I think that in some cases, captive breeding is necessary until the animal's natural habitat is secure again. Look at the Rhinocerous population - there have been many bred in America, and they are careful to keep mixing up the gene pool by moving animals around to different zoos/sanctuaries. Some day, I hope the descendants of these animals will be safe in their native Africa, but this is simply not now the case.

Pandas are slaughtered in China, and their numbers are growing perilously scarce in many regions. Shouldn't we, as humans, try to keep the species viable, even if it means doing so in captivity?

I would not take any wild mammal around here captive, but the world has enough chipmonks, squirrels, chickadees, raccoons, etc. - they have adapted well to living amongst humankind, and are in no danger as a species. That doesn't mean I can't enjoy Chippie or any of the wild critters that live in or pass through my yard, I love seeing them, wild as they are.