Dave Taylor's African Safari: Trophic Level II - The Herbivores - Primitive Ungulates: Hyraxes

Dave Taylor's African Safari: Trophic Level II - The Herbivores - Primitive Ungulates: Hyraxes - Page 18

Trophic Level II - The Herbivores
Primitive Ungulates: Hyraxes
Page 18

Introduction

Hyraxes are brown, almost tail-less animals. They are classed as near-ungulates. Their ancestry pre-dates the development of true hoofed animals. However, 25 or 30 million years ago, their relatives were among the dominant herbivores of their era. They were totally replaced by the development of the ruminant body plan and only today's hyraxes survive.

Why did this family all but vanish? Hyraxes process plant matter at least as well as ruminants today do. Presumably the hyrax’s extinct relations could too. The ability to digest plants was probably not a factor in bringing about their extinction. It probably had more to do with Hyracoidea's poor ability to regulate its body temperature coupled with its short legs. It probably was not very good at escaping predators.

Teeth patterns and other structural similarities of the skeleton have caused the hyraxes to be lumped together with elephants. The grouping is tenuous at best. More recent testing suggests a relationship with odd-toed ungulates. Again, this would be a distant one. Still, other work on DNA suggests that elephants, elephant shrews and perhaps hyrax came from related stock in much the same way Australia's marsupials are all related.

This book presents the two species most commonly seen in the Serengeti-Mara ecosystem. A third species, the tree hyrax, is almost never seen but may be heard giving its call at night.

Rock Hyrax (Johnston's Hyrax or Black-necked Hyrax)
Procavia johnstoni

Length: 38-60 cm (15-24")

Weight: 1.8-5.5 kg (4-12 lb.)

Status: Not endangered, still common across its range

Habitat: Rock hyraxes are mainly found on rocky outcrops. They are common on the rocky hills and kopjes of the Serengeti-Mara region. These rocky cliffs allow the hyrax to control its body temperature. Exposure to 22 C (72° F) temperatures for two hours leads to heat stress. The hyrax avoids this by seeking shade under the rocks. At the same time, these rocky crevices also help the rock hyrax to keep warm at night by providing it with a safe, snug area in which to huddle together.

Food: Rock hyraxes will occasionally browse on trees like their close relatives, bush hyraxes, do but most of their diet consists of grasses and herbs. They will sometimes venture 60 meters (196 feet) from their hiding spaces to feed, exposing themselves to predation by eagles, caracals and other predators. To give themselves a measure of protection, they usually venture forth in groups and they feed for only one hour.

Social System: Rock hyrax males are territorial. Each territory contains about 25 animals made up of the male, several females and their young. The females are usually related and spend their nights in close contact. The territorial male expels young males from his area. Expelled males travel at least 2 kilometers (1 mile) from their birth range. Many will be taken by predators. Females outnumber males by a ratio of 3:2 or even 3:1!

Behavior: Breeding seasons vary throughout the hyrax's range. Males are very vocal during this season. Females will give birth to up to six young after a gestation period of 214-240 days. The young will climb on their mother's back.

Male hyraxes make a series of sharp, harsh yips that build to a climax and then end with a series of grunts.

All members of a territorial group share common latrines. One type of latrine can be easily identified. Urine is dribbled down the cliff face and the calcium carbonate is dissolved and deposited as white streaks. These markings serve to advertise the location of the colony to other hyrax.

The other latrine is a place where communal dunging and urinating occurs. This is situated in a shaded, protected place where the mixture slowly turns hard. This is most likely a scent post, marking the territory.

Predators: Leopards, eagles, small cats, and snakes are all predators. Hyraxes will flee from most predators but they may mob a smaller predator.

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