The Lions of Ngorongoro Crater

Packer, Craig

1992

Book ID 465

See also

Packer, Craig The Lions of Ngorongoro Crater, 1992
Extract Author: Craig Packer
Page Number: a
Extract Date: 1979

The Lions of Ngorongoro Crater

In January 1979 Craig Packer with colleague and wife Anne Pusey, began their study of lions in Nogorongoro Crater, a 2,000-foot-deep caldera with a hundred square mile floor located at the eastern edge of Tanzania's Serengeti Plain. The craters's cliff walls serve to isolate about 100 lions from their nearby Serengeti counterparts.

Suspecting the lions were subjected to repeated inbreeding and that they may conceal genetic vulnerabilities, the Packers set about reconstructing the family tree of at least five generations of every lion that lived in the crater. The scientific mystery would take ten years to solve.

Extract ID: 1416

See also

Packer, Craig The Lions of Ngorongoro Crater, 1992
Page Number: b
Extract Date: 1975-1978

Catalogued on an ID card

Each lion on the crater floor between 1975-1978 had been carefully catalogued on an ID card by the previous wife and husband research team of Jeannette Hanby and David Bygott, with one side of the ID card containing a series of closeup photographs, and a stylized drawing of the lion's face one the other. The drawings emphasized markings on an individual's face including scars, ear notches, and the whisker spots on either side of its muzzle. Whisker spots are the Morse code of lion identification -- a permanent signature of each individual which is present at birth and never changes -- and as unique as a human fingerprint.

Extract ID: 3904

See also

Packer, Craig The Lions of Ngorongoro Crater, 1992
Page Number: c
Extract Date: 1961

Stomoxys calcitrans

There were two reasons to suspect the crater lions were inbred:

No new lions had entered the crater during the previous four years

A report suggesting the population of crater lions had been devastated by a plague of biting flies in 1962

According to Henry Fosbrooke, conservator of the Ngorongoro Conservation Area during 1961 and 1962, exceptionally heavy rains permitted the biting fly Stomoxys calcitrans to breed constantly for more than six months. By May 1962 the crater had switched from heaven to hell for the lions. Most lions became emaciated and covered with festering sores, and while many sought shelter by climbing trees or hiding in hyena burrows, they eventually became so ill they were no longer able to hunt. By the time the rains finally abated, Fosbrooke estimated the population of at least 70 lions had been reduced to about ten.

Extract ID: 3905

See also

Packer, Craig The Lions of Ngorongoro Crater, 1992
Page Number: d
Extract Date: 1972-75

Recovery

By 1972 the population was reported to have recovered to its former levels and was distributed among three prides and by 1975, the Bygotts reported lions on the crater floor dispersed among five prides.

Extract ID: 3906

See also

Packer, Craig The Lions of Ngorongoro Crater, 1992
Page Number: e
Extract Date: 1984

Genetic studies of the crater lions

The Packers invited Steve O'Brien at the National Cancer Institute and his colleagues from Washington's National Zoo to conduct genetic studies of the crater lions in 1984. O'Brien had surveyed the genetics of several different cat species through his research on feline leukemia. Genetics and reproductive physiology of the crater lions were assessed by comparing them with the nearby Serengeti lions, since long-term studies of the Serengeti population had shown that close inbreeding is almost nonexistant in that area.

Extract ID: 3907

See also

Packer, Craig The Lions of Ngorongoro Crater, 1992
Page Number: f
Extract Date: 1979

All the lion photographs

The method used by the Packers incorporated the monumental task of assembling and organizing all the lion photographs they could find from around the world, from biologists and scientists who had studied the crater lions, through to film crews and tourists who had journeyed to the crater floor since the road granting access was completed in 1959.

In 1979 Packer and Pusey began using lion ID cards with pictures of individuals at various ages, noting field marks such as whisker spots and ear notches to pinpoint lions. They contacted preceding researchers who had photographed or drawn the same lions or their forebears and solicitied photographs taken by tourists, receiving hundreds to help fill in the gaps.

Eventually their catalog put faces on more than 500 individuals, most now dead. Their detective work determined that all of today's crater lions descend from only 15 lions that either survived the flies or invaded Ngorongoro shortly thereafter.

This photo chronology revealed that the entire crater population descended from 15 animals. Only eight individuals survived the plague while the others were males that may have entered the crater from the Serengeti. The plague had removed so many adult males from the crater that fresh blood was able to enter. Once the residents resumed breeding, they had several large sets of sons that monopolized the crater prides and kept any additional immigrant males out. Thus the current crater population has been subject to close inbreeding since 1969, about five lion generations.

Extract ID: 3908

See also

Packer, Craig The Lions of Ngorongoro Crater, 1992
Extract Author: Craig Packer
Page Number: h

Ngorongoro Lions

"I visited Henry Fosbrooke again in October 1990. When I told him that I suspected the crater lions had been through previous periods of genetic decline, he led me into his large library and said, 'You should read these.' They were accounts of big-game expeditions that went into the crater in the early twenties. During two weeks in 1922 one hunting party bagged seven adult lions and badly wounded another three. The last expedition was in 1924, when five more lions were killed. Considering that there are never more than about 30 adult lions in the crater and that most of the wounded animals probably died as well, the breeding population must have been severely reduced. Our genetic assays more than 60 years later may well have revealed the results of this onslaught.

The Serengeti and Ngorongoro were declared wildlife sanctuaries in the late twenties to protect the lions from further hunting. Ngorongoro Crater became a world heritage in 1979 in recognition of its special significance as a microcosm of African savanna. The popular appeal of charismatic carnivores such as lions has often led to the conservation of habitat that sustains a host of other species. But living at the top of the food chain inevitably means that predators often end up in small, threatened populations.

The history of the crator lions may represent the future for many other large vertebrates. Increased human habitation around Africa's national parks has formed virtually impermeable boundaries, and recently many species have become isolated in small populations, making them even more vulnerable to environmental catastrophe. Add to this the effects of close inbreeding, and many small populations may well be caught in a downward spiral.

A trio of males patrol their crater territory. Ironically, they are strong enough to deter what their population most needs -- the entry of outside lions with new genes 'Perpetuating these populations will require more than just protecting them from hunters and poachers. The crater lions are conspicuous and have therefore proved surprisingly easy to monitor. The fates of most other small populations will run their course undetected.'

Craig Packer

Extract ID: 3910
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