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Hyena (or Hyæna) is any terrestrial mammal in the subfamily Hyaeninae of the family Hyaenidae of the order Carnivora, typically characterized by a dog-like appearance, powerful jaws, and hind limbs shorter than fore limbs. There are three extant (living) species of hyenas: Crocuta crocuta (spotted hyena or laughing hyena), Hyaena hyaena (striped hyena), and Parahyaena brunnea (brown hyena). A fourth living member of the Hyaenidae family is Proteles cristatus (the aardwolf); however, it is a member of the Protelinae subfamily. The Hyaenidae family is also known as the hyena family, and all members of this family, including the aardwolf, are sometimes designated as hyenas.
Hyenas are native to Africa, Arabia, Asia, and the Indian subcontinent. Although they resemble dogs in appearance, they are more closely related to cats, and are placed in the suborder Feliformia ("cat-like") of the order Carnivora, rather than the suborder Caniformia ("dog-like").
There is a historical tendency for people to have strongly negative views toward hyenas. Their scavenger nature, including scavenging graves for food, has led people to associate hyenas with gluttony, uncleanliness, and cowardice, and in some local cultures they have been associated with demons and witches. The haunting laughter-like calls of the spotted hyena, which resembles hysterical human laughter, has only added to those negative feelings and inspired the idea in local cultures that they could imitate human voices and call their victims by name. While also seen as wise and clever, the hyenas' knowledge has been seen to be that of the debased, profane, and earthly kind, and they have been looked at as greedy hermaphrodites, and associated with deviant sexual behavior.
Notwithstanding these negative associations of people, hyenas actually are key components of most African ecosystems and some ecosystems in Asia. The spotted hyena is perhaps the most abundant carnivore on the African continent, and all are integral to food chains. Their ability to fulfill their role in harmony with humans requires a greater awareness of their importance, viewing hyenas in a more positive light.
Description
Hyenas bear some physical resemblance to canids. However, they are placed in a biological family that is most closely related to Herpestidae (the family of mongooses and meerkats). The three living species of hyenas have among the strongest jaws in the animal kingdom and an adult of the species has only the big cats (lions) to fear. The fourth member of the hyena family, the insectivorous aardwolf, does not have such powerful jaws, given its diet consists mainly of termites, other insect larvae, and carrion.
All three hyena species, and the aardwolf, have a distinctly bear-like gait and sloping posture due to their front legs being longer than their hind legs. The aardwolf, striped hyena, and brown hyena have luxurious, striped pelts and manes lining the top of their necks, which erect when frightened. The spotted hyena's fur is considerably shorter and is spotted rather than striped. Unlike other species, its mane is reversed forwards.
Hyenas are highly intelligent animals. One indication of hyena intelligence is that they will move their kills closer to each other to protect them from scavengers; another indication is their strategic hunting methods (Lind 1977).
The majority of hyena species show little sexual dimorphism, usually with males being only slightly larger than the females. The spotted hyena is an exception to this, as females are larger than the males and dominate them. One unusual feature of the spotted hyena is that females have an enlarged clitoris called a pseudo-penis or demi-penis. Female hyenas give birth, copulate, and urinate through their protruding genitalia, which stretches to allow the male penis to enter for copulation, and it also stretches during birth. The anatomical position of the genitalia gives females total sexual control over who is allowed to mate with them. Researchers originally thought that one of the things that causes this characteristic of the genitals is androgens that are expressed to the fetus very early on in its development. However, it was discovered that when the androgens are held back from the fetus, the development of the female genitalia was not altered.
All species, including the aardwolf, excrete an oily, yellow substance from their anal glands onto objects to mark their territories. When scent marking, the anal pouch is turned inside out, or everted. Hyenas also do this as a submissive posture to more dominant hyenas. Genitals, the anal area, and the anal glands are sniffed during greeting ceremonies in which each hyena lifts its leg and allows the other to sniff its anal sacks and genitals. All four species maintain latrines far from the main denning area where dung is deposited. Scent marking is also done by scraping the ground with the paws, which deposits scent from glands on the bottoms of the feet.
With the exception of the striped hyena, which have been seen in the jungles of India, hyena species generally reside in arid environments like African savannas and deserts.
With the exception of the aardwolf, all extant members of Hyaenidae are efficient scavengers. Not only do they have extremely strong jaws in relation to their body size, but they also have a very powerful digestive system with highly acidic fluids, making them capable of eating and digesting almost their entire prey, including skin, teeth and bones, parts of horns, and even hooves. Parts of the hair, horns, and hooves that are not completely digested are regurgitated. Since they eat carrion, their digestive system deals very well with bacteria. The spotted hyena, however, is primarily a predator, unlike its cousins.
Species
Spotted hyena
The spotted hyena or laughing hyena (Crocuta crocuta) are native to Africa and are best known for a chirping, birdlike bark that resembles the sound of hysterical human laughter. Though often labeled incorrectly as a scavenger, the spotted hyena is actually a powerful hunter, the majority of its nourishment being derived from live prey. Spotted hyenas are the most common predator in sub-Saharan Africa, living in savanna, dry woodland, and desert habitats. Spotted hyenas are successful pack hunters of small to large sized ungulates.
Striped hyena
The striped hyena (Hyaena hyaena) is closely related to the brown hyena. It lives in Africa, the Middle East, Pakistan, and western India. It is extinct in Europe, but can occasionally be spotted in Anatolia, Turkey. It is the smallest of the three extant hyena species. Striped hyenas are largely scavengers, but will also eat small animals, fruit, and insects. Larger subspecies are known to hunt animals as large as wild boar. They are nomadic, moving from water hole to water hole, but never straying more than 6 miles from one. Like many other animals of hot climates, their ears radiate heat.
The striped hyena is generally considered solitary, but has some social organization. It forages individually and is rarely seen in groups. It does, however, associate in small family groups at the den. Striped hyena live in the tropical savanna, grasslands, semi-desert, scrub forest, and woodland.
Brown hyena
The brown hyena (Parahyaena brunnea, formerly Hyaena brunnea) lives mainly in the Kalahari and Namib deserts of southern Africa. The intermediate-sized extant hyena, this species is 110-136 cm (43-53 in) in body length, 64-88 cm (25-35 in) tall at the shoulder, and weighs 37-55 kg (82-121 lb), though exceptional larger individuals are known. It is smaller than the spotted hyena, and unlike its spotted cousin, is largely a scavenger. It is the largest land animal to derive most of its diet from scavenging, although they will also hunt small mammals. Because of the scarcity of food in the desert, the brown hyena supplements its diet with fruit and vegetables, and along the Namib coastline they are known to snatch seal pups.
Like spotted hyena, the brown hyena lives in packs. However, brown hyena clans are much smaller (ranging between 4 and 15 members) and less organized, and do not hunt cooperatively. A particularly large food source may draw several of the clan to it, and they will work together to defend their find. They will also defend their territories as a group. Brown hyena can generally chase off leopard, caracal, or cheetah, but spotted hyena will drive them from kills. Brown hyena often feed from lion kills, but lions dominate and occasionally kill brown hyena.
Unlike the spotted hyena, the females do not have enlarged clitoris, and males are slightly larger than females.
The Hyena Language
Hyena's giggle is not actually laughter, but a sound of frustration. New research found a way to distinguish individual hyenas based on the peculiarities of their, well, let's call them fighting words.
Until now these squeaky cackles have not been well understood by scientists. Researchers recorded the sounds and did the first ever acoustic analysis of them to understand how the calls vary between individuals, and when they are used.
The scientists found that hyenas usually made these noises when they were fighting for food, or in some kind of social conflict.
"When a group of hyenas is feeding upon the prey you hear a lot of these giggles, especially during conflict between two individuals," said biologist Nicolas Mathevon of the Jean Monnet University in France, who is a visiting professor at the University of California, Berkeley.
Mathevon and colleagues monitored 17 captive hyenas at Berkeley, and measured the length, frequency (pitch) and the amplitude (volume) of each of their giggles. They found that the pitch of the sound depended on the hyena's social status: Subordinate individuals made noises that were more varied and higher in pitch.
the hyena call is actually a sign of frustration, according to research that has been presented May 21, 2009 at an Acoustical Society of America meeting.
The Hyena Society
Hyena society is very complex, and is matrilineal, meaning females rule the roost. There is intense competition for food, and social status plays a big role in an individual's life.
"The females are dominant, and there's very strong hierarchy, especially when they are feeding," Mathevon told LiveScience. "Apparently the subordinate animals emit more giggles than the dominant ones. That’s why we think it's more a frustration call."
Though the study was conducted in captivity, much of the hyena's social behaviors appear unchanged. The researchers think their results apply to hyenas in the wild, though doing more tests in the field will confirm the findings.
"The hyena society is so complicated that they really need efficient means of communication between individuals," Mathevon said. "I think this call is just part of a very complex communication system which includes a lot of different sounds, as well as chemical systems and visual systems."
The biologists found that they could tell many individuals apart from their giggles alone, which often have peculiarities of pitch and volume related to their age and social standing in the group. A future research goal is to try to determine if hyenas use the calls to identify each other. This study is part of a larger project to study the role of acoustic communication in various animal species.