Campbell's dwarf hamster

Campbell's dwarf hamster== Campbell's dwarf hamster (Phodopus campbelli) is a species of hamster in the genus Phodopus. It is distinguished from the closely related Djungarian hamster as it has smaller ears and no dark fur on its crown. Campbell's dwarf hamster typically has a narrow dorsal stripe compared to the Djungarian hamster and grey fur on the stomach. It was given its common name is honour of W.C. Campbell, who collected the first type species in Mongolia on July 1, 1902. Campbell's dwarf hamster inhabits the deserts of Asia, the mountains of Tuva and the Hebei province in northeastern China.
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In the wild, the breeding season for Campbell's dwarf hamster is different, depending on the location. For example, the breeding season begins towards the middle of April in Tuva and towards the end of April in Mongolia. However, in captivity, there is no fixed breeding season and they can breed frequently throughout the year. Females are usually sexually mature at two weeks of age and the gestation period is around 20 days. Campbell's dwarf hamster is crepuscular, along with all species of Phodopus and is active throughout the year.

Biology
The size of Campbell's dwarf hamster varies depending on its location. For example, eight wild specimens examined from Mongolia showed an average head and body length of 80 millimetres (3.1 in), an average hind foot length of 13.5 millimetres (0.53 in) and an average tail length of 5 millimetres (0.20 in).[2] In captivity, they are proportionally larger as commercial pet food and fruits provide more nutrition than food found commonly in the wild.[3] The lips and cheeks have white fur and the rest of the fur around the face can be either grey or brown. A dark and narrow dorsal stripe runs along the center of the back from the nape of the neck to approximately 2.5 centimetres (0.98 in) above the tail. The surface of the hands and feet are white to ensure that the animal stays warm in colder climates in countries such as Mongolia.[4] In both the wild and captivity, Campbell's dwarf hamster marks it scent around its territory using harderian glands, skin glands located behind the ears, urine and feces for communication.[5]

Campbell's dwarf hamster is distinguished to the similar looking Djungarian hamster as it has smaller ears and no dark patch on the crown of its head.[4] [6] The dorsal stripe of Campbell's dwarf hamster is narrower, shorter and darker than that of the Djungarian hamster and the fur on the stomach of Campbell's dwarf hamster is grey, but it is white on the Djungarian hamster.[2] Campbell's dwarf hamster does not turn white in the winter and has a grey tint to its fur. It has a smaller interorbital breadth but has a larger auditory bulla.[2] [6] Campbell's dwarf hamster is much less tolerant to lower temperatures than the Djungarian hamster. The lowest tolerated temperature from a laboratory experiment showed that Campbell's dwarf hamster can resist temperatures as low as −31.8 °C (−25.2 °F), where the Djungarian hamster can withstand temperatures as low as −44.7 °C (−48.5 °F) .[7]

Campbell's dwarf hamster has cheek pouches, which are an extension of the mouth.[8] Food is transferred into these pouches through the diastema. The inside of the pouch contains a large number of folds of dermal papillae. When the pouch is full, it extends and becomes part of the structure of the skin.[9] By eleven days of age, the cheek pouches are fully grown and can carry objects up to the size of a sunflower seed.[10] When the cheek pouches become full, they extend back to the shoulder blades, which restrict movement.[8]

Habitat
Campbell's dwarf hamster inhabits burrows in the steppes and semi deserts of central Asia, the Altai mountains, autonomous areas of Tuva and the Hebei province in northeastern China.[8] The burrow can contain four to six horizontal and vertical tunnels. The tunnel leading to the nesting area can be as deep as 1 metre (3 ft 3 in) below the ground, but are usually 20–30 centimetres (7.9–12 in) deep.[11] <sup class="reference" id="cite_ref-11">[12] The burrows are lined with either dry grass or sheep's wool.<sup class="reference" id="cite_ref-Flint_10-1">[11] <sup class="reference" id="cite_ref-Yudin_12-0">[13] They may sometimes share burrows with Daurian pikas, but only in the steppes and semi deserts of northern Manchuria.<sup class="reference" id="cite_ref-Loukashkin_13-0">[14] In parts of Mongolia, the hamsters may also share burrows with species of Meriones to save them from digging their own.<sup class="reference" id="cite_ref-Allen_1-3">[2] <sup class="reference" id="cite_ref-Thomas_1908_14-0">[15] In Tuva, Campbell's dwarf hamster has been found living with other hamsters such as the Chinese striped hamster, the roborovski hamster and the long-tailed dwarf hamster. The diets of the three types of hamsters are different to avoid fighting over the same type of food.<sup class="reference" id="cite_ref-Golovkin_15-0">[16]

Campbell's dwarf hamster may also live near areas of human civilisation. In Mongolia, they may be found yurts during the winter to keep warm as they do not have thermoregulation like the Djungarian hamster.<sup class="reference" id="cite_ref-Flint_10-2">[11] Campbell's dwarf hamster has five main predators: the Eurasian eagle owl, the steppe eagle, the corsac fox, the common kestrel and the saker falcon.<sup class="reference" id="cite_ref-Diversity_16-0">[17] <sup class="reference" id="cite_ref-Brom_17-0">[18] <sup class="reference" id="cite_ref-Lipajev_18-0">[19] <sup class="reference" id="cite_ref-19">[20] In all distribution areas, there are more females than males. This is because males are at higher risk to predators as they cannot move as quickly.<sup class="reference" id="cite_ref-Meyer_20-0">[21] In a laboratory experiment, the average life span for a male Campbell's dwarf hamster in captivity was 278 days and the average life span for a female was 356 days.<sup class="reference" id="cite_ref-Herberg_21-0">[22] In a different experiment, hamsters kept in captivity born in the summer lived for an average of 2–2.5 years.<sup class="reference" id="cite_ref-Hamann_22-0">[23]

Breeding
Breeding Campbell's dwarf hamsters is much simpler than breeding Syrian hamsters as they will live together in mixed sex pairs or groups and breed naturally. Pairs or groups are best established at a young age as introducing older hamsters can often result in fighting. Males will naturally mate with the females if kept together and when in season the female will allow the male to mount her. He will thrust a few times before dismounting and washing himself and then often will remount and mate again. The male will usually mate with the female several times. Not all unproven males will get a female pregnant after the first mating and some males may need to mate several times before a successful pregnancy occurs. The actual mating may not always be observed.

The gestation period of Campbell's dwarf hamsters is 18–21 days and if mating was observed then the time of the expected arrival of the litter can be roughly calculated. If mating was not observed then it is often not possible to know tell when the litter is expected. Many females do not appear pregnant until a couple of days before the birth but an increased aggressiveness of the female towards her mate, colony hamsters or humans is often an indication of pregnancy. The female will often banish the male or other hamsters from the nest a couple of days before pregnancy and/or after the birth. Therefore as soon as it is noticed the female is pregnant, it is best to clean the cage.

Females usually give birth during the evening, night or early morning but sometimes give birth during the day. The female is active right up to the moment of birth. Before giving birth to each baby, she tightens her abdominal muscles two or three times, then sits up and crouches over as she gives birth to a single baby within a couple of minutes. A placenta, which looks like a small red blood sac, may be released after the birth of each baby and this is normally eaten by the mother as it is a good source of protein. Babies are born at approximately 10-minute intervals and the mother may be active between each birth. Therefore babies may be born around the cage but the mother will usually collect them all up and place them in the nest when birthing is complete. After the female has given birth, there are often spots of blood on the bedding or around the cage. This is caused by the passing of the placentas and is normal and nothing to be alarmed about. Severe bleeding from the female, though, should be cause for alarm. The pups are born naked, blind and deaf, weighing only 3 grams. If the hamsters are to be dark-eyed, the eyes can be seen under the skin but if they are to be red-eyed, the eyes cannot be seen at birth. They are born with teeth which allow them to suckle. Their skin is transparent and, when they are fed, milk can even be seen in the stomach.

A lactating Campbell's dwarf hamster will wean its litter slowly. Weaning is usually completed by the mother when her pups reach 21 to 25 days of age, but she may start bringing solid food to her litter as early as seven to ten days after birth. Young hamsters that are provided a widely varied diet early in life are less likely to suffer digestive problems as they mature.

Social aspects
Unlike other hamster species, especially the Syrian hamsters, the male may play an active role in birth and rearing. He may assist the female in pulling pups from the birth canal, cleaning them, and ensuring the new mother has enough to eat. He may also guard them while the female is away from the nest. Since the pair is likely to mate again quickly, the male should be separated from the female before birth unless more pups are desired and the female is fit enough for a repeat pregnancy.

Like other hamsters, Campbell's dwarf hamster will eat its young in certain emergency (or perceived emergency) situations, such as a protein deficiency in the mother or a threat toward the young. "Threat" may include anything from a predator (including a re-introduced father) to a habitat that the parent hamster does not believe will provide adequate size, covering, food, or water for its new inhabitants.

Unlike Syrian hamsters, Campbell's dwarf hamsters are sociable and may be kept in colonies. If the hamsters are introduced at a young age, generally younger than eight weeks, they will often happily coexist in same- or mixed-sex groups. (Note that mixed-sex groups should be avoided as hamsters are lively breeders.) Contrary to some claims, as long as the dwarf hamsters are the same breed they will hopefully live together peacefully. Some Campbell's dwarf hamsters live together for long periods of time, such as over a year, only to eventually and unexpectedly end up fighting to the point of requiring separation. Pet owners should plan for the possibility of providing additional accommodations should this occur.

Campbell's dwarf hamsters are crepuscular, meaning that they are most active at dawn and at dusk.

Diet
As an omnivore, Campbell's dwarf hamster can eat a variety of foods. A well-balanced diet for a hamster consists of 16-24% protein, 60-65% carbohydrates, and 5–7% fat, with constant access to fresh water.<sup class="reference" id="cite_ref-24">[25] In their natural habitat, dwarf hamsters feed almost exclusively on plant materials.<sup class="reference" id="cite_ref-25">[26] A pet hamster's basic dietary needs can usually be met with a quality packaged food designed specifically for hamsters. Commercially available hamster foods typically contain a mix of dry grains, nuts, and seeds that may be fortified with vitamins and minerals. An excess of any one particular seed or nut (even sunflower seeds) can lead to digestive problems, obesity and some form of nutritional deficiency.<sup class="reference" id="cite_ref-Richardson_23-1">[24]

In addition to a commercially prepared seed mix, a balanced diet for a domesticated Campbell's dwarf hamster includes a regulated variety of fresh vegetables and fruits. Fresh food, which can make up to 20% of a hamster's weekly intake, should be served dry and at room temperature. Leftovers should always be removed before spoiling. Very dark greens like kale and collards are rich in vitamins and minerals. Some wild vegetables, like yarrow, chickweed, and dandelion and raspberry leaves, are also a good source of variety that help prevent obesity.<sup class="reference" id="cite_ref-Richardson_23-2">[24] Small amounts of fruit low on the glycemic index, like apples, pears, strawberries, pitted cherries, and peaches, are also part of a well-rounded hamster diet.

In the wild, Campbell's dwarf hamster is a natural predator of burrowing worms and grubs.<sup class="reference" id="cite_ref-Richardson_23-3">[24] A hamster in captivity will relish the occasional mealworm or earthworm as a high-protein treat. Boiled egg whites and small pieces of clean, raw chicken are also acceptable sources of extra protein. Red meats, which are higher in fat, should be avoided.

The teeth of a Campbell's dwarf hamster never stop growing. Like all rodents, they must therefore gnaw regularly to keep their incisors from growing into the skin of the mouth and causing health problems. Smooth, young wood from non-toxic trees, especially apple and willow, is readily used by most dwarf hamsters. Most pet stores sell non-toxic wooden chews designed for rodents. Dog biscuits or thick, uncooked, whole wheat noodles can also be used.<sup class="reference" id="cite_ref-Richardson_23-4">[24] Teeth should be examined regularly to ensure they are not growing unchecked.

Certain food items commonly consumed by humans are toxic to hamsters and should be avoided completely. After being completely weaned at around 21 days of age, hamsters are lactose intolerant and cannot digest milk. Raw or cooked onion or garlic is very dangerous and can cause severe haemolytic anemia.<sup class="reference" id="cite_ref-26">[27] Cabbage, celery, and lettuce contain too much water for their volume and can have a dangerous laxative effect on small animals. All parts of the parsley, rhubarb, and avocado plant are toxic. Potatoes and kidney beans are also highly toxic for hamsters unless well cooked.<sup class="reference" id="cite_ref-27">[28] Although a single feeding is not typically lethal, grapes and raisins may contribute to acute renal failure.<sup class="reference" id="cite_ref-28">[29] Chocolate is most often lethal, and sticky foods like peanut butter may solidify in a hamster's cheek pouches and lead to serious infections.<sup class="reference" id="cite_ref-Richardson_23-5">[24]

Diabetes is becoming a common problem in Campbell's dwarf hamsters. Although diabetes can be an inherited disease, its emergence is heavily influenced by diet. Unless an individual hamster's ancestry is known to be free of the illness, a Campbell's dwarf hamster should never be fed any foods high in refined sugar (including yogurt drops and many mass-manufactured treats.)

Other health issues
Campbell's dwarf hamsters have extremely poor eyesight and even worse depth perception. Cataracts can be common in older hamsters. To compensate for this disability, the hamster has many scent glands, which are located on the face, behind the ears, on the cheek pouches, and on the belly near the rectum and genitals. Many pet owners observe that the hamster may groom itself when in an unfamiliar location. This is done to scent the feet, creating a trail which enables the hamster to find its way back to the burrow. This behavior may also be used to revisit a location with plentiful food. These scent trails may persist for up to eight days.

In addition to diabetes, hamsters can develop tumors (both benign and malignant), as well as glaucoma. It is possible to remove benign and malignant tumors with surgery. Glaucoma is possible to treat with eye drops containing Dorzolamide 2% or Travoprost ophthalmic solution.

The "starter pet" reputation of hamsters may cause some to dismiss the idea of veterinary care. Although many pet hamsters live their entire lives without needing to visit a veterinarian, prospective hamster owners should remember this possible expense when considering the dwarf hamster for a pet.

Colors and markings
Campbell's dwarf hamsters are born with one of four coat types: normal, satin, wavy and rex. The normal coat is short and flat. The satin coat is shiny and gives the appearance of being wet or greasy and the gene enhances the fur's color and gives it lift. The wavy coat is slightly long and wavy; the whiskers are curly when young and, although the coat moults out to a normal coat, the curly whiskers remain through adulthood. The rex coat is a soft, short coat which is curled so as to be "lifted" from the body and the whiskers are curly. The rex coat is often sparse and remains curled even in adult hamsters.

Campbell's dwarf hamsters are available in six basic colors plus many variations thereof. All are marked by a dark stripe down their back, the colour of which varies depending on the shade of their fur.

Basic colors include: Marking types include: Not all white hamsters with red/pink eyes are albino. Some are so heavily mottled or tinged with platinum that they will appear to be white. Hamsters carrying the black gene (almost half of all variations) are prone to "silvering"; in extreme cases the eventual result is an almost white hamster.
 * agouti (the normal grey brown wild color with white belly and black eyes)
 * argente (cinnamon or sandy with white belly and red eyes)
 * black eyed argente (dull brownish orange with white belly and black eyes)
 * albino (white with red eyes)
 * opal (blue grey with white belly and black eyes)
 * black (black all over with black eyes)
 * mottled (irregular white patches or spots – also called banded, spotted, or collared, if the mottling is confined to the neck)
 * ruby-eyed mottled (mottled with ruby eyes which usually appear black)
 * platinum (white hairs mingled in the coat ranging from a few to almost total coverage – sometimes incorrectly called pearl)

When two ruby-eyed mottled hamsters are bred, approximately 25% of the litter are born lacking teeth and eyes; these pups, called "eyeless toothless," generally do not live past weaning. Whether a mottled hamster has ruby eyes (which often appear black) can be difficult to determine; pointing a flashlight at the hamster in the dark may reveal the hint of ruby. Furthermore, some mottling may be too small to be noticed, or the mottling may be misidentified as platinum markings, and in these cases two ruby-eyed mottleds may accidentally be bred, resulting in the ill-fated pups.

Combining the different mutations has produced new colors, including blue, blue fawn, lilac fawn, beige, chocolate, champagne, dove, and others. Contrary to some claims, the different colors and markings of hamsters do not indicate personality differences. Most breeders attempt to predict personality by closely examining the bloodline and any neurological diseases the hamster's ancestors displayed.

Winter white/Campbell's dwarf hybrids
Of the five species of hamsters usually kept as pets, only the Winter White and Campbell's dwarf hamsters are able to interbreed and produce live offspring (hybrids). Hybrids are most often unknowingly produced through incorrect identification of the two similar species of hamsters, such as mislabeling at a pet store.

Unfortunately, the number of hybrids is increasing, leading to a rise in health problems (such as the emergence of diabetes in the Winter White and glaucoma in Campbell's dwarf hamster) and a decrease of pure species in captivity. Breeding of hybrids is discouraged, and the amount of accidental hybrid breeding and its repercussions underscores the cautions of casual breeding already expressed above.