The Oregon Zoo has a national reputation for its success at breeding Asian elephants and California condors. Zoo curator Chris Pfefferkorn has an additional responsibility that gets far less attention: preventing chimpanzees, lions, gazelles and giraffes from procreating.  

While there is a national shortage of elephants and condors, there is an abundance of other zoo animals and limited room to hold them.  Hence the need to prevent procreation. Pfefferkorn and his staff have promoted a zoological version of safe sex.

For chimpanzees and other primates, it is as simple as providing them a once-daily birth control pill with their meals. For other animals such as large cats, gazelle, giraffes and elephants, zookeepers must use a process in which the animal is anesthetized before a small, barrel-shaped implant is surgical embedded into the animal's skin. For some animals, the danger of anesthesia is too great and the males are simply separated from the females.

The issue has become newsworthy because of a recent story in The New York Times about the differences between zoos in this country—many of whom practice some form of birth control—and zoos in Europe that deal with overpopulation with euthanasia.

Many European zoos allow animals to breed, let the parents have the experience of mating and nurturing their young, and then euthanize the young animals when they mature.

"I don't think that we have a culture here in the United States that accepts that," Pfefferkorn said.

He says he understands his European counterparts' allowing animals their natural instinct to breed and nurture. But he adds, "For us to be responsible animal managers here in the states, I don't think that (euthanasia) is the right solution,"