Proteles cristata
aardwolf

Aardwolves (Proteles cristata, Sparrman 1783) are found in two, disjunct populations in Africa. Aardwolves are found in southern Zambia, Angola, and Mozambique, as well as northeastern Uganda and Somalia. The northeastern population, the subspecies Proteles cristata septentrionalis, also extends into central Tanzania, Ethiopia, Sudan, and Egypt. Southern populations are considered the subspecies Proteles cristata cristata. (Gingerich, 1974; Koehler and Richardson, 1990; Sliwa, 1996)

Aardwolves inhabit dry, open savannas and grasslands, where annual rainfall averages below 80 cm. They avoid deserts or heavily wooded areas. Northeastern and southern populations are separated entirely by wet woodlands. Aardwolves are shy, solitary foragers who require up to 4 square kilometers of territory for optimal survival. This area is typically only shared with a mating partner and/or young from the current or previous year. During daylight hours, times of whelping, and extreme environmental conditions, aardwolves retreat to subterranean dens, usually previously dug by aardvarks or springhare species. (Anderson and Richardson, 2005; Gingerich, 1974; Koehler and Richardson, 1990)

Aardwolves have dark stripes on buff-yellow or dark brown fur, as well as a thick mane running from the back of the head to the tail. Intermittent spots or stripes on a pale gray-white neck may be seen. Feet are usually dark solid black with irregular horizontal stripes on the legs. Total length ranges from 850 to 1050 mm and the tail alone makes up 200 to 300 mm of this total length. Weight ranges from 8 to 14 kg. Males and females exhibit no sexual dimorphism in color or size. All aardwolves have large, pointed ears, slender skulls, and reduced molars due to a diet exclusively of termites. Like all members of Hyaenidae, they have forelegs longer than hind legs, creating a sloped stature.

Aardwolves bear a striking resemblance to striped hyenas (Hyaena hyaena), which are sympatric in the northeastern portion of their range. Both have similar fur texture and color, though aardwolves tend to have more regular stripes and are only a quarter the body mass of striped hyenas. Questions have been raised about this similarity as a rare form of Batesian mimicry among mammals, but no conclusive evidence is recognized. (Gingerich, 1974; Goodhart, 1975; Koehler and Richardson, 1990; Sliwa, 1996)

Mating occurs during the last two weeks of June and the first two weeks of July. Scent "pasting" with anal gland secretions by both males and females is used to attract partners. Males are extremely territorial over both land and mates, in and out of mating season. They will not necessarily remain monogamous; aggressive males are known to copulate with neighboring females already with weaker mates, and litters may be fathered by more than one male. (Koehler and Richardson, 1990)

Aardwolves copulate and produce offspring during summer. Females gestate for approximately 90 days after fertilization, giving birth to 2 to 5 cubs. These cubs remain solely underground in a den for the first month and continue to increase their foraging distance from the den every couple of months (with parental supervision). Weaning is usually completed by four months of age, yet complete independence may not be established until almost one year of age. (Koehler and Richardson, 1990; Sliwa, 1996)

Males and females care for their young through the first, juvenile year. Aardwolf pups remain under parental supervision up to one year old, with solitary foraging beginning around 7 months old. While pups are still small, male aardwolves invest most of their energy in guarding the den, while females leave to forage. (Koehler and Richardson, 1990)

No data on the average lifespan of aardwolves in the wild has been recorded. However, closely related spotted hyenas (Crocuta crocuta) and many other species in the Family Hyaenidae may exceed 18 years in the wild. The maximum lifespan documented for aardwolves was a 20 year-old captive female. (Holekamp and Smale, 1998; Koehler and Richardson, 1990; de Magalhaes, et al., 2009)

Aardwolves are mainly nocturnal mammals that remain solitary or in pairs for the majority of their lifespan. During the day aardwolves retreat to subterranean dens to rest and escape extreme heat, although during winter months they may resurface during late afternoons to forage. Small groups in the same territory may forage together during winter, but only within a distance of approximately 100 meters of another aardwolf. Females spend both days and nights in dens while supervising cubs, relying on the male partner for protection. Dens are occupied no longer than 8 weeks at a time before aardwolves relocate. (Anderson and Richardson, 2005; Koehler and Richardson, 1990; Nel and Bothma, 1983; Sliwa and Richardson, 1998; Sliwa, 1996; Walker, 1996)

Home range size is from 1 to 4 square kilometers per individual or pair. (Koehler and Richardson, 1990)

Aardwolves communicate primarily through anal gland scent marking. These smear marks are rubbed on foliage to establish territories and attract potential mates. Males tend to mark more often than females. Scent marks from a foreign P. cristatus may cause a male or female to relocate dens, but marks from a mate are continuously over-marked until the scent is covered. Vocal communication is rare, only being used when startled, fighting, or stressed. These distress calls range from clucking to roaring. Keen sight and sound perception are used when searching for termites at night. (Apps, 2008; Koehler and Richardson, 1990; Mills, et al., 1984; Nel and Bothma, 1983; Sliwa and Richardson, 1998)

Abundant scent marking by both genders is used to communicate. Within a home range, aardwolves bury their feces in common middens that are marked by anal gland secretions. If intruders are discovered on any marked territory, they show aggressive behavior and warn by erecting a tall mane of hair down the backside that makes them seem much larger than they are. Pups begin to exhibit fluffing of the tail while learning to play with siblings. This defensive stance may initially be used between two familiar aardwolves in the same territory, but will be suppressed upon successful recognition. Though molars and canine teeth are reduced, powerful jaws and claws have been retained for combat. If startled, a foul secretion from the anal glands may be released. (Apps, 2008; Koehler and Richardson, 1990; Mills, et al., 1984; Nel and Bothma, 1983; Sliwa and Richardson, 1998)

The diet of aardwolves consists solely of termites belonging to the groups Trinervitermes and Hodotermes. Consumption of these termites depends on their abundance and seasons; Trinervitermes species remain active only during warmer months and Hodotermes species remain active into cooler months. Harvester termites from the Trinervitermes group release a terpene toxin that deters many of their predators, however, aardwolves shows no aversion to this secretion. Aardwolves consume their prey by licking termites off surfaces using a flat, sticky tongue. With this method, they may consume up to 300,000 termites every night. Very little water is required, as termites usually supplement needed fluid intake. (Koehler and Richardson, 1990; Matsebula, et al., 2009; Richardson and Levitan, 1994)

Adult aardwolves have no significant predators. Pups are vulnerable to black-backed jackals (Canis mesomelas) unless well-protected by males in dens. Humans (Homo sapiens) may affect populations; African farmers mistake these passive hyaenids as threats to livestock and kill aardwolves discovered on their land. Motor vehicle collisions contribute to mortality as well, although aardwolves usually avoid roadways. Domestic dogs (Canis lupus familiaris) trained to hunt foxes and jackals will also mistakenly attack aardwolves in the wild. (Anderson, 2005; Koehler and Richardson, 1990)

Aardwolves significantly limit termite populations throughout their range, preventing extensive wood damage for both humans and natural habitats. Aardwolf density and foraging techniques have noninvasive impacts on the ecosystem. Aardwolves and brown hyenas (Hyaena brunnea) are the only known hosts of two subspecies of mallophagous louse, Felicola intermedius intermedius and F. i. hyaenae. Aardwolves may also carry the parasite Haemaphysalis zumpti, a tick that favors small burrowing mammals. (Hoogstraal and El Kammah, 1974; Koehler and Richardson, 1990)

Aardwolves play a key role in pest control, consuming up to 105,000,000 termites per individual a year. The grasslands where these termites feed are the main food source for domestic livestock, and aardwolves may prevent significant crop damage for African farmers. (Koehler and Richardson, 1990)

There are no known adverse effects of P. cristata on humans.

Aardwolf populations remain stable across the majority of their African habitat and are not considered threatened. However, sightings are rare due to their timid and nocturnal behavior; aardwolf densities usually do not exceed 1 adult per square km. (Koehler and Richardson, 1990; Skinner and van Aarde, 1983)

Despite numerous similarities to other hyaenid species, aardwolves were once classified in their own family, Protelidae. (Koehler and Richardson, 1990)