(This article first appeared on
focusingonwildlife.com)
The Dassie Rat (Petromus typicus)
is endemic to the Southwest Arid Zone of Africa.
Their range encompasses northwestern South Africa
(Northern Cape Province), central and western Namibia
and southwestern Angola.
These cute, squirrel-like, long tailed rodents occur regularly and sometimes
commonly in rocky areas within this vast swathe of desert and semi-desert land.
What makes this creature rather sought-after is that it is the only surviving
member of the family Petromuridae. Translated as “rock mouse”, the Petromuridae
family used to be a widespread and diverse group of rodents known from fossil
and subfossil records throughout Africa. They
are believed to be most closely related to the giant Cane Rats that still occur
in grasslands and canefields of more moist areas of Africa.
The name Dassie Rat is derived from the Afrikaans word for a hyrax; “dassie”,
and is a rather apt name as Rock Hyrax co-habit the same rocky outcrops that
the Dassie Rats enjoy, and superficially, a Dassie Rat resembles a young hyrax,
that is until its long fluffy tail is spotted! The Dassie Rat’s alternative
name is the Noki.
A Dassie Rat sun basking in the
early morning rays
Rock Hyraxes are much larger than
Dassie Rats but co-habit the same rock outcrops. The Dassie Rat’s name
originates from the Afrikaans word “dassie” meaning “hyrax”
Dassie Rats are well known for
their ability to wedge themselves into extremely narrow crevasses from which
they are almost impossible to extract. They have evolved narrow, flattened
skulls and very flexible ribs to master this talent. Female Dassie Rats even
have teats on the sides of their torso, rather than underneath, so that their
young can nurse in the very confined and narrow spaces in which they den.
Dassie Rats usually give birth to a pair of offspring and only once per annum,
a particularly slow reproductive rate for a rodent. As their gestation period
is an extremely protracted period of three months, the young are well developed
when born; fully furred, with eyes and ears open and ready to run! These young
are known as ‘kittens, nestlings, pinkies or pups’, whereas female Dassie Rats are
termed ‘does’ and males ‘buck’. They feed predominantly on soft vegetable
matter, especially grass stems and leaves and flowers of the daisy family, but
will also take fruit, seeds and insects when available. They have been observed
climbing trees to pluck leaves and are also coprophagous, meaning they eat
feces, sometimes even their own. Dassie Rats obtain all their moisture from
their diet and are thus able to survive without drinking, another essential
characteristic in their arid environment.
A pair of Dassie Rats during
courtship
Dassie Rats copulating
A male Dassie Rat is left exposed
after copulation
Other physical features of this
species include unusually large eyes, a prominent yellowish nose, bare feet
with pads and short, silky fur (however their bellies are naked) of a grey,
brown or buff colouration that is perfect camouflage in their rocky
environments. As with other rodents, their front teeth continue growing
throughout their lives, however their cheek teeth are not evergrowing. They
groom themselves with their hind claws which have evolved stiff hairs that are
believed to act like combs. Adults weigh from 6 to 11 ounces (170 to 300 grams)
and reach a length of 5.5 to 8.3 inches (14 to 21 cm), with their tails adding
an additional 6.69 inches (17 cm).
Frontal view of a Dassie Rat
enjoying early morning sunlight
Dassie Rats are colonial, living
in small family groups of several adults and young (maximum recorded group size
is 22 individuals). They have numerous predators including snakes, mongoose,
jackal and avian raptors. Group members give off a distinctive whining whistle
as a danger warning. Hyraxes don’t predate on Dassie Rats but do chase them
away from food sources. They are diurnal and most active at dawn and dusk, and
enjoy basking in early and late sunlight. This solar basking also conserves
energy, a useful trait due to their slow metabolic rates and low nutrient diet.
Their favourite basking spots are close to their shelters and are often stained
yellow from their urine. Dassie Rats are very docile yet playful animals.
Reliable sites where I have encountered these lovely creatures include the Erongo Mountains,
Spitskoppe, Twyfelfontein and Spreetshoogte
Pass, all in Namibia.
Dassie Rat in typical rocky
habitat in Namibia’s Erongo Mountains
