Hyrax - Rabbit-sized ungulates

Hyrax - Rabbit-sized ungulates

When you first see a hyrax (‘dassie' in South Africa) you might take it for a rodent or a rabbit. Indeed they bear a superficial resemblance to European marmots and for many years were commonly known as ‘rock rabbits'. In fact, the hyraxes - of which there are eleven species in three distinct groups - are unique and fascinating creatures. And despite their small size, they play an important role in the ecology of African kopjes and mountains.

Akin to Elephants

Perhaps the most intriguing aspect surrounding hyraxes is their ancestry. Fossil evidence shows that they were among Africa's dominant medium-sized herbivores about 40 million years ago. Some ancient species were as large as the modern-day Wild Boar. At some point prior to this, is it thought that elephants and hyraxes may have evolved from a common ancestor. Today, the species share some interesting but obscure traits, most notably the arrangement of their toes - four front and three rear, which are equipped with rounded hoof-like nails. Like elephants, hyrax have internal testicles and they have an extraordinarily long gestation period (seven months) for an animal that weighs only between one and four kilogrammes.

Life Among Rocks

With their rubbery-soled feet and dense coat of hair, hyrax are adapted for life among rocks. They are adept at bounding among boulders and able to withstand extremes of heat and cold. Families can typically be seen sunning themselves in the early morning, and then retreating into shady crevices in the heat of the day. Their dental structure allows them to eat virtually any type of vegetation, although certain plants are generally favoured. Hyrax obtain all of their moisture requirements from their food and hardly, if ever, drink. One species of Rock Hyrax lives on rocky massifs in the Sahara desert.

Named for Habitats

The three genera of hyrax - rock, bush and tree - are named after their preferred habitats. The diurnal Rock Hyraxes (five geographically separated species) live among boulder outcrops (kopjes), rocky cliffs and boulder screes, often in the company of Bush Hyraxes (three geographically separated species). According to mammalogist Richard Estes, the two species frequently "share the same rocks and associate more closely than any two known mammals, except for monkeys that live in multi-species troops". In fact, it takes a good observer to tell the two species apart. The Bush Hyrax (also known as the Yellow-spotted) has a bold white eyebrow (and very indistinct buffy-yellow dorsal spot), whereas the Rock Hyrax is more uniformly coloured. Rather different in appearance is the largely nocturnal Tree Hyrax which is typically much darker (almost black in central African rainforest) with distinct facial markings, has denser fur, and a pale dorsal crest which is raised in alarm.

Tormented Souls?

All hyrax are noisy, but the Tree Hyrax is one of the most vociferous of all mammals. The following description by Richard Estes will be agreed upon by anyone who has ever been in earshot of these creatures: "the call starts with a series of spaced cracking sounds, likened to the rusted hinge of a huge gate slowly opening, followed by a series of expiring screams suggesting a soul in torment". Dramatic indeed, but singularly appropriate! Males have favoured calling perches and may call for up to an hour, before suddenly falling silent.

Hyrax Beware!

Hyrax have many predators, including man who relishes their meat and uses their fur for garments. By far their biggest enemy, however, is the rapacious Verreaux's (Black) eagle which shares the hyrax's rocky home. Studies in Zimbabwe and the Karoo have demonstrated that hyrax may form over 90% of the eagle's diet! These dashing birds of prey frequently hunt in pairs, one bird panicking a family of hyrax, the other snatching up a confused straggler. Leopard, Caracal, Martial Eagle, Giant Eagle-Owl, Black Mamba and Rock Python are among other predators. Interestingly, when the hyrax's natural enemies are eradicated - as has happened in parts of South Africa where eagles have been destroyed by sheep farmers - the small mammals proliferate to such an extent that they soon encroach upon the grazing lands of sheep, and ultimately leave the farmer in a far worse position than if he'd allowed an eagle or two to capture an occasional lamb.

CC Africa's Hyrax Hotspots

Rock Hyrax and Bush Hyrax are resident on kopjes in the Serengeti-Mara and are thus frequently seen at Klein's Camp, Grumeti and Kichwa Tembo. Large numbers of both species also occur at Lake Manyara at the foot of the Rift Valley wall. Isolated kopjes at Londolozi are home to family groups of Rock Hyrax, which are also fairly common at Kwandwe and Sossusvlei Mountain Lodge. The Tree Hyrax can be seen in riverine forest along the Grumeti River which flows past Klein's Camp and also in forest patches in and near to Kichwa Tembo and Ngorongoro Crater.

Posted: Mammals by CC Africa, Date: 21 November 2006