Do the droppings of a crow that fall on chairs and tables render the clothes of whoever sits on them impure?

If the raven eats carrion, its droppings are impure. If it is a rook (farm crow) that does not eat carrion, its droppings are pure. Impure droppings do not render clothes impure upon contact if both the droppings and the clothes are dry. However, if the droppings are wet, or the clothes are damp, then the portion of the clothing that is affected becomes impure.