One of the most distinctive is its fluffy coat, which changes colour from brown to white and grows longer for the bleakest season. In certain areas it can double in length; on its underside the longer fur helps insulate the fox from the cold ground when it sits or lies down and even the soles of its feet are furry.
When it curls into a ball, nose tucked under its tail, only the thickest fur is exposed to the elements.