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.