European Goshawks were extinct in Britain at the end of the 19th century (and remained rare for over half a century) but in the last 50 years have made an incredible comeback. In the new forest, in the south of England, there are thought to be hundreds of pairs living wild.
In Thetford forest in Norfolk, an estimated 52% of the goshawks diet was grey squirrel. While it is true that they will also take red squirrels, these are generally better at escaping. More importantly, it is thought that Goshawks could be used to stop the grey squirrels population from growing any further.
As I have written before, the pine marten is also important for the recovery of the red squirrel, as it is far more successful at hunting grey squirrels, and they generally do not cohabit in any part of the country.
This will likely not eliminate the direct need for grey squirrel population to be culled by humans, far from it, but may well help towards the idea of giving red squirrels breathing room.
Complete elimination of grey squirrels is still a far off dream, and there is much discussion about so called refuges – pine martens do not like being close to humans, so do not tend to enter places like London. However, what has been shown by repeated studies, is that while grey squirrels are readily seen in town centres, these large populations are not self-sustaining, but instead survive only by a steady flow of more individuals, from green belt areas around the city. This suggests, that a recovery of pine martens, in areas surrounding cities, like the green belt around London, would likely lead to the extinction of grey squirrels within the city as well. There are likely to be refuges which humans have to deal with, but we definitely have the means to undo foolish damaging moves made by our Victorian ancestors, should we wish to (and given the impact that grey squirrels have on forestry stock, it is not merely a conservation priority to succeed here.
Estimates vary of grey squirrel numbers, but are thought to be between 2.7 and 3.5 million individuals. This number is still growing, but as the pine marten population recovers, this will hopefully change. It has been shown, in both Scotland, and in the forest of dean, that the pine marten can be used as an effective bouncer to block grey squirrels from areas. There is still much work to do, but it is clear that with sensible methods, this damaging invader can be removed. I like others, do enjoy the sight of a grey squirrel, but they should not be here. It is not racist to prefer the red squirrel over the grey, rather it is fantastic for biodiversity (and the grey squirrel still has a great deal of native range, so is in no danger of extinction itself)