Introduction
The rock hyrax (Procavia capensis) is a medium-sized terrestrial mammal native to Africa and the Middle East, often referred to as the dassie in South Africa. As the only extant terrestrial afrotherian in the Middle East, this tail-less creature exhibits unique physical and behavioral traits, including specific dietary habits. This article explores the rock hyrax's diet, foraging behavior, and its role as a key herbivore in its ecosystem.
Physical Characteristics and Habitat
The rock hyrax is a squat, heavily built animal, with adults reaching about 50 cm (20 in) in length and weighing around 4 kg (8.8 lb). Males are slightly larger than females. Their coat is dense and varies greatly in color, typically brownish-grey on the upper parts and lighter underneath. A characteristic marking on their back, colored black, yellow, or orange, covers a special gland that emits a specific odor used for social communication and territorial marking.
Their natural range spans most of sub-Saharan Africa (excluding the Congo basin and Madagascar) and extends eastwards to the western and southern coasts of the Arabian Peninsula. Rock hyraxes prefer arid environments like deserts, savannas, and scrub forests, as well as rocky terrains with moderate vegetation, particularly areas with abundant rock crevices and cavities used as shelters. Even when traveling between suitable habitats, rock hyraxes do not normally stray from areas with some form of cover or refuge.
Social Behavior and Activity Patterns
Rock hyraxes are highly sociable animals, living in groups of 2-26 individuals, typically consisting of one breeding male and multiple adult females with their young. These animals are generally active during the day but have also been observed communicating and being active during moonlit nights.
They emerge from their shelters to sunbathe for 1-2 hours to warm up, often foraging by the afternoon. During overcast, rainy, or cold days, they rarely leave their shelters, and during extremely hot days, they remain in shady sites. As grazers, they feed on the ground, sometimes climbing trees to reach fresh leaves. While feeding in groups, a breeding male or female stands guard on a high rock or tree branch, emitting a sharp barking call to alarm the group of any detected threats.
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Adult hyraxes spend 95% of their time resting. Resting often involves heaping, which usually takes place inside their den as animals lay on top of one another. Evidence suggests that resting behavior is correlated with ambient temperature. As temperatures become increasingly warm, resting behavior changes from heaping to huddling to solitary resting.
Dietary Habits
Rock hyraxes are primarily grazers, consuming a variety of plant species. Their diet varies based on regional preferences and seasonal availability. They forage on many different plant species per foraging bout. For example, on Mount Kenya's western slope, they prefer giant lobelia and certain daisy species, while swampy vegetation is consumed near valley bottoms. In lowland areas, their diet includes new shoots, fruits, berries, and figs.
Grasses constitute a significant portion of their diet, making up 78% during the wet season but decreasing to 57% during the dry season. During moist conditions, such as the wet season or after rainfall, rock hyraxes prefer new shoots, buds, and leaves. In drought conditions, they may consume coarser materials like bark, lichens, and liverworts. Plant water content significantly influences the amount of food ingested, with daily food consumption varying with body weight.
The feeding habits of rock hyraxes are comparable to those of ungulates. Giraffes and elephants are their most likley competitors for food. Hyraxes can feed very rapidly and entire colonies may spend less than one hour per day feeding. Most feeding is concentrated in two feeding periods of about twenty minutes: one about three hours after sunrise and the other about two hours before sunset.
Hyraxes have a three-chambered stomach with bacteria to help digest the plants they eat.
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Rock hyraxes do not manipulate or carry their food, and they use their feet only to reach or hold twigs. While foraging, they often hold their head at a 90˚ angle to best utilize their wide gape, and they bite off large amounts of vegetation. By eating large amounts of food quickly, and spending most of their time resting, rock hyraxes are able to survive on resources too sparse or nutrient-poor to support more active mammals of a comparable size.
Foraging Behavior
Rock hyraxes may travel up to 60 meters from their burrows to forage, though this distance may increase during droughts. While grazing, individuals maintain their spacing and remain vigilant for potential predators.
Rock hyraxes forage for food up to about 50 m from their refuge, usually feeding as a group and with one or more acting as sentries from a prominent lookout position. The rock hyrax also makes a loud, grunting sound while moving its jaws as if chewing, and this behaviour may be a sign of aggression.
They feed in groups, where the breeding male or a female always stands guard on a high rock or tree branch: once a threat is detected, the animal emits a sharp barking call, which acts as an alarm, after which members of the group flee to their shelters.
Competition and Predation
The feeding habits of rock hyraxes are comparable to those of ungulates, with giraffes and elephants being their most likely competitors for food. Leopards are the main predator of Procavia capensis, especially in high mountainous areas. Other predators include snakes (e.g., Egyptian cobras and puff adders), eagles (e.g., Verreaux’s eagles and martial eagles), owls, jackals, African wild dogs, and various cat species (e.g., servals, caracals and lions). Mongooses sometimes prey on neonates.
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Rock hyraxes evade predators by staying alert and remaining close to cover while foraging. They respond immediately to alarm calls from territorial males and other species, such as bush hyraxes and certain birds. They also use burrows smaller than most predators in their habitat. Some have been known to escape predation by playing dead or working together to scare off smaller predators from the safety of a burrow.
Ecological Role
As the dominant herbivores in rocky areas throughout their geographic range, rock hyraxes control the growth of local vegetation. They are preyed upon by numerous vertebrate species and host up to 25 species of lice. Their colonies also contribute to the ecosystem by urinating and defecating in designated latrine areas. Over time, this material congeals into a large, sticky solid, known as hyraceum, which has been used in traditional medicine.
Reproduction and Development
Rock hyraxes have a polygynous mating system, where one male mates with 3-7 females, controlling them in a territory of up to 4000 square meters. Breeding occurs depending on geographical location. Thus, the population in Israel mates in August-September, whereas those in Kenya typically mate in August-November. The gestation period lasts for 202-245 days, yielding 1-6 babies in a rocky crevice.
Newborns are well-developed, starting to move around with ease by the second day of their lives. At 3-4 days old, they are ready to eat food, whereas solid food is included in their diet during the first 2 weeks. Weaning occurs at 3 months old. The age of reproductive maturity for this species is 16 months old.
Baby rock hyraxes eat adult hyrax feces to get the bacteria they need to digest plant material in their stomachs.
Conservation Status and Threats
The Rock hyraxes currently face habitat loss across much of their original range due to land clearing for agriculture as well as increased development of human settlements. In many areas of its range, the Rock hyraxes are considered pests due to damaging crops. As a result, in South Africa, there have been campaigns, intended to cull this species. According to IUCN, the Rock hyrax is abundant in some areas and widely but no overall population estimate is available.
Procavia capensis is hunted for its meat throughout its geographic range. In areas where humans are prevalent, especially South Africa, rock hyraxes are sometimes considered pests, as they inhabit road culverts and/or crevices in stone walls. Agricultural plots that have been recently cleared are often bordered by rocks that were removed during clearing, thus providing prime habitat for rock hyraxes. Fields such as these are often used for cultivating fruit trees, upon which hyraxes browse and cause considerable damage. In addition, rock hyraxes are a known reservoir for Leishmania tropica, a flagellate parasite that infects rodents and humans.
Although Procavia capensis is classified as a species of least concern on the IUCN's Red List of Threatened Species, current population trends are unknown. While it is hunted for its meat throughout its geographic range and has experienced local extirpations, there are no major threats to the long-term persistence of the species.