One of the things we discussed at my course on the Water of Leith earlier this week (see this post) was introduced species and the effect they can have on the ecology of an area.
We looked at some of the UK's invasive species. These include Giant Hogweed introduced as a garden ornamental but which since escaped and grows on rough ground and has a corrosive sap that can cause injury. American Mink has been a problem since it was released from fur farms by animal activists. It eats the chicks of water birds and competes with otters.
Not all introduced species are problematic. Trees such as the sycamore and horse chestnut were introduced into the UK a long time ago but have become naturalised and are part of our ecology.
So we come to rabbits. Many readers of this blog think of rabbits as the ideal pet and so they are! But they are also a wild animal. They were introduced into the UK by the Romans and again by the Normans as a food source. They then escaped and bred very successfully. They are a well known part of our countryside and an excellent food source for many predators.
Rabbits were introduced in 1859 to Australia where their only natural predators were being hunted to extinction, so there was no check on their numbers. In ten years the population increased to many millions. Myxomatosis was introduced in 1950 and numbers dropped from 600 million to 100 million in ten years but numbers increased again to around 250 million by 1991. Other methods of control are being used but rabbits are still a huge problem in Australia. I'm saying all this to outline the problem rather than to advocate culling animals.
So the status of an introduced species depends to a large extent on the ecology of the area it is introduced into.