It's a tricky call to make, whether or not the introduction or even reintroduction of a species is a good move or not. Despite all the scientific data and research that are available to us, it always throws up surprises and problems that no amount of planning revealed. There are just as many examples of great success in reintroduction as there are failures. Let's look at some, analyse and interpret them and try to come to a definitive answer.
One of the main arguments for the introduction of animals is often that, if it wasn't for human beings, they wouldn't be needing reintroduction in the first place. Through poaching or the expansion of human territories or even previously failed attempts, the finger of blame usually ends up point back at us. Still, surely there's merit in trying to right a wrong, right?
The poster child for re/introduction which must be Yellow Stone National Park. Back in 1995, Grey Wolves were set free in an attempt to re-establish the species in the area again. It's safe to say that no-one expected quite the success that was achieved by it. The wolves hunted and changed behaviour of the elk, which allowed the trees and vegetation to recover from decades of uncontrolled elk feasting. The resurging vegetation allowed birds to come back and beavers to expand which allowed fish, reptile, amphibian and further bird species to flourish too as a result of the beaver's work. The wolf presence kept the population of coyotes stable too, allowing rabbits and mice to flourish which allowed eagles and weasels and foxes to flourish. Feeding on the wolf leftover carrion, other bird and bear populations improved. The bears also benefitted from the flourishing vegetation as they fed on the increased number of berries once emerging from hibernation. The last big domino to fall was the stabilizing of the rivers. Yes, introducing wolves helped out the rivers. Thanks to the regenerated vegetation the river banks stabilized, meandered and eroded less. River channels narrowed and more pools formed. All from just reintroducing the Grey Wolf.