Environmental own goals: Invasive species

The Small Indian Mongoose was introduced to many islands such as Mauritius, Fiji and Hawai'i from ... rel=
The Small Indian Mongoose was introduced to many islands such as Mauritius, Fiji and Hawai'i from its native southern Asia to help control rats but lead to the extinction of many local species
© WWF
In at number 2, is us thinking we always know best (there's a surprise!).
As a race we're pretty good at this and nowhere is it better proven than us taking species from one place on the planet and putting them in another. Fantastic.

Admittedly, the first few times this happened we didn't know better, but then (and you will be shocked to discover) we kept on doing it.

The usual scenario for introducing a species goes something like this (this is a simplified explanation)... We come along to some corner of the world, usually an island, and see something we don't like. But we do know that in another part of the world there's something that eats this thing we don't like in this new place. So we bring it over. And – if we're lucky – it may eat the thing we don't like. But it also eats the things we do like. And a lot more besides. The problem being that this new bad-thing-eater no longer has any predators in the new place to keep it in check. So it runs rampant. It goes, if you'll pardon the pun, wild.
Introduction of the Nile Perch in Lake Victoria has contributed to the extinction of 200 local fish ... / ©: WWF
Introduction of the Nile Perch in Lake Victoria has contributed to the extinction of 200 local fish species
© WWF
Take for example the Small Indian Mongoose – introduced to many islands such as Mauritius, Fiji and Hawai'i from its native southern Asia to help control rats. Many local species – birds, reptiles, amphibians – were not used to such a fast moving predator. It wasn't long before they could no longer be found on the islands. They became what scientists call "locally extinct".

Or how about the Rosy wolfsnail – introduced to control another invasive species (the giant African snail – which was meant to provide a new source of food, but went rampant). The Rosy wolfsnail was so good at its job that it went to on to "control" all the other species of snails as well. The impacts have been profound with Rosy wolfsnail chalking up several extinctions to its name.

Or the Nile perch. Introduced to Lake Victoria in Africa in 1954 to counteract the drastic drop in native fish stocks caused by over-fishing (there we go with that over-fishing again…). Yet the Perch's introduction contributed to the extinction of more than 200 local fish species through predation and competition for food.

Got the stomach to read more?

> And at number 1 our unlucky winner is....

Is it all doom and gloom?

No. You can read about the success which WWF has achieved with its partners over the last few years. Together we're making progress – the team is strong and we're out to win. If you feel like helping, we'd love to have you with us.

Subscribe to our mailing list

* indicates required