Make them hate your boat!
We had a major problem with Cormorants in our marina in the northern Chesapeake Bay. The birds roosted on our spreaders. They only liked the boats out on the moorings...not in the slips. We all tried everything listed here in these postings...but the birds eventually ignored them and continued crapping up our boats. One day, I was on my boat checking out the solutions of my neighbors with my binoculars. As I scanned the boats, with their very creative solutions, they all had bird poop all over, except one. From my vantage point, I could not see his method of deterrence. I hopped in my dinghy to take a closer look. It was brilliant in its simplicity! He had hung a PVC pipe a few inches above the spreaders. It was attached, in the exact middle of the pole, to the main halyard, and tied a bit loosely so it constantly swung in and out of the space on top of the spreaders on both sides of the mast where the birds wanted to roost. It does not take much movement to cause it to swing so it is like a constantly moving "bird swatter". Also, since it is hanging behind the mast, it is directly in the way of their landing path. The birds NEVER get used to a place where they are constantly being whacked by a pole! It is even more fullproof if other boaters near your boat don't do this. The birds will be much more eager to sit on someone else's boat than to be inconvenienced so much on your boat. Finally, I tied a line all along the boom, from the mast to the backstay at about 6-8 inches above the mast. So if the Cormorants decided to sit on the boom instead of the spreaders (which is their second choice..not as desireable to them) they would also find this spot impossible to roost. Haha...take that you Cormorants! Cormorants are smart....but we are smarter!! I have not had any problems with the birds ever since.
