There's often talk of the grey squirrel and how it's a pest, was introduced into the UK, and is wiping out the indigenous red squirrel. But this isn't the whole story. Once, the red squirrel was considered a pest in Britain and a bounty was placed on it. Hundreds of thousands were slaughtered in the mistaken belief that it harmed trees and was basically tree vermin.
The environment in which squirrels of either hue live is woodland, and woodland has been disappearing in Britain for centuries since the old oak forests were systematically felled to build ships to conquer the seas and build an empire. There is not a lot of woodland left in this tiny island. The red squirrel had already suffered severe reductions in numbers by man when the grey was introduced.
The grew squirrel is more robust and aggressive than the red [it's an American!] and can survive in habitats the red finds difficult. It eats much the same diet as the red, so deprives red squirrels of food, but can survive on foods the red can't eat. It has quite naturally been more successful in surviving in the modern world, but now, because of this, many are blaming it for 'wiping out' the red squirrel, when all along it is man who does the wiping out.
In the same way as the red squirrel was vilified as a pest and vermin, so now the grey is thus described. But this is just a human view, the animal is just doing what comes naturally, surviving as it knows best. There wouldn't be many more reds now even if the greys had never been introduced, they are too delicate to compete with man and are now mostly surviving in Scotland where there's more untouched forest and wild places where men tend not to go.
We interfere with nature at our peril. Introducing a species from another continent is never a good idea, and, as in the case of Rhododendrons [imported from the Himalayas by the Victorians] can lead to unseen consequences - Rhododendrons have colonised Snowdonia and wiped out native plants on a grand scale. People are employed to wander around killing them, but it's an enormous job, they cover mountains now, and are a very hardy plant, not easily killed.
Rabbits were imported into Australia as a 'good idea' to provide cheap meat. They are now a plaguen there being no native predator in sufficient numbers to control them. Man has often done this, while attempting to wipe out all the top predators as 'competitors' to humans. We are at last learning that to interfere in the finely balanced web of life, the ecosystem composed of millions of species all closely interrelated and dependent on each other, is to invite disaster.
