**Guest post from Felicia M.**
Campbell’s Dwarf Hamster Phodopus campbelli was once considered to be a subspecies of the Winter White Dwarf Hamster Phodopus sungorus, but they are now considered to be two separate species. The two species are separated by the Altai Mountain range in Siberia with the Winter White Dwarf Hamsters north of the mountain range in Kazakhstan and Siberia, and the Campbell’s Dwarf Hamsters south of the mountain range in Mongolia. It is very difficult to tell the difference between a Winter White and a Campbell’s Dwarf Hamster, and until recently the two were often hybridized unknowingly by novice breeders.
The Campbell’s Dwarf Hamster is more commonly seen for sale in pet shops, but the Winter White is gaining popularity. Both species in the agouti (natural) coloration are brownish grey in color with a black dorsal stripe running from head to tail and a cream white belly. The easiest way to tell the difference between the two species is to look at the sides of the hamster where the body color meets the white belly. In the Campbell’s, there is usually a cream/beige coloration between the transition of the brown/grey body color to the white belly. The Winter White, however, has darker lines contrasting between the brown/grey body color and the white belly. The Winter White usually has a thicker, darker black dorsal stripe.
The Winter White Dwarf Hamster has a more compact, rounder body with a shorter face to conserve body heat in the cold. The Campbell’s Dwarf Hamster has a more lean, sleek body and mouse-like face with larger ears. These characteristics may only be noticeable to the trained eye, even when individuals of the two species are right next to one another.
It is also notable that the Winter White hamster, when exposed to shorter photo-periods, will gradually turn all white except for the black dorsal stripe. Some captive color variations of the Campbell’s are white in color, but the black dorsal stripe is missing. So if you find a Dwarf Hamster in a local pet shop that is totally white, it is likely a Campbell’s. If you find a white Dwarf Hamster with a black dorsal stripe, it is either a Winter White in its winter coat, or the Pearl color variation of the Winter White Dwarf Hamster, which keeps its winter coat all year round.
Hybridizing Dwarf Hamsters is not recommended because Campbell’s Dwarf Hamsters may pass on hereditary problems like diabetes or some rare lethal genes. Hybrids are often infertile and sometimes suffer from defects like tilted heads or missing limbs. Although the two species are typically the same size, the slightly differing body shape can cause a female and her hybrid young to die in labor. If you are thinking of adopting a hamster however, there is no reason that a Hybrid Dwarf Hamster would make a less interesting or lovable pet than a pure-bred hamster.