Hyraxes

Hyrax Facts

Classification:

• Kingdom: Animalia
• Subkingdom: Bilateria
• Phylum: Chordata
• Subphylum: Vertebrata
• Class: Mammalia
• Order: Hyracoidea (hyraxes)
• Family: Procaviidae
• Genera:Dendrohyrax (tree hyrax, two or three species);Heterohyrax (bush hyrax, one species);Procavia (rock hyrax, one species)
• Geographical location: Africa and the Middle East up to Syria
• Habitat: Among rocks and boulders, from dry lowlands to mountains fourteen thousand feet high, in trees near coasts, in rain forests, and evergreen forests twelve thousand feet high
• Gestational period: Seven to eight months
• Life span: Nine to twelve years
• Special anatomy: Feet with rubbery pads containing sweat glands; rudimentary hooves on the first and third toes of the rear feet; a midback gland, surrounded by erectile fur

Hyraxes are rabbit-sized mammals that look like rodents, but are closely related to elephants. There are three kinds of hyraxes, all found in Africa: rock hyraxes, bush hyraxes, and tree hyraxes. These vegetarians eat different kinds of food and differ in social interactions. Some live in groups and others are often solitary.

Physical Characteristics of Hyraxes

Hyraxes are one to two feet long and weigh three to fourteen pounds. They have stumpy tails, brown to gray fur on their backs, and lighter pelage on their sides. Hyrax fur is short on individuals living in warm, dry regions, and thick and soft on those living in colder areas.

The three types of hyraxes walk on all fours and are excellent climbers, because their feet end in rubbery pads having sweat glands. When hyraxes run, their feet sweat, and the resultant lubrication improves traction on rocks or trees. However, hyraxes also have small hooves on the first and third toes of their hind feet. All hyraxes have a gland in the middle of the back, surrounded by a ring of erectile, dark brown to yellow fur. When a hyrax becomes excited, this hair stands on end.

Life Cycles of Hyraxes

Bush and rock hyraxes are social animals which live in family groups of up to three dozen members. Each group is led by a dominant male. Its other members are adult females and young of various ages. Group members care for each other. The dominant male marks off their territory and defends it, using scent markers to warn off other hyraxes.

Single groups of bush and rock hyraxes may share a territory peacefully, even using the same burrows. They cluster together for warmth. The young of both species play together. Part of the basis for this coexistence is that they do not compete for food. Although hyraxes can eat grasses or other soft plants, bush hyraxes eat soft plants but not grasses, and rock hyraxes eat grasses. However, while the two species live together, they do not interbreed, since both their mating behaviors and the anatomy of their sex organs differ.

Tree hyraxes differ from the other types in being usually solitary. However, they may live with one or two others. They never live in large groups or with other kinds of hyraxes. This is partly due to their habitats in trees. Rock and bush hyraxes are diurnal, while the tree hyraxes are nocturnal.

In all types of hyrax, mating season depends on species and habitat. Gestation is seven to eight months. All females in a family group of rock or bush hyraxes give birth within a few weeks of each other, each having one to four young which are nursed for five months. Tree hyraxes litter one or two young. The offspring of all species can mate at approximately sixteen months old. Females join rock or bush hyrax groups, and males leave by age 2.5 years. Tree hyrax offspring are solitary after weaning. Hyraxes can live for nine to twelve years.

The Three Types of Hyrax

Rock hyraxes (dassies) live in diurnal family groups among rocks and boulders, from dry lowlands to mountains 14,000 feet high. They inhabit and hide in rocks or their crevices. Dassies are one to two feet long and weigh four to fourteen pounds. Their back fur is light to dark brown and the erectile fur around their midback glands is dark brown or yellow-orange. Rock hyraxes eat grasses. Their eyes can look right into the sun, enabling them to escape avian predators. They can live for nine to twelve years.

Bush hyraxes are diurnal and live amid rocks and boulders or in hollow trees from south to northeast Africa. Up to two feet long, they weigh three to twelve pounds, have light gray back fur, and yellow fur around the midback glands. These hyraxes eat soft plants and live in groups of up to thirty-four. Often they share territory with rock hyraxes. They can live for ten to twelve years.

Tree hyraxes (dendrohyraxes) live in Africa. Eastern tree hyraxes inhabit Kenya’s coast and Zanzibar. Southern tree hyraxes inhabit southeastern and East Africa. Western tree hyraxes live in West and Central Africa. All make tree nests in savannas, rain forests, and evergreen forests at altitudes up to 12,000 feet. They are up to two feet long, and weigh three to nine pounds, less than rock or bush hyraxes. Their long, dark brown back fur and dark yellow erectile fur around midback glands blend with shadows in trees. They eat soft plants, are nocturnal and hide during daylight, are most often solitary, but may live with one or two others.

Hyraxes and Their Predators

Hyraxes are of relatively little interest to humans, though some Africans eat them. All hyraxes are preyed on by eagles, lions, leopards, jackals, hyenas, and snakes. Other predators are more selective in hyrax predation, due to their different habitats. For example, special predators of tree hyraxes include civet cats, servals, and caracals.

Conservation

Locally abundant in a few well-protected sites, the tree hyrax known as Dendrohyrax validus (eastern tree hyrax) was categorized as “near threatened” by the International Union for Conservation of Nature and Natural Resources (IUCN) in 2015, compared to other hyrax species which were listed in the “least concern” conservation category. The IUCN considers D. validus a distinct species from Dendrohyrax arboreus (southern tree hyrax), while other scientists and organizations such as the Integrated Taxonomic Information System list them as synonyms for the same species.

Principal Terms

diurnal: active during the day

gestation: duration of pregnancy

nocturnal: active at night

pelage: animal fur

solitary: lives alone

Bibliography

Crispens, Charles G. The Vertebrates: Their Forms and Functions. Springfield, Ill.: Charles C Thomas, 1978.

Hoeck, H., et al. “Dendrohyrax validus,” The IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources, 2015, www.iucnredlist.org/details/136599/0.

Orrell, T., custodian. ITIS Global: The Integrated Taxonomic Information System, Apr. 2016, Integrated Taxonomic Information System, http://www.catalogueoflife.org/col/browse/tree/id/4313bc7637e1fc1feb316a4dea2b668b. Species 2000 & ITIS Catalogue of Life, 28th September 2016, Y. Roskov, et al., eds., 28 Sept. 2016, Naturalis, www.catalogueoflife.org/col., 4 Oct. 2016.

Parker, Sybil. Grzimek’s Encyclopedia of Mammals. New York: McGraw-Hill, 1990.

Prothero, Donald R., and Robert M. Schoch. The Evolution of Perissodactyls. New York: Oxford University Press, 1989.

Ricciuti, Edward R. What on Earth Is a Hyrax? Woodbridge, Conn.: Blackbirch Press, 1997.