Fat sand rat (Psammomys obesus)

French: Rat De Sable
GenusPsammomys (1)
SizeTotal length: 25.1 - 35.6 cm (2)
Tail length: 10 - 15.7 cm (2)
Weight32 - 43 g (2)

Classified as Least Concern (LC) on the IUCN Red List (1).

The appropriately named fat sand rat is a heavy-built, gerbil-like rodent, native to desert regions (3). It typically has dark reddish-brown fur speckled with black on its upperparts and lighter fur on the underside, although the exact colour of the fur may vary depending on the environment (2). The sturdy limbs bear blackish claws and the short, stout tail has a noticeable black tip (2). The small, rounded ears are covered with dense whitish to yellowish hair (2). This species apparently communicates through high-pitched squeaks and by drumming its feet (3).

Found in North Africa and the Middle East, the fat sand rat has been recorded in Mauritania, Morocco, Algeria, Tunisia, Libya, Egypt, Sudan, Israel, Jordan, Saudi Arabia and Syria (1). 

The fat sand rat inhabits deserts, semi-desert, rocky habitats and grasslands, provided that succulent shrubs, on which the rat feeds, are present (1).

The fat sand rat lives in colonies in complex burrow systems, which have separate areas for nesting and the storage of food (3). 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 (granivorous) (4). Its diet consists of leaves and stems 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 (5). 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 (Atriplex halimus), which are up to 90 percent water (4). However, this water has an extremely high concentration of salt, and so the fat sand rat must produce very salty, concentrated urine in order to expel the salt from its body (4) (5).

Breeding may take place all year round, although a peak of breeding activity has been reported between September and May (6). The female gives birth to a litter containing two to ten pups after a gestation period of 23 to 25 days (7). This species reportedly has a lifespan of around three years (7)

There are no major threats to this species, although it is persecuted as a pest in some areas (1).

There are no specific conservation actions in place for the fat sand rat, although it does inhabit a number of protected areas throughout its range (1).

Checked (24/08/10) by Dr Francis Gilbert, Associate Professor, University of Nottingham.

  1. IUCN Red List (April, 2010)
  2. Hoath, R. (2009) A Field Guide to the Mammals of Egypt. The American University in Cairo Press, Cairo.
  3. Qumsiyeh, M.B. (1996) Mammals of the Holy Land. Texas Tech University Press, Texas.
  4. Feldhamer, G.A., Drickamer, L.C., Vessey, S.H., Merritt, J.F. and Krajewski, C. (2007) Mammology: Adaptation, Diversity, and Ecology. The Johns Hopkins University Press, Baltimore, Maryland.
  5. Degan, A.A., Kam, M. and Nagy, K.A. (1991) Seasonal water influx and energy expenditure of free-living sand rats. Journal of Mammals, 72: 421-429.
  6. Osborn, D.J. and Helmy, I. (1980) The contemporary land mammals of Egypt (including Sinai). Fieldiana Zoology, 5: 1-579.
  7. Sharp, P.E. and La Regina, M.C. (1998) The Laboratory Rat. CRC Press, Boca Raton, Florida.