Pine martens and red squirrels are both arboreal species, meaning they spend a lot of time in trees. They both have similar diets as well, although the pine marten is larger and more predatory. However, the two species are not often considered friends. This is because pine martens are predators of red squirrels. While red squirrels are able to escape pine martens most of the time, they are still a major source of food for the marten. In fact, some studies have shown that pine martens can kill up to 50% of the red squirrels in an area. As a result, red squirrels are often wary of pine martens and will avoid areas where they are known to live.