I was a bit confused because there's a related species in North America, Martes americana, that is also sometimes called the pine marten (more properly, the Ame

I was a bit confused because there's a related species in North America, Martes americana, that is also sometimes called the pine marten (more properly, the American marten or American pine marten). The European species is Martes martes. The American species clearly doesn't extirpate gray squirrels, but in North America red and gray squirrels do coexist. However, these red squirrels are also a different species, Tamiasciurus hudsonicus, not the European species, Sciurus vulgaris. The American pine marten is a predator of the American red squirrel. Squirrel taxonomy seems to be in a state of flux at present due to DNA information becoming available.