pPhPhoto by Catherine Rainbow

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General Description & Social System

Rock hyraxes are the smallest ungulates that are approximately the size of a large rabbit or marmot. They have small tusks and rounded toes with rounded toenails just like other ungulates including elephants. Their mouths are also exceptionally large in order to facilitate eating quickly in order to avoid predators. They have rubbery feet with sweat glands that allow their feet to stick to the rocks as they travel across them. Rock hyraxes have a short brown or gray bristly coat with a characteristic large dorsal glad in the middle of their back. This gland is surrounded by erectile hair and secretes a clear, scented fluid that is important in communicating arousal to other rock hyraxes. Both males and females are similar in appearance and live approximately 12 years (Estes 1991, Olds and Shoshani 1982).

The rock hyraxes depend on their rocky shelters for protection and survival. Thus, they are only found where there are kopjes. Related females live in a kopje with a territorial male that defends the kopje from other peripheral males. The territorial male defends the kopje with chasing, biting, teeth gnashing and territorial calls in order to have exclusive access to the females who live there in a home range. The combination of the territorial male, the related females and their young is generally called a colony. A colony usually can consist of up to 35 individuals (Estes 1991, Fourie and Perrin 1987, Hoeck, Klein and Hoeck 1982).

There is a dominance hierarchy in the male population of rock hyraxes, which is not found in the female population. Within a colony there are four types of males: territorial males, peripheral males, early dispersing males and late dispersing males. A territorial male is the dominant male who protects his harem of females as well as the kopje from peripheral males. This male will watch over the colony as it feeds and will use alarm calls to inform the colony if there is a predator close to them. He is also particularly aggressive during the breeding season. Peripheral males are those males that have dispersed from other nearby kopjes. They live on the periphery of the dominant male’s territory in the outskirts of the kopje. If there are multiple peripheral males, they will have a dominance hierarchy in which the oldest and strongest peripheral male outranks the other peripheral males. If the territorial male weakens or dies, the highest-ranking peripheral male will challenge the territorial male in order to take over the territory. Early dispersing males leave their natal kopje before they reach sexual maturation in order to establish themselves as a peripheral male at another kopje (Hoeck, Klein and Hoeck 1982). They usually leave their natal kopje between 16 and 24 months (Fourie and Perrin 1987). Late dispersing males, on the other hand, leave their natal kopje after they have reached sexual maturity. Although these males have reached sexual maturity, the territorial male does not appear to show additional aggression towards them. While males must always disperse from their natal kopjes, females rarely leave their natal kopjes, maintaining the close relationships and bonding between the females in the colony (Hoeck, Klein and Hoeck 1982).

 

Habitat

Rock hyraxes live in rocky outcrops known as kopjes throughout Northern and East Africa as well as in the Middle East. They prefer to live in kopjes found within savanna zones, semi-desert vegetation and mountains while avoiding kopjes within forests (Estes 1991). These rocky outcrops were usually the result of ancient volcanic activity. They provide rock hyraxes with the necessary shelter from both predators and extreme temperatures (Sale 1966).

Predation pressure on rock hyraxes is high because they do not have significant size or weapons for defense. The rock hyrax’s main predators include black eagles, leopards, Egyptian cobras, puff adders, wild dogs and caracals (Olds and Shoshani 1982). The only way that rock hyraxes can prevent physical harm from predators is to hide to in their rocky shelter. The kopjes must have large enough crevices for the rock hyraxes to enter, but small enough crevices so that predators cannot penetrate the shelter (Sale 1966). Thus, rock hyraxes are vigilant animals that remain close to their shelter throughout the day.

Rock hyraxes have a difficult time maintaining their body temperature. In the mornings, they must huddle together in the sunlight to warm their bodies. They prefer to warm their bodies on flat rocks that aid in the group basking process. If the day is exceptionally hot, the rock hyraxes will retreat to their shelters to avoid the midday heat. At night, the rock hyraxes return to their shelters for protection from predators, cold temperatures and the wind (Estes 1991, Hoeck 2003, Olds and Shoshani 1982, Sale 1966).

While the rocky outcrops provide shelter and protection, they do not provide the necessary vegetation for rock hyrax survival. Rock hyraxes must travel a short distance away from the kopje in order to find food. They are browsers and opportunistic grazers since their diet varies according to the seasonal vegetation. They prefer to eat new shoots, fruits, berries and figs. However, the main component of the rock hyrax diet is grass since grass is fairly abundant throughout the year (Fourie and Perrin 1989, Olds and Shoshani 1982). Rock hyraxes only graze approximately for approximately one to two hours of the day and use their large mouths to eat quickly. They eat quickly in order to avoid confrontations with predators. The dominant territorial male of the kopje will stand guard on a high rock observing his harem as they feed. If he sees a predator, he will give a warning call to the feeding hyraxes who will then run back to the kopje to seek shelter (Estes 1991, Old and Shoshani 1982).

 

Social Spacing

Rock hyraxes live in colonies on kopjes where a territorial male defends a kopje from other peripheral males in order to have exclusive access to the females who live there. Related females live together in groups with their young within a home range that includes the vital kopje that the territorial male defends. Thus, females have home ranges that overlap with a territorial male’s mating and nesting territory, which is usually defined by the size of the kopje. Peripheral males live on the outskirts of the dominant male’s territory in their individual rocky shelters that they defend from other peripheral males. If the peripheral males encroach upon the dominant male’s territory, they risk being chased, bitten, and the object of both teeth gnashing and territorial calls. Juvenile males are forced to disperse to another, nearby kopje once they reach sexual maturity in order to try to establish their own colony ( Estes 1991, Fourie and Perrin 1987, Hoeck, Klein and Hoeck 1982).

The hyraxes must live in colonies in kopjes because their predation pressure is extremely high. Predators include black eagles, leopards, Egyptian cobras, puff adders and wild dogs (Olds and Shoshani 1982). Thus, rock hyraxes spend most of their day either within the shelter of the kopje or basking on the kopje’s flat surfaces. Their food, especially grass, is abundant in the area surrounding the kopje. This is accommodating to a rock hyrax’s needs because it will thrive in an area abundant with food that is close to its shelter in order to minimize its vulnerability to local prey (Estes 1991, Fourie and Perrin 1987, Hoeck, Klein and Hoeck 1982).

 

Social Relationships

The rock hyrax mating system is polygyny, in which the territorial male mates with a harem of females. The dominant male may mark his territory with urine or feces as well as with territorial calls. The rock hyrax polygynous mating system evolved because rock hyrax females must live together in groups in kopjes in order to survive the high predation pressure. Since the females are always clumped together, a dominant male is able to defend them and the kopje in order to achieve the right to breed them exclusively (Estes 1991, Fourie and Perrin 1987).

Adult female rock hyraxes come into estrus at the same time during the breeding season, which peaks in April. Throughout the breeding season, the territorial male will constantly roam through his females smelling their urine and searching for receptive females. Females that are in estrus will approach the territorial male with their dorsal gland erect. They will then sniff the male’s anogenital region and then present their hindquarters to him for breeding. Once the breeding takes place, the relationship between the male and female returns to its previous state in which the male’s only responsibility to the females is to protect them. Rock hyraxes do not show any signs of allogrooming or caring for their mates. The only social interaction that takes place between rock hyraxes is their huddling and stacking together in order to warm their bodies (Fourie and Perrin 1987).

Females display forms of bonding since they are usually related to each other. They often remain together for life on the same kopje, feeding and watching for predators as a group. Males, on the other hand, constantly compete against each other in order to achieve the status as the territorial male. This competition leads to confrontations in which one male asserts his dominance through chasing, teeth gnashing, biting, showing an erect dorsal gland and calling. A subordinate male will close his dorsal gland, flatten his ears and present his rump to the dominant male in a submissive manner. These competitions help to establish the social organization of the males assuring that only the largest, strongest, mature males will breed with the females (Estes 1991).

When the young are born after approximately seven and a half months of gestation, they are fairly developed and immediately imprint upon the scent of their mother’s dorsal gland secretion. The mother will care for her offspring for three months before weaning them. During these three months, all of the mothers will share care-taking responsibilities with the exception of communal nursing (Barry and Mundy 1994). Males will not partake in parenting, but will protect his offspring. Young females will be allowed to remain in the colony while young males will be forced to disperse upon sexual maturation (Estes 1991, Fourie and Perrin 1987).

 

Summary of Adaptations

Rock hyraxes are the smallest ungulates that are related to both elephants and manatees. Before the Miocene period, hyraxes of all sizes lived throughout earth. When the first radiation of the Miocene took place, however, many of the hyraxes that could not find shelter or a specific niche with an advantage died. At this time, elephants, rock hyraxes and manatees had a common ancestor whose population diverged in habitat utilization in order to survive the radiation. This divergence caused new species of animals to develop including elephants, rock hyraxes and manatees that each utilizes a different habitat (Hoeck 2003).

Rock hyraxes live under a great deal of predation pressure, which causes them to clump together in colonies that reside in protective kopje shelters. They depend on the kopje for shelter from both predators and extreme weather. Rock hyraxes are browsers that eat a large portion of grass as well. This food is abundant around the kopje, accommodating the rock hyraxes’ need to be close to the shelter for fear of predation (Estes 1991, Olds and Shashoni 1982).

A territorial male establishes a mating and nesting territory on the kopje, defending this resource that attracts the females. Females live in a home range together and are usually related. The territorial male protects the females from other males as well as predators. Since the females live together in groups, it is evolutionarily beneficial for the males to become dominant within a territory because the dominant male will be able to reproduce exclusively with the females that reside within his territory. There is a male hierarchy within the peripheral males that helps to assure that the strongest and healthiest male will breed with the females. Young are fairly developed when they are born, and are raised by their mother until they are approximately three months old. Juvenile males are forced to disperse while juvenile females remain within the colony, maintaining the female bonds (Estes 1991, Fourie and Perrin 1987, Hoeck, Klein and Hoeck 1982).

 

References

Barry, R. E. 1994. Synchronous parturition of Procavia capensis and Heterohyrax brucei during drought in Zimbabwe. South African Journal of Wildlife Research, 24, 1-5.

Estes, R. D. 1991. Chapter 16: Hyraxes: Order Hyracoidea, Family Procviidae. In: The Behavior Guide to African Mammals Including Hoofed Mammals, Carnivores, Primates, pp. 250-258. Los Angeles: University of California Press.

Fourie, L. J. and Perrin, M.R. 1987. Social behavior and spatial relationships of the rock hyrax. South African Journal of Wildlife Research, 17, 91-98.

Fourie, L. J. and Perrin, M.R. 1989. Quantitative and qualitative aspects of the diet of the rock hyrax (Procavia capensis Palla, 1766) in the Mountain Zebra National Park. Journal of African Zoology, 103, 361-370.

Hoeck, H. N. (2003) Hyrax: Behavior ecology of two species. Max Planck Institute for Behavior Physiology Seewiesen. Online. Accessed 2/18/2003. www.calacademy.org/research/bmammals/afrotheria/Hyracoidea.html

Hoeck, H. N., Klein, H. and Hoeck, P. 1982. Flexible social organization in hyrax. Zeitschrift fur Tierpsychologie, 59, 265-298.

Olds, N. and Shoshani, J. 1982. Procavia Capensis. Mammalian Species, 171, 1-7.

Sale, J. B. 1966. The habitat of the rock hyrax. Journal of the East Africa Natural History Society, 25, 205-214.

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