Spotted hyaenas in most parts of Africa give birth at any time of year to litters containing one or two cubs, although triplet litters are occasionally reported as well (Frank et al. 1991; Wahaj et al 2007). Females may give birth at the communal den or in a private birth den (East et al. 1989, Henschel and Skinner 1990b; White 2006). Mothers with low social status probably use birth dens away from the communal den to ensure that they can maintain continuous access to their cubs (White 2006). Mothers might also use isolated birth dens to ensure they become acquainted with their cubs before they transfer them to the communal den (East et al. 1989), although this seems unlikely as efficient mother-infant recognition occurs even when cubs are born in communal dens. As there are often several animals present at the communal den, cubs probably benefit from the vigilance of adults that can alert young to the presence of predators. Social interactions at the communal den between cubs and older members of the clan probably play an important role in helping cubs to integrate themselves into the dominance structure of the clan (Holekamp and Smale 1991, 1993, East et al. 1993; Drea et al. 1996). Cubs are maintained at the communal den for a period of 8 to 12 months; during this period the major source of food for cubs is milk provided solely by their mother (Hofer and East 1993c, Frank et al. 1995a).
Spotted hyaenas mating. Photos by Sofia. A Wahaj (right) and Jacob Bro-Jorgensen (left).
Females give birth through their penis-like clitoris. During parturition, the clitoris ruptures to permit the passage of the young, creating a large bleeding wound of several centimetres that can take weeks to heal. Age at first parturition varies substantially between two and five years (Frank et al. 1995a, Holekamp et al 1996; Hofer & East 1996). As all females reproduce and females rear their young together in the communal den, occupied dens may contain up to 30 young of different ages from up to 20 litters. Females usually nurse only their own cubs and reject approaches by other cubs. An exception to this rule was observed during a difficult period in the Kalahari when several mothers suckled offspring communally (Knight et al. 1992). Cubs are nursed for a prolonged period and not weaned until they are between 14 and 18 months of age (Hofer & East 1993c; Holekamp et al. 1996). The milk of the spotted hyaena has the highest protein content (mean 14.9%) recorded for any terrestrial carnivore, a fat content (mean 14.1%) exceeded only by that of palaearctic bears and the sea otter, and a higher gross energy density than the milk of most terrestrial carnivores (Hofer & East 1995a). Due to their milk’s high energy content and the long nursing period, spotted hyaenas have the highest energetic investment per litter of any carnivore (Oftedal & Gittleman 1989).
Reproductive success is related to dominance status in that high-ranking females have a higher reproductive success because they have a shorter interbirth interval and a better chance of rearing young successfully (Frank et al. 1995a; Holekamp et al. 1996; Hofer & East 2003). Sex ratios amongst adults are usually even or slightly female-biased (Mills 1990, Hofer & East 1993a, Frank et al. 1995a). Significant deviations in offspring sex ratios in singleton and twin litters are observed in some populations when cubs can first be sexed at the age of two to three months (Frank et al. 1991) and remain until weaning (Hofer and East 1997). Such deviations in the sex ratio from the expected distribution may be either due to changes in the sex ratio at conception (Holekamp & Smale 1995) or to sex-specific siblicide after birth (Hofer & East 1997).
Males disperse from their natal clan shortly after becoming reproductively mature, which is usually when they are two years old (Smale et al. 1997; Boydston et al. 2005), thus reproductively successful males are usually immigrants (Engh et al. 2001; Honer et al. 2007). Newly immigrant males join the male dominance hierarchy at the very bottom, beneath all females and natal males (Smale et al. 1997). Males increase in social status as their tenure in the clan increases (Frank 1986a, Mills 1990, East et al. 1993). Males invest considerable time in developing amicable relationships with clan females (East et al. 2003; Szykman et al. 2001; 2007). They do this in some cases by forming consortships and following females for periods of days or weeks (East et al. 2003; Szykman et al. 2007). Males that have devoted many years to developing relationships with females may be favoured by females and thus these males may father more cubs than immigrants with short-term tenure in a clan. Males attempting to mate with females in their natal clans fare very poorly compared to immigrants, so female preferences for immigrants may have promoted the evolution of natal dispersal by males n this species (Engh et al. 2002).
The spotted hyaena is one the most highly gregarious of all carnivores; it lives in groups containing up to 90 individuals, and exhibits the most complex social behaviour. These animals live in social groups called clans that defend group territories. The society is characterised by a strict dominance hierarchy. The rank ordering among the adult females in one Kenyan study clan is shown below. Females are ordered on the left as winners in fights, arranged from top to bottom in descending order of the number of other females they can defeat in the group. The same females are listed as losers in fights across the top horizontal axis, and the numbers in the matrix represent the number of fights observed within female dyads in which there was a clear winner and a clear loser. Notice how few fight outcomes are inconsistent with the rank order assigned here.
Females are dominant over males, and even the lowest ranking female is dominant to the highest ranking male. Although males typically disperse from their natal clans when they are between two and six years of age (Smale et al 1997; Boydston et al. 2005), females usually remain in their natal clan, so large clans may contain several different matrilines. Although cubs of both sexes ‘inherit’ their mothers’ social ranks, males voluntarily forsake those to assume much lower ranks in the neighboring cans to which they disperse. (Smale et al 1997; Holekamp & Smale 1998). It appears that female mate choice drives male dispersal (Honer et al. 2007), although it remains controversial whether females merely prefer immigrants over natal males or whether they follow alternative rules of thumb.
Watch a number of spotted hyenas join forces to drive some lions off their kill at the following URL: http://www.youtube.com/watch?v=8zjPWpdyC74
Here you will hear the hyenas giggling (expressing nervousness) and whooping (calling in more recruits to help deal with the lions) and lowing. Lowing appears to be a vocalization that functions to bring all hyenas present to the same state of arousal in order for them to engage in a coordinated attack on the lions. Notice that the vocalizations stop as soon as the hyenas displace the lions from thir kill.
Spotted hyaenas live in a “fission-fusion” society, so clan members do not remain together continuously, but instead frequently forage alone or in small groups. Clan members co-operate in communal defense of the territory, of food resources, and the clan den. As with many monkeys and apes, female spotted hyaena cubs normally acquire dominance immediately below that of their mother. “Social politics” among clan members are very important in hyaena society, with individuals regularly forging alliances and coalitions. Overall, spotted hyaena society is characterized by its flexible nature, as demonstrated by impressive variation in group size, territorial behavior, foraging tactics, and nursing behavior.
Clan Size: Unlike many other social species where all group members are usually seen together, spotted hyaena clan members frequently wander alone or in small groups and only sometimes meet in large numbers. This occurs at kills, at the communal den, or when clan members rally together to defend individual carcasses or group territories (Kruuk 1972a, Tilson and Hamilton 1984, Henschel 1986, Frank 1986a. Cooper 1989, Mills 1990, Hofer and East 1993a).
The average number of adults and subadults in a clan varies from three in desert and semi-desert areas of southern Africa, to nearly 90 in the prey-rich savannah areas of east Africa. Territory size and the density of prey inside a clan’s communal territory usually limit clan size, with a couple of interesting exceptions. First, in the Serengeti, an ecosystem dominated by migratory herbivores, hyaena density and clan size are not limited by resident herbivore density, as Serengeti spotted hyaenas regularly undertake foraging trips to feed on nearby migratory herds (Hofer and East 1993a,b, 1995a). Second, in Etosha national Park, Namibia, Trinkel et al. (2004) have found that spotted hyaenas engage in seasonal expansion or contraction of the size of their territories to accommodate distributional changes in their migratory prey.
Territories: Territory size in the spotted hyaena is highly variable, ranging from less than 40 km2 in the Ngorongoro Crater (Kruuk 1972a) to over 1,000 km2 in the Kalahari (Mills 1990). Clans defend communal territories through vocal displays (East and Hofer 1991b; Theis et al. 2007a), scent marking (Gorman and Mills 1984; Theis et al 2007b) and boundary patrols (Kruuk 1972a; Boydston et al 2001). Clan members also cooperate in defending territories during boundary disputes with neighbouring clans (Boydston et al 2001). Long distance calls, particularly whoops, are used to quickly rally clan members to such sites of conflict (Kruuk 1972a, Henschel and Skinner 1991, East and Hofer 1991 b; Theis et al 2007a). Spotted hyaenas scent mark their territories by pasting a secretion from the anal gland onto grass stalks, and by depositing a secretion from interdigital glands when they scratch the ground (Kruuk 1972a. Mills 1990′; Theis et al 2007b). Spotted hyaenas also scent mark their territories by defecating in communal latrines (Kruuk 1972a. Mills 1990). Pasting sites and communal latrines are normally scattered throughout a clan’s territory and this “hinterland” scent marking strategy (Gorman and Mills 1984) may be a way of optimising the distribution of scent marks over a large area with a limited amount of scent and time (Mills 1990). Some spotted hyaena territories in the eastern portion of the Masai Mara National reserve, Kenya, are shown in the figure below.
In the Serengeti, clans defend territories against neighbouring clans but individual animals may move in transit through other clan territories when they commute to distant migratory herds (Hofer and East 1993b). When migratory herds are present inside a clan territory, many non-residents also enter the territory to feed. Non-residents typically signal submission and retreat when detecting residents, and at kills non-residents usually wait at a distance and feed after residents have departed. Aggression between residents and non-residents is rare when commuters are in transit. Aggression is more common when residents encounter intruders searching for food, and most intense at kills where agonistic encounters may escalate into fights causing serious damage (Hofer and East 1993b). The commuting system of Serengeti hyaenas and the flexible response of territory owners to intruders illustrate the flexible nature of the social behaviour of spotted hyaenas (see also Knight et al. 1992).
Female dominance: Spotted hyaena society is female-dominated (Kruuk 1972a), with a clear, linear dominance hierarchy amongst first the female and then the male clan members (Frank 1986b). Top-ranking females have priority of access to large carcasses and this provides increased reproductive success in comparison with low-ranking females (Frank et al. 1995a; Holeamp et al 1996; Hofer & East 2003). Apart from males dispersing from natal territories, clans may split (fission) if current clan size exceeds a threshold above which the food base of the territory is insufficient (Mills 1990), or if a territory in the neighbourhood has become vacant (Holekamp et al. 1993).
Vocalizations: The highly social nature of the spotted hyaena has led to the evolution of a wide variety of vocalisations (Kruuk 1972a, Henschel 1986, Mills 1990). The best known spotted hyaena vocalisation is the whoop, which can be heard over several kilometres. Spotted hyaenas can recognise each other individually by their whoops, at least within their clan (East and Hofer 1991a). Whoops can function as a rallying call to gather scattered clan members together to defend territory boundaries, food resources, and the communal den. Mothers whoop to locate their wandering cubs and some animals whoop to recruit hunting partners. Whoops are also used as a form of individual display, particularly by animals of high rank (East and Hofer 1991b). Adult males whoop more frequently than females, and top-ranking males put more effort into vocal displays than lower ranking males (East and Hofer 1991b). Another well-known vocalisation is the laugh or giggle, which is a signal of submission. A submissive individual giggles to signal to its partner that it accepts a lower status.
Greeting ceremonies: The spotted hyaena has a ritualised greeting or meeting ceremony during which two individuals stand parallel and face in opposite directions. Both individuals usually lift the hind leg nearest to the other and sniff or lick the anogenital region of the other. The unique aspect of greetings between individuals is the prominent role of the erect “penis” in animals of both sexes. This is used to signal submission. Greetings occur between all ages and both sexes, although greetings between adult females and males are uncommon and are typically restricted to males above median rank, principally the alpha male. Cubs can erect their penis or clitoris and engage in greeting ceremonies as early as four weeks after birth (East et al. 1993).
The social life of a clan is centered around the communal den. Some clans use particular den sites for years whereas others may use several different dens within a year or even several den sites simultaneously. These may be separated by up to 7 km (Hofer and East 1993a). The dens are not excavated by hyaenas. Instead, dens have usually been abandoned by other species, mostly warthog, aardvark and bat-eared fox (Kruuk 1972a). The structure of dens does not normally permit the access of adult animals, so cubs must emerge at the den entrance to have contact with their mother. This structure of small channels underground has been considered an effective anti-predator device which protects cubs during the absence of their mother (Kruuk 1972a). Circumstantial evidence suggests that predation on cubs by other hyaenas (infanticide) or other carnivores may occur but is considered rare (Mills 1990). Infanticide has been observed in the Masai Mara (Holekamp et al unpublished data) and in the Serengeti (Kruuk 1972; Hofer and East 1995a). In Serengeti, only high-ranking females have been observed killing the offspring of low ranking females in the same clan (H. Hofer and M.L. East, unpublished data), but in the Masai Mara, low-ranking females have also been observed killing infants of higher-ranking females (Holekamp et al unpublished data).
These animals weigh 45-85 kg as adults, depending on sex (males weigh less than females) and capture location (hyaenas in southern Africa are larger than those in other parts of Africa).
Spotted hyaenas are hunters and scavengers and can even chase lions away from their kills.
Spotted hyaenas are intelligent, noisy, and gregarious, living in groups of as few as five or as many as 80 individuals. Spotted hyaenas are highly unusual among mammals because females in this species are socially dominant to males, the reverse of the situation in most mammalian species. This hyaena’s loud, cackling ‘giggle’ vocalization inspired the phrase “laughing like a hyena”. Many beliefs about spotted hyaenas are false: they do not have any magical powers, witches do not ride on their backs and they are not hermaphrodites. They produce unusually small litters relative to dogs or cats; spotted hyaenas give birth to 1 or 2 cubs (very rarely 3) at a time, and the mother typically feeds her young with rich milk for many months, often for over one year.
The spotted hyaena is still widely regarded as a scavenger that picks up leftovers at the kills of other carnivores (cheetah, leopard, lion) or feeds on carrion. However, this is not correct: all studies demonstrate that the spotted hyaena is an efficient predator in its own right. Although spotted hyenas will scavenge opportunistically, they kill as much as 95% of the food they eat (Cooper et al. 1999). The spotted hyaena is impressively versatile in its choice of prey, as its food varies greatly between ecosystems. In addition, it has developed a wide diversity of hunting techniques.
The spotted hyaena primarily kills and scavenges mammalian herbivores. These include small, medium and large-sized antelope, Cape buffalo, and other herbivores such as zebra, warthog, and the young of giraffe, hippopotamus and rhinoceros. It can be very opportunistic and has been recorded eating almost any mammal, bird, fish or reptile, irrespective of size or species (see Brown and Root 1971, Pienaar 1969, Kruuk 1972a, Eloff 1975, Kingdon 1977, Kruuk 1980, Tilson et al. 1980, Steizner and Strier 1981, Hitchins and Anderson 1983, Mills 1984, 1990, Henschel and Skinner 1990a, Sillero-Zubiri and Gottelli 1992a, Salnicki et al. 2001). It may also pick up carrion and human-associated organic material, including cooked porridge, offal, garbage, a variety of vegetable matter, and buffalo and wildebeest dung. The spotted hyaena has a reputation for killing and scavenging domestic stock, mostly cattle, sheep and goats, but also poultry, cats, dogs, horses, donkeys, and camels (see below). These predatory activities have actually been observed.
The spotted hyaena detects live prey by sight, hearing, and smell. It detects carrion by smell, the noise of other predators feeding on the carcass, or during daytime, by watching vultures descending on a carcass. Its hearing is acute enough to pick up noises emanating from predators killing prey or feeding on carcasses over distances of up to 10 km (Mills 1990).
Typically the spotted hyaena hunts solitarily or in small groups of two to five, although larger parties have been observed (Kruuk 1972a). During a hunt, individuals often run at moderate speeds through a herd of ungulates apparently looking at herd members before deciding which individual to attack. The spotted hyaena chases its prey over long distances, often several kilometers, at speeds of up to 60 km/h (Kruuk 1972a. Mills 1990). The maximum distance recorded was 24 km in pursuit of an eland in the Kalahari (Mills 1990). It has also been observed to run down flamingoes in shallow soda lakes (Brown and Root 1971) and to drown lechwe in flood plains by swimming after the fleeing prey (Child and Robbel 1975). Ambush attacks on resting wildebeest in the Serengeti (H. Hofer and M.L. East unpublished data) or solitary, standing topi in the Masai Mara in Kenya may also occur (Rainy and Rainy 1989).
The spotted hyaena travels long distances in search of prey. In the Kalahari, the average distance travelled between significant food items varied between 42 and 80 km (Eloff 1964, Mills 1990). In the Namib Desert, the maximum distance between the core area of a clan’s range and distant carcasses was 30 km (Tilson and Henschel 1986). In Chobe hyaenas walked up to 28 km between a clan range and a permanent source of water. In the Serengeti, all clan members frequently leave their territory during periods when migratory herds are absent from the clan territory, and go on foraging (commuting) trips to the nearest concentrations of migratory wildebeest, zebra and Thomson’s gazelles (Hofer and East 1993a,b,c). These trips last on average three days for lactating females, who need to return to the clan territory to nurse their young, and nine to ten days for non-lactating females and males. Lactating females commute between clan territory and migratory herds 40 to 50 times per year; other adults undertake fewer trips. As the average one-way distance between clan territory and the nearest migratory herds is 40 km, lactating females commute at least 2,880-3,680 km per year (Hofer and East 1993C). This is three times the annual distance covered by the migratory herds (Sinclair and Norton Griffiths 1979).
This large, dog-like animal has a spotted coat and is strongly built. Its general color is sandy, ginger or dull grey to greyish brown, with blackish or dark brown spots on the back, flanks, rump, and legs. Spots may turn brown and fade with age. The forelegs are longer than the hind legs so that the back slopes downwards to the base of the tail. The long, thick neck provides a highly muscular structure that complements the powerful cutting and ripping movements of the massive jaws. The hyaena’s jaws are sufficiently powerful to generate enormous bite forces. The head is large, rounded and powerful with a short and blunt muzzle. The ears are rounded, in contrast to the pointed ears of other hyaena species. The hair is short, coarse and woolly, and is composed of moderately fine underfur with a length of 15-20 mm, and longer, stouter, flat-sectioned bristle hairs with a length of 30-40 mm. Their four-toed feet have short, blunt, non-retractable claws and broad and flat pads. They have a short tail, comprised of approximately 24 cm of bone with an added 12 cm of hair only. The tail is narrow and fairly thin and ends in a black, bushy tip. Total body length is around 1.3 m and front shoulder height is 0.75 m. Body mass ranges from 45 kg for males and 55 kg for females in the Serengeti (H. Hofer and M.L. East, unpublished data) to more than 70 kg in southern Africa (see Mills 1990).
Scent glands, situated on either side of the rectum, discharge secretions into a sac situated between the tail and the anus. During scent marking the sac is everted and the secretions are deposited by the hyaena from a semi-crouched position while walking or standing over a grass stalk or small bush.
Spotted hyaenas are the most abundant large carnivore in Africa. Since the late 1990s, confirmed records of C. crocuta have come from Tanzania, Kenya, Zambia, Zimbabwe, Mozambique, South Africa, Botswana, Namibia, Congo, Sudan, Central African Republic, Cameroon, Nigeria, Burkina Faso, Ivory Coast, Mali, Senegal, and Sierra Leone. Although spotted hyaenas occur throughout sub-Saharan Africa, their density varies widely among different habitats; they have been extirpated from many parts of South Africa, but high densities occur in the Serengeti ecosystem, including Ngorongoro Crater in Tanzania, and in the Aberdare Mountains of Kenya.
Spotted hyaenas occur throughout most of sub-Saharan Africa in a suprisingly diverse array of habitat types. The figure below shows four of the habitat types in which spotted hyaenas occur: the open grassland of the Serengeti National Park in Tanzania (top left), the forests of Aberdares National Park in Kenya (top right), the Namib desert in Namibia (bottom left) and the Okavango Delta of Botswana (bottom right).
The spotted hyaena also inhabits semi-desert habitat, swamp and marshy areas, open woodland, dense dry woodland, and montane forest up to 4,000 m altitude (Kruuk 1972a). It is absent from or occurs in only very low densities in tropical rainforests and along coasts (e.g. Namibia). In west Africa, preferred habitats include the Guinea and Sudan savannahs. It does not occur in the belt of dense forest along the coast (Happold 1973). In the Namib Desert, it is found in riverine growth along seasonal rivers, the subdesertic pro-Namib and the adjoining inland plateau (Coetzee 1969). In prime habitat, densities of the spotted hyaena are higher than those of other large carnivores, including those of both the striped hyaena and brown hyaena. In desert and semi-desert regions, however, the brown hyaena and striped hyaena can occur at higher densities than the spotted hyaena (Mills 1990).
The spotted hyaena most frequently competes with the lion for kills (Kruuk 1972a, Schaller 1972a, Bearder 1977, Eaton 1979). Dominance relations between the spotted hyaena and competing species are not absolute but depend on the numerical presence of both parties. For instance, lions usually displace spotted hyaenas at kills. However, if hyaena group size is large and the ratio of the number of spotted hyaenas to the number of female and subadult lions exceeds four, hyaenas are often able to displace lions from kills unless a male lion is present (Cooper 1991). A single spotted hyaena usually dominates a cheetah, leopard (but not always), striped hyaena, brown hyaena, any species of jackal, and an African wild dog (but not a pack) (Kruuk 1972a, Eaton 1979, Mills 1990).
The proportion of diet that the spotted hyaena scavenges from kills of other predators, or loses to other predators, varies substantially between ecosystems. When spotted hyaenas outnumbered lions ten to one in the Ngorongoro Crater, lions usually scavenged from kills made by spotted hyaenas (Kruuk 1972a; Honer et al 2002; 2005). In the Serengeti and in Timbavati, where lion and spotted hyaena numbers are much more even, both species scavenge approximately the same proportion of their diet from each other’s kills (Kruuk 1972a, Schaller 1972a, Bearder 1975). In the Kruger National Park spotted hyaenas scavenge far more from lions than vice versa (Mills and Biggs 1993). The ability of spotted hyaenas to scavenge from lions may also vary over time as the relative numbers of the two species change (Honer et al 2002; 2005).
The spotted hyena has been, and still is, widely shot, poisoned, trapped, and snared, even inside some protected areas. Persecution most often occurs in farming areas after confirmed or assumed damage to livestock, or as a preventative measure to protect livestock. However, it may also take place “for fun” and as “target practice” (Namibia, Kenya), and out of fear of the animal. Persecution appears to be the prime source of population decline, which appears to be more pronounced outside protected areas than inside. Most populations in protected areas in southern Africa are considered to be stable, whereas many populations in eastern and western Africa, even in protected areas, are considered to be declining, mostly due to incidental snaring and poisoning. Although sport hunting is permitted in several countries after purchasing a sport hunting license, the numbers killed by sport hunters are small as hyaenas are not considered an attractive species. Spotted hyaenas are also killed for use of their body parts as food or medicine. Destruction of habitat operates mostly indirectly; habitat loss and degradation and overgrazing by domestic stock reduce the habitat available to populations of wildlife that are suitable prey for the spotted hyaena.
Spotted hyaenas sometimes attack livestock owned by African farmers or pastoralists and these people may retaliate by large-scale poisoning of local hyaenas.
Official attitudes towards the spotted hyaena vary widely from positive attitudes of active protection, through benign neglect, to negative ones of considering the species vermin. Legal classification varies from “vermin” (Ethiopia) to fully protected in conservation areas. Thus, while it is fully protected in the Serengeti National Park in Tanzania, the spotted hyaena may be legally shot by sport hunters in the adjacent Maswa Game Reserve. According to a questionnaire survey performed by the HSG, regulations and wildlife laws in most countries are only enforced as far as financial, logistical and manpower constraints allow them to be (often inadequately). Bounty systems do not operate any more in eastern or southern Africa, although there are still countries where farmers may kill hyaenas at their discretion. A bounty is apparently still offered in Cameroon. There is no information on the presence or absence of bounty systems available from a number of Sahel countries in west Africa.
The total world population size of the spotted hyaena is well above 10,000 individuals, several subpopulations exceed 1000 individuals and its range well exceeds 20,000 sq.km. The rapid decline of populations outside conservation areas due to persecution and habitat loss makes the species increasingly dependent on the continued existence of protected areas. The HSG therefore agrees with the latest classification of the spotted hyaena as Lower Risk: conservation dependent (IUCN 2000).