Sources : Squirrel

Pliny the Elder [1st century CE] (Natural History, Book 8, 58): Squirrels also foresee a storm, and stop up their holes to windward in advance, opening doorways on the other side; moreover their own exceptionally bushy tail serves them as a covering. Consequently some have a store of food ready for the winter and others use sleep as a substitute for food. - [Rackham translation]

Alexander Neckam [1147-1217 CE] (De naturis rerum, Book 2.124): It is also argued that man is ignorant through laziness, while he does not pay attention to the cleverness of the squirrel. The instinct of nature makes of it a sailor, for it uses the width of its erect tail for a sail, and for the ship he uses bark, to which it firmly clings. Who showed the squirrel the certainty of a stable wind? It crosses the broadest rivers in its boat, and takes possession of the desired bank. And the squirrel took its name from running, but some also call it hesperiolum, from Hesperia. But he tames both the weasel and the squirrel, and exchanges necessity for will. O shame! There are many men who scarcely put off their wild manners, scarcely, even with much care, are they changed for the better. But what is either impossible or difficult for man is easy for Almighty God. - [Wright/Badke]

Thomas of Cantimpré [circa 1230-1245 CE] (Liber de natura rerum, Quadrupeds 4.24, 4.94, 4.110: [Thomas describes the squirrel under the names cirogrillus, pyrolus and varius.] [Quadrupeds 4.24] The cirogrillus is an animal prohibited by law. It is however a small animal and naturally weak and for the most part astonishing in this, because although it may be weak it is nevertheless hostile and greedy and it is deadly to other living things of the earth. [Quadrupeds 4.94] Pyrolus, he says [i.e. Liber rerum], is a small beast, larger but not longer than a weasel. The body is red and the belly is white. It has wonderful agility and moves restlessly. It lives in trees and nurtures its offspring there. It migrates from tree to tree but not by flight, although it sometimes uses its tail as a wing. For having a hairy tail nearly equal to its own size, it moves without effort in leaping. It lives more willingly on nuts and food that is sweet. It accumulates food in the summer, by which it lives in the winter. If this beast ever has the desire to cross the waters, changing its country, it puts a very light piece of wood on the water, on which it sits, and like the sail of a ship it raises its tail high, and with a second blow of the wind, it is carried across the water by making its tail wave. [Quadrupeds 14.10] Varius is a small animal, a little larger than a weasel. It has this name [from variegated] because it is white on the belly, and on the back it has a gray color so elegant that you marvel at the beast's creation. It is a kind of squirrel [pyroli]: it lives in trees and produces offspring there. People of both sexes are wont to glory in the skins of these beasts in the adornment of their garments, and especially in mantles; - [Badke translation/paraphrase]