Collisions with fences can be a significant source of mortality for woodland birds such as capercaillie and black grouse. The construction of new fencing to protect woodland and trees in habitats supporting these two grouse species should be minimised, and the fences removed as soon as management objectives have been achieved. Fences that are necessary to protect young trees from high deer populations should be well marked to make them more visible to flying birds, thereby reducing the number of collisions. This Note describes options for marking both new and existing deer and stock fences, and provides information on materials and methods of attachment. The choice of marking technique will require consideration of the visibility of the marking material to capercaillie and black grouse, the ability of the material to cope with wind exposure, and the costs of the material and installation. A balance needs to be struck between the creation of a highly visible barrier, the practicability of sustaining the fence for its principal purpose, and the overall cost. The guidance in this Note applies to Capercaillie Core Areas in Scotland and all areas where black grouse are present.