However, opponents of zoos say that the vast majority of captive breeding programmes do not release animals back into the wild. Surplus animals are sold not only to other zoos but also to circuses or hunting ranches in the US or South Africa, where some people are willing to pay a lot of money for the chance to kill an animal in a fenced enclosure. Often, these animals are familiar with humans and have very little chance of escaping.

So, are zoos good for animals or not? Perhaps it all depends on how well individual zoos are managed, and the benefits of zoos can surely outweigh their harmful effects. However, it is understandable that many people believe imprisoning animals for any reason is simply wrong.

Zoos save endangered species by bringing them into a safe environment, where they are protected from poachers, habitat loss, starvation, and predators. ... A good zoo provides an enriched habitat in which the animals are never bored, are well cared for, and have plenty of space

-Tạm dịch:Các vườn thú cứu các loài có nguy cơ tuyệt chủng bằng cách đưa chúng vào một môi trường an toàn , nơi chúng được bảo vệ khỏi những kẻ săn trộm, mất môi trường sống, nạn đói và những kẻ săn mồi. ... Một vườn thú tốt cung cấp một môi trường sống phong phú, trong đó các loài động vật không bao giờ buồn chán, được chăm sóc tốt và có nhiều không gian