Note that the Zoo Evaluation Essentials guide and toolkit focus primarily on animal welfare and minimally on the conservation impact of zoos.
The reason is simple: despite the claims that the modern zoos are conservation driven, the reality is that currently the vast majority are not –accredited zoos included, a negligible minority excepted. As a matter of fact, a study of AZA conservation expenditure in the 2000s showed an average expenditure of only 0.1% of their operating budget (median 0.3%), and in this calculation was included captive research, field conservation and staff time [ZA10]. Then according to Paul Boyle (senior vice president for conservation and education at the Association of Zoos and Aquariums), the majority contributes currently still less than 1% of their budget to in-situ conservation.
It is also important to note that there is no scientific evidence yet about the true and long-term impact of the educational aspect of zoos ([ML10], [MA13], [RN16], [JE14]). As well as the will to learn about animals from the visitors is also lacking. Studies found that visitors are mostly concerned about viewing animals and not particularly interested in learning about them [ZA10].
As for the captive breeding programs for the purpose of soft and hard releases into the wild (as opposed to ensuring insurance populations for captivity institutions), there is more and more scientific evidence that the average ROI is at this point negative –including cost; impact on local wildlife and conspecifics; unsuccessful predator/competitor avoidance; disease spread and immunity issues, exotic genes and parasite effects; and generally wild fitness issues (e.g., deficiencies can be seen in foraging/hunting that can lead to starvation, social interactions, breeding and nesting, and locomotory skills [JK08]). Of course, it does not invalidate the success in reintroducing individuals for a few species but it came at an extremely high cost and with many failures along the way that we should now avoid replicating. It is also known that in-situ protection works better on average (w.r.t. economics, species successes). Besides being a last resort strategy which tries to alleviate symptoms rather than tackling the causes of the problem, captive breeding can also only work for very few specific species as well as it can’t scale up for the majority of species it says it helps ([DP15], [JK08], [SN96], [FD08], [CR03]).
The above does not invalidate zoos –quite the contrary. It rather simplifies the discussion and puts the emphasis on what zoos are primarily at this point in time: Animal Welfare research & practice institutions. In other words the justification of their existence is essentially about Animal Welfare Science, which is an incredibly hard field & job. Maybe it would be better to not try to take on additional gigantic other goals outside their direct influence. Regardless… the way an institution treats the animals publicly is the first indicator of how serious this institution is regarding both its welfare and conservation ethics –it is as simple as that. The executive director of the Detroit Zoological Society Ron Kagan recently stated in a 2015 TED talk that “Unless an animal can thrive in our environment in our region whether its climate or space or social dynamics we shouldn’t do it” –’it’ referring to holding this species in captivity (we know now that this applies already to large mammals, and so many more animals of various sizes, including apes, carnivores. We could not agree more, and we welcome this attitude…