I was sad to the the sifaka exhibit holding black and white ruffed lemurs (not nearly as exciting as sifakas) on my most recent visit. I hope it is only temporary.
Sadly, the sifaka lemurs had died from environmental disease. It had infected the other lemurs but the sifaka lemur's system could not cope This is a good example of why their native habitat needs to be protected. Some species do not do well outside their native habitat.
They seem to be slowly increasing their presence in U.S. zoos. They are both beautiful and extremely fun to watch as they bounce around. They are also social and interact with each other. I think that they may be future zoo superstars. They also have a media presence so even non-zoo nerds recognize them (there is an American children's nature show called "Zoobamafoo" that stars a Coquerel's sifaka and they were the models for the lemurs in the movie "Dinosaur").
If you are ever on the west coast of the U.S. you can see them at the Los Angeles and Sacramento Zoos.
