Baumidger

Baumidgers (Meles Arboricolus) are the only known species of magical Mustelidæ.

Description
Baumidgers (whose name is drawn from the German word for tree, Baum, and badger) are small mammals which resemble non-magical badgers, for whom Muggles often mistake them. They are generally harmless mammals living in trees throughout Europe, including Scotland; the Forbidden Forest is home to an indeterminate number of baumidgers.

Color Shifting
Their fur can change colour to be green or brown in order to blend into the leaves and bark of the trees they live and hunt in. During mating season, the males will often sport garish strips of gold and black to attract females.

Use in Potions
Powdered bone of baumidger is a component in the Invisibility Potion.

British Ministry of Magic Classification
Baumidgers are classified as Beasts. Their threat level is XX, although, after being bit by one on a forest outing, Cornelius Fudge unsuccessfully moved for their classification to be moved up to XXX.

Canon

 * Baumidgers do not exist in Harry Potter canon.