In the case of the various frog species that they’re currently breeding here in the Zürich Zoo, they may successfully reindroduce them in the wild when conditions are more favorable. But species that rely on learned behaviors to survive typically can’t be reintroduced into the wild, and even if they could, the main problem is that their wild habitats are being lost and destroyed.

I think that zoos can assist in conservation efforts (through education, scientific study of the animals, and occasionally by providing additional genetic diversity, if useful ). But a wild ecosystem is composed of so many different types of species on so many levels (down to tiny ones in the soil and air ), that there’s no way a zoo could come close to conserving the whole thing. And preserving a few specimens in captivity shouldn’t be mistaken for actual conservation, which requires protection and preservation of wild habitats and ecosystems.

In that sense Zoos can’t be conservation centers – at least not for nature. What they can be, however are great entertainment and learning opportunities for people. I think they can be justified on that basis alone without having to graft a worthy agenda to them.