Vair is fur obtained from which animal?

Vair (from Latin 'varius'), originating as a processed form of squirrel fur, gave its name to a set of different patterns used in heraldry. Heraldic vair represents a kind of fur common in the Middle Ages, made from pieces of the greyish-blue backs of squirrels sewn together with pieces of the animals' white underbellies. Vair is the second-most common fur in heraldry, after ermine.

The squirrel in question is a variety of the Eurasian red squirrel, 'Sciurus vulgaris'. In the coldest parts of Northern and Central Europe, especially the Baltic region, the winter coat of this squirrel is blue-grey on the back and white on the belly, and was much used for the lining of cloaks called 'mantles'. It was sewn together in alternating cup-shaped pieces of back and belly fur, resulting in a pattern of grey-blue and grey-white which, when simplified in heraldic drawing and painting, became blue and white in alternating pieces.