According to Formosow the stock of several burrows indicate an almost insect-based diet. Also the consumption of snails has been reported. In Tuva, the share of animal food is marginal. Flint and Golowkin determined in 1958 and 1959 that nearly 100 percent of the cheek pouches' content consisted of plant food, whereas animal food was only found in 23 percent of the hamsters' pouches at all in 1958 and 32 percent in 1959. The daily dietary intake of the Roborovski hamsters heavily depends on its body weight. Juveniles have higher intakes of food compared to their weight than adult hamsters. Based on its population structure, Wan et al. calculated an average food intake of ca. two gram plant seeds per day. They specify the functional relation between the daily food intake (N) and the body-weight (M) to be Pups, juveniles as well as adult hamsters are foraging food in their burrows. History of human contact Russian expeditioner Lt. Vsevolod Roborovski first made note of these hamsters, discovering them on an expedition in July 1894, though they were not studied scientifically for the best part of another decade, until Konstantin A. Satunin made observations in 1903. The London Zoo imported them into the UK in the 1960s, but the first Roborovski hamsters studied in Britain were imported in the 1970s from Moscow Zoo. (None of them, however, bore offspring.) Continental European countries had more success in breeding some Roborovskis, however, and those currently in the UK are descendants of a batch imported from the Netherlands in 1990. They were imported to the US in 1998, though they are now commonly found in pet shops in several countries. In South Korea, they are almost as common as the winter-white Russian dwarf hamster. Variation The Roborovski hamster is distinguished from the Djungarian hamster (Phodopus sungorus) and Campbell's dwarf hamster (Phodopus campbelli) due to its smaller size, sandy coloration of fur and its lack of a dorsal stripe. When observed from behind, the neurocranium is rounded and does not appear to be as rectangular as Phodopus campbelli and Phodopus sungorus. The cusps of the lower molars are directly opposite and not alternate, as seen in other members of the genus, and the incisive foramen of the Roborovski hamster is greater than in length and is shorter than the length of the upper tooth row, which is uncharacteristic of the other two members of the