The spotted hyena (Crocuta crocuta), also known as the laughing hyena, is a hyena species, currently classed as the sole extant member of the genus Crocuta, native to sub-Saharan Africa. It is listed as being of least concern by the IUCN due to its widespread range and large numbers estimated between 27,000 and 47,000 individuals. The species is, however, experiencing declines outside of protected areas due to habitat loss and poaching. Populations of Crocuta, usually considered a subspecies of Crocuta crocuta, known as cave hyenas, roamed across Eurasia for at least one million years until the end of the Late Pleistocene. The spotted hyena is the largest extant member of the Hyaenidae, and is further physically distinguished from other species by its vaguely bear-like build, rounded ears, less prominent mane, spotted pelt, more dual-purposed dentition, fewer nipples, and pseudo-penis. It is the only placental mammalian species where females have a pseudo-penis and lack an external vaginal opening.
The spotted hyena is the most social of the Carnivora in that it has the largest group sizes and most complex social behaviours. Its social organisation is unlike that of any other carnivore, bearing closer resemblance to that of cercopithecine primates (baboons and macaques) with respect to group size, hierarchical structure, and frequency of social interaction among both kin and unrelated group-mates. The social system of the spotted hyena is openly competitive, with access to kills, mating opportunities and the time of dispersal for males depending on the ability to dominate other clan-members and form ally networks. Females provide only for their own cubs rather than assist each other, and males display no paternal care. However, the spotted hyena is also very cooperative with their clan-mates; often hunting, eating, and resting together, and making use of their numeracy and communication skills to fight off a common enemy. Spotted hyena society is matriarchal; females are larger than males and dominate them.
The spotted hyena is a highly successful animal, being the most common large carnivore in Africa. Its success is due in part to its adaptability and opportunism; it is primarily a hunter but may also scavenge, with the capacity to eat and digest skin, bone and other animal waste. In functional terms, the spotted hyena makes the most efficient use of animal matter of all African carnivores. The spotted hyena displays greater plasticity in its hunting and foraging behaviour than other African carnivores; it hunts alone, in small parties of 2–5 individuals, or in large groups. During a hunt, spotted hyenas often run through ungulate herds to select an individual to attack. Once selected, their prey is chased over a long distance, often several kilometres, at speeds of up to 60 kilometres per hour (37 mph).
The spotted hyena has a long history of interaction with humanity; depictions of the species exist from the Upper Paleolithic period, with carvings and paintings from the Lascaux and Chauvet Caves. The species has a largely negative reputation in both Western culture and African folklore. In the former, the species is mostly regarded as ugly and cowardly, while in the latter, it is viewed as greedy, gluttonous, stupid, and foolish, yet powerful and potentially dangerous. The majority of Western perceptions on the species can be found in the writings of Aristotle and Pliny the Elder, though in relatively unjudgmental form. Explicit, negative judgments occur in the Physiologus, where the animal is depicted as a hermaphrodite and grave-robber. The IUCN's hyena specialist group identifies the spotted hyena's negative reputation as detrimental to the species' continued survival, both in captivity and the wild.
Spotted hyenas are social animals that live in large communities (referred to as "clans") which can consist of at most 80 individuals. Group-size varies geographically; in the Serengeti, where prey is migratory, clans are smaller than those in the Ngorongoro Crater, where prey is sedentary. Spotted hyena clans are more compact and unified than wolf packs, but are not as closely knit as those of African wild dogs.
Females usually dominate males, including in cases where low-ranking females generally dominate over high-ranking males, but they will also occasionally co-dominate with a male. There have also been cases in which a clan has been led by a male rather than a female. Cubs take the rank directly below their mothers at birth. So when the matriarch passes away (or, in rare instances, disperses into another clan, their youngest female cub will take over as matriarch. It is typical for females to remain with their natal clan, thus large clans usually contain several matrilines, whereas males typically disperse from their natal clan at the age of 2½ years. When a male co-dominates with a female or is otherwise able to lead, this is because the male was born to the matriarch of the clan and has taken the rank directly below his mother.
The clan is a fission–fusion society, in which clan-members do not often remain together, but may forage in small groups. High-ranking hyenas maintain their position through aggression directed against lower-ranking clan-members. Spotted hyena hierarchy is nepotistic; the offspring of dominant females automatically outrank adult females subordinate to their mother. However, rank in spotted hyena cubs is greatly dependent on the presence of the mother; low-ranking adults may act aggressively toward higher-ranking cubs when the mother is absent. Although individual spotted hyenas only care for their own young, and males take no part in raising their young, cubs are able to identify relatives as distantly related as great-aunts. Also, males associate more closely with their own daughters rather than unrelated cubs, and the latter favor their fathers by acting less aggressively toward them.
The length of the gestation period tends to vary greatly, but the average length is 110 days. In the final stages of pregnancy, dominant females provide their developing offspring with higher androgen levels than lower-ranking mothers do. The higher androgen levels – the result of high concentrations of ovarian androstenedione – are thought to be responsible for the extreme masculinization of female behavior and morphology. This has the effect of rendering the cubs of dominant females more aggressive and sexually active than those of lower ranking hyenas; high ranking male cubs will attempt to mount females earlier than lower ranking males.] The average litter consists of two cubs, with three occasionally being reported. Males take no part in the raising of young. Giving birth is difficult for female hyenas, as the females give birth through their narrow clitoris, and spotted hyena cubs are the largest carnivoran young relative to their mothers' weight. During parturition, the clitoris ruptures to facilitate the passage of the young, and may take weeks to heal.
Territory size is highly variable, ranging from less than 40 km2 in the Ngorongoro Crater to over 1,000 km2 in the Kalahari. Home ranges are defended through vocal displays, scent marking and boundary patrols. Clans mark their territories by either pasting or pawing in special latrines located on clan range boundaries. Spotted hyenas use scent gland secretions to distinguish between members of their own clan and members of neighboring clans. Within the same clan, differences in scent gland compositions can help individuals differentiate the reproductive states and sex of their members. One study analyzed the scent gland secretions of several hyenas belonging to three different clans and discovered a high degree of similarity in fatty acid composition among members of the same clans, while hyenas of different clans had more dissimilar scent gland secretions. Further studies have proposed a symbiotic relationship between spotted hyenas and their scent gland bacteria, where the differences in fatty acids can be attributed to fermentation by different microbes. Clan boundaries are usually respected; hyenas chasing prey have been observed to stop dead in their tracks once their prey crosses into another clan's range. Hyenas will however ignore clan boundaries in times of food shortage. Males are more likely to enter another clan's territory than females are, as they are less attached to their natal group and will leave it when in search of a mate. Hyenas travelling in another clan's home range typically exhibit bodily postures associated with fear, particularly when meeting other hyenas. An intruder can be accepted into another clan after a long period of time if it persists in wandering into the clan's territory, dens or kills.
The clan's social life revolves around a communal den. While some clans may use particular den sites for years, others may use several different dens within a year or several den sites simultaneously. Spotted hyena dens can have more than a dozen entrances, and are mostly located on flat ground. The tunnels are usually oval in section, being wider than they are high, and narrow down from an entrance width of ½–1 metre (1.6–7.7 ft) to as small as 25 cm (9.8 in). In the rocky areas of East Africa and Congo, spotted hyenas use caves as dens, while those in the Serengeti use kopjes as resting areas in daylight hours. Dens have large bare patches around their entrances, where hyenas move or lie down on. Because of their size, adult hyenas are incapable of using the full extent of their burrows, as most tunnels are dug by cubs or smaller animals. The structure of the den, consisting of small underground channels, is likely an effective anti-predator device which protects cubs from predation during the absence of the mother. Spotted hyenas rarely dig their own dens, having been observed for the most part to use the abandoned burrows of warthogs, springhares and jackals. Faeces are usually deposited 20 metres (66 feet) away from the den, though they urinate wherever they happen to be. Dens are used mostly by several females at once, and it is not uncommon to see up to 20 cubs at a single site. The general form of a spotted hyena den is tunnel-shaped, with a spacious end chamber used for sleeping or breeding. This chamber measures up to 2 metres (6.6 feet) in width, the height being rather less. Females generally give birth at the communal den or a private birth den. The latter is primarily used by low status females to maintain continual access to their cubs, as well as ensure that they become acquainted with their cubs before transferral to the communal den.
