Success and Ongoing Efforts

It can be difficult to define success in terms of a reintroduction program. For example, if 20 animals are reintroduced and half of them die within a few months, is this a success or failure?

One way to approach this issue is to look at the current population numbers based on the population before reintroduction. For example, the black-footed ferret only had 18 known individuals in its wild population in 1981. Now, thanks to multiple different reintroduction sites, there are close to 1,000 individual ferrets wild in the U.S. Even though many more ferrets were introduced than survived in the wild, the program can still be considered a success in reestablishing the population of a species once  believed to have been extinct in the wild.

Another way to evaluate the success of a reintroduction is to look at the quality of life of the animals in the wild compared to in captivity. A classic example of this point is the story of Keiko the killer whale from the Free Willy movies. About $20 million over the course of 5 years were spent trying to rehabilitate him to be able to live in the wild. He was able to successfully swim nearly 1,000 miles on his own before spending the last year of his life being cared for by trainers but free to come and go as he pleased.


Some say that the program was a failure because Keiko spent only a few months completely independent of humans, but it can also be argued that Keikoís quality of life improved drastically, from being confined in a tank to being able to swim wherever he wanted to.

Dr. Devra Kleiman, who played a major role in starting the reintroduction of golden lion tamarins in Brazil, developed a list of criteria needed for a reintroduction to be successful. This list included first having a self-sustaining captive population, protected habitat, and funding before beginning the introduction, as well as ways to monitor the animals after the reintroduction and to educate the local people about them.


These criteria are exemplified in the Golden Lion Tamarinís story. Once at only a few hundred individuals, the population now consists of 1,600 animals in Brazil. There is also now strong national pride in efforts to save this species.

Test your knowledge of determining the success of a reintroduction here!

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CAC is a program of the Institute for the Study of Human-Animal Relations at Canisius College in Buffalo, NY.