But there are drawbacks. Contributions to conservation "cannot be considered without balancing against the losses imposed on those individual animals who have been denied so much by the same industry," Liz Tyson, the director of the Captive Animals' Protection Society, says in an email to The Dodo. "If you are concerned about the conservation of species, please do not support zoos."
Breeding programs can also be hampered by international legislation meant to stop wildlife trafficking, which prevents potential mates from crossing country borders. These laws are "a seriously huge barrier to developing breeding programs of endangered animals," said Dalia Conde, a University of Denmark biologist, in a statement last year.
Zoo experts agree that some of the most important work is done in animals' home countries. Ferrying animals across the world poses "a risk that new diseases could be introduced," says Benjamin Tapley, a herpetologist at the Zoological Society of London who works with mountain chickens. "It's better to breed the animals in the country of origin."
The population of mountain chicken frogs has been in freefall since 2002, following an outbreak of the deadly chytrid fungus. On the frog's home island of Dominica, the Zoological Society of London helped establish a mountain chicken breeding program. "It's not possible at this stage to treat the environment," Tapley says. Other frogs on the island carry the disease - but don't appear to have any problems - acting as a reservoir of the fungus.
A mountain chicken. (Photo: Gerardo Garcia, Chester Zoo)