Israel's Negev Desert is a rough place to live, offering extreme temperatures, paltry rainfall and sparse food. But instead of feuding over elusive resources, two native carnivores may have learned to deal with adversity by working together.
Those two carnivores — the striped hyena (Hyaena hyaena) and the gray wolf (Canis lupus) — are not natural allies, and don't normally get along with other carnivores in the wild. Yet as a new study reveals, they've been seen roaming in mixed packs through canyons of the southern Negev, apparently traveling as a team.
That's unusual for both species, the study's authors write. Hyenas aren't known for diplomacy, instead earning a reputation as brutal scavengers who regularly steal food — and sometimes cubs — from fellow carnivores. They fight animals from cheetahs to lions, and "easily kill domestic dogs, no matter the size, in one-on-one fights," according to the researchers. Wolves are also known to kill an array of rivals, including lynxes, coyotes and even dogs, their closest relatives.
It's unclear why wolves would tolerate a hyena in their midst, researchers say. (Photo: Wikimedia Commons)
Normally, you'd think living in a harsh desert habitat would amplify the animosity between two carnivores like these. But according to lead author Vladimir Dinets, who studies behavioral ecology and evolution at the University of Tennessee, the opposite seems to have happened for at least one strategic hyena, and possibly others.
The first hint came only from footprints, writes Dinets and his co-author, Israel-based biologist Beniamin Eligulashvili. Dinets initially found wolf tracks mixed with hyena tracks near Eilat, Israel, something he had often seen in the area. Such mixed tracks weren't normally well-preserved due to dry sand, but this time a recent flash flood had moistened the sand and left the tracks more durable.
"Remarkably, in many places the hyaena tracks were on top of wolf tracks, but in other places the sequence was the opposite," the researchers write in the journal Zoology in the Middle East. "[T]he tracks of the three wolves also overlapped each other in all possible orders, indicating that the tracks of all four animals were left at the same time and that the hyaena was sometimes following the wolves and sometimes was being followed by at least some of them."
Four years later, that interpretation was backed up by visual evidence. About an hour after sunset, Eligulashvili and two other researchers spotted a group consisting of four adult gray wolves, three subadult gray wolves and one striped hyena.
"The animals were observed for 2-3 minutes as they climbed up the wadi [valley] slope, repeatedly stopping to look back at the car," the study's authors write. "The hyaena was not following the wolves, but moving in the middle of the pack."
The Negev Desert gets only about 20 centimeters (7.8 inches) of rainfall per year. (Photo: Wikimedia Commons)
There are at least three possible explanations for this, they add. It could just be aberrant behavior by a single hyena, since the species' 12-year life span could bridge the four-year gap between observations. But that still wouldn't explain the wolves' apparent tolerance of hyenas. Another possibility is that hyenas were acting as "kleptoparasites," following wolves so they could steal bones and other leftovers from a kill. "But if this is the case," the researchers write, "why did the hyaenas move in the middle of the packs, and the wolves tolerate them?"
In a third scenario, however, the wolves and hyenas may have worked out a symbiotic, mutually beneficial relationship. "The hyaenas could benefit from the wolves' superior ability to hunt large, agile prey," Dinets and Eligulashvili explain, "while the wolves could benefit from the hyaenas' superior sense of smell and their ability to break large bones, to locate and dig out fossorial animals such as tortoises, and to tear open discarded food containers such as tin cans."
All this is even more amazing because striped hyenas are mostly solitary, unlike their more famous — and social — relative, the spotted hyena. Gray wolves are famously social, of course, but this kind of alliance is unusual even for them. The researchers suspect the two carnivores were driven to cooperate by ecological necessity, since food is so scarce in the Negev. And while this could help us better understand these animals, Dinets points out there's also a lesson for our own species.
"Animal behavior is often more flexible than described in textbooks," he says. "When necessary, animals can abandon their usual strategies and learn something completely new and unexpected. It's a very useful skill for people, too."