Hyenas: Profile and Information

Hyena or hyaena (from the Ancient Greek word hýaina, ὕαινα) is a feliform carnivoran mammal from the family Hyaenidae.

With only four still existing species (in three genera), it is known to be the fifth smallest biological family of Carnivora and the smallest in the class Mammalia.

Despite their low diversity, hyenas are vital and unique components of the African ecosystem.

Some phylogenetic reports state that hyenas are closer to viverrids and felines because they belong to the suborder of Feliformia.

Hyenas are morphologically and behaviourally similar to canines in several elements of convergent evolution.

Both canines and hyenas are cursorial, non-arboreal hunters who catch their prey with their teeth, not claws.

Both animals devour food quickly and may choose to store it. Their hard-skinned feet with blunt, large, non-retractable claws are adapted for making sharp turns and running.

However, the hyena’s scent-marking, grooming, defecation, parental, and mating behavior are consistent with the behavior of other feliforms.

Hyenas feature prominently in the mythology and folklore of human cultures that live alongside them.

In various cultures, hyenas are thought to influence grave robbery, people’s spirits, and the stealing of livestock and children.

In other cultures, hyenas are also associated with witchcraft, using their body parts in African traditional medicine.

Evolution

Hyenas have been known to originate from the jungles of Miocene Eurasia 22 mya (million years ago), during the period when most early feliform species were still largely arboreal. The first hyenas were most likely identical to the modern African civet, one of the earliest hyena species described.

 Plioviverrops were named hyaenid by the structure of their dentition and middle ear. The lineage of Plioviverrops thrived and gave rise to descendants with more pointed jaws and longer legs. It was a similar trait taken by canids in North America.

Hyena was later diversified into two distinct types: robust bone-crushing hyenas and lightly built dog-like hyenas. Although the dog-like species prospered 15 million years ago (mya), their extinction was due to the change in climate and the arrival of canids into Eurasia.

Among the dog-like lineage, only the survivor is the insectivorous aardwolf. The bone-crushing hyenas (including the brown, striped, and extant spotted hyenas) became the undisputed top scavenger in Africa and Eurasia.

Rise and Fall of the Dog-like Hyenas

As one of the descendants of the Plioviverrops, the dog-like hyena peaked 15 million years ago (mya) and has over 30 identified species. Distinct from modern hyena species, considered specialized bone-crushers, the dog-like hyenas were wolfish, nimble-bodied animals.

Among the species of the dog-like hyena was the Ictitherium viverrinum, which could be traced back to the jackal. The dog-like hyenas were numerous in the Miocene fossil sites, which meant that the remains of the dog-like hyenas and the Ictitherium outnumber those other carnivores combined.

The extinction of the dog-like hyenas began 5 to 7 million years (mya) during a climate change, escalating when canids crossed the Bering land bridge to Eurasia. Chasmaporthetes ossifragus was the only species that managed to cross the land bridge into North America and survive for some time in North America.

It survived by deviating from the bone-crushing hyena and cursorial niches monopolized by canids and transforming into a cheetah-like sprinter. The extinction of most dog-like hyenas occurred 1.5 million years ago (mya).

Bone-crushing Hyenas

By 10 to 14 million years ago, the hyena family had split into two genera, bone-crushing and dog-like hyenas. The existence of the ancestral bone-crushing hyenas coincided with the extinction of the similarly built family Percrocutidae.

The bone-crushing hyenas thrived during the period of climate change and also the arrival of the canids, unlike the dog-like hyenas. They never crossed into North America despite their habitat being taken over by the dog subfamily Borophaginae.

5 million years ago, the bone-crushing hyenas were known to be the dominant scavengers of Eurasia, which primarily fed on large herbivore carcasses left behind by saber-toothed cats.

Another genus called Pachycrocuta was a 200kg (440 lb) mega-scavenger that could shatter the bones of elephants. The Pachycrocuta was replaced by Crocta due to the decline in large herbivores by the late ice age.

Rise of Modern Hyenas

There are four still-existing species, which include the brown hyena (Hyaena brunnea), the striped hyena (Hyaena hyaena), the aardwolf (Proteles cristata), and the spotted hyena (Crocuta crocuta).

1. Aardwolf

15 million years ago (mya), the lineage of the aardwolf traces back to Plioviverrops, and it is the only still existing dog-like hyena. Its survival was partially due to its insectivorous diet, for which it had no competitors like the canids that migrated from North America.

It has an unrivaled ability to digest soldier termite’s terpene excretions. This digestive system is modified by its ancestor, used to consume fetid carrion.

2. Striped Hyena

The striped hyena probably evolved from the Hyaena namaquensis of Pliocene Africa. Striped hyena fossils found in Africa are dated back to the Villafranchian but are absent in the Mediterranean region.

They were native to Europe during the Pleistocene, especially Germany and France. It also occurred in Hollabrunn in Austria, Montmaurin, Genista Caves in Gibraltar, and the Furninha Cave in Portugal.

The striped hyena that appeared in Europe was larger than the Brown hyena.

3. Spotted Hyena

10 million years ago (mya), the spotted hyena (Crocuta crocuta) metamorphosed from the brown and striped hyena. The Indian Crocuta sivalensis was the spotted hyena’s direct ancestor that lived during the Villafranchian.

Some research indicates that ancestral spotted hyenas might develop social behaviors in response to increased pressure from rivals on carcasses. This made them operate in teams, and the spotted hyenas developed sharp carnassials behind their crushing premolars. This means they don’t have to wait for their prey to die, making them formidable scavengers and pack hunters.

They began creating larger territories in case prey started migrating. So they wouldn’t have to chase their prey into another clan’s turf. During the Middle Pleistocene, the spotted hyenas spread from their original homeland to a wider area from southern Africa to Europe and China.

Due to the decline of Greenlands 12,500 years ago, several lowland habitats favored by spotted hyenas were lost, which corresponded with the increase in mixed woodland.

The spotted hyenas were outdone by the humans and wolves, which were much favored in open lands (in highlands and lowlands). The spotted hyena’s population began to shrink about 20,000 years ago. The spotted hyena disappeared from Western Europe 11 to 14 thousand years ago.

Scientific Classification

Genera of the Family Hyaenidae (Extinct and Present)

The Protelinae (aardwolf) is included in the Hyaeninae and not treated as a separate subfamily.

The living brown hyena and its closest extinct relatives are included in the genus Hyaena, not Pachycrocuta.

Family Hyaenidae

•  †Tongxinictis (Middle Miocene of Asia)

†Subfamily Ictitheriinae

• †Herpestides (Early Miocene of Eurasia and Africa)
• †Plioviverrops (including Protoviverrops, Jordanictis, Mesoviverrops; Early Miocene to Early Pliocene of Europe, Late Miocene of Asia)
• †Ictitherium (=Galeotherium; including Sinictitherium, Lepthyaena, Paraictitherium; Late Miocene to Early Pliocene of Eurasia, Middle Miocene of Africa)
• †Thalassictis (including Miohyaena, Palhyaena, Hyaenalopex, Hyaenictitherium; Late Miocene of Europe and Africa, Middle to Late Miocene of Asia)
• †Hyaenotherium (Late Miocene to Early Pliocene of Eurasia)
• †Miohyaenotherium (Late Miocene of Europe)
• †Lycyaena (Late Miocene of Eurasia)
• †Tungurictis (Middle Miocene of Eurasia and Africa)
• †Protictitherium (Middle to Late Miocene of Europe, Middle Miocene of Africa and Asia)

Subfamily Hyaeninae

• †Palinhyaena (Late Miocene of Asia)
• †Ikelohyaena (Early Pliocene of Africa)
• Hyaena (=Parahyaena, =Euhyaena; including brown hyena, striped hyena, Pliocrocuta, Pliohyaena, Anomalopithecus) Early Pliocene (Middle Miocene) to Recent of Africa, Late Pliocene to recent in Asia, Late Pliocene (Late Miocene) to Late Pleistocene of Europe
• †Hyaenictis (Late Miocene of Europe, Late Miocene of Asia, Early Pliocene (Early Pleistocene) of Africa)
• †Leecyaena (Late Miocene or Early Pliocene of Asia)
• †Chasmaporthetes (=Ailuriaena; including Euryboas, Lycaenops; Late Miocene to Early Pleistocene of Eurasia, Early Pleistocene of Africa or Early Pliocene to Late Pliocene, Late Pliocene to Early Pleistocene of North America)
• †Pachycrocuta (Pleistocene and Pliocene of Africa and Eurasia)
• †Adcrocuta (Late Miocene of Eurasia)
• Crocuta (=Crocotta; including Eucrocuta; cave hyena and spotted hyena. Late Pliocene to Late Pleistocene of Eurasia, Late Pliocene to recent of Africa)

Subfamily Protelinae

• Proteles (=Geocyon; aardwolf. Pleistocene to Recent of Africa)

Characteristics

Hyenas are known to have short torsos and are fairly massive wolf-like build. Their high withers, lower hindquarters, and back are known to have a downward slope toward their rumps. The hind legs are very short, the forelegs are high, and their necks are short & thick.

Their skulls are similar to large canids but are much heavier and larger, with shorter facial portions. Hyenas are digitigrades, the hind and forepaws having four digits each and sporting bulging paw pads. Like canids, hyenas have blunt, short, non-retractable claws. Their pelage is sparse and coarse with absent or poorly developed underfur.

Most hyena species have a rich mane of long hair running from the head or the withers. Hyaenids are known to display striped coats, which are most likely inherited from the Viverrid ancestors, except for the spotted hyena.

They have large ears with simple basal ridges and no marginal bursa. It has one more pair of ribs than the canids, and their tongues are rough like those of viverrids and felids. Most male hyena species are larger than the females. The only exception is the spotted hyena, where the female species dominates and outweighs the male.

Distinct from other hyenas, the female spotted hyena has external genitalia similar to that of a male. It has dentition similar to a canid but more specialized for crushing bones and consuming coarse food.

The carnassials are very powerful, especially the upper part, which is shifted back to the point of exertion of peak pressure on the jaws. All other teeth, save for the underdeveloped upper molars with cutting edges and broad bases, are very powerful. The canines are short but robust and thick.

Labiolingually, hyena’s mandibles are much stronger than canids’ canine teeth. This reflects that hyenas crack bones with both premolars and anterior dentition, unlike post-carnassial molars, which the canids use. The strength of their jaws is so strong that it has been recorded that striped and spotted hyenas kill dogs with a single bite to the neck.

Only a few animals (including the Tasmanian devil) have a stronger bite proportional to their body than a spotted hyena. The aardwolf has the most reduced cheek teeth among all hyenas, sometimes absent in fully developed adults. The dental formula for all hyena species is 3.1.4.1 for the upper and 3.1.3.1 for the lower.

They have a large pouch of naked skin located at the anal opening but lack perineal scent glands. Most sebaceous glands are present in the opening of the anal glands and above them.

The glands secrete a white, creamy substance that hyenas paste on grass stalk to mark its territory. Although the striped hyena and the aardwolf will spray the secretion when attacked, the secretion has a very strong odor. It gives out a burning or boiling cheap, soapy odor, which humans can detect several meters away.

Description and Size

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Hyenas have been compared to dogs, but they are similar to cats. They are classified under the suborder Feliformia as members of the cat-like carnivores. There are four extant species of the hyena family.

1. Spotted Hyena

The spotted hyena is the largest extant hyena species, growing to 1.2 – 1.8 meters (4 – 5.9 ft) long & 77 – 81 cm (2.5 – 2.6 ft) tall from paw to shoulder. They weigh 40 – 86 kg (88 – 190 lbs). The spotted hyena has yellowish, sandy, or gray fur with black or dark brown spots all over the body.

2. Brown Hyena

Brown hyenas are the second-largest extant hyena species, and according to ADW, they range from 130 – 160 cm (51 – 63 in) long and weigh 34 – 72.6 kg (75 – 160 lbs). The hair on its neck can grow as long as 30.5 cm (12 in).

A brown hyena can be identified by its long, shaggy hair, which is black or dark brown on the body and tan on the neck and shoulder.

3. Striped Hyena

According to the San Diego Zoo, the striped hyena is 100 – 115 cm (39 – 45 in) long and 66 – 75 cm (26 – 30 in) tall from paw to shoulder. Their tails add another 30 – 40 cm (12 – 16 in), weighing 26 – 41 kg (57 – 90 lbs).

Striped hyenas have long hair that is straw-colored to gray. Their muzzle is black, with black stripes on the torso, head, and legs.

4. Aardwolf

They are the smallest extant hyena species. They weigh 8 – 14 kg (17.6 – 30.8 lbs), and their length ranges from 85 – 105 cm (33 – 41 in). According to ADW, the tail is one-fourth of its full length. Aardwolf has the same fur color as the striped hyena.

Habitat

The habitat varies depending on the species. Brown hyenas have a limited range and live in Southern Africa, including the Namib and Kalahari deserts. They are usually found between the Orange River and the Angola-Namibia border in South Africa.

There are two different populations of aardwolves. One subspecies lives in southern Angola, Zambia, Mozambique, northeastern Somalia, and Uganda. The other subspecies extends into central Ethiopia, Tanzania, Egypt, and Sudan.

Spotted hyenas have a larger range and live south of the Sahara Desert. They can be found throughout sub-Saharan Africa, and most large predators are in Serengeti.

The striped hyena inhabits the northeast and North Africa, the Middle East and Asia, and southern Siberia.

According to the National Wildlife Foundation, hyenas inhabit almost any habitat, such as woodlands, grasslands, savannas, sub-deserts, forest edges, and mountains as high as 3962.4 m (13,000 ft).

Diet

The hyena species are carnivores, which means they only eat meat, except for the aardwolf. The aardwolves are insectivores; they only eat termites. According to ADW, termites produce a toxin that seems ineffective on aardwolf. They ingest about 30,000 termites every night. They ingest the termites by licking them off surfaces with a long, sticky tongue.

While other hyenas are scavengers that take advantage of other animals’ kill for an easy meal. They also hunt in clans and fill their diet with antelope, wildebeest, birds, hippos, lizards, jackals, snakes, fishes, porcupines, foxes, insects, and eggs.

The size of the meal varies on the size of the hyena’s clan. A clan works together to hunt prey; the bigger the prey, the more members it needs to take it down. Hyenas often hide their remains in watering holes. They generally consume every part of an animal, including hooves and bones.

Offspring

Mating usually occurs outside the clan. Males and females from different clans will mate after a courtship that lasts several days. After three months of gestation, the female hyena gives birth to 2 – 4 young. Baby hyenas are regarded as cubs.

Mothers in the clan will assist each other in nursing each other cub, and they also take care of other members of the clan that bring food to the den. After birth, the cub’s eyes are shut for 5 – 9 days.

At two weeks old, they roam outside the den, take only the mother’s milk for six months, and are nurtured for a year. They are considered mature at 2 years, and they leave their mother. The lifespan of a hyena is around 10 – 21 years in the wild but more in captivity.

Source(s)

• Facts About Hyenas – livescience
• Hyena – wikipedia