Sad as it is to see one species wane; yet there is more to this story. Back in the early 20 Century, the native Eurasian red squirrel of Germany were blamed for damage to spruce forests and branded a pest to where it was hunted to eradicate their kind. Since it was confirmed that the main cause of damage to the coniferous forests was bud worms, which ironically red squirrels consume in great numbers where they infest these trees.

Now scientists have sought to lay claim that the cause of the reduction of the numbers of the native red squirrels of the UK arose solely came about from the introduction of the N.A. Eastern gray squirrel, that was introduced long after near all of the damage occurred taking up residence in former Red squirrel territory. Yet, most of the habitat formerly now inhabited by the Eastern Gray squirrel was in fact decimated from farming long prior to the introduction of the N.A. gray squirrel. So when Eastern Grays were introduced into regions long since vacated by the native reds of Europe (a different species than that of the N.A. Red squirrels) and thrived there, where the native red could no longer do so for lack of specific food trees that that the reds squirrels require, the introduced gray squirrels thrived.

“Grey squirrels are not as crazy invaders as we think – their spread is far more our own fault.” The research is published in two papers, in the journals Biological Conservation and Diversity and Distributions.
There are UK websites that explain this. Interestingly, researchers found that where the Red squirrel in Scotland is well entrenched in good numbers, grays have not effected

Here is a website that elaborates on these very issues:

And though true that the introduced E. Grays to the UK have flourished in the abscess of healthy number of native reds, they compete for food. One project in Scotland is restoring the Caledonian forest and placing red squirrels in this area that was decimated by overharvesting trees and damaging the habitat that favors the Euro Red squirrel. Good news is that the Reds are increasing in numbers in Scotland. There is also scientific evidence that the Red squirrel of Europe were effected by squirrel pox prior to the introduction of the N.A. gray squirrel.