Animal rights advocates oppose keeping animals in zoos, but support sanctuaries. They oppose keeping animals in zoos because imprisoning the animals for our entertainment violates their right to live free of human exploitation. Even if the animals are of an endangered species, keeping them in a zoo for the sake of the species violates their rights because the good of the species cannot be put above the rights of the individual. On the other hand, sanctuaries rescue animals who cannot live in the wild and can survive only in captivity.
How Zoos and Sanctuaries Are Similar
Both zoos and sanctuaries confine wild animals in pens, tanks, and cages. Many are operated by non-profit organizations, display animals to the public and educate the public about animals. Some charge admission or request a donation from visitors.
How They're Different
The main difference between zoos and sanctuaries is how they acquire their animals. A zoo might buy, sell, breed, or trade animals, or even capture animals from the wild. The rights of the individual are not considered. Animals are often overbred because zookeepers like having a constant supply of baby animals to attract the public. Zoo patrons expect to see lively, active animals, not old, tired animals. But the overbreeding leads to overcrowding. Excess animals are sold to other zoos, circuses, or even canned hunting. The animals are acquired to satisfy the interests of the zoo.
A sanctuary does not breed, buy, sell or trade animals. A sanctuary also does not capture animals from the wild but acquires only animals who can no longer survive in the wild. These might include injured wildlife, confiscated illegal exotic pets, exotic pets who are surrendered by their owners, and animals from zoos, circuses, breeders, and laboratories that close down. A Florida animal sanctuary, Busch Wildlife Sanctuary, intentionally keeps some animals out of sight so the animals don't interact with the public. These animals have a chance of being released back into the wild if they recover from their injury or illness. The animals that will never have a chance at release, such as orphaned baby black bears who were raised in captivity and don't know how to survive in the wild; Florida Panthers who were once "pets" so their claws and some teeth have been removed; and snakes who have been hit with shovels and blinded or otherwise impaired, allowed to be seen by the public.
While a zoo may argue that they serve an educational purpose, this argument does not justify the imprisonment of the individual animals. They may also argue that spending time with the animals inspires people to protect them, but their idea of protecting the animals consists of taking them out of the wild to confine them in cages and pens. Furthermore, animal advocates would argue that the main lesson taught by the zoo is that we have the right to imprison animals for humans to gawk at. Zoo's love to use the old, tired argument that when children see an animal, they will have an affinity for it and want to protect it. But here's the thing, every kid on earth loves dinosaurs but not one kid has ever seen a dinosaur.
Some animal welfare advocates distinguish between accredited zoos and "roadside" zoos. In the United States, the Association of Zoos and Aquariums (AZA) grants accreditation to zoos and aquariums that meet their standards, including procedures for animal health, safety, guest services, and recordkeeping. The term "roadside zoo" is often used to mean a zoo that is unaccredited, and generally is smaller, with fewer animals and inferior facilities.
While the animals at roadside zoos may suffer more than animals at larger zoos, the animal rights position opposes all zoos, regardless of how big the cages or pens are.
Endangered species are those that are in danger of becoming extinct in a significant portion of their range. Many zoos participate in breeding programs for endangered species, and may someday be the only places where some species exist. But imprisoning a small number of individuals for the sake of the species violates the rights of the individual. A species does not have rights because it is not sentient. "Species" is a scientific category designated by people, not a sentient being capable of suffering. The best way to save endangered species is by protecting their habitat. This is an effort everyone has to get behind because we are in the middle of the sixth mass extinction, and we are losing animals at a terribly rapid rate.
It may seem confusing to people when they see animal rights advocates boycotting zoos while supporting sanctuaries. The same might be true when animal advocates oppose keeping pets but have rescued cats and dogs from shelters. The important factor to consider is whether we are exploiting the animals or rescuing them. Shelters and sanctuaries rescue animals, while pet shops and zoos exploit them. It's really very simple.