Sometimes they might go further on suitable thin branches, but I doubt that this matters much. I have never heard of a case when a marten could not advance towards a squirrel due to fear of breaking the branch.
What red squirrels can do and martens cannot do, is to jump down from the tree from a relatively great height without injury, due to their low weight and fluffy hair and then climb into another tree, far from the marten.
It is likely that this behavior of some squirrels is what has lead to the evolution of the flying squirrels.
What red squirrels can do and martens cannot do, is to jump down from the tree from a relatively great height without injury, due to their low weight and fluffy hair and then climb into another tree, far from the marten.
It is likely that this behavior of some squirrels is what has lead to the evolution of the flying squirrels.