Elephant Contraception

According to a news article published yesterday in California, the San Diego Zoo's female elephants "are all on contraception. The advanced age could cause complications during a pregnancy, so the decision was made to put them on contraception."

It was announced in December 2010 that Tina and Jewel, new residents to the Los Angeles Zoo, were also put on contraception if they are later to mix with the zoo's young male Asian elephant, Billy.

Does anyone have more information regarding other elephants in American (or world) zoos that are also on contraception to prevent births?

>> "Sometimes, zoos can have too much of a good thing" by Michael Stetz, SignOnSanDeigo.com, 2011-01-20

>> "Zoo Elephant Contraception" at ZooChat