[an excerpt from Leopards in the Twilight Zone, Natural History, October 2011]

Secretive, silent, smooth and supple as a piece of silk, he is an animal of darkness, and even in the dark he travels alone.
    —Maitland A. Edey, The Cats of Africa

Leopards (Panthera pardus) are solitary stealth hunters. Camouflaged by their spots, they look like the dappled shade in trees and rock piles. They creep to within a few yards of their quarry before lunging forward. Once the prey is seized, powerful jaw muscles clamp down in a lethal hold, severing the spinal cord at the back of the neck of a smaller animal or compressing the throat and windpipe of a large one to suffocate it.

One of the smallest of their big-cat genus (lions, tigers, snow leopards, and jaguars are also members), leopards once lived in eastern and southern Asia and all of Africa, from Siberia to the Cape of Good Hope. They are now found mostly in sub-Saharan Africa, with fragments of populations in Indonesia, Pakistan, India, Sri Lanka, Indochina, Malaysia, China, North Korea, and eastern Russia. Because of that decline, the species is listed as “near threatened” by the International Union for Conservation of Nature (IUCN), and of its nine recognized subspecies, five are endangered or critically endangered, bringing the species as a whole to the brink of the next IUCN level, “vulnerable.”

“Leopards have vanished from almost 40 percent of their historic range in Africa,” says biologist and leopard specialist Luke Hunter, president of Panthera, an organization headquartered in New York that works to ensure the future of wild cats through scientific research and conservation efforts. “The decline is the result of relentless habitat loss, conflict with livestock herders, and the lucrative and illegal market for leopard skins and other body parts.”

Now, studies by Hunter and Panthera’s Philipp Henschel, as well as by scientists at the University of Oxford and mates of their numbers in places like the Seronera Valley in the Serengeti, and in fact across Africa.” have identified a new threat to Africa’s leopards: competition with human hunting for “bushmeat.” That finding comes not from Africa’s mountains or savannas, but from the rainforests of the Congo Basin. Cats and humans both target medium-size herbivores such as antelopes and bushpigs. At sites where leopards’ prey is scarce, densities of the cats are less than one-quarter of those in areas more remote from human settlements, where antelopes still roam. In the most overhunted of the project’s sites, leopards have disappeared without a trace.

“Humans throughout the Congo Basin rely primarily on bushmeat for protein, so the implications for leopards are immense,” says Henschel. “Where leopards can hang on, they’re forced to switch their diets to smaller prey species and so don’t reach their normal densities.”

Although the leopards themselves may be revered as totems, and so protected from direct hunting, the loss of their prey can wipe them out. “It’s the ‘empty forest’ phenomenon,” says Hunter. “You can have intact forest that looks pristine but is so heavily hunted that few large mammals—and no top carnivores—can live there.”

Leopards can adapt to varied, even human-occupied environments, but live very secretive, hidden lives,” says biologist Markus Borner, director of the Frankfurt Zoological Society’s Africa Regional Office, headquartered in the Serengeti in Tanzania. “That makes leopards difficult to study, and hard for us to make estimates of their numbers in places like the Seronera Valley in the Serengeti, and in fact across Africa.”

One reason the cats are elusive is their use of caves. In 1983 paleontologist Charles K. Brain, former director of the Transvaal Museum of Natural History in Pretoria, South Africa, called attention to the leopard connection with caves in his book The Hunters or the Hunted? An Introduction to African Cave Taphonomy (taphonomy is the study of how plant and animal remains accumulate and may—or may not—be preserved). “Leopards are particularly relevant to this study [of animals in caves],” Brain says, because “they are secretive predators, making use of caves as retreats, feeding places, and breeding lairs.”

Although frequent passing reference is made in the scientific literature to the use of caves by leopards, there have been few specific descriptions of caves that are leopard lairs, Brain laments. Some of the best evidence Brain has seen has come from Kenya’s Mount Suswa, or Oldoinyo Nyokie (“Red Mountain”), a dormant volcano some thirty miles northwest of Nairobi. On the northeast slope of Oldoinyo Nyokie is a series of about forty five holes; all collapse into underlying lava tunnels that formed when the volcano was still active. Those passages where no light penetrates conceal the remains of leopard meals. The floor of one such dark hallway is strewn with the bones of baboons and small antelopes.

Another extensive cave system used by leopards lies in western Namibia, at the side of a gorge with walls of white crystalline quartz, the only outcropping of its kind in a vast sea of gray schist. A small stream, fed by a perennial spring, makes its way through the sparkling valley. The water source in an otherwise arid place attracts ungulates, which fall prey to the leopards. Brain describes the cave, called the Quartzberg Lair, as having “a rounded entrance partially obscured by a fig tree and by large fallen blocks of rock.” Beyond two glistening stones at the cave’s entrance is a dimly lit chamber that grows darker the farther one penetrates. A low passage leads to a second cavern lined with stalactites. There a tunnel opens, growing ever narrower until it finally disappears into a dead-end wall of rock. Those recesses, Brain thinks, were formed by the dissolution of a calcite seam in the white quartz.

When Brain and his colleagues sought to sketch a detailed plan of the cave, a leopard sunning itself at the entryway retreated into the blackness. “We followed its tracks across the floor of the outer cave, through the low passage into the dark inner cavern, and thence into the tunnel,” Brain later recalled. “Here we left it, deciding that peaceful coexistence was preferable to confrontation.”
 
From his investigations at the Quartzberg Lair, Brain found that leopards appear equally at home in a cave’s light, twilight, and dark zones, feeding most often at the entrance to the cave, but retreating into the darkest interior when necessary to give birth, protect and feed cubs, or sequester a kill from scavenging hyenas. In hot, dry environments, leopards use caves to escape high daytime temperatures and to reduce water loss. One such cave in hyper-arid Namibia has been used by leopards for at least forty years. Anthropologists Darryl J. de Ruiter of Texas A&M University and Lee R. Berger of the University of the Witwatersrand in South Africa have discovered several similar leopard caves at South Africa’s John Nash Nature Reserve. The bones of several kinds of antelopes littered the floors of the caves.

“In contrast to the ‘leopard in the tree’ idea that these cats cache their kills most often in large branches,” says de Ruiter, “they may well prefer to use the deep recesses of caves as cache sites.” In and around the John Nash reserve, at least, tree-stashing behavior is a rare leopard event. Not that trees are lacking: in fact, most caves in the Highveldt area of South Africa, where the reserve is located, have trees growing right in their entrances. “Nonetheless,” says de Ruiter, “leopards drag carcasses into caves, avoiding the trees entirely. In our study, 83 percent of the cached carcasses were in caves, and only 17 percent in trees.” He thinks this may be a general rule in leopard behavior: when available, leopards use caves to protect their kills, rather than dragging the kills up into trees.” De Ruiter suspects the main attraction of caves is that vultures, hyenas, and lions, which might steal a leopard’s kill, don’t go there. “In a cave, a leopard truly has it made in the shade,” he says.

Another attraction, he believes, may be that caves enable leopards to store larger prey than they could in trees. Gravity would help, not hinder, in hauling kills into caves. “We found very large prey—elands and zebras, for example—clearly killed by leopards. The prey leopards are capable of capturing, killing, and transporting has clearly been underestimated.”

A small cave in the reserve had been used by a female leopard. By the time de Ruiter entered the cave, the leopard had “regrettably” been killed, he says, “due to her prolific feeding habits and subsequent impact on the local antelope population.” Two chambers of the cave preserved the remains of no less than eight sizable antelopes and a caracal, as well as the skulls of two porcupines.

Humans and leopards have long crossed paths. The late anthropologist John A. Cavallo argued that early hominids in Africa may have scavenged leopard kills stashed in trees [see “Cat in the Human Cradle,” February 1990]. Hominids surely were prey as well.

Drakensberg (“dragon mountain”) is a spiked mountain range in South Africa. In Zulu it is called uKhahlamba, “barrier of spears.” The high, jagged peaks shadow a deep, low overhang, a cave hidden in a sandstone cliff. To reach the hideout, a hiker must first scale Solar Cliffs and Cathedral Peak, and pass through Ndedema Gorge, a steep-sided valley. Beyond lies the cave. The inhabitant may well have been a leopard. The site is known as Leopard Cave: one of the wall paintings there shows a leopard chasing a man. The man escaped, to return another day to tell his tale in art.

A world away, our ancestors left their mark in Chauvet Cave, a system of interconnected dark caverns that lies in the valley of the Ardèche River in France. The setting resembles that of Leopard Cave in South Africa or Namibia’s Quartzberg Lair, albeit in northern forest sur-roundings. The Ardèche sluiced through limestone rocks and eventually carved a canyon, one whose steep walls are latticed with caves.

Rediscovered on December 18, 1994, by modern humans (including one caver named Jean-Marie Chauvet), Chauvet Cave is filled with paintings, engravings, and drawings of cave lions, mammoths, rhinos, bison, cave bears, and foxes. Archaeologist Jean Clottes of the French Ministry of Culture, whose research on the site is featured in the 2011 movie Cave of Forgotten Dreams, headed the team that discovered by radiocarbon dating that the paintings were made more than 30,000 years ago. Representing at least thirteen species, they include the oldest known human depiction of a leopard.

In Chauvet there are seventy-five “big cat” artworks, Clottes reports, “mostly cave lions but one sure leopard, and perhaps another not far from it. The leopard is in the first section of the cave. On the same panel is an animal that’s likely a hyena” [see photograph above]. Many of the animals in the paintings have “switched parts”—a lion whose paws are drawn as hooves, for example. Such changelings may reflect a belief that animals, including people, can take on the characteristics of other species.

Biologist Craig Packer of the University of Minnesota, who has studied lions in the Serengeti in Tanzania for three decades, visited Chauvet Cave and coauthored a Natural History article about it with Clottes [see “When Lions Ruled France,” November 2000]. “The artists who created this wealth of imagery,” they speculate, “may have considered the huge, deep cave to be a genuinely supernatural underworld that humans could physically enter on certain occasions.”

The cave also contains the fossilized remains and marks of many animals that are now extinct. Did ancient leopards hide their kills—and protect their young in its cathedral-like recesses? And, more provocatively: did the humans of that time somehow share the cave with them? The last evidence of ancient human presence in Chauvet Cave is a child’s footprint. It is still visible in the dust, 27,000 years later.

The leopards depicted in Chauvet Cave vanished long ago. The region they roamed no longer supports their kind. Will we someday be forced to say the same of Africa and other parts of the world where the gift of a leopard lives on?