A separate register is maintained in the flock book for black Wensleydales, which occur naturally as a result of a double recessive black gene (this is not exclusive to the Wensleydale). Although referred to as “black” Wensleydales, the colour will vary from silver to jet black.  Lambs are generally born black or charcoal grey. The darker fleeces have a tendency to ‘grey’ with age as a result of the appearance of white fibres and the tips of the staples weather to a golden brown or beige