LOS ANGELES -- The Los Angeles Zoo has had it with all the monkey business among the chimpanzees.
After the surprise birth of Toshi a month ago and tests confirming two more pregnancies, four of the adult female chimps at the zoo are being given birth control pills.The mystery is that the three breeding-age males have had vasectomies. The oldest male, 45-year-old Toto, didn't have a vasectomy because he's never produced offspring or showed an interest in breeding.
Two other males -- 2-year-old Ripley and 4-year-old Glenn -- are believed to be too young to breed.
Blood samples from Jedeo, 20, Shaun, 10, Herrard, 9, and Glenn will be taken to determine paternity. They will also take a blood or semen sample from Toto.
"He hasn't been ruled out, but it's unlikely," said Vicki Bingaman, the zookeeper who crushes the birth control pills and mixes it with the chimps' morning strawberry yogurt.
Tests show 12-year-old Gracie will likely give birth at the end of the month and 15-year-old Regina should deliver sometime this summer.
"We thought we had a fail-proof method with the vasectomies. But the urologist who helped with these vasectomies told me that there is a 1 percent failure rate in humans. The rate for chimps is unknown," Dr. Cynthia Stringfield said last week.
The zoo now has 14 chimps, 11 of them zoo-born.