The King's Enemies

Made famous (or perhaps infamous) in ‘The Lion King’ as the antagonists alongside the dastardly lion Scar, hyenas have often found themselves the victims of both a bad reputation and taxonomic misclassification. With their outwardly canine resemblance, you could certainly be forgiven for thinking that hyenas are just large dogs. While deceptively doglike, hyenas are surprisingly more closely related to our furry feline friends, though they are still distant cousins. But if neither canine nor feline, then what exactly is a hyena?

Mammalian carnivores can be split into two different groups: the Caniformia (dog-like) and the Feliformia (cat-like). Caniformia includes animals like dogs, bears, and seals, while Feliformia includes cats, mongooses, and hyenas. Within Feliformia, we find that hyenas have been given their own family, the Hyaenidae. The evolutionary history of hyenas is fascinating in its own right. A relatively recent entrant to the mammals, hyenas first arose around 20 million years ago, splitting off from a civet-like ancestor and then forming two distinct lineages: dog-like and bone-crushing.

The dog-like hyenas experienced as rapid an extinction as they did diversification, ironically due to being outcompeted by ancestral canids in the face of a changing climate. The bone-crushers fared somewhat better, adapting to the presence of competitors by carving out a new niche largely as scavengers. Today, the once-flourishing Hyaenidae is one of the smallest mammal groups, represented by just four living species. The chart below, called a cladogram, highlights the evolutionary relationships between today’s hyena species and was constructed using a mitochondrial gene called cytochrome oxidase I. This gene is often used in genetics work because it is generally good at distinguishing different species as it evolves relatively fast compared to other genes. Recent work using complete hyena genomes also agrees with this version of events.

As you may have inferred from the cladogram underneath, the aardwolf, or Proteles cristata is thought to be the most ancient of the hyena species. Without closer inspection, one might mistake this creature for one of the fox species that shares its African homeland due to its diminutive size and decidedly vulpine features. It is perhaps this that betrays its status as the sole-surviving remnant of the dog-like hyena lineage. Like some canid species, aardwolves have evolved similar social behaviour, living in packs of a single male, female, and their offspring. Their superficial and social similarity with canids is where the association ceases.

While it may be expected that the nocturnal aardwolf would be a voracious predator of small mammals and birds like other carnivores its size, it is in fact a rather strict insectivore. In a single night, aardwolves are said to be able to eat some 250,000 unsuspecting insects. Despite this, they are picky eaters. Though dietary analysis has revealed the occasional snack of arachnids and other arthropods, aardwolves overwhelmingly subsist on certain species of termites which inhabit the grasslands of southern and eastern Africa. This fussiness leads aardwolves to be rather elusive as they must live in low densities to avoid competition for their scarce food sources. Despite general rarity, their conservation status is perhaps the least precarious of all hyenas, and numbers remain stable throughout their range.

Unfortunately, the same cannot be said for the three remaining descendants of the bone-crushing lineage, all of which are suffering from declining populations. The brown hyena (Parahyaena brunnea) is sympatric (i.e. found together) with the aardwolf across much of its range in southern Africa, although the former is adapted to a greater number of habitat types rather than just grasslands, including wetlands, montane, and surprisingly coastal where it may be observed opportunistically feeding on fur seal pups. As its name suggests, it sports a scruffy brown coat. Its sloped top line and very canine facial features almost give it the outline of a German shepherd, if not for the hairs on its back that can be raised at will to scare off would-be aggressors.

This is apparently not scary enough to humans however. The brown hyena’s conservation status is currently Near Threatened and its overall population is thought to be the lowest of the four species. Often, this hyena comes into conflict with people due to the belief that they represent a threat to livestock. While this may be true for the other bone-crushers featured later in this article, the brown hyena is a comparatively terrible hunter and almost completely relies on scavenging from carrion or stealing food from other predators (known as kleptoparasitism). Still, studies have found that a large percentage of farmers (some 40% in South Africa, and as great as 72% in Namibia) believe that this species is responsible for livestock kills, in spite of evidence to the contrary.

As the cladogram above suggests, the brown hyena is very closely related to the striped hyena (Hyaena hyaena), a species whose range spans not just northern and eastern Africa, but throughout the Middle East and well into central and southern Asia. This makes it the most widespread of all hyenas. The striped hyena has a smaller, yet similar build to that of the brown hyena but its raisable mane is much more impressive, and superficially shows the group’s close relationship to the civet family (see pictures).

Much like the aardwolf, it has a sandy coloured coat with striking black stripes. While a marginally better hunter than the brown hyena, striped hyenas are also largely scavengers, feeding from the kills of a large variety of predators across their range. While they often yield to large cats, striped hyenas have been reported to not just coexist with but live alongside grey wolves in the Eurasian parts of their range in what appears to be a mutually beneficial association.

Like brown hyenas, the striped hyena’s conservation status is also Near Threatened. Interestingly, both species have had low levels of genetic diversity throughout much of their evolutionary history though have surprisingly escaped many of the problems that arise in such a scenario (e.g. poor reproductive output, skeletal and tissue deformities, susceptibility to disease and environmental change). However, with a declining population, the striped hyena may not be able to withstand such pressures much longer.

This animal is not just threatened by farmers, but also because of the fear of rabies in some areas, leading to indiscriminate and often indirect poisoning. Additionally, there is a whirl of superstition surrounding the striped hyena. They are associated with death due their main ecological role as scavengers. They are thought of - and despised - among some cultures as grave robbers and witches’ steeds, and in others as devil-touched. Such negative associations have not put off other regions such as Arabia, where they are both considered a Halal delicacy and used in traditional medicine due to the belief that they wield magical powers. This makes them a lucrative catch for hunters. Persecution and recently increased demand for meat and medicine is wholly unsustainable, leaving populations in the Mediterranean areas of the Middle East and North Africa stricken, particularly in Morrocco where it is at severe risk of local extinction. Around the Mediterranean, the striped hyena has a separate conservation status of Vulnerable compared to its global assessment because of these threats. Despite the fear and hated these animals are subject to, attacks on humans are extremely unusual and they have even been described as ‘quite gentle’.

Perhaps the best-known hyena, due to its characteristic laughing call is the largest extant species, the spotted hyena (Crocuta crocuta). Having diverged from the brown and striped hyenas over 10 million years ago, this species became widespread across Eurasia and Africa and has had a long and enduring association with humans throughout our own history. Today, they are confined to Sub-Saharan Africa but remain the most numerous of all hyenids. Owing to their once wide range, their levels of genetic diversity are much higher than that of their cousins. It is known that they extensively interbred with the much larger (and maybe luckily for us, now extinct) European cave hyena, considered a subspecies of today’s spotted hyena.

Superficially, these hyenas lack the extensive mane and large, triangular ears of the other species, their coats switching stripes for spots. Their social behaviours and reproductive morphology, however, is unlike anything else seen within mammals and makes them fascinatingly unique. While other bone-crushing hyenas are either solitary or come together in small groups (called clans), spotted hyenas’ social structures are extremely fluid. Clans converge, sometimes in massive numbers, and then diverge into smaller groups over time in what is known as a fission-fusion society. This social system has parallels with those of some whale species (e.g. orcas). Both are also heavily matrilineal (led by the females) and comparisons can be drawn between the impressive arrays of communicative noises used by these animals.

However, where whale pods are largely cooperative, spotted hyena clans determine rank by conflict and dominance. In this species, females down the hierarchy generally outsize and outrank males. They display other typically male characteristics including increased aggression from birth - which can and does result in the death of littermates. Unlike other hyenas, spotted hyenas are not monogamous and females choose to mate with several males throughout their lifetime. Though there is no obvious pair bonding, females may preferentially mate with males that they have a longstanding association with. Perhaps their most unique trait of all is highly masculinised exterior reproductive morphology (to save you an embarrassing Google search, I can confirm it essentially looks, and functions similarly - it can also make males and females outwardly indistinguishable much to the chagrin of some zoos who thought they had a breeding pair). This makes both mating and births extraordinarily difficult, the latter leading to death in many cases. Both cubs and their mothers may not survive the birthing process. This completely novel female ‘equipment’ is thought to have evolved as a result of dominant females providing high levels of male-associated hormones such as testosterone to their offspring, allowing them to be better competitors from the outset. Due to this, high rank within clans is largely inherited by female offspring. Young males usually leave to join other clans, though sons of top-ranking females may remain and codominate with their mothers.

Like the striped hyena, the spotted hyena is sometimes hunted for traditional medicine, though most fatalities arise from accidental trapping in snares placed for game animals. Where they are thought to actively prey on livestock, whole clans can be shot or poisoned. Even in protected areas, if they are considered a threat to species of conservation interest they may be heavily managed through culls. Although widespread and a species classed as Least Concern status, numbers have been trending downwards.

It has been established that part of the reason that conservation efforts are somewhat lower for the spotted hyena is that it often evokes negative emotions and is thought of as an ugly, wicked and cowardly animal. This originates from the writings of Aristotle and Pliny the Elder, now perpetuated by media such as The Lion King in western society, and through superstition and folklore across Africa. As such, spotted hyenas are shunned in favour of perhaps more charismatic animals in conservation, and are underrepresented in captive breeding programmes. In the UK, the only breeding pair is currently kept at Colchester Zoo and only feature as of writing in one more collection (Longleat Safari Park). Some organisations are attempting to challenge their undeserved reputation, allowing visitors to get closer and learn more about their fascinating life histories and behaviour. The spotted hyena also has a penchant for problemsolving and teamwork, often exceeding the abilities of primates. Though they might not be considered the cutest animal around, spotted hyenas are not as cowardly as cartoons depict. Unlike the other species, they are extremely efficient hunters, rarely needing to scavenge. Time spent hunting tends to be on par with other African predators and levels of success are far greater than those of cheetahs and lions. More often than not, lions will try their luck stealing hyena kills which they will often not give up without a fight.

Despite the few species present today, the Hyaenidae are a fascinating and unique group whose members are plagued by incorrect assumptions and negative depictions. One hopes that bias towards these animals can be overcome so that more focus can be placed on understanding their unique biology, ecology, and behaviour. There is still so much we do not know about hyenas, but perhaps eventually they may become as beloved as our dear feline friends, from whom they are not so far removed.

By Thea Mainprize