Aardwolf

Aardwolf
Scientific classification
Kingdom Information
Domain	Eukaryota
Kingdom	Animalia
Subkingdom	Bilateria
Branch	Deuterostomia
Phylum Information
Phylum	Chordata
Sub-phylum	Vertebrata
Infraphylum	Gnathostomata
Class Information
Superclass	Tetrapoda
Class	Mammalia
Sub-class	Theriiformes
Infra-class	Holotheria
Order Information
Superorder	Preptotheria
Order	Carnivora
Sub-order	Feliformia
Family Information
Family	Hyaenidae
Sub-family	Protelinae
Genus Information
Genus	Proteles
Species Information
Species	P. cristata
Synonyms	Proteles cristatus
Population statistics
Conservation status	Least concern

The aardwolf (Proteles cristata) is an African carnivore of the family Hyaenidae. The smallest member of that family, the aardwolf differs immediately from its bone-crushing, carrion-eating relatives by subsisting on a diet of termites.

Description

The aardwolf is 22 to 31 inches long and weigh 18 to 26 pounds; the weight is subject to seasonal fluctuations and can vary in southern Africa, while reaching up to 30 pounds in the east of the continent. Males and females are of equal size.

The body structure is characterized by the sloping back, with the front legs longer than the hind legs; in general the legs are long and slender. The front paws are provided with five toes and the hind paws with four toes - the other hyena species lack the first toe (dewclaw) of the front paw. The aardwolf, like all hyenas, walks digitigrade (i.e. on the toes), with the toes bearing non-retractable claws.

The primary color of the fur is yellowish-gray, but it can vary from whitish-yellow to reddish-brown. On the back and on the flanks there are several dark, vertical strips, diagonally across the front and hind legs. On the lower parts of the legs are irregular transverse strips, the paws themselves are dark. Sometimes there are also spots on the nape of the neck; The throat is light gray or whitish. Aardwolf stripes are similar to those on the striped hyena, but they are smaller by half and their stripes are much more regular. Along the back is a crest of hair from head to tail, which are up to 20 inches long at the shoulders; in case of danger or a threat the crest can be raised to make the animal appear larger.

The slim head sits on a long neck. The ears are large and pointed, the eyes are also enlarged and have excellent night vision. In particular the sense of hearing and the sense of smell are well developed. As with many other inhabitants of dry regions, the bulla tympanica - the lower pocket of the tympanic cavity in the ear - is noticeably enlarged, enabling the aardwolf to hear deep sounds at great distances.

The most distinctive difference between the aardwolf and the other species of hyenas are the jaws, which are much smaller; they are reduced to minute, far-apart pegs, and their number is irregular. The canines, which serve in a defensive manner, are well-formed, but in older animals they are often worn out. The incisors are inconspicuous. The tooth formula is I 3/3 - C 1/1 - P 3 / 1-2 M 1 / 1-2, so in total they have 28 to 32 teeth. In their mouths there are further adaptations to a termite diet: the palate houses a broad spatula-shaped tongue covered with large conical papillae, with the salivary glands produce large amounts of sticky saliva.

Range and habitat

Aardwolfs are located in two geographically separated areas of Africa, separated by a gap of around 900 miles. The northern range extends from the extreme southeast of Egypt along the Red Sea coast in Sudan and Eritrea via Ethiopia, Somalia to Kenya and Central Tanzania. The southern range extends from south-western Angola and southern Zambia to South Africa.

Aardwolfs prefer open, rather dry habitats with an annual rainfall average of no more than 30 inches; this includes grasslands and bushy savannahs, in forests and pure deserts. In Ethiopia they can live at an elevation of up to 6000 feet. Nowhere in their distribution area are they particularly frequent; in favorable habitats the average population density is one adult animal per square kilometer.

Behavior

Aardwolfs are predominantly nocturnal, yet depending on availability they will sometimes go out for food in the late afternoon. During the day or even during nighttime rest breaks, they retreat into the den, which is usually a hole in the ground dug out by themselves or by another animal. The den has have a single entrance, and consists of a chamber at the end of a fairly long tunnel.

Aardwolfs live together in pairs; these pairs are relatively stable with a duration of two to five years. Outside of the mating season, the social behavior of the aardwolf is poorly developed: they inhabit separate dens and go alone for food searches. When they meet, they ignore each other; in contrast to other hyenas, they do not have any specialized greetings.

The territories are about 1 to 2.5 mi² in size, the size varies according to the number of termites, with a territory containing around 3000 termite mounds. Aardwolfs mark their territories by rubbing their anal region against grass, logs, or other objects. The anal bag separates an orange-yellow secretion, which turns black in the air. Both the male and the female show their markings, but the males are more frequent - up to twice every 300 feet. These markings are usually found along the boundaries of their territory, but less frequently at the entrance to the den. If a stranger is discovered, the owner will set up his mane and try to drive the intruder out, with the chase ending at the territorial boundary.

Diet

In contrast to the other hyenas, aardwolfs eat almost exclusively from termites. Unlike other insect-eating mammals, such as aardvarks or anteaters, the aardwolf has no strong claws for breaking up the termite mound; rather, the broad, sticky tongue is ideally adapted to licking the termites from the ground. Aardwolfs are specialized in termites of the genus Trinervitermes: T. bettonianus in East Africa, T. rhodesiensis in Zimbabwe and Botswana, and T. trinervoides in South Africa are the preferred species. These termites are nocturnal and search for food in groups of 2,000 to 4,000 on the surface, making them easier to capture than other genera that largely remain in the subsurface. They are also disdained by most other insectivorous mammals, as the soldiers of these termites secrete a toxin made of diterpenes and monoterpenes which dissuades all other predators from eating them but the aardwolf, which is extremely tolerant of the toxin.

Every night an aardwolf eats up to 300,000 termites, which is two to four pounds. During the food search it moves in a zig-zag pattern, trotting at about 1/2 mile per hour, holding its head down with ears bent forward - presumably termites are detected by smell or hearing. Young animals have been observed vomiting after eating; presumably an immunity to the termite's toxin is built up rather than acquired.

If Trinervitermes termites are not sufficiently available, such as in the South African winter or in the rainy season in East Africa, aardwolfs will also eat other termites such as Hodotermes, Microhodotermes, Odontotermes or Macrotermes, with the drawback that they swarm in much smaller numbers. Aardwolfs will consume other insects or spiders, but rarely. They generally do not need to drink, but absorb the liquid they need from the termites. Exceptions are very cold winters, when there are few termites. forcing the animals to go considerable distances in order to reach water sources.

Reproduction

In southern Africa the mating season is in the last week of June or in the first two weeks of July; in the warmer regions further north, the reproduction is probably less seasonal. The gestation period is around 90 days, in South Africa the births fall into the early October. The litter size in the wild is two to four cubs, in captivity it can be up to five.

After about a month, they explore outside the den for six to nine weeks, but not more than 100 feet from the entrance. At nine to twelve weeks they accompany adult animals for the first time, but they remain at a maximum distance of 300 feet from the den. At twelve to sixteen weeks they roam the whole territory with the adults, and are weaned at the end of this period. In contrast to the other hyena species, young aardwolfs grow rapidly and reach their full weight at four months. This is probably an adaptation to minimize the high mortality rate in the first winter, the time with the least food supply.

Up to the age of about seven months, the young animals are sometimes accompanied by an adult when looking for food, after which they undertake their forays alone. With about a year lead their forays more and more away from the parental area. When the one-year-olds leave the den for the first time, they move away completely and try to establish their own territories. Sexual maturity is about 1.5 years.

In a study carried out in South Africa between 1981 and 1984, 68% of the young animals survived the first year of life. The maximum age of an animal in human custody was 15 years; life expectancy in the wild is not known, but is undoubtedly lower.

Threats

Domestic dogs, jackals, any of the larger cats, and roadside accidents are threats to aardwolfs, and at one time human persecution under the mistaken belief that they attacked sheep and chickens. Some African tribes hunt aardwolfs to eat their meat or use their body parts for medicinal purposes.

The greatest danger comes from insecticides used to control grasshoppers or termites, which can significantly decimate aardwolf populations or can even lead to local eradication. Farmers and ranchers, although not hunting them as in the past, have also inadvertently driven away aardwolfs by removing termite mounds.

The IUCN estimates the overall population as stable and lists the species as least concern. Estimates of the total population amount to at least several thousand individuals, but because of their shy, nocturnal way of life, the species could be more frequent than previously thought.

References

• Kay E. Holekamp and Joseph M. Kolowski: "Family Hyaenidae (Hyenas)". In: Don E. Wilson, Russell A. Mittermeier: Handbook of the Mammals of the World. Volume 1: Carnivores. Lynx Editions, 2009