The Rock Hyrax - A Monotypic Species
According to which source is consulted, there are three or four species of hyrax. These herbivorous mammals belong to the order Hyracoidea. 'Hyrax' comes from the Greek word for 'shrewmouse'. However the rock hyrax (Procavia capensis) is monotypic, meaning it is the only living species in the genus Procavia. There are a number of animals which are now the sole representative of their genus. Some of these are the okapi, giraffe, numbat and pronghorn.
The yellow-spotted rock hyrax has the scientific name of Heterohyrax brucei while the western and southern tree hyraxes belong to the genus Dendrohyrax. The hyrax is mentioned in the Bible but generally as 'rabbit', 'hare' or 'coney' as early translators had no knowledge of the animal.
These animals are native to the Middle East and Africa. They were once more widespread than they are now. Although relatively closely related to the elephant, it is believed that sirenians (sea-cows such as the dugong and manatee) are more closely related (I kid you not!).
There is DNA support for this assumption including the fact that hyraxes share a number of traits that also appear in elephants including:
- Sensitive pads on the feet
- Good memory
- High brain function compared to other mammals
- Shape of some bones
- Excellent hearing
- Small tusks
- Lack of a scrotum – the testicles remain tucked up next to the kidneys. Manatees and dugongs share this characteristic with the hyrax and elephant.
The hyrax also has traits which are found in early mammals such as a poorly developed regulatory system for maintaining body temperature. The incisors continue to grow throughout the animal's lifetime but are not used for biting off leaves and grass. Instead the molars at the side of the jaw are used for this purpose.
The Rock Hyrax
The rock hyrax is found across the Middle East and sub-Saharan Africa but not in the Congo basin or Madagascar.
The rock hyrax is found mostly on rocky terrain where rocky crevices provide good protection from predators.
The squat hyrax is thickset and rotund, somewhat similar to a guinea pig with short ears and tail. They are quite small although fossil remains have shown that there were once hyraxes as big as oxen.
It is well-furred and about 50cm long and around 4 kg in weight. Males are slightly heavier. The head is pointed with a blunt nose and short neck. The ears are round and there are long black whiskers on the muzzle. The upper incisors are long, pointed and prominent, reminiscent of the tusks of an elephant.
The hyrax walks with the forefeet flat on the ground but more on the toes of the hind feet. The forefeet each have four toes and the back feet three toes. These are used for grooming and scratching.Credit: By Arikk (Own work) [CC-BY-SA-3.0 (www.creativecommons.org/licenses/by-sa/3.0) or GFDL (www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
The soles of the feet have thick, rubbery pads and numerous sweat glands. This combination gives them good grip when travelling at speed up steep, rocky surfaces.
The fur varies from dark brown to light grey depending on the habitat. There is a dorsal gland believed to be unique to the hyrax. This is covered with long, black or yellow hair and is most visible in dominant males. The gland secretes an odour used for marking territory and for communication.
Because of very inefficient thermoregulation, hyraxes huddle together for warmth and also bask in the sun.
Body temperature varies with the time of day but even where the animals are kept in controlled environments, such variations are still present leading researchers to believe that the temperature mechanism may be related to water balance regulation.
The rock hyrax live in small family groups, led by a single male. The territory is fiercely defended from rivals. If there is plenty of living space, a male may dominate several groups of females, each group having its own range. Other males live alone, often on the outskirts of the females' home ranges. They may mate but only with younger females.
The hyrax groups have a sentry system with one or more standing guard in prominent positions while others are feeding. They rarely stray more than 50 metres from their refuge.
The hyrax is noisy and sociable, using at least 21 different vocalisations. High trills signal a perceived danger. Their calls are referred to as 'songs' and their length, pattern, complexity and frequency give researchers much information as to age, size, status and hormonal state of the singer. A loud grunting performed while making chewing motions may be a sign of aggression but not of cud-chewing as was once thought.
Like the koala, the hyrax spends a large amount of time resting – up to 95%.
Hyraxes have complex stomachs consisting of multichambers where symbiotic bacteria break down tough cellulose and fibre from the coarse leaves and grasses that form the diet of the hyrax. It has an efficient renal system, retaining water as an aid to survival in arid environments. They can go for many days without water. Although rather clumsy in appearance, they climb quite well and have no qualms about entering domestic gardens to feed on the foliage of citrus and other trees.
Rock hyraxes produce a large amount of hyraceum, a sticky mass of dung and urine which is used by natives in the treatment of, among other things, epilepsy and convulsions. There have also been some attempts at producing a musk-like scent for men from hyraceum.
The gestation period is 6 to 7 months. This is unusually long for an animal of this size. Up to four young are born in a well-developed state. The eyes are open and the young are fully furred from birth. Females have four teats in the groin and another two near the shoulders.
The young eat solids at two weeks and are weaned at ten weeks. By 16 to 17 months of age, they will be sexually mature. The typical lifespan is ten to twelve years.
Males are sexually inactive between May and January and the weight of the reproductive organs increases dramatically from February onward as the breeding season approaches.
Predators in Africa include the leopard, cobra, puff adders, wild dogs and eagles. A specialist hunter of the hyrax is Verreaux's eagle.
Over most of its range, it is not considered endangered. Locally, it is sometimes regarded as a minor pest.