Whilst searching for Fat Sand Rats I came across a couple digging a new entrance to their burrow and feeding on nearby shrubs. Presumably the two Fat Sand Rats together indicate a male and female as although they live in near proximity to each other they do not like each other’s company. Their burrow systems are up to 0.5 metres deep but with many entrances, which have separate areas for nesting and the storage of food. Compared to other members of the Muridae family (the mice, rats and gerbils), the Fat Sand Rat is rather unusual as it is diurnal and wholly herbivorous; most other species in this family are nocturnal and feed primarily on grains. During the winter months, the peak activity occurs around midday when they come out of their burrows to sunbath, flattening their body and absorbing heat by outstretching their legs. Throughout the summer months, activity usually takes place in the early morning and afternoon and in areas where the night temperature is warm enough, they may also exhibit some activity during the night-time hours. Fat sand rats usually sit up on their hind limbs and observe surroundings to detect the threat. When alarmed, they flee to their burrows. Its diet consists of leaves and stems that they hold with one 'hand' and often wipe before eating and, unlike high-energy seeds, these foods are rather low in energy. As a result, it has to eat around 80 percent of its body weight in food each day to obtain sufficient energy. The fat sand rat does not need to drink water, a useful adaptation in arid habitats, and instead can get all the water it needs by feeding on the leaves of the saltbush which are up to 90 percent water and licking morning dew. However, this water has an extremely high concentration of salt, and so the fat sand rat must produce very salty, concentrated urine, up to 18 times as concentrated as that of humans, in order to expel the salt from its body.
