Given the appearance of the wine bottle, and the plum colour of the wine, the gold colour of the squirrel's fur seemed the best choice. Of course, nature doesn't made squirrels in that colour, as far as I know. I never cared about such details anyway. The details about the wine, and the bubbles in the wine were more important than whether or not squirrels walked upright and drank wine. The colouring is entirely with Laurentian colour pencils.