Sand rat
The fat sand rat (Psammomys obesus ) is a terrestrial mammal from the gerbil subfamily that is mostly found in North Africa and the Middle East, ranging from Mauritania to the Arabian Peninsula. This species usually lives in sandy deserts, but may also be found in rocky terrain or saline marsh areas. Fat sand rats are very selective in their diet, only eating stems and leaves of plants from the family Amaranthaceae, more commonly known as the amaranth family. In captivity, fat sand rats can become obese and rapidly develop diabetes-like symptoms when fed the diet typically given to other rodents. P. obesus has an average lifespan of 14 months in the wild and 3–4 years in captivity.
The Fat sand rat is a gerbil species, endemic to desert areas, where it maintains a usual rodent diet, primarily consisting of leaves. This species was accidentally found in Egypt by the US Naval Medical Research Unit. In spite of the common name, this heavy-built rodent is not a rat. As a matter of fact, the sand rat is so called due to occurring on the sandy beaches of the Nile Delta, where it has been trapped. Meanwhile, they are called 'fat rats' because of their bulky appearance, which is more prominent in mature males. Females of this species are distinguished by leaner body as well as agility.
The Fat sand rats are distributed throughout North Africa and the Arabian Peninsula. Their African range extends eastwards from Mauritania to Egypt and Sudan. As ground-dwelling rodents, they generally occur in sandy deserts. Other suitable habitats include rocky terrain, saline-marsh areas and loess plains.
The Fat sand rats are solitary and diurnal animals. Their daytime activity largely depends on season and temperature above the ground. During the winter months, the peak activity occurs in the midday, lasting for around 5 hours. Coming out of their dwellings, these rodents spend their time sunbathing, flattening their body as well as absorbing heat by outstretching their legs. Throughout the summer months, activity usually takes place in the early morning and afternoon. During this period, the rodents try to escape scorching midday sun. In areas where the night temperature is warm enough, they may also exhibit some activity during the nighttime hours. Communication is generally made by foot drumming as well as vocalizations such as high-pitched squeaks, although the purpose of these types of communication is unknown. However, these high-pitched squeaks are believed to serve as an alert against when threatened.
The diet of these herbivores (folivores) rodents generally consists of leaves of various succulent plants. They are known to especially favor salt bushes of the Chenopodiaceae family, supplementing this diet with barley and other grains.
The reproductive system of this species is insufficiently explored, although the dominant males are known to have considerably larger territories that overlap with these of multiple females. Hence, the Fat sand rats may have a polygynous mating system, where one male mates with a number of females. Breeding occurs from December to April. Gestation period lasts for 24 days, yielding a litter of 1 - 7 babies. Females are able to produce 2 - 4 litter during each season. Newborn rats are completely hairless. They come with closed eyes that open at 1 week old. The young are weaned by 3 weeks old. The age of sexual maturity is 4 months old for males and 3 - 3.5 months old for females.
Currently, the population of these animals as a whole is not threatened.
According to IUCN, the Fat sand rat is common and widespread throughout its range but no overall population estimate is available. Today, this species’ numbers are stable and it is classified as Least Concern (LC) on the IUCN Red List.
Fat sand rats may have an impact on the populations of the bushes they consume. In addition, they are an important prey for the local predators.
