The life story of a hyena.

The life story of a hyena.

The life story of a hyena.

News and commentary about environmental issues.
April 12 2010 7:07 AM

Sad Yowlers?

The story of the hyena.


Hyenas at the Masai Mara National Reserve.
Hyenas at the Masai Mara National Reserve

Is there any other mammal that people find as despicable as the hyena? If a creature is furry and nurses its young, usually we're willing to admit some mammalian fellow feeling. Among furred creatures, only the rat vies with the hyena for most loathed.

Hyenas, particularly the African spotted hyena, with its massive jaws, hulking shoulders, and startling laugh, have been terribly misunderstood. The creatures may not be beautiful, but they don't deserve contempt. They are intelligent and gregarious with a well-organized social system of clans patrolling discrete territories. The clans are ruled by females. Maybe the female hyenas gain a little extra authority or assertiveness from the surprising fact that male and female hyenas have nearly indistinguishable external genitals, about eight inches worth. Their appearance has aroused amazement, confusion, and sometimes disgust.

But the hyenas' primary public-relations problem is that laugh. To the unprejudiced ear it sounds like a chortle or a giggle, but many human beings hear it as a maniacal cackle; the hyenas are laughing because they have an evil plan. In fact, the distinctive sound occurs when the animals don't have access to something they want; it's an expression of excitement mixed with frustration. Variations in the pitch also say something about the laugher's age and social status. Hyenas have one of the richest vocal repertoires of any terrestrial mammal, primates included. The laugh is one of many vocalizations, including a cheerful whoop that says, "I'm over here," and an affecting array of mother-and-cub groans and murmurs.


Another disparaging belief is that hyenas are skulking scavengers, subsisting on what's left over from the kills of the glamorous predators—lions and leopards. Hyenas, the most numerous predators in the savannas of sub-Saharan Africa, are in fact excellent hunters. Three-quarters of their diet comes from large hoofed animals they kill and digest with astounding efficiency. Their massive molars pulverize bones; hair, teeth, and hooves are regurgitated later. A few hyenas can reduce a 400-pound African Cape buffalo to a pair of horns and a patch of blood on the ground in less than an hour.

(In any case, scavenging is an honorable and essential profession. Lions hunt, but they're not above consuming prey that was slaughtered by somebody else. Almost every other carnivore, including human beings, does the same.)

The female hyena's faux penis may be amazing, but it is not efficient. In fact it ranks with the human knee as one of evolution's truly bad designs. It's through this elongated clitoris that the female urinates, mates (with great difficulty for the male), and—ouch—gives birth. She even has a sham scrotum—fused labial tissue with no payload.

Seriously misled, Aristotle concluded that all hyenas were male, which would be a drawback for the species. Ernest Hemingway believed that every hyena possessed both male and female organs. His mistake is the first word in a vivid description from the travelogue, Green Hills ofAfrica: "Hermaphroditic, self-eating devourer of the dead, trailer of calving cows, ham-stringer, potential biter-off of your face at night while you slept, sad yowler, camp-follower, stinking, foul with jaws that crack the bones the lion leaves …" (Hemingway liked to sit outside his tent and shoot them.)


A female hyena's internal reproductive organs are those of a normal quadruped. But her quasi-male external equipment makes birth painful and costly. The first cub—hyenas usually bear twins—is stillborn more than half of the time. The unlucky trailblazer moves along the straitened birth canal like a softball moving through a narrow party balloon. The death rate for newborns is a serious disadvantage, but there may be compensation. The females, all of whom are larger and more aggressive than any male, make sure that their young have priority at the kill. (Among the lions, males eat first and swat the cubs away.)

At first scientists believed that the masculinization of the female hyena had one simple cause—a big dose of male hormones delivered in utero. (One of these is androstenedione, which you can buy at health food stores, and is one of the substances that helped Mark McGwire's home-run totals.) Further research found that even when dosed with drugs that blocked the male hormones, the females emerged with external genitalia unaffected (PDF). It turns out that the female hyenas' hormone receptor has a mutation that causes it to misfire. It keeps sending the message of incoming male hormones even when they're absent. The same kind of mutation may be the culprit when human prostate cancer, male-hormone-driven, fails to respond to the usual drugs.

The effect of hormones on fetal development is one thing Stephen Glickman, UC-Berkeley professor emeritus of psychology, has been studying at the hyena colony he founded in the mid-1980s. (The Masai herdsmen who took Glickman to the burrow in Kenya to gather cubs were disappointed when he didn't want to take hundreds, only 20, back to Berkeley.) His fellow authors on research papers include a developmental biologist with an interest in prostate cancer and a pediatric urologist looking for the causes of human genital anomalies.

It's pretty unusual to have large, dangerous predators as lab-research animals. Mice are easier. Visitors to the colony, including this visitor, are surprised when they see Glickman's 26 hyenas. They're big, each one larger than a St. Bernard, almost bear-size, 130 to 200 pounds. They have an unwavering gaze, curious, confident, and undeniably appealing. They don't avert their eyes as dogs and wolves do. Surprisingly, they're not canids at all but belong to a catlike family that includes the mongoose, the civet, and the meerkat.


They don't slink or skulk. Some of the Berkeley hyenas have been hand-raised and bottle-fed, and they galumph over to lick a keeper's hand through the fence. They do not smell bad, another common slander; what comes out of their unusually long digestive tracts is dry, white as bone, and scentless. They do mark territory with an anal gland secretion that smells like bad soap and is less offensive than the spray from an un-neutered domestic cat.

Those who care for the hyenas, including Mary Weldele, who has been there 25 years, follow clan rules, feeding the dominant females first to keep the peace. In the wild, a hyena hunting pack of 20 to 80 usually has one or two female chieftains. The females take the initiative and the males eat last.

Because hyenas hunt alone as well as in packs, clan members can be separated and when they reunite they go through a greeting ceremony much more elaborate and time-consuming than a domestic dog's. After some head-sniffing, the two animals turn head-to-tail and raise the inside hind leg. Both expose their genitalia for inspection and establish who's the dominant one. As Weldeld says, "it's an appeasement, a reconciliation, an acknowledgment of rank, and sometimes an agreement to cooperate."

The animals form alliances to wear down galloping prey, to help each other win fights with lions, and to defend their kills against other meat eaters. The Berkeley hyenas' cooperating skills were demonstrated by a test in which a reward would be dropped only when two animals pulled on two separate ropes at the same time. They are not inclined to cooperate with human beings, though, and don't make great pets. A group of men in Nigeria have enlisted muzzled and chained hyenas to give themselves an aura of magic and power.


"They are always very aware of what another hyena is doing," notes Kay Holekamp, a Michigan State University zoologist who is basically the Jane Goodall of hyenas, observing them in the wild and sticking up for them whenever she can. There are hundreds of YouTube clips of hyenas, many dopey. The best photos, films, and information are at Holekamp's Web site.

When some of the drawing team for the Disney animated feature The Lion King came to visit the Berkeley colony (saving themselves a trip to Africa) Glickman and Holekamp hoped for hyenas to be represented, if not in a positive way, at least with accuracy. The result was disheartening: Disney's lion heroes, voiced by James Earl Jones among others, are brave and philosophical. The hyenas are cruel, gluttonous, and treacherous—lowly scavengers, dependent on the lions for food.

The creatures are adaptable in real life, and, happily, they don't care what Ernest Hemingway or you or I think of them. The shooting of hyenas in Africa is as common as the shooting of wolves in Alaska, and poisoning is also common, but hyenas are not officially endangered. Most people understand that without predators to limit the population, wildebeests, antelope, and the other ungulates would die from starvation and disease.

The live animals are not as cruel and treacherous as the cartoons, but they are wild. Holekamp is pictured on her Web site hugging a hyena, which seemed like a risk. "I'm not nuts," she said. "He was tranquilized."

