Craig Packer, a University of Minnesota behavioral ecologist who has been studying several groups of lions in Tanzania since 1978, estimates that between 40 and 70 of his 250 subjects have died. The virus may have come from dogs owned by local tribesmen. Vaccines are impractical for wild animals; researchers hope the epidemic will taper off, leaving survivors with natural immunity. The 3,000 lions on the Serengeti appear to be in no danger of extinction. Well protected and beloved by tourists, the population of big cats has been increasing steadily since the mid-’60s.
