But do zoos have enough of the 5,624 species of vertebrate species that are rated as vulnerable or endangered globally in their collections? Or do they focus on charismatic megafauna that dominate the world of conservation in order to attract customers? A study in the journal Science analyzed the 2.6 million animals housed in 800 institutions all over the world. This represents only 25 percent of the world's described bird species, 20 percent of mammals, 12 percent of reptiles and four percent of amphibians. Around 20 to 25 percent of these are classed as threatened and only 9 percent are critically endangered in the wild, the proportion is also skewed towards charismatic mammal and bird species, over reptiles and amphibians, which are less likely to draw the general public through the gates.
But is the number of endangered species a fair yardstick to judge zoos' contribution to conservation by? After all; the definition of a species that is endangered means they are hard to find and may have trouble breeding, therefore they are unlikely to be distributed widely across the zoos of the world. A single zoo should not aim to have a small number of individuals of each endangered species on its own; zoos should specialize on certain at risk species on which they have expertise to generate a healthy population. Without zoos we would not have kept certain species in existence, 29 of the 34 animal species classified as extinct in the wild are still actively bred in zoos, hopefully waiting for a time when their habitat is rejuvenated. This may not be possible for the Panamanian golden frog, whose forests have been infected with the deadly chytrid fungus which has blighted amphibians globally. It may never be possible to safely return this species to the wild and will therefore only be reared in zoos.