Tokitok Spring in the Ngorongoro Crater.

The lions of Ngorongoro Crater are the subject of an ongoing research project dating back 30 years. As we see in THE CRATER LIONS, scientists have been carefully tracking the births and deaths of these lions in an effort to understand how a closed lion population works. Begun by Dr. George Schaller of the Wildlife Conservation Society, the research is now performed by Dr. Craig Packer of the University of Minnesota, whose team lives in the crater.

The Tokitok pride is one of six lion groups living in the crater, each of which is associated with a body of water that it vigorously defends. The animals featured on NATURE live near the Tokitok Spring; the Munge lions, who threaten them, are tied to the Munge River. The Tokitok pride has two mature males, the brothers Hook and Ahab, as well as six females and eight cubs. Hook seems to have established himself as the one lion to sire cubs by Wedge, Bounce, and the other Tokitok females.

Hook and Ahab share the responsibility of driving away other males keen on stealing the pride and siring their own offspring. Although these two may wander, they are always monitoring their females in case of danger. Meanwhile, the females do all the hunting and work together to nurse and protect the pride's cubs.

Recent studies have shown that these females do not share the work load equally. Dr. Packer found that often one or two females take the lead role in hunting while others hang back. Group hunting is about twice as successful as lone hunting, but many lionesses will sit out the hunt if a single female looks as if she has the situation under control. This may be a result of the abundance of potential prey in Ngorongoro Crater.

Packer and his colleagues have also found a link between the amount of food available to each mother and the amount of milk she produces. Therefore, a well-fed Tokitok female with only one cub may permit a nephew or niece to nurse, since the lioness has more than enough milk for her only child.

Packer, who began working in the crater in 1979, created a 30-year family tree for the lions. He traces the lineage of every lion now in the crater back to a single group of animals: in 1962, a plague of biting flies wiped out nearly the entire population, which plunged from 70 lions to 15. Biologists fear that the resulting genetic inbreeding poses a serious threat to the crater lions.

For instance, NATURE features a lioness named Nimue, an outcast of the Tokitok pride. Inbreeding may have caused the crook in her tail, but it is her

The brothers Hook and Ahab.

behavior that worries the researchers. During the filming of THE CRATER LIONS, five cubs were killed in the night, and Nimue may have been the culprit.

Scientists are working on solutions to this problem of inbreeding, but finding one is a difficult challenge. Introducing new lions to the crater would not work, as it would provoke immediate fights over territory. The lion population in the Crater is in danger of being further whittled down by a raging epidemic of canine distemper, a disease spread by local dogs that is currently decimating the lions of the nearby Serengeti. If the Ngorongoro males are further weakened by illness, they are likely to crumble before an invasion of lions from outside the crater. Ironically, this may work to save the crater lions' heritage: immigrants will mate with the remaining females, enriching the stock of the Ngorongoro lions with new bloodlines.

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