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August 15, 2014 — Sarah Benson-Amram is a fan of the Disney classic “The Lion King.” However, she takes issue with the animated film’s portrayal of hyenas as skulking scavengers that are none too bright.
The University of Wyoming assistant professor of zoology says the spotted hyena, native to Kenya, is quite intelligent, has a highly developed communication system and the special ability to count animal calls to assess the number of its friends and enemies.
“Hyenas are often maligned, but they are actually smart and self-reliant. More than 80 percent of what they eat, they hunt themselves,” she says.
Benson-Amram was featured in a segment of a recent British Broadcasting Corporation (BBC) documentary called “Talk to the Animals” that aired in the UK July 16-17. The segment was filmed last summer at Masai Mara National Reserve in southwest Kenya, where Benson-Amram conducted research for two years. In the documentary, she shows how hyenas communicate with their own and assess the strength and number of their enemies.
Hyenas live in large clans and defend communal territory. As part of that defense, hyenas make a “whoop” sound to communicate with clan mates. During the documentary, Benson-Amram explains how hyenas can recognize if a “whoop” vocalization comes from a familiar hyena or a stranger.
“They can recognize each other’s voices,” she says. “Sound analyses reveal that the structure of whoops is different for different hyenas, and studies have shown that hyenas take advantage of that information to recognize each other as individuals.”
Hyenas can hear whoops to a distance up to five kilometers (3.1 miles), she says.
Hyenas also have the ability to count whoop vocalizations, which helps them decide if they have the numerical advantage required to win a fight. As shown in the documentary, if six hyenas are present and hear “whoop” vocalizations from only three unfamiliar hyenas, they become aggressive and move toward the sounds. If the vocalizations, instead, reveal that they are outnumbered, the group will move in the opposite direction or remain in hiding, Benson-Amram says.
In a paper in the scientific journal Animal Behavior, Benson-Amram confirmed these hypotheses. Throughout various locations in the wildlife reserve, she played different sounds to hyenas through loudspeakers attached to her car. This counting method is similar to that found among lions, chimpanzees and howler monkeys, Benson-Amram says.
An additional aspect of her research -- not featured as part of the BBC documentary -- involves giving tests to hyenas to see how smart they are. Benson-Amram gives hyenas “puzzle boxes” filled with meat. To gain access to the food, the hyenas have to figure out how to unlatch the lock on the metal box. While many hyenas figured it out, they initially were not all very skilled at the task. However, many of them became better at solving the puzzle over time.
“Initially, it took them about five minutes to figure it out,” Benson-Amram says. “By the end, some got so good at it that they could open it in under 30 seconds.”
More “creative” hyenas -- those that tried more ways to open the box, and hyenas that were less afraid of the box -- were more successful than hyenas that only tried one or two ways to open the box, or that acted cautiously. Showing a bit of cunning, some hyenas, unable to open the box themselves, waited for other hyenas to open the box and then stole the meat.
From elephants to hyenas
Before starting her Ph.D. on hyenas at Michigan State University, Benson-Amram studied elephant behavior in Kenya. At the same time, she met some of the Michigan State researchers who studied hyenas. She often went out in the field with them to observe the animals’ behavior. Benson-Amram became fascinated with the creatures and eventually decided to study hyenas during her Ph.D work.
“Hyenas are coursing predators. They don’t sneak up on prey,” Benson-Amram says. “They have incredible endurance, like a long-distance runner. They run and run and run, until they tire out their prey.”
Hyenas either hunt solo or in groups. Individually, one hyena can take down a gazelle. For larger prey, such as a zebra or buffalo, hyenas often attack in groups. Their jaws are so powerful that adult hyenas can bite through the femur of a giraffe. One hyena even chewed through the wing of a plane in which Benson-Amram rode. Being in the middle of nowhere, the pilot simply duct-taped the hole in the wing and flew home.
A hyena, on average, weighs 90 pounds and can devour 30 pounds of food in 30 minutes.
“By the time the hyenas have finished eating, all that’s left is just a blood spot in the grass,” Benson-Amram says.
And while many television animal programs feature footage of what appears to be hyenas waiting for scraps as lions finish a large meal, Benson-Amram says that’s a misconception. Lions steal meals from hyenas just as often as hyenas try to steal food from larger predators, she says.
Similar to chimpanzees, dolphins and elephants, spotted hyenas live in a “fission-fusion” society, which means members frequently separate and come back together, Benson-Amram explains. Clans number around 90, but hyenas often hang out in smaller groups or alone.
“They have to be smart to separate and come back together,” she says of the hyenas’ social structure.
The hyena pecking order is unique as well. Females are considered dominant to male hyenas. And the youngest female born in a litter is considered first in line to inherit the rank of her mother, with the other siblings obtaining a rank in inverse order of age. Wild hyenas can live more than 20 years. Such a system can provide increased longevity to high-ranking offspring: If a hyena becomes a queen at two years old, that increases the possibility of a long reign, which generates increased fitness advantages to that family.
“If the British royal family were like hyenas, Harry would be next in line for king -- not William,” says Benson-Amram.
The distinctive giggle sound hyenas make does not mean they are laughing, as many think. Rather, it is a submissive sign of anxiety when hyenas experience aggression. Benson-Amram discussed why hyenas laugh in a 2009 National Public Radio interview.
Sarah Benson Amram, a UW assistant professor of zoology, cradles an anesthetized hyena during a study of the animals in Kenya. A recent BBC documentary included a segment in which she explains hyenas’ communicative behavior. (Mara Hyena Project, Michigan State University)