Saving cheetahs: adults come first.

Cheetah populations worldwide are declining, and researchers continue to debate whether to blame genetic or environmental factors.

While some scientists argue that this speedy creature is quickly inbreeding its way to extinction, other investigators disagree (SN: 9/25/93, p. 200).

They say predation-particularly of the young-has caused the animal's population woes. Lions and hyenas kill about 75 percent of the wild cubs.

Polarization around the cheetah controversy has escalated, yet rigorous quantitative analysis has not established the role of either predation or genetics in cheetah demography, says biologist Kevin R. Crooks.

So Crooks and his coworkers at the University of California, Santa Cruz, developed a computer model to predict what would happen to the cheetah population if the animals reproduced with varying degrees of success and died at certain ages and rates. The researchers used rates ranging from the average observed in nature to extreme possibilities.

In a variety of scenarios, including the complete prevention of predation, survival of adults-not of cubs-had by far the largest influence on population growth, they assert. Adults are key, because after losing a litter, females produce another within a year.

Protecting cheetahs by focusing on safeguarding the infants, as some scientists have recommended, would therefore prove not only difficult and expensive, but also unsuccessful, the Santa Cruz team predicts.