Beat me to it! Which is a shame, since it ruins my excuse to start with "wot no pine martens?"
Here's a fuller report, also
from the BBC» :
The pine marten has emerged as an unlikely ally for the beleaguered native red squirrel in its battle with the grey squirrel.
This is according to scientists at the University of Aberdeen, who carried out an in-depth forensic study of the relationship between the three species.
The pine marten is a predator of the reds, but in areas where it thrives, the number of grey squirrels reduces.
...
"Red squirrels co-evolved with pine martens," explained Dr Sheehy. "They've managed to co-exist over such a long time and their population doesn't seem to be affected by losing the odd individual to a predator."
Grey squirrels on the other hand were introduced from the eastern coast of North America, where there are no pine martens.
"They aren't used to living with a predator so adept at climbing trees, and they spend a lot more time on the ground. So, theoretically, they are much more susceptible," Dr Sheehy told BBC News.
"We have the case of the recovery of one very rare protected species actually helping the recovery of another species, for which we didn't know what the future held.
"So it's kind of a two-in-one good news conservation story."
Co-author, Xavier Lambin, a professor of ecology at Aberdeen, commented: "Over time, this should lead to the near elimination of grey squirrels, though much uncertainty remains on the time required before this outcome materialises.
I think my crotchety old friend Mr. Darwin might have something so say about their prediction, though.