DESERT SPECIALISTS: Arabia's elegant mice
Text and pictures by Paul Bates
(with many thanks to Dr David Harrison for his most useful comments)

There are thought to be some 1700 species of rodent worldwide, of these 48 live in Arabia. All but two, the Indian porcupine (Hystrix indica) and the rare Persian squirrel (Sciurus anomalus), can be classified as 'mice' in the broadest sense of the word. All have the classic rodent character of one pair of ever growing, greatly enlarged, chisel-like incisor teeth in the upper and lower jaws and an awe-inspiring capacity to breed. A female spiny mouse (Acomys russatus) for example may become sexually mature at just 31 days old; produce between two and five young; may become pregnant again whilst still lactating and may live two to three years in the wild or five years in captivity. Amongst the gerbils, it is known that a female Tristram's Jird (Meriones tristrami) produced 13 litters in 523 days or one litter of 2 young every 40 days. It is indeed fortunate that rodents have so many enemies; reptile, mammal and bird.

Although the number of species in Arabia is low when compared to rodent 'hot-spots' such as the Andes Mountains in South America or the island archipelagos of South-east Asia, the diversity of forms is impressive. This is a result partly of Arabia's geographical position which enables it to act as a zoological crossroads linking the faunas of Africa to central Asia and India to Europe, and partly as a consequence of its climatic diversity, such that desert, oak forest and even alpine habitats may be found in close proximity.

Of all the faunal types found in Arabia, it is perhaps the desert specialists that attract the most attention. The evolutionary prototypes of the present-day jerboas probably originated some 8 million years ago on the arid plains of Central Asia, in Turkmenia and Kazakhstan and on the Mongolian plateau. Subsequently their range expanded westwards to the deserts of north Africa and even for a time to western Europe. Today, there are 15 living species, three of which are present in Arabia. Of these the lesser jerboa (Jaculus jaculus) is one of the more remarkable. This elegant little creature with its greatly enlarged hind-legs, long tufted tail, lustrous eyes and short rounded snout is exclusively nocturnal. Unlike the true mice that run on all four legs, it hops like a miniature kangaroo and when pursued each bound may exceed 1 m in length. Although living in some of the most arid areas on earth, it has never been known to drink, gaining all its essential fluids from foodstuffs such as seeds, leaves and grasses. Equally at home in the sand deserts and stony steppe of northern and peninsular Arabia, its only concession to such a hostile environment is an ability to aestivate (summer hibernation) in deep subterranean burrows during the intense heat of July and August. The burrow entrances are blocked with sand in order to preserve a favourable microclimate within.

True gerbils (Gerbillus) and their larger relatives the jirds (Meriones) are also essentially creatures of the arid zone, although some frequent the wooded hills of the eastern Mediterranean. Like the jerboas, they concentrate their urine to minimize moisture loss and have long hind limbs and tails to maximize speed and mobility. Their hearing is also highly developed enabling them both to detect predators in wide open spaces and to locate a mate in areas of low population density. Both groups probably evolved in the deserts of Africa, following the increasing aridification of the region which began some 20 million years ago. In Arabia they can be subdivided into two groups - the sand-dwellers (psammophiles) and those that frequent the rocky outcrops, stone steppes and salt plains. Typical of the sand-dwellers is Cheesman's gerbil (Gerbillus cheesmani). A solitary rather than communal species, it lives in the most arid regions of central and southern peninsular Arabia. As with its western cousin the Egyptian gerbil (Gerbillus gerbillus) the soles of its feet are covered with hairs. This characteristic is typical of mammals living in loose shifting sand and is seen in other unrelated taxa such as Rüppell's sand fox (Vulpes rueppellii) and the Arabian sand cat (Felis margarita). Tristram's jird (Meriones tristrami) is found in less arid regions. A rock dweller and typically a nocturnal feeder, its population numbers fluctuate wildly in response to food availability. Capable of breeding throughout the year, a female has the potential to produce over 30 young per annum.

Elegance is one of the trade marks of Arabia's rodent fauna and none exhibits this more strikingly than the rare Arabian garden dormouse (Eliomys melanurus). An evolutionary off-shoot of the tree-dwelling European dormouse (Eliomys quercinus), it has become adapted to a non-arboreal existence during the last 1.2 million years. It lives in diverse habitat types such as the arid mountains of Sinai; the hills of the Negev and the high alpine zone of Lebanon where it is found amongst boulders and meltwater streams. Relict populations have also been located in the acacia woodlands of the Asir and Hejaz Mountains of Saudi Arabia. Its diet includes insects, centipedes and snails. Such a diet is positively encouraging as compared to that of the wild golden hamster (Mesocricetus auratus). The cheek pouches of just one individual of this latter species were found to contain 13 saw bugs, seven ants, four cockroaches, two flies and a hornet. It also feeds on other rodents! Curiously, the entire captive population of this familiar household pet was apparently derived from a single male and three females collected by the eminent zoologist Professor Aharoni from near Aleppo in Syria in 1930. The original stock was kept at the Hebrew University in Jerusalem from where it was subsequently disseminated worldwide.

There are many other rodents of interest in the region. The fat jird (Psammomys obesus) which lives in wadi beds, especially those rich in vegetation cover, is an endearing figure superficially more akin to North American chipmunks than Old World gerbils. Often seen by day, it sits on its back legs at the entrance to its burrow from where it darts for cover at the slightest hint of danger. The fat jird, whose feeding habits have an elegance that belies its somewhat unfortunate name, wipes its foodstuffs clean before it feeds and uses only one 'hand' to transfer the vegetation to its mouth. Spiny Mice have no such pretensions. Of the two local species, one the Russet Spiny Mouse (Acomys russatus) feeds by day; the other the Egyptian Spiny Mouse (Acomys cahirinus) by night. In consequence, competition between these two 'pigmy porcupines' is avoided. The spines which replace the hairs on the animal's back are relatively robust, curiously the skin to which they are attached is extremely friable and is frequently torn if roughly handled. The tail is also fragile and is often partially or totally lacking in wild-caught individuals. The deterrent effect of the spines has not been studied in detail; initial reports suggest that the domestic cat, at least, finds these spine-clad mice difficult to swallow.

Worldwide, rodents are a flourishing and cosmopolitan group. Quick to breed, resilient and adaptable, they are found in a myriad of niches from the temperate to the positively inhospitable. Providing every effort is made to maintain habitat diversity, the elegant mice of the jabals and wadis, the steppes, the littoral, the maquis and the sandy wastes will continue to prosper and the cool Arabian nights will be home to a million little footsteps as the 'feran', the 'jirdi' and the jerboas go about their business.

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Arabian Wildlife. Volume 2, Number 3
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