A New Look At Breeding Problems

By the early 1990's, scientists were also questioning the link, first suggested by O'Brien and Wildt, between the cheetah's lack of genetic diversity and the cat's poor breeding history in zoos. Caro and his team, for instance, pointed out in 1992 that cheetahs in the wild have the same sperm defects as captive cheetahs, yet they seem to have no breeding problems. Then, in January 1993, researchers working with the Cheetah Species Survival Plan (Cheetah SSP) of the American Zoo and Aquarium Association, based in Bethesda, Md., published the results of nearly five years of exhaustive studies on the North American captive cheetah population. The reports included a detailed study by Wildt of reproduction among 128 cheetahs in American zoos. The males showed the same high levels of abnormal sperm Wildt had seen before. But surprisingly, these abnormalities seemed to bear no relation to the animals' fertility. Successful sires like Punchow had lab reports that looked just as bad as those of males that had failed to father cubs.

Other SSP researchers pointed out that even as scientists debated the genetics-fertility link, the tide of opinion in the zoo community was turning away from genetic factors as the chief cause of the cheetah's breeding problems. These researchers noted that as zoos changed how they managed cheetahs, the number of captive births in North America had risen to 201 cubs in 58 litters during the five years between 1987 and 1991. That was nearly half the number of cubs born in these institutions during the previous 30 years. These results convinced most cheetah specialists that the main reason for captive cheetahs' failure to breed lay not with the cheetahs' genes, but with how the cats' keepers have managed them.