Scottish conservationists are expending time and effort to hunt down American mink and shoot them.
Their intent is to protect local species such as water voles and moorhen, who apparently cannot compete with minks.
Why the favoritism? Why should we care whether one species is predominant, or another?
It's one thing if a species, foreign or domestic, is causing direct damage to humans. But if it's just displacing one set of species in the ecosystem with another, what's the problem?
The ecosystem will adapt.