The tawny owl (Strix aluco), also called the brown owl, is commonly found in woodlands across Europe to western Siberia, and has seven recognized subspecies. It is a stocky, medium-sized owl, whose underparts are pale with dark streaks, and whose upper body may be either brown or grey. (In several subspecies, individuals may be of either color.) The tawny owl typically makes its nest in a tree hollow where it can protect its eggs and young against potential predators. It is non-migratory and highly territorial: as a result, when young birds grow up and leave the parental nest, if they cannot find a vacant territory to claim as their own, they will often starve.