus auratus) is a rodent belonging to the hamster subfamily, Cricetinae. Their natural geographical range is in an arid region of northern Syria and southern Turkey. Their numbers have been declining in the wild due to a loss of habitat from agriculture and deliberate elimination by humans. Thus, wild golden hamsters are now considered endangered by the International Union for Conservation of Nature. However, captive breeding programs are well established, and captive-bred golden hamsters are often kept as small house pets. They are also used as scientific research animals. Syrian hamsters kept as pets are sensitive to their housing condition...

Syria

Under typical laboratory conditions, Syrian hamsters apparently do not exhibit food-anticipatory activity (FAA) – that is, when on a restricted feeding schedule where food is given at specific times of day, they do not demonstrate increased wheel-running prior to feeding time. This is in contrast to most other rodents. However, standard laboratory conditions include bright light during the daytime; when subjected to a light cycle simulating dawn and dusk with darkness during the day, they do exhibit the behavior. The arcuate, ventromedial and dorsomedial nuclei are all involved in FAA in Syrian hamsters. In a study of their food-hoarding behavior, Syrian hamsters were given access to food for only limited periods of time. It was expected that they would consume more in each sitting than usual; instead, they exhibited hoarding behavior, taking the food during the given time period and then continuously eating it the rest of the time as though they were on a free-fed schedule. This allowed them to maintain typical body weight, and mimic the adaptive feeding strategies they may use in their natural habitats. Females have shown signs of anorexia and anxiety when separated from social interactions. Social separation of hamsters has a bias toward females, thus providing a model for the differences between sexes when experiencing anorexia and anxiety in their adulthood.

A solitary species, Syrian hamsters are very territorial and intolerant of each other; attacks against each other are commonplace. Exceptions do occur, usually when a female and male meet when the female is in heat, but even so, the female may attack the male after mating. In captivity, babies are separated from their mother and by sex 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 become territorial and 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, as any foreign scent is treated as a threat. Females also eat their dead young in the wild. Golden hamsters mark their burrows with secretions from special scent glands on their hips called flank glands. 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.

longest observed 3.9 years.

The female Syrian hamster has anatomic features that are unique from other animals. They mature between 8–10 weeks of age and have a 4-day estrous cycle. Female Syrian hamsters show mate preference before they engage in copulation by displaying vaginal marking, known to solicit males. She often chooses to mate with an alpha male, who will flank mark (a scent-marking behavior associated with aggression and competition) more frequently than any subordinate males present. Male offspring are at higher risk than female offspring of enduring effects from maternal social stress. In the presence of a dominant pregnant female, subordinate pregnant female hamsters have the ability to reabsorb or spontaneously abort their young (most often males) in utero. The subordinate females produce smaller litters overall, and any male offspring they do produce will be smaller in size than those that were produced by the dominant female. After a mother hamster gives birth, normal behavior from the mother in the postpartum period can include establishing a maternal bond with the babies, the mother being aggressive to protect the babies, or infanticide in rodents of the mother to her young. The male Syrian hamster has a requirement for both hormonal cues and chemosensory cues in order to engage in copulation. Further, the integration of steroid cues (i.e. testosterone) and odour cues (relayed through the olfactory bulb) is crucial for mating. It has also been shown that within the medial amygdala, the anterior and posterior regions work together to process the stimuli (odors), showing that their mating behavior relies on the main olfactory system's communication to nuclei in the amygdala regions. Their behavior has demonstrated this phenomenon, as they are attracted to the odor of female hamster's vaginal discharge. Males have even demonstrated mounting behavior on other males who are scented with the female vaginal discharge. When one male and two females are placed in the same environment, the male is likely to engage in copulation with both females as it provides him with a reproductive advantage. In all observed scenarios where there was one male and two females, he did not demonstrate preference for either female and engaged in copulation with both the females present. There has been no reproductive disadvantage to the female when another female is present, other than decreased stimulation as compared to a one-male one-female situation. The practice of selective breeding of golden hamsters requires an understanding of their care, knowledge about breed variations, a plan for selective breeding, scheduling of the female body cycle, and the ability to manage a colony of hamsters.

Adult golden hamsters can reach around 7.1 in (18 cm) long. Females are usually larger than males, with a body mass of around 100–150 grams (3.5–5.3 oz) and lifespan of 1.5–2 years. Syrian hamsters from private breeders can be in the range of 175–225 grams (6.2–7.9 oz). 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. Sexually mature female hamsters come into heat (estrus) every four days. Golden hamsters and other species in the genus Mesocricetus have the shortest gestation period in any known placental mammal at around 16 days. Gestation has been known to last up to 21 days, but this is rare and almost always results in 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.

Golden hamsters originate from Syria and were first described by scientists in the 1797 second edition of The Natural History of Aleppo, a book written and edited by two Scottish physicians living in Syria. The Syrian hamster was then recognized as a distinct species in 1839 by British zoologist George Robert Waterhouse, who named it Cricetus auratus or the "golden hamster". The skin of the holotype specimen is kept at the Natural History Museum in London. 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. Descendants of the captive hamsters were shipped to Britain in 1931, where they came under the care of the Wellcome Bureau of Scientific Research. These bred 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. In 1946, Albert Marsh began the first commercial hamster breeding business, Gulf Hamstery, to promote the Syrian hamster as pets and laboratory animals. A separate stock of hamsters was exported from Syria to the United States in 1971, but mitochondrial DNA studies have established that all domestic golden hamsters are descended from one female – likely the one captured in 1930 in Syria. 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. The sleep cycle of the Syrian hamster lasts approximately 10–12 minutes. In the laboratory, Syrian hamsters are observed to be nocturnal and in their natural circadian rhythm they wake and sleep on a consistent schedule. In all kinds of laboratory settings hamsters do 80% of their routine activities at night. They are most active early in the night, and become less active as the night passes. The sleeping behavior of wild hamsters is not well understood; a study found that in the wild, Syrian hamsters are active almost exclusively during the daytime, contrary to observations in the laboratory.