changed the name to priority sungorus and determined the hamster as a subspecies of Campbell's dwarf hamster called Phodopus sungorus sungorus. Today winter white dwarf hamsters and Campbell's dwarf hamsters are considered separate species with the winter white officially known as Phodopus sungorus. Physical description The coat of the winter white dwarf hamster is less woolly than that of Campbell's dwarf hamster, and apart from the normal colouring, they can be coloured sapphire, sapphire pearl, or normal pearl. The head and body length of the winter white dwarf hamster is 70–90 mm, the length of the tail is 5–15 mm, and the hind legs are 11–15 mm. The body weight changes dramatically throughout the year. It is at its lowest during the winter. In males, the body weight ranges from , and in females, . In human care, they are slightly heavier. The average lifespan of the winter white dwarf hamster is one to three years in captivity, though they can live longer. In the wild, they are known to live as little as one year. In summer, the fur of the winter white hamster on the back changes from ash-grey to dark brown, or sometimes pale brown with a tint. The face changes to grey or brown, while the mouth area, the whisker area, and the ears are slightly brighter. The outer ears and the eyes have black edges. The rest of the head is dark brown or black. From the head to the tail runs a black-brown dorsal stripe. The throat, belly, tail and limbs are white. The ears are grey with a pinkish tint with scattered black hairs. The hairs on the underside are completely white. The bright coat the bottom extends to the shoulders, flanks, and hips in three arches upward. It is distinguished from the darker fur on the top of the existing black-brown hair, three curved line. Apart from the typical colouration, winter white dwarf hamsters can also be coloured pearl, sapphire, sapphire pearl, and marbled. Other colorations are available, but these are strongly suspected to appear only in hybrid crossings with Campbell's dwarf hamsters. Some of these colorations are mandarin, blue, argente, yellow blue fawn, camel, brown, cream, merle, and umbrous. In the winter, the fur is more dense. They sometimes have a grey tint on their heads. More than 10% of the hamsters kept in the first winter develop the summer coat.