Roosting birds can make a huge mess in a small amount of time, covering any area underneath their roost with droppings. Birds are creatures of habit; once they find a convenient place to perch they will continue to come back, usually bringing others with them. To keep birds off your TV aerial, and their droppings off the area below, make it impossible for the birds to perch on the antenna.
Lay the bird-spike strips along the top edge of all horizontal surfaces of the TV aerial, make sure the soft flexible spikes point upward. The spikes will not injure the birds, but they don't allow the bird's feet to reach down far enough to acquire a purchase on the antenna.
Trim the length of the strips along the base as needed with wire cutters so the strips do not overhang the ends of the antenna. Do not cut the height of the spikes themselves.
Wrap a cable tie around the base of the spike strip and the mounting surface on the antenna. Insert the tapered end of the cable tie into the locking slot at the opposite end of the cable tie.
Pull the end of the tie through the back of the slot with your fingers, until the tie is firmly in contact around the antenna surface and the spike strip. Snug the cable tie down by pulling on the end of the tie with a pair of pliers. Trim the ends of the cable ties with the wire cutters.